P obing he Local En i onmen in Po assium Sal s and Po assium-
P omo ed Ca alys s by Po assium Valence- o-Co e X‑ ay Emission
Spec oscopy
A anu Rana, Se gey Pe edko , Mal e Beh ens, and Se ena DeBee *
Ci e This: Ino g. Chem. 2024, 63, 16217−16223
Read Online
ACCESS Me ics & Mo e A icle Recommenda ions *
sı Suppo ing In o ma ion
ABSTRACT: Po assium plays an impo an ole in biology as well as a
p omo e in he e ogeneous ca alysis. The e a e, howe e , limi ed cha ac e -
iza ion echniques o po assium a ailable in he li e a u e. This s udy
elucida es he po en ial o elemen -selec i e X- ay emission spec oscopy
(XES) o cha ac e izing he coo dina ion en i onmen and he elec onic
p ope ies o po assium. A se ies o XES measu emen s we e conduc ed,
p ima ily ocusing on he V C ansi ion (Kβ2,5) o po assium halides (KCl,
KB , and KI) and oxide-bound po assium sal s, including po assium ni a e
(KNO3) and po assium ca bona e (K2CO3). Ac oss he se ies o po assium
halides, he V C ansi ion ene gy is obse ed o inc ease, as accu a ely
ep oduced by TDDFT calcula ions. Molecula o bi al analysis sugges s ha
he Kβ2,5 ansi ion is p ima ily de i ed om halide np con ibu ions, wi h he p ima y ac o in luencing he ene gy shi being he
me al−ligand dis ances. Fo oxide ligands, an addi ional Kβ″ ansi ion appea s alongside he Kβ2,5, which is a ibu ed o a low-
ene gy ligand ns, as elucida ed by heo e ical calcula ions. Finally, he XES spec a o wo po assium-p omo ed ca alys s o ammonia
decomposi ion/syn hesis we e measu ed. These spec a show ha po assium wi hin he ca alys is dis inc om o he K sal s in he
V C egion, which could be p omising o unde s anding he ole o po assium as an elec onic p omo e .
■INTRODUCTION
Po assium plays an essen ial ole in coun less biological and
chemical p ocesses.
1,2
No able examples include he ole o K+
in egula ing ion channels,
3−5
which con ol a di e se a ay o
cellula p ocesses,
6,7
including he unc ion o neu onal,
muscula , and ca diac issue.
8
In chemis y, po assium se es
as an elec onic p omo e in he e ogeneous ca alys s, whe e i
is essen ial o ob aining op imal ac i i y in Fische −T opsch,
Habe -Bosch ca alys s, and e e se wa e gas shi (RWGS)
ca alys s.
9−15
Despi e he wide ange o impo an p ocesses in
which po assium is in ol ed, expe imen al p obes o K ions
a e ela i ely limi ed. K ions a e no isible om op ical
abso p ion, and he [A ] elec on con igu a ion o he ca ion
also ende s i EPR silen . In biology, mos o ou p esen
unde s anding o po assium coo dina ion en i onmen s has
come om p o ein c ys allog aphy.
7,16,17
Mo e ecen ly,
de elopmen s using magic angle spinning 39K NMR ha e
shown p omise as an al e na i e me hod o he cha ac e -
iza ion o he local K en i onmen .
18,19
Fu he , we no e ha
elemen -selec i e p obes, such as X- ay abso p ion (XAS) and
XES, should, in p inciple, p o ide ano he means o selec i ely
cha ac e ize he changes ha occu in he po assium
coo dina ion en i onmen . While se e al epo s ha e been
made using po assium ex ended X- ay abso p ion ine s uc u e
(EXAFS),
21,22
o ou knowledge he e a e only a ew p e ious
epo s o K XES spec oscopy, and o da e, epo s ha e
ocused only on po assium halides (KCl, KB , and KI).
20−22
The ela i e spa si y o bo h XES (and XAS/EXAFS) s udies
on K is, in ou iew, due in la ge pa o he limi ed numbe o
synch o on beamlines whe e such measu emen s can be
ca ied ou .
23−27
Recen ly, we ha e designed and commis-
sioned he PINK beamline a BESSY, which is an ideal se up
o XES in he ende X- ay egime,
28
hus enabling
measu emen s on po assium and opening up he possibili y
o K measu emen s on ca aly ic sys ems. O pa icula in e es
in his con ex a e Kβand alence- o-co e (V C) XES spec a,
which ha e in ecen yea s seen widesp ead use o a ange o
i s ow ansi ion me als due o he now well-es ablished
sensi i i y o ligand iden i y and p o ona ion s a e.
29−38
In
con as , he applica ions o XES o alkali and alkali ea h
me als ha e been e y limi ed,
39,40
and o ou knowledge, no
applica ions o K XES o ca aly ic ma e ials ha e been
p e iously epo ed.
He ein, we pe o m a sys ema ic calib a ion s udy on a se ies
o po assium sal s in o de o es ablish he in o ma ion con en
Recei ed: May 19, 2024
Re ised: Augus 9, 2024
Accep ed: Augus 13, 2024
Published: Augus 20, 2024
A iclepubs.acs.o g/IC
© 2024 The Au ho s. Published by
Ame ican Chemical Socie y 16217
h ps://doi.o g/10.1021/acs.ino gchem.4c02069
Ino g. Chem. 2024, 63, 16217−16223
This a icle is licensed unde CC-BY 4.0
Downloaded ia CHRISTIAN-ALBRECHTS-UNIV KIEL on Sep embe 9, 2024 a 11:48:13 (UTC).
See h ps://pubs.acs.o g/sha ingguidelines o op ions on how o legi ima ely sha e published a icles.
o Kβand V C XES. The sensi i i y o he K V C XES o
ligand iden i y and po assium-ligand dis ance is es ablished.
Ou expe imen al esul s a e co ela ed o densi y unc ional
heo y (DFT) calcula ions in o de o mo e quan i a i ely
assess he spec al changes. The po en ial o K V C XES o
u u e s udies in chemical ca alysis is highligh ed h ough
applica ion o his me hod o a po assium-p omo ed i on
ammonia syn hesis ca alys .
41,42
■MATERIALS AND METHODS
Sample P epa a ion. Po assium chlo ide (KCl), po assium
b omide (KB ), po assium iodide (KI), po assium ni a e (KNO3),
and po assium ca bona e (K2CO3) we e pu chased om Sigma-
Ald ich and used wi hou u he pu i ica ion.
Fe/MgO ca alys s we e syn hesized om MgFe2O4p eca alys s,
which we e ob ained om Fe/Mg laye ed double hyd oxide (LDH)
p ecu so samples based on a p e iously epo ed p ocedu e,
41,42
and
p omo ed by imp egna ion wi h KNO3. The ollowing comme cially
a ailable chemicals we e used wi hou u he pu i ica ion: i on(II)
sul a e hep ahyd a e (≥99.5% p.a., ACS, Ca l Ro h GmbH & Co.
KG), i on(III) ni a e nonahyd a e (≥98% p.a., ACS, Al a Aesa
GmbH), and magnesium ni a e hexahyd a e (≥98%, ACS, Al a Aesa
GmbH). The p ecipi a ion agen was a mix u e o sodium ca bona e
(p.a., AppliChem GmbH) and sodium hyd oxide (≥99%, VWR
In e na ional BVBA). Fo we -imp egna ion, po assium bica bona e
(pu iss., Riedel-de Haen) was used wi hou u he pu i ica ion. The
syn hesis o he LDH phase was conduc ed h ough pH-con olled
cop ecipi a ion a pH = 10.5 and 50 °C using an au oma ed Op iMax
syn hesis wo ks a ion p o ided by Me le Toledo. A solu ion wi h a
1:1:1 a io o Mg2+, Fe2+, and Fe3+ and a o al me al ca ion
concen a ion o 0.8 mol/L was codosed wi h he p ecipi a ing agen
(0.60 mol/L Na2CO3and 0.09 mol/L NaOH) o keep he pH
cons an . The p ecipi a e was aged o 1 h in he mo he liquid,
washed, eco e ed by cen i uga ion, and d ied a 80 °C o yield he
LDH p ecu so .
The Ca alys _K1and Ca alys _K2we e p epa ed using wo dis inc
me hods, which a ied depending on he addi ion s eps o he
p omo e . In bo h samples, he mass o KNO3was adjus ed o yield a
K loading o 2 w %. In he p epa a ion o Ca alys _K1, KNO3was
imp egna ed on o he LDH p ecu so p io o he calcina ion s ep,
whe eas o Ca alys _K2, he LDH p ecu so was i s calcined,
ollowed by imp egna ion o KNO3and subsequen ecalcina ion. The
calcina ion p ocess was ca ied ou in a mu le u nace a 600 °C (wi h
a hea ing a e o 2 K/min) o 2 h. Calcina ion led o he
decomposi ion o he LDH s uc u e and he o ma ion o a K-
p omo ed MgFe2O4spinel. In he unp omo ed e e ence sample39 as
well as in Ca alys _K2, an α-Fe2O3(hema i e) byphase was de ec ed.
Subsequen o ca alys p epa a ion, he ca aly ic ac i i y was es ed in
bo h ins ances.
All samples we e inely g ound and p essed in o pelle s. Po assium
sal s we e sealed using 30 μm Kap on ape windows. Samples
con aining iodide and b omide we e addi ionally shielded wi h 800
nm Al oil o p e en de ec o in e e ence om isible ligh
luo escence. Fo ammonia syn hesis ca alys s (Ca alys _K1and
Ca alys _K2), 8 μm Kap on ape se ed as a p o ec i e co e . The
ca alys s we e s udied in hei calcined s a e. Subsequen ly, he
samples we e ans e ed in o he spec ome e ’s acuum sys em and
measu ed a oom empe a u e.
XES Measu emen s. All po assium KβX- ay emission spec os-
copy (XES) da a we e collec ed a he PINK ende X- ay beamline a
BESSY II. The beam size was 30 ×500 μm whm (V×H). The
exci a ion ene gy was 4000 eV, and he incoming pho on lux was
∼1013 ph/s. The whm a his exci a ion ene gy is 80 eV. The spec a
we e eco ded by he use o a dispe si e in acuum on Hamos
spec ome e equipped wi h a Si(110) cylind ically ben c ys al
(bending adius R= 250 mm) and a G ea Eyes CCD (26 μm×26
μm pixel size, 256 ×1024 pixels) de ec o . The Si(220) e lec ion was
u ilized a B agg angles om 62 o 65°. Unde hese condi ions, he
spec ome e esolu ion was abou 0.8−1 eV.
28
Calib a ion o he ene gy scale was done by measu ing he emission
lines o he Sb oil. The ene gy poin s used o he ene gy calib a ion
we e Sb Lα1:3604.72 eV and Lα2:3595.32 eV (X- ay da a bookle ).
43
To de ine he peak posi ions, hese lines we e i ed wi h spli Voig
unc ions
44
(an asymme ic shape o La1,2 lines is a sum o na u al
line and ins umen al unc ion asymme ies), in which he wid h o
he dis ibu ion is di e en be ween le and igh slopes. Ene gies
we e ansla ed in o B agg angles, and a i wi h a angen ial unc ion
was applied.
Compu a ional De ails. All calcula ions we e pe o med using
he ORCA p og am package e sion 5.0.1.
45
DFT calcula ions we e
pe o med using he BP86
46
unc ional in he de 2-SVP basis se .
47,48
All calcula ions we e ca ied ou using he c ys allog aphically
epo ed coo dina es wi hou addi ional op imiza ion.
49−55
Fo
in ini e la ice compounds, calcula ions we e pe o med by ei he
(1) using a minimum quan um clus e (small QC) comp ised o he
po assium and i s nea es neighbo s, a o al o 7 a oms, o (2)
embedding he la ge quan um clus e (la ge QC), a o al o 80
a oms. Fo la ge quan um clus e o ma ion, he “C ys al P ep”
echnique
56
has been used, which is a ailable in he p esen e sion o
ORCA. I was de e mined ha he minimum quan um clus e
app oach mo e closely ag eed wi h expe imen al ends as compa ed
o he embedding quan um clus e me hod. The e o e, calcula ions
u ilizing solely he minimum quan um egion a e he p ima y ocus.
Calcula ed V C XES spec a a e based on he combined elec ic and
magne ic dipole and elec ic quad upole con ibu ions.
29,57,58
Howe e , only elec ic dipole ansi ions we e ound o ha e non-
negligible in ensi ies. The calcula ed ene gy axis is no an absolu e
ene gy axis. To make ou compa ison mo e easonable, he calcula ed
ene gy axis is shi ed by a cons an alue o 104.4 eV o align wi h he
expe imen al ene gy axis. Repo ed spec a a e Gaussian b oadened by
2.0 eV. This b oadening was chosen in o de o ob ain he bes isual
ag eemen be ween he calcula ed and expe imen al spec a. The
b oadening accoun s o he spec ome e esolu ion and he K 1s
co e hole li e ime as well as addi ional ac o s such as si e
he e ogenei y and possible cha ge ans e and/o mul ielec on
exci a ions, which also con ibu e o he expe imen al b oadening.
■RESULTS AND ANALYSIS
Po assium Halide Sal s. Figu e 1 ( igh panel) compa es
he Kβmainline o KCl, KB , and KI. All spec a show a
maximum a ∼3589.7 eV, which co esponds o a 3p−1s
ansi ion (Figu e S1). The simila ene gy o all po assium
sal s is consis en wi h he expec ed simila K desc ip ion in all
compounds. Only he Kβmain line o KB is ∼0.1 eV lowe
Figu e 1. Simpli ied MO diag am schema ically depic ing he o igin
o he ansi ions in he K KβXES spec um (le ) and he
expe imen al XES spec a o KCl, KB , and KI, wi h he V C egion
enla ged app oxima ely 50- old in he inse ( igh ). The KβXES
spec al in ensi ies we e no malized o 1.0 a he maximum o he
Kβ1,3 mainline.
Ino ganic Chemis y pubs.acs.o g/IC A icle
h ps://doi.o g/10.1021/acs.ino gchem.4c02069
Ino g. Chem. 2024, 63, 16217−16223
16218
han o he s, which migh a ise due o some ligand-de i ed
con ibu ion o his ansi ion. In addi ion, all o he po assium
sal s show a shoulde a ∼3593.8 eV. The 4 eV spli ing is
clea ly oo la ge o be a ibu ed o K 3p spin-o bi spli ing
and may po en ially esul om a wo-elec on p ocess. We
no e ha his ea u e was also obse ed in he p e iously
epo ed Kβspec um o po assium halide sal s, whe e i was
assigned as a sa elli e ea u e esul ing om a double ioniza ion
e en .
25,26
We no e ha o all i e po assium samples
measu ed in his s udy, he Kβmain line does no a y by
mo e han 0.1 eV (Figu e S1). Hence, o he emaining
compounds, we ocus on he high-ene gy V C ea u es, which
show clea a ia ions ac oss he se ies.
Figu e 2A depic s he V C XES images o he po assium
halides. Based on analogy o ansi ion-me al V C XES, he
obse ed ea u es may be a ibu ed o ansi ions om he
illed halide np alence le els o he K 1s co e hole (o so-
called Kβ2,5 ea u es). Ongoing om KCl o KB o KI, hese
ea u es shi up in ene gy by ∼1.6 eV (Table 1). This is
consis en wi h a dec ease in he ligand alence ioniza ion
ene gy. We no e, howe e , ha he alence ioniza ion ene gies
change by only 0.55 eV on going om Cl− o I−and hence he
di e ence in ioniza ion ene gy is no he only sou ce o he
obse ed shi .
59
In o de o mo e quan i a i ely unde s and he o igin o he
modula ions in ene gy and in ensi y o he Kβ2,5 ea u es ac oss
he halide se ies, DFT calcula ions we e pe o med. The
calcula ions we e ca ied ou in wo di e en ways: (i)
calcula ing he la ge quan um clus e (la ge QC includes 80
a oms pe calcula ion) and (ii) conside ing a minimum
quan um clus e composed o a [KX6]5−uni (Figu e S2). As
shown in Figu e 2B, he calcula ed XES spec a wi h minimal
QC clus e success ully ep oduce he ela i e ene gy and
in ensi y ends o he Kβ2,5 ea u es o all o he halides. We
no e, howe e , ha in he expe imen al V C spec um o KI
and KB , he e is an asymme y in he Kβ2,5 ea u es ha is no
cap u ed by ou calcula ions. These may a ise om he ene gy
di e ences be ween he halides (B −and I−) in hei P1/2 and
P3/2 s a es, as es ablished by Gomes and co-wo ke using
ela i is ic embedded equa ion o mo ion coupled clus e
heo y.
60
Howe e , he le el o heo y employed in his s udy
is no su icien o cap u e such e ec s. The embedded QC
calcula ions somewha unde es ima e he shi s among di e -
en complexes. This may sugges ha he e is oo much cha ge
compensa ion om he la ice (Figu e S3C). Gi en he al eady
good ag eemen wi h a minimal quan um clus e , all u he
analyses ha e hus been pe o med conside ing only he small
QC calcula ions in ou s udy.
The calcula ed spec a we e hen analyzed in e ms o he
ansi ions shown in Figu e 1. The ansi ions a e Kβ1,3 (3p o
1s), Kβ″(ligand ns o K 1s), and Kβ2,5 (ligand np o 1s)
acco dingly (Figu es S4−S6). We no e in he p esen case,
bo h expe imen ally and compu a ionally, he e is signi ican
o e lap be ween he Kβ1,3 and Kβ″ ea u es. Hence he o bi al
popula ion analysis is gi en in e ms o K 3p, L ns, and L np
con ibu ions. In he Kβ1,3 egion, he K 3p cha ac e
domina es in all cases (>92% o KCl and KI, ∼73% o
KB ), while in he Kβ2,5 egion, ligand p con ibu ions
domina e (>92%, Table S2). Howe e , he low-in ensi y Kβ″
ea u es a e no well esol ed o he halides, as hese appea o
la gely o e lap wi h he Kβ1,3. The o bi al analysis shows ha
he ela i e ene gy o he ligand ns o bi al dec eases om I− o
B − o Cl−. The B −ns o bi al has an ene gy le el closes o K
3p, esul ing in a highe deg ee o o bi al o e lap.
Consequen ly, he B ns cha ac e (25%) signi ican ly inc eases
in he Kβ1,3 egion ela i e o he o he wo halides.
The expe imen al and calcula ed V C XES spec a a e
compa ed in Figu e 2B and show ha he ends in bo h
ene gies and in ensi ies a e well ep oduced a his le el o
heo y. As ioniza ion ene gy di e ences can accoun o only a
po ion o he obse ed shi , addi ional calcula ions we e
pe o med in o de o unde s and he impac o po assium-
halide dis ance on he V C ene gies as well as hei in ensi ies.
As is expec ed, he K-halide dis ance inc eases ac oss he se ies
going om dK−Cl: 3.14 Å o dK−B : 3.29 Å o dK−I: 3.53 Å, due
o he di e ence in he ionic adius o he co esponding
halides. The e o e, in addi ion o he in insic ioniza ion ene gy
con ibu ions, he K-halide dis ance may also play a ole in he
obse ed Kβ2,5 ene gies and in ensi ies. To sys ema ically es
his, calcula ions we e pe o med by changing he a e age
po assium-halide dis ances om 3.0 o 3.6 Å wi h a pe iodic
inc emen o 0.2 Å.
As shown in Figu e 3A,B, he Kβ2,5 ansi ion ene gy
inc eases linea ly wi h inc easing K−Cl bond leng h, while he
peak in ensi y co espondingly dec eases. These ends a e
consis en wi h he bonding molecula o bi al being less
s abilized (hence, he highe ene gy) and ha ing less po assium
cha ac e (hence, he dec eased in ensi y). A simila end is
also obse ed o KB and KI (Figu e S7) wi h a simila
dis ance-dependen ene gy shi and dec ease in in ensi y upon
Figu e 2. (A) Expe imen al and (B) calcula ed spec al compa ison o
he V C XES egion o KCl, KB , and KI. The DFT calcula ed ene gy
axis is shi ed by 104.4 eV.
Table 1. Expe imen al and Calcula ed Ene gy o Kβ1,3 and
Kβ2,5 T ansi ions
a
elec onic ansi ion KCl KB KI
Kβ1,3(eV) expe imen al 3589.9 3589.81 3589.91
calcula ed 3592.05 3592.05 3592.13
Kβ2,5(eV) expe imen al 3601.9 3602.5 3603.62
calcula ed 3602.00 3602.56 3603.58
a
The calcula ed ene gy axis is shi ed 104.4 eV.
Ino ganic Chemis y pubs.acs.o g/IC A icle
h ps://doi.o g/10.1021/acs.ino gchem.4c02069
Ino g. Chem. 2024, 63, 16217−16223
16219
elonga ion o he K−X bond. Figu e 3B shows an o e lay o
he calcula ed KCl, KB , and KI Kβ2,5 ansi ion ene gies a he
expe imen al K-halide dis ances (g een, ed, and blue iangles
o KCl, KB , and KI, espec i ely) as compa ed o he
calcula ed KCl Kβ2,5 ene gies o K−Cl dis ances om 3.0 o
3.6 Å (black diamonds). The black line is a i h ough he
poin s gene a ed om he hypo he ical K−Cl se ies. The
compa ison plo indica es ha he modula ions in he ene gy
o he Kβ2,5 ea u es ac oss he halide se ies mainly o igina e
om he inhe en me al-ligand bond dis ances o he
co esponding po assium halide. The sligh de ia ions o he
KB and KI om he K−Cl dis ance-dependen end line a e
likely a e lec ion o he di e ences in ioniza ion ene gy o B
and I ela i e o Cl. These shi s o 0.13 and 0.20 eV o KB
and KI ela i e o he end line a e in good ag eemen wi h he
ela i e changes in he B and I ioniza ion ene gies ela i e o
ha o Cl (0.25 and 0.55 eV, espec i ely). I has been
obse ed ha he V C ansi ion in ensi y dec eases ongoing
om KCl o KI bo h in expe imen al and heo e ical calcula ed
esul s. A simila end is obse ed in calcula ed esul s when
inc easing he hypo he ical K−X (X = Cl, B , I) dis ance.
These obse a ions indica e ha he K−X dis ance also plays a
signi ican ole in he ansi ion in ensi y. To u he in es iga e
he e ec o ligand iden i y on his ansi ion in ensi y, we ha e
compa ed KCl and KB Kβ2,5 in ensi ies a a K−X dis ance o
3.2 Å, and a signi ican di e ence in he in ensi y a io was
obse ed (In ensi y a io (IKB /KCl) = 1.39). A no iceable
di e ence o all he halides is he di e en a omic adii (1.81,
1.96, and 2.2 Å o Cl−, B −and I−, espec i ely), an indica ion
o di e en pola izabili ies (3.69, 4.81, and 7.16 Å3 o Cl−, B −
and I−, espec i ely).
61
The pola izabili y a io be ween B −
and Cl−is 1.31, simila o he di e ence in Kβ2,5 in ensi y
a ios, as no ed abo e. These esul s indica e ha he V C Kβ2,5
in ensi y depends on bo h he me al-ligand dis ance and he
ligand pola izabili y.
KNO3 s K2CO3.Ha ing es ablished ends in he V C XES
ene gies and in ensi ies o po assium halides, we hen
ex ended his app oach o oxygen-bound po assium complexes,
including K2CO3and KNO3. The esul s showed ha he Kβ1,3
ansi ions o K2CO3and KNO3occu a ene gies simila o
hose o he po assium halides, a ound 3589.7 eV (Figu e S1).
Figu e 4A depic s an o e lay plo o he expe imen al V C XES
egion o K2CO3and KNO3wi h KCl, included as a e e ence
halide o compa ison. The highes ene gy V C ea u e o
K2CO3is a a simila ene gy o ha o KCl (3601.9 eV o
K2CO3 s 3601.97 eV o KCl), albei lowe in in ensi y.
Fu he K2CO3exhibi s an addi ional V C ansi ion a
3597.43 eV in he egion ypically e e ed o as he Kβ″
egion. In con as o KNO3, only a single Kβ2,5 ansi ion
appea s a 3600.79 eV, which is ∼1.1 eV lowe han ha o
KCl and K2CO3.
Theo e ical calcula ions we e pe o med o unde s and hese
ansi ions. The expe imen al XES spec um was measu ed
using a powde o m o po assium sal s. Howe e , he c ys al
s uc u es o po assium sal s in heo e ical calcula ions can be a
use ul s a ing poin o a logical ini ial guess. Fo ou
calcula ion, he s uc u al coo dina es ha e been aken om
he epo ed c ys al s uc u es.
52,54,55
The K2CO3has wo inequi alen po assium coo dina ion
si es in i s c ys al s uc u e. One si e is six-coo dina ed wi h six
monoden a e ca bona e ligands, while he o he is nine-
coo dina ed wi h i e ca bona e ligands (one monoden a e and
ou biden a e, Figu e S8C). The calcula ed KβX- ay emission
spec um o K2CO3con ains bo h high-ene gy Kβ2,5 and low-
ene gy Kβ″ ea u es. This is in good ag eemen wi h he
expe imen al obse a ions (Figu e 4). The o bi al popula ion
analysis o he calcula ed spec um indica es ha he Kβ″
ansi ion a ises om he hyb idiza ion o K 3p o bi als wi h O
2s alence o bi als. The lowe he ene gy o he Kβ″ ansi ion,
he g ea e he con ibu ion om O 2s o bi als. To
decon olu e he indi idual con ibu ions o he wo po assium
Figu e 3. (A) Calcula ed K V C XES egion o KCl o a ying K−Cl dis ances om 3.0 o 3.6 Å. (B) Co ela ion o K-halide dis ances wi h he
Kβ2,5 ansi ion ene gies. The colo ed iangles co espond o he expe imen al dis ances, while he black diamonds co espond o he hypo he ical
dis ances om panel A. The DFT calcula ed ene gy axis is shi ed by 104.4 eV.
Figu e 4. (A) Expe imen al and (B) calcula ed spec al compa ison o
he V C XES spec a o KCl, KNO3, and K2CO3. The DFT calcula ed
ene gy axis is shi ed by 104.4 eV.
Ino ganic Chemis y pubs.acs.o g/IC A icle
h ps://doi.o g/10.1021/acs.ino gchem.4c02069
Ino g. Chem. 2024, 63, 16217−16223
16220
coo dina ion si es o he V C spec um, wo sepa a e
calcula ions ha e been pe o med (Figu e S9B). The esul s
show ha bo h si es con ibu e o he Kβ2,5 egion, bu he
nine-coo dina ed si e [K(CO3)5] domina es he spec al
in ensi y in his ene gy egion. In con as , he six-coo dina ed
si e [K(CO3)6] is he dominan con ibu o in he Kβ″ egion
(Figu e S9). No ably, in he K2CO3c ys al s uc u e, he
a e age K−O bond dis ance o he six-coo dina e si e is 2.67 Å,
and o he nine-coo dina e si e, i is 2.96 Å. Compa ing he
coo dina ion-si e-speci ic ela i e in ensi ies and he a e age
me al-ligand dis ances, i is clea ha sho e K−O dis ances
lead o highe ansi ion in ensi ies.
KNO3is known o exis in ou c ys al phases: α,β,γ, and
del a (δ). The αand δphases a e s able a oom empe a u e,
while he βand γphases a e me as able.
53
The βand γphases
can be induced by hea ing o cooling he αphase in a ce ain
empe a u e ange. As he cu en s udy was ca ied ou a
oom empe a u e, he αand δphases (Figu e S9) we e
explo ed o he DFT calcula ions. The esul s o hese
calcula ions a e shown in Figu e S10. While bo h phases show
a p edic ed Kβ2,5 ansi ion a ∼3601.2 eV, in bo h cases, he
calcula ed spec um is ∼0.4 eV highe in ene gy ela i e o he
expe imen . I is possible ha he powde o m o he KNO3
sample in oduces some diso de ha is no modeled by he
DFT calcula ions o he c ys allog aphic models. We no e,
howe e , ha he quali a i e ene gy and in ensi y ends o
KNO3 ela i e o KCl and K2CO3a e easonably well cap u ed
by heo y, clea ly showing ha he Kβ2,5 ansi ion o KNO3
appea s o lowe ene gy wi h dec eased in ensi y.
K-XES Compa ison wi h NH3Syn hesis/Decomposi ion
Ca alys . Ha ing assigned he K V C XES spec a o a se ies
o K sal s o known composi ion, we hen ex ended ou K V C
XES o po assium-imp egna ed MgFe2O4ca alys s u ilized in
NH3syn hesis and decomposi ion eac ions.
39,62
In he e oge-
neous ca alysis, small amoun s o po assium ions a e equen ly
used as ca aly ic p omo e s. In he p esen case, KNO3was
used as a po assium sou ce as desc ibed in he ma e ials and
me hod sec ion o esul in an app oxima e po assium loading
o 2 w % (2,05% o Ca alys _K1, 1,76% o Ca alys _K2as
de e mined by AAS). Depending upon when he po assium
was in oduced o he ca alys s (be o e calcina ion on he LDH
p ecu so o a e calcina ion on he spinel p eca alys ), wo
di e en ypes o ca alys s ha e been p epa ed o ou
measu emen s, which a e labeled as Ca alys _K1and
Ca alys _K2. A simila Kβ1,3 ansi ion ene gy (∼3589.7 eV)
is obse ed o bo h ca alys s ela i e o he po assium sal s
(Figu e S11), again indica ing he p esence o a simila
po assium elec onic s a e.
Figu e 5 depic s an o e lay o he V C XES o he ca alys s
along wi h he p ecu so KNO3, which shows weak V C XES
ea u es o bo h ca alys s wi h a lowe in ensi y and a b oade
ene ge ic sp ead ela i e o he KNO3 e e ence wi h a sligh
shi o highe ene gy. These da a sugges ha he s a e o
po assium in ca alys s a e calcina ion has changed ela i e o
i s con o ma ion in he KNO3sou ce ma e ial. This can be
a ibu ed o he calcina ion a 600 °C, which igge s he α- o-
βphase ansi ion o KNO3a app oxima ely 130 °C, he
mel ing o KNO3a 334 °C, and he beginning o he he mal
decomposi ion in o oxygen and po assium ni i e abo e 550
°C. These empe a u es e e o he bulk compound and may
di e om hose o highly dispe sed ma e ials, which can be
ob ained by he we ing o he ca alys ’s po es wi h a mol en
sal laye (mel in il a ion).
63
U ilizing he lessons, we ob ained om he in es iga ion o
he known sal s i appea s ha he po assium is in e ac ing
weakly wi h he su ounding ligands, mani es ing in he shi o
highe ene gy and dec ease in in ensi y. In hese ca alys s, i is
an icipa ed ha po assium will p edominan ly eside on he
su ace, exhibi ing a high dispe sion. Consequen ly, he
in e ac ion be ween po assium and su ounding ligands is
expec ed o be ela i ely weake compa ed o ha o bulk
species wi hin a c ys al la ice. Ou indings a e consis en wi h
his obse a ion. This modula ion in he po assium, howe e , is
he same in Ca alys _K1and Ca alys _K2, ega dless o he
s age o po assium imp egna ion. While a he p esen s a e o
unde s anding, we canno p edic he exac coo dina ion si e o
po assium in he ca alys s, hese esul s sugges ha i
po assium is di ec ly in ol ed as an elec onic p omo e du ing
ca alysis, his spec al egion should p o ide expe imen ally
obse able changes. Hence, he p esen s udy p o ides he
g oundwo k o po en ial u u e applica ions in ca alysis.
■CONCLUSIONS
This wo k in oduces K XES esul s o a ious po assium sal s
and wo po assium-p omo ed ca alys s. A p og essi e ene gy
shi om KCl o KB o KI is obse ed in he Kβ2,5 V C XES
ansi ion o po assium halides. Theo e ical calcula ions
suppo he conclusion ha po assium-halide dis ances a e
he p ima y ac o s in luencing his ene gy shi in halide sal s.
Fu he mo e, i is con i med ha he Kβ″ ansi ions o all
po assium halides a e obscu ed by he in ense Kβ1,3 ansi ion.
In oxygen-liga ed complexes such as K2CO3, alongside he
Kβ2,5 ansi ion, an addi ional Kβ″ ansi ion eme ges due o
he low-ene gy con ibu ion om he ligand (O)2s and he
sho K−O dis ances, which gi e ise o inc eased spec al
in ensi y. The K2CO3c ys al s uc u e has wo inequi alen
po assium coo dina ion si es ha gi e ise o dis inc ea u es
in he V C XES. The six-coo dina ed si e, wi h sho e K−O
dis ances, domina es he Kβ″ egion, while he nine-
coo dina ed si e domina es he Kβ2,5 egion. This in o ma ion
can be u ilized o unde s and he elec onic s uc u e and
bonding in e ac ions in K2CO3. Fo KNO3, while ull
quan i a i e ag eemen is no achie ed, he quali a i e ends
ela i e o hose o o he po assium sal s a e cap u ed. Finally,
K XES spec a o an NH3syn hesis/decomposi ion ca alys
e eal ha he po assium wi hin he ca alys is clea ly
modula ed ela i e o he KNO3p ecu so in he V C egion
and is also dis inc om o he K sal s. Ou unde s anding a
p esen indica es subs an ial al e a ions in he coo dina ion
Figu e 5. O e lay plo o Kβ2,5 ansi ion egion o KNO3wi h he
NH3syn hesis ca alys s Ca alys _K1and Ca alys _K2.
Ino ganic Chemis y pubs.acs.o g/IC A icle
h ps://doi.o g/10.1021/acs.ino gchem.4c02069
Ino g. Chem. 2024, 63, 16217−16223
16221

en i onmen o he p ecu so pos calcina ion. Howe e ,
addi ional esea ch is impe a i e o p ecisely o ecas he
exac po assium con igu a ion wi hin he ca alys . The esul s
p esen ed he e o m he ounda ion o u u e ope ando
s udies o ca alys s aimed a elucida ing he ole o po assium
as a p omo e .
■ASSOCIATED CONTENT
Da a A ailabili y S a emen
All ele an da a, including he expe imen al XES da a o all
po assium sal s, NH3decomposi ion ca alys s, and he
calcula ed ORCA iles, a e a ailable a 10.17617/3.TTWAOX.
*
sı Suppo ing In o ma ion
The Suppo ing In o ma ion is a ailable ee o cha ge a
h ps://pubs.acs.o g/doi/10.1021/acs.ino gchem.4c02069.
Addi ional expe imen al and calcula ed spec a, as well
as ansi ion assignmen s (PDF)
■AUTHOR INFORMATION
Co esponding Au ho
Se ena DeBee −Max Planck Ins i u e o Chemical Ene gy
Con e sion, D-45470 Mulheim an de Ruh , Ge many;
o cid.o g/0000-0002-5196-3400;
Email: [email p o ec ed]
Au ho s
A anu Rana −Max Planck Ins i u e o Chemical Ene gy
Con e sion, D-45470 Mulheim an de Ruh , Ge many;
o cid.o g/0000-0002-2397-5869
Se gey Pe edko −Max Planck Ins i u e o Chemical Ene gy
Con e sion, D-45470 Mulheim an de Ruh , Ge many
Mal e Beh ens −Ins i u e o Ino ganic Chemis y, Kiel
Uni e si y, 24118 Kiel, Ge many; o cid.o g/0000-0003-
3407-5011
Comple e con ac in o ma ion is a ailable a :
h ps://pubs.acs.o g/10.1021/acs.ino gchem.4c02069
Funding
Open access unded by Max Planck Socie y.
No es
The au ho s decla e no compe ing inancial in e es .
■ACKNOWLEDGMENTS
The au ho s acknowledge he Max Planck Socie y o unding.
The au ho s hank he PINK beamline s a a BESSY o he
alloca ion o beam ime. A.R. acknowledges unding om he
Alexande on Humbold Founda ion. The au ho s would like
o hank he Fede al Minis y o Educa ion and Resea ch,
Ge many (Bundesminis e ium u Bildung und Fo schung,
BMBF, Hyd ogen lagship p ojec : T ansHyDE Fo schungs-
e bund AmmoRe (FKZ 03HY203E and FKZ 03HY203A)
o unding. A.R. hanks Dimi ios Manganas o help ul
discussions ega ding he C ys al-P ep o ca calcula ions.
Denise Rein is acknowledged o syn hesizing he ca alys
samples.
■REFERENCES
(1) Sa dans, J.; Penuelas, J. Po assium: a neglec ed nu ien in global
change. Glob. Ecol. Biogeog . 2015,24, 261−275.
(2) S one, M. S.; Ma yn, L.; Wea e , C. M. Po assium In ake,
Bioa ailabili y, Hype ension, and Glucose Con ol. Nu ien s 2016,8
(7), 444.
(3) Kuang, Q.; Pu honen, P.; Hebe , H. S uc u e o po assium
channels. Cell. Mol. Li e Sci. 2015,72, 3677−3693.
(4) Mi onenko, A.; Zacha iae, U.; de G oo , B. L.; Kopec, W. The
Pe sis en Ques ion o Po assium Channel Pe mea ion Mechanisms. J.
Mol. Biol. 2021,433, No. 167002.
(5) Kilbou n, B. T.; Duni z, J. D.; Pioda, L. A. R.; Simon, W.
S uc u e o he K+ complex wi h nonac in, a mac o e olide
an ibio ic possessing highly speci ic K+ anspo p ope ies. J. Mol.
Biol. 1967,30, 559−563.
(6) Clausen, M. J. V.; Poulsen, H. Sodium/Po assium Homeos asis
in he Cell. In Me al Ions in Li e Sciences; Sp inge : Do d ech , 2013;
Vol. 12; pp. 41−67.
(7) Zhou, Y.; Mo ais-Cab al, J. H.; Kau man, A.; MacKinnon, R.
Chemis y o ion coo dina ion and hyd a ion e ealed by a K+
channel−Fab complex a 2.0 Å esolu ion. Na u e 2001,414, 43−48.
(8) Humph ies, E. S. A.; Da , C. Neu onal and Ca dio ascula
Po assium Channels as The apeu ic D ug Ta ge s: P omise and
Pi alls. SLAS Disco e y 2015,20, 1055−1073.
(9) Second, C. R.; Edi ion, E.; E l, G.; Knözinge , H.; Schu h, F.;
Wei kamp, J. KGaA, Handbook o he e ogeneous ca alysis; Wiley-VCH:
Weinheim, Ge many, 2008.
(10) Huo, C.-F.; Wu, B.-S.; Gao, P.; Yang, Y.; Li, Y.-W.; Jiao, H. The
Mechanism o Po assium P omo e : Enhancing he S abili y o Ac i e
Su aces. Angew. Chem., In . Ed. 2011,50, 7403−7406.
(11) Lin, B.; Wei, K.; Ma, X.; Lin, J.; Ni, J. S udy o po assium
p omo e e ec o Ru/AC ca alys s o ammonia syn hesis. Ca al. Sci.
Technol. 2013,3, 1367−1374.
(12) Jedynak, A.; Kowalczyk, Z.; Szmigiel, D.; Ra óg, W.; Zielinski, J.
Ammonia decomposi ion o e he ca bon-based i on ca alys
p omo ed wi h po assium. Appl. Ca al., A 2002,237, 223−226.
(13) E l, G.; P igge, D.; Schloegl, R.; Weiss, M. Su ace
cha ac e iza ion o ammonia syn hesis ca alys s. J. Ca al. 1983,79,
359−377.
(14) Loiland, J. A.; Wul e s, M. J.; Ma inko ic, N. S.; Lobo, R. F. Fe/
γ-Al2O3 and Fe−K/γ-Al2O3 as e e se wa e -gas shi ca alys s.
Ca al. Sci. Technol. 2016,6, 5267−5279.
(15) Wang, Y.-X.; Wang, G.-C. A Sys ema ic Theo e ical S udy o
Wa e Gas Shi Reac ion on Cu(111) and Cu(110): Po assium
E ec . ACS Ca al. 2019,9, 2261−2274.
(16) Coa es, L. Ion pe mea ion in po assium ion channels. Ac a
C ys allog . D 2020,76, 326−331.
(17) Doyle, D. A.; Cab al, J. M.; P ue zne , R. A.; Kuo, A.; Gulbis, J.
M.; Cohen, S. L.; Chai , B. T.; MacKinnon, R. The S uc u e o he
Po assium Channel: Molecula Basis o K+ Conduc ion and
Selec i i y. Science 1998,280, 69−77.
(18) Moud ako ski, I. L.; Ripmees e , J. A. 39K NMR o Solid
Po assium Sal s a 21 T: E ec o Quad upola and Chemical Shi
Tenso s. J. Phys. Chem. B 2007,111, 491−495.
(19) Wu, G.; Gan, Z.; Kwan, I. C. M.; Fe inge , J. C.; Da is, J. T.
High-Resolu ion 39K NMR Spec oscopy o Bio-o ganic Solids. J.
Am. Chem. Soc. 2011,133, 19570−19573.
(20) Chika a Sugiu a, C. S.; Hi oyuki Yamasaki, H. Y. X-Ray
Spec oscopic S udies o Po assium Halides. Jpn. J. Appl. Phys. 1993,
32, 1135.
(21) Pa a , L. G.; Jossem, E. L. X-Ray Spec oscopy o he Solid
S a e: Po assium Chlo ide. Phys. Re . 1955,97, 916−926.
(22) Miyano, K. E.; Ma, Y.; Sou hwo h, S. H.; Cowan, P. L.; Ka lin,
B. A. Resonan Raman sca e ing in po assium and chlo ine KβX- ay
emission om KCl. Phys. Re . B 1996,54, 12022−12028.
(23) Ka cic, M.; Zi nik, M.; Buca , K.; Mihelic, A.; S uhec, M.;
Szlache ko, J.; Cao, W.; Alonso Mo i, R.; Gla zel, P. Sepa a ion o
Two-Elec on Pho oexci ed A omic P ocesses nea he Inne -Shell
Th eshold. Phys. Re . Le . 2009,102, No. 143001.
(24) Da ies, C. J.; Maye , A.; Gabb, J.; Walls, J. M.; Degi menci, V.;
Thompson, P. B. J.; Cibin, G.; Golunski, S.; Kond a , S. A. Ope ando
po assium K-edge X- ay abso p ion spec oscopy: in es iga ing
po assium ca alys s du ing soo oxida ion. Phys. Chem. Chem. Phys.
2020,22, 18976−18988.
Ino ganic Chemis y pubs.acs.o g/IC A icle
h ps://doi.o g/10.1021/acs.ino gchem.4c02069
Ino g. Chem. 2024, 63, 16217−16223
16222
(25) Desla es, R. D. KβEmission Spec a o A gon and KCl. I. Phys.
Re . 1964,133, A390−A398.
(26) Desla es, R. D. KβSpec a o A gon and KCl. II. Sa elli e
Exci a ion. Phys. Re . 1964,133, A399−A407.
(27) Glezakou, V.-A.; Chen, Y.; Ful on, J. L.; Schen e , G. K.; Dang,
L. X. Elec onic s uc u e, s a is ical mechanical simula ions, and
EXAFS spec oscopy o aqueous po assium. Theo . Chem. Acc. 2006,
115, 86−99.
(28) Pe edko , S.; Pe ei a, N.; G ö zsch, D.; Hendel, S.; Wallache ,
D.; DeBee , S. PINK: a ende X- ay beamline o X- ay emission
spec oscopy. J. Synch o on Radia . 2024,31, 622−634.
(29) Lee, N.; Pe enko, T.; Be gmann, U.; Neese, F.; DeBee , S.
P obing Valence O bi al Composi ion wi h I on KβX- ay Emission
Spec oscopy. J. Am. Chem. Soc. 2010,132, 9715−9727.
(30) Beckwi h, M. A.; Roemel , M.; Collomb, M.-N.; DuBoc, C.;
Weng, T.-C.; Be gmann, U.; Gla zel, P.; Neese, F.; DeBee , S.
Manganese KβX- ay Emission Spec oscopy As a P obe o Me al−
Ligand In e ac ions. Ino g. Chem. 2011,50, 8397−8409.
(31) Pollock, C. J.; DeBee , S. Insigh s in o he Geome ic and
Elec onic S uc u e o T ansi ion Me al Cen e s om Valence- o-
Co e X- ay Emission Spec oscopy. Acc. Chem. Res. 2015,48, 2967−
2975.
(32) Lassalle-Kaise , B.; Bo on, T. T., III; K ewald, V.; Ke n, J.;
Beckwi h, M. A.; Delgado-Jaime, M. U.; Sch oede , H.; Alonso-Mo i,
R.; No dlund, D.; Weng, T.-C.; Soka as, D.; Neese, F.; Be gmann, U.;
Yachand a, V. K.; DeBee , S.; Peco a o, V. L.; Yano, J. Expe imen al
and Compu a ional X- ay Emission Spec oscopy as a Di ec P obe o
P o ona ion S a es in Oxo-B idged MnIV Dime s Rele an o Redox-
Ac i e Me allop o eins. Ino g. Chem. 2013,52, 12915−12922.
(33) Cu sail, G. E., III; DeBee , S. Challenges and Oppo uni ies o
Applica ions o Ad anced X- ay Spec oscopy in Ca alysis Resea ch.
ACS Ca al. 2022,12, 5864−5886.
(34) Lancas e , K. M.; Roemel , M.; E enhube , P.; Hu, Y.; Ribbe,
M. W.; Neese, F.; Be gmann, U.; DeBee , S. X- ay Emission
Spec oscopy E idences a Cen al Ca bon in he Ni ogenase I on-
Molybdenum Co ac o . Science 2011,334, 974−977.
(35) Rees, J. A.; Ma in-Diaconescu, V.; Ko acs, J. A.; DeBee , S. X-
ay Abso p ion and Emission S udy o Dioxygen Ac i a ion by a
Small-Molecule Manganese Complex. Ino g. Chem. 2015,54, 6410−
6422.
(36) Pollock, C. J.; Delgado-Jaime, M. U.; A anaso , M.; Neese, F.;
DeBee , S. KβMainline X- ay Emission Spec oscopy as an
Expe imen al P obe o Me al−Ligand Co alency. J. Am. Chem. Soc.
2014,136, 9453−9463.
(37) Pollock, C. J.; G ubel, K.; Holland, P. L.; DeBee , S.
Expe imen ally Quan i ying Small-Molecule Bond Ac i a ion Using
Valence- o-Co e X- ay Emission Spec oscopy. J. Am. Chem. Soc.
2013,135, 11803−11808.
(38) Pollock, C. J.; Tan, L. L.; Zhang, W.; Lancas e , K. M.; Lee, S.
C.; DeBee , S. Ligh -A om In luences on he Elec onic S uc u es o
I on−Sul u Clus e s. Ino g. Chem. 2014,53, 2591−2597.
(39) Ma he, Z.; Pan azis, D. A.; Lee, H. B.; Gnewkow, R.; Van
Kuiken, B. E.; Agapie, T.; DeBee , S. Calcium Valence- o-Co e X- ay
Emission Spec oscopy: A Sensi i e P obe o Oxo P o ona ion in
S uc u al Models o he Oxygen-E ol ing Complex. Ino g. Chem.
2019,58, 16292−16301.
(40) Ma he, Z.; McCubbin S epanic, O.; Pe edko , S.; DeBee , S.
Phospho us KβX- ay emission spec oscopy de ec s non-co alen
in e ac ions o phospha e biomolecules in si u. Chem. Sci. 2021,12,
7888−7901.
(41) Folke, J. M. Reac i i y s udies in ammonia syn hesis; Doc o al
disse a ion; Ruh -Uni e si y Bochum: Bochum, 2022.
(42) O ega, K. F.; Rein, D.; Lu mann, C.; Heese, J.; Ozcan, F.;
Heidelmann, M.; Folke, J.; Kähle , K.; Schlögl, R.; Beh ens, M.
Ammonia Decomposi ion and Syn hesis o e Mul ina y Magnesio-
e i es: P omo ional E ec o Ga on Fe Ca alys s o he
Decomposi ion Reac ion. ChemCa Chem. 2017,9, 659−671.
(43) Thompson, A. C. X- ay Da a Bookle ; Law ence Be keley
Na ional Labo a o y, Uni e si y o Cali o nia, 2009.
(44) Hölze , G.; F i sch, M.; Deu sch, M.; Hä wig, J.; Fö s e , E. K-
alpha and K-Be a-1,3 x- ay emission lines o he 3d ansi ion me als.
Phys. Re . A 1997,56, 4554−4568.
(45) Neese, F. So wa e upda e: The ORCA p og am sys em�
Ve sion 5.0. WIREs Compu . Mol. Sci. 2022,12, No. e1606.
(46) Becke, A. D. Densi y- unc ional exchange-ene gy app oxima-
ion wi h co ec asymp o ic beha io . Phys. Re . A 1988,38, 3098−
3100.
(47) Weigend, F.; Ahl ichs, R. Balanced basis se s o spli alence,
iple ze a alence and quad uple ze a alence quali y o H o Rn:
Design and assessmen o accu acy. Phys. Chem. Chem. Phys. 2005,7,
3297−3305.
(48) Ma in, F.; Zipse, H. Cha ge dis ibu ion in he wa e
molecule�A compa ison o me hods. J. Compu . Chem. 2005,26,
97−105.
(49) Zhang, H.; Jiang, W.; Yang, J.; Liu, Y.-Y.; Song, S.; Ma, J.-F.
Fou coo dina ion polyme s cons uc ed by a no el oc aca boxyla e
unc ionalized calix[4]a ene ligand: syn heses, s uc u es, and pho o-
luminescence p ope y. C ys EngComm 2014,16, 9939−9946.
(50) O , H. XI. Die S uk u en on MnO, MnS, AgF, NiS, SnJ4,
S Cl2, BaF2; P azisionsmessungen einige Alkalihalogenide. Z.
K is allog . -C ys all. Ma e . 1926,63, 222−230.
(51) Wycko , R. W. G. C ys al S uc u es; 2nd ed.; In e science
Publishe s New Yo k: New Yo k, 1963; Vol. 1, p. 467s.
(52) Adiwidjaja, G.; Pohl, D. Supe s uc u e o [alpha]-phase
po assium ni a e. Ac a C ys allog . C 2003,59, i139−i140.
(53) Nimmo, J. K.; Lucas, B. W. The c ys al s uc u es o γ- and β-
KNO3 and he α< – γ< – βphase ans o ma ions. Ac a C ys allog .
B1976,32, 1968−1971.
(54) Wol , S.; Alam, N.; Feldmann, C. δ-KNO3: Syn hesis and
S uc u e o a New Modi ica ion o Po assium Ni a e. Zei sch i u
ano ganische und allgemeine Chemie 2015,641, 383−387.
(55) Ga ehouse, B. M.; Lloyd, D. J. C ys al s uc u e o anhyd ous
po assium ca bona e. Dal on T ans. 1973, 70−72.
(56) Di me , A.; S oyche , G. L.; Maganas, D.; Aue , A. A.; Neese,
F. Compu a ion o NMR Shielding Cons an s o Solids Using an
Embedded Clus e App oach wi h DFT, Double-Hyb id DFT, and
MP2. J. Chem. Theo y Compu . 2020,16, 6950−6967.
(57) Maganas, D.; DeBee , S.; Neese, F. A Res ic ed Open
Con igu a ion In e ac ion wi h Singles Me hod To Calcula e Valence-
o-Co e Resonan X- ay Emission Spec a: A Case S udy. Ino g. Chem.
2017,56, 11819−11836.
(58) Rees, J. A.; Wandzilak, A.; Maganas, D.; Wu s e , N. I. C.;
Hugenb uch, S.; Kowalska, J. K.; Pollock, C. J.; Lima, F. A.;
Finkels ein, K. D.; DeBee , S. Expe imen al and heo e ical
co ela ions be ween anadium K-edge X- ay abso p ion and Kβ
emission spec a. J. Biol. Ino g. Chem. 2016,21, 793−805.
(59) Holb ook, J. B.; Sab y-G an , R.; Smi h, B. C.; Tandel, T. V.
La ice en halpies o ionic halides, hyd ides, oxides, and sul ides:
Second-elec on a ini ies o a omic oxygen and sul u . J. Chem. Educ.
1990,67, 304.
(60) Boucha a, Y.; Shee, A.; Réal, F.; Valle , V.; Gomes Se e o
Pe ei a, A. P edic i e Simula ions o Ioniza ion Ene gies o Sol a ed
Halide Ions wi h Rela i is ic Embedded Equa ion o Mo ion Coupled
Clus e Theo y. Phys. Re . Le . 2018,121, No. 266001.
(61) Pauling, L. C.; Somme eld, A. J. W. The heo e ical p edic ion
o he physical p ope ies o many elec on a oms and ions. Mole
e ac ion, diamagne ic suscep ibili y, and ex ension in space. P oc. R.
Soc. Lond. Se . A Ma h. Phys. Eng. Sci. 1927,114, 181−211.
(62) Chen, S.; Jelic, J.; Rein, D.; Naja ishi a i, S.; Schmid , F.-P.;
Gi gsdies, F.; Kang, L.; Wandzilak, A.; Rabe, A.; Do onkin, D. E.;
Wang, J.; F iedel O ega, K.; DeBee , S.; G unwald , J.-D.; Schlögl, R.;
Lunkenbein, T.; S ud , F.; Beh ens, M. Highly loaded bime allic i on-
cobal ca alys s o hyd ogen elease om ammonia. Na . Commun.
2024,15, 871.
(63) Munnik, P.; de Jongh, P. E.; de Jong, K. P. Recen
De elopmen s in he Syn hesis o Suppo ed Ca alys s. Chem. Re .
2015,115, 6687−6718.
Ino ganic Chemis y pubs.acs.o g/IC A icle
h ps://doi.o g/10.1021/acs.ino gchem.4c02069
Ino g. Chem. 2024, 63, 16217−16223
16223