Ci a ion: Co edoi a-Vázquez, J.;
O ei o-Ma ínez, P.; Nie o-Pas o iza,
D.; Ga cía-Deibe, A.M.;
Sanma ín-Ma alobos, J.; Fondo, M.
Dy4,Dy
5, and Ho2Complexes o an
N3O2Aminophenol Dono : A
Dy5-μ3-Pe oxide Single Molecule
Magne . In . J. Mol. Sci. 2023,24, 9061.
h ps://doi.o g/10.3390/
ijms24109061
Academic Edi o s: Wol gang Line
and JoséMa ínez-Lillo
Recei ed: 31 Ma ch 2023
Re ised: 26 Ap il 2023
Accep ed: 16 May 2023
Published: 21 May 2023
Copy igh : © 2023 by he au ho s.
Licensee MDPI, Basel, Swi ze land.
This a icle is an open access a icle
dis ibu ed unde he e ms and
condi ions o he C ea i e Commons
A ibu ion (CC BY) license (h ps://
c ea i ecommons.o g/licenses/by/
4.0/).
In e na ional Jou nal o
Molecula Sciences
A icle
Dy4,Dy
5, and Ho2Complexes o an N3O2Aminophenol Dono :
ADy
5-μ3-Pe oxide Single Molecule Magne
Julio Co edoi a-Vázquez 1,2 , Paula O ei o-Ma ínez 1, Daniel Nie o-Pas o iza 1, Ana M. Ga cía-Deibe 1,
Jesús Sanma ín-Ma alobos 1,3 and Ma ilde Fondo 1,*
1Depa amen o de Química Ino gánica, Facul ade de Química, Uni e sidade de San iago de Compos ela,
15782 San iago de Compos ela, Spain
2Phan om-g, CICECO—A ei o Ins i u e o Ma e ials, Depa men o Physics, Uni e si y o A ei o,
3810-193 A ei o, Po ugal
3Ins i u e o Ma e ials (iMATUS), Uni e sidade de San iago de Compos ela,
15782 San iago de Compos ela, Spain
*Co espondence: [email p o ec ed]
Abs ac :
The eac i i y o he new flexible po en ially pen aden a e N
3
O
2
aminophenol ligand H
4
L
(2,2-((py idine-2,6-diylbis(me hylene))bis(azanediyl))diphenol) owa ds di e en dysp osium sal s
and holmium(III) ni a e was in es iga ed. Acco dingly, his eac i i y seems o g ea ly depend on
he me al ion and sal employed. In his way, he eac ion o H
4
L
wi h dysp osium(III) chlo ide in ai
leads o he oxo-b idged e anuclea complex [Dy
4
(H
2
L
)
3
(Cl)
4
(
μ3
-O)(E OH)
2
(H
2
O)
2
]
·
2E OH
·
H
2
O
(
1·
2E OH
·
H
2
O), while he same eac ion jus changing he chlo ide sal by he ni a e one ende s
he pe oxo-b idged pen anuclea compound [Dy5(H2L )2(H2.5L )2(NO3)4(μ3-O2)2]·2H2O(2·2H2O),
whe e bo h pe oxo ligands seem o come om he fixa ion and educ ion o a mosphe ic oxygen.
Howe e , i holmium(III) ni a e is used ins ead o dysp osium(III) ni a e, no e idence o a pe oxide
ligand is obse ed, and he dinuclea complex {[Ho
2
(H
2
L
)(H
3
L
)(NO
3
)
2
(H
2
O)
2
](NO
3
)} 2.5H
2
O
(
3·
2.5H
2
O) is isola ed. The h ee complexes we e unequi ocally cha ac e ized by X- ay di ac ion
echniques, and hei magne ic p ope ies we e analyzed. Thus, while he Dy
4
and Ho
2
complexes do
no show magne -like beha io e en in he p esence o an ex e nal magne ic field,
2·
2H
2
O is a single
molecule magne , wi h an U
e
ba ie o 61.2 K (43.2 cm
−1
). This is he fi s homonuclea lan hanoid
pe oxide SMM, which also shows he highes ba ie among he epo ed 4 /3d pe oxide ze o field
SMMs o da e.
Keywo ds: lan hanoid; SMM; pe oxide ligand; N3O2aminophenol
1. In oduc ion
Molecula magne ism is a g owing field in which single-molecule magne s (SMMs) oc-
cupy a p e e en ial place. The g ea in e es in SMMs is based on hei po en ial applica ions,
which include ul ahigh-densi y in o ma ion s o age o quan um compu ing [1,2]. In con-
as o classical magne s, he molecula na u e o SMMs o e s unique p ope ies ha could
enable unp eceden ed in o ma ion s o age speed, and p ocessing densi ies [
2
]. The main
equi emen o achie e his end is he abili y o block he magne iza ion o he molecule
a ele a ed empe a u es, a goal ha has so a no been achie ed. The high in insic spin
and aniso opy o lan hanoids make hem p e e ed candida es in he sea ch o molecule
magne s wi h en iched p ope ies. Acco dingly, since he disco e y o he fi s single ion
magne (SIM) in 2003 [
3
], he pe o mance o SMMs has s eadily imp o ed. Thus, he bes
unc ioning magne s a e mononuclea Dy
III
compounds, so ha , a p esen , he blocking
empe a u e (T
B
) eco d o 80 K is held by [(Cp
iP 5
)Dy(Cp*)][B(C
6
F
5
)
4
][
4
]. Howe e , his
kind o me allocene is uns able in ai , and he T
B
eco d o an ai -s able compound is
held by [Dy(bmbpen-F)B ] (bmbpen-F = N,N’-bis-(5-me hyl-2-hyd oxybenzyl)-N,N’-bis(5-
fluo o-2-me hylpy idyl)e hylenediamine) [
5
] a 36 K, al hough he highes ene gy ba ie
In . J. Mol. Sci. 2023,24, 9061. h ps://doi.o g/10.3390/ijms24109061 h ps://www.mdpi.com/jou nal/ijms
In . J. Mol. Sci. 2023,24, 9061 2o 16
(>1800 K) o an ai -s able SMM is owned by a Dy
III
SIM wi h hexagonal bipy amidal
geome y [6].
The e o e, as i is logical, and based on Long’s heo y [
7
], i seems easie o con ol he
aniso opy o mononuclea complexes, which leads o be e magne ic esul s. Howe e ,
e en so, he pe o mance o magne s wi h mo e han one me al cen e is also imp o ing
significan ly. Thus, i has ecen ly been desc ibed ha he dinuclea mixed- alen complex
[(Cp
iP 5
)
2
Dy
2
I
3
][
8
], which ea u es me al- o-me al bonding, shows an eno mous coe ci e
magne ic field, and hys e esis up o 80 K, al hough i is also uns able in ai . In addi ion, he
Dy–Sc ni ide clus e ulle ene Dy
2
ScN@C80-I
h
, wi h a ni ogen b idge be ween he Dy
III
ions, p esen s an U
e
ba ie o ca. 1735 K [
9
], e y close o he eco d o an ai -s able SIM.
In addi ion, among ai s able complexes, we ha e desc ibed he phenoxo-b idged dinuclea
dysp osium complex wi h he highes ene gy ba ie o spin e e sal o his ype o
compound o da e [
10
]. This was achie ed wi h an N
4
O
3
aminophenol dono , a ligand ha
also leads o fluo ide-b idged complexes, some o hem wi h unp eceden ed s uc u al and
magne ic ea u es [
11
]. Acco dingly, ollowing his line o wo k, his pape desc ibes he
e sa ili y in he coo dina ion chemis y o a new pen aden a e N
3
O
2
aminophenol wi h
Dy
III
and Ho
III
, which includes he isola ion o a a e Dy
III
pen anuclea pe oxo-complex,
and he s udy o he magne ic p ope ies o all he ob ained compounds.
2. Resul s and Discussion
2.1. Syn hesis
H
4
L
, which is o iginal om his wo k, is ob ained by educing he p e iously e-
po ed Schi base H
2
L[
12
–
14
] wi h sodium bo ohyd ide, as summa ized in Scheme 1.
The analy ical and spec oscopic s udies o H
4
L
(Expe imen al sec ion, and Figu e S1)
comple ely ag eed wi h i s isola ion wi h high pu i y.
Scheme 1. Syn he ic ou e o he isola ion o H4L and i s me al complexes.
The eac i i y o H
4
L
owa ds lan hanoid sal s in ai seems o g ea ly depend on
he lan hanoid employed bu also on he anion o he me al sal , as shown in Scheme 1.
Acco dingly, when he ligand eac s wi h dysp osium(III) chlo ide in a basic medium,
single c ys als o he Dy
4
complex
1·
2E OH
·
H
2
O wi h a
μ3
-oxide b idge a e isola ed. The
composi ion o hese c ys als is app oxima e, gi en ha SQUEEZE [
15
] has o be applied
due o he g ea diso de o he apped sol en . Thus, hese c ys als seem o lose he
e hanol sol a e on d ying, and he elemen al analyses o he d ied c ys als ag ee wi h
o mula 1·5H2O.
In . J. Mol. Sci. 2023,24, 9061 3o 16
When he aminophenol ligand eac s wi h dysp osium(III) ni a e ins ead o chlo ide,
he pe oxo-b idged Dy
5
complex
2·
2H
2
O is ob ained. Ne e heless, i holmium(III) ni a e
is used in he place o he dysp osium(III) one, he dinuclea holmium compound
3·
2.5H
2
O,
wi hou any e idence o pe oxide as ligand, is sepa a ed. Acco dingly, his indica es ha
he o ma ion o he pe oxo dono is achie ed in he p esence o ni a e and Dy
III
bu no
o Ho
III
. This may seem somewha s ange since one would expec he chemical beha io
o Dy
III
and Ho
III
o be simila . In his espec , we should poin ou ha a sea ch was
made in CSD [
16
] o c ys allog aphically cha ac e ized pe oxo-lan hanoid complexes in
which he e is no doub as o he na u e o he oxygena ed ligand. This sea ch show ha
homonuclea pe oxo-complexes has been ob ained om ai wi h Ce
IV
[
17
–
22
], Nd
III
[
23
–
25
],
Sm
III
[
26
–
28
], Eu
III
[
23
,
24
,
26
], Gd
III
[
26
], Tb
III
[
29
], Dy
III
,[
30
], Yb
III
[
23
,
31
–
34
], and Lu
III
[
35
]
ions, in addi ion o 3d/4 M
3
Ln
3
(M = Ni, Cu o Zn; Ln = Gd, Tb, o Dy) [
36
,
37
] and
Zn
4
Ln
7
(Ln = Gd, Dy) pe oxo compounds [
38
]. Howe e , as a as we know, no holmium
pe oxo-complexes ha e been ob ained by in e ac ion wi h oxygen. In addi ion, some o he
lan hanoid pe oxo-complexes o he men ioned ions o La
III
ha e been mos ly isola ed
om pe oxides as eagen s [
39
–
42
]. Among hese, i is wo h no ing ha he e is a se ies
o pe oxo-complexes o Gd, Tb, Dy, and E wi h he same ligand, bu no he Ho one [
42
].
Acco dingly, based on his li e a u e sea ch, in which no a single pe oxo-Ho complex was
ound, he esul s desc ibed he e a e no su p ising, and, as expec ed, he in e ac ion o
HoIII wi h he pe oxide ligand does no appea o be a o ed.
A emp s we e made o de e mine he o igin o he pe oxide species. Consequen ly, he
eac ion o H
4
L
and Dy(NO
3
)
3·
6H
2
O was epea ed in a s ic ine a mosphe e unde A .
Un o una ely, i was no possible o ob ain single c ys als o his sample o su ficien quali y
o be sol ed. Howe e , he elemen al analysis o his compound seems o be in ag ee-
men wi h he empi ical o mula {[Dy
2
(H
2
L
)(H
3
L
)(NO
3
)
2
(H
2
O)
2
](NO
3
)}
·
2E OH
·
H
2
O
(
4·
2E OH
·
H
2
O), simila o ha o he holmium complex
3·
2.5H
2
O. Ob iously, in he ab-
sence o a single c ys al s uc u e, i does no make sense o specula e mo e on he possible
s uc u e o his compound, bu IR spec oscopy seems o help de e mine he na u e o he
species. Thus, he IR spec um o
2·
2H
2
O (Figu e S2) shows a band a 831 cm
−1
, absen
in he spec a o he ni a e holmium complex
3·
2.5H
2
O and o he ni a e dysp osium
compound
4·
2E OH
·
H
2
O. The posi ion, shape, and in ensi y o his band seems o ag ee
wi h he ib a ion o he pe oxide ligand [
25
,
37
,
38
]. The p esence o his dono is also
confi med by he Raman spec um, which shows a weak peak a 831 cm
−1
(Figu e S3),
whose shape and in ensi y a e simila o ha p e iously desc ibed o o he lan hanoid
pe oxo-complexes [
18
,
37
]. In addi ion, he IR spec oscopy seems o indica e ha he pe -
oxo g oup does no o m in he absence o ai , as his band is no p esen in he spec um
o
4·
2E OH
·
H
2
O (Figu e S2). Howe e , addi ionally, when he mo he liquo om he
syn hesis o
4·
2E OH
·
H
2
O in ine a mosphe e is le in ai , a small po ion o a new solid
5
p ecipi a es, whose IR spec um is iden ical o ha o
2·
2H
2
O be ween 2000 and 500 cm
−1
,
and i again shows he p esence o he band a 831 cm
−1
(Figu e S4). Acco dingly, he
pe oxide ligand seems o come om ai educ ion.
2.2. X- ay Di ac ion S udies
Single c ys als o
1·
2E OH
·
H
2
O-
3·
2.5H
2
O we e ob ained as de ailed abo e. The
expe imen al de ails o da a acquisi ion and esolu ion a e summa ized in Table S1.
Dy
4
(H
2
L
)
3
(Cl)
4
(
μ3
-O)(E OH)
2
(H
2
O)
2
]
·
2E OH
·
H
2
O(
1·
2E OH
·
H
2
O). An ellipsoid di-
ag am o
1
is shown in Figu e 1, and hei main bond dis ances and angles a e lis ed
in Table S2.
In . J. Mol. Sci. 2023,24, 9061 4o 16
Figu e 1.
Ellipsoids diag am (50% p obabili y) o [Dy
4
(H
2
L )
3
(Cl)
4
(
μ3
-O)(E OH)
2
(H
2
O)
2
](
1
). Only
me al ions and hei co es a e labeled, o cla i y.
The uni cell o
1·
2E OH
·
H
2
O con ains neu al molecules o [Dy
4
(H
2
L
)
3
(Cl)
4
(
μ3
-O)(E OH)
2
(H
2
O)
2
](
1
) and wa e and e hanol as sol a es. I should be no ed ha
SQUEEZE [
15
] was applied o hese c ys als o co ec ly sol e he s uc u e due o he
high diso de o he sol en . Acco dingly, he composi ion o he sol a es in he c ys als
is inexac .
[Dy
4
(H
2
L
)
3
(Cl)
4
(
μ3
-O)(E OH)
2
(H
2
O)
2
] does no con ain symme y elemen s. How-
e e , in o de o simpli y i s desc ip ion, he e anuclea compound can be conside ed as
o med om 3 mononuclea building blocks, each o which uses some o i s dono a oms
o bind a ou h Dy
III
ion. Two o hese h ee mononuclea uni s, hose con aining Dy1
and Dy3, which we will he e o e call
1
.1 and
1
.3, a e chemically equi alen bu c ys allo-
g aphically di e en , and w i en as he neu al agmen s [Dy(H
2
L
)(Cl)(H
2
O)] (Figu e 2a).
The mononuclea uni con aining Dy2, which we call
1
.2, is he monoanionic agmen
[Dy(H2L )(Cl)2(E OH)]−(Figu e 2b).
Figu e 2.
Mononuclea blocks ha a e p esen in
1
:(
a
) schema ic ep esen a ion o neu al
1
.1 and
1
.3 blocks; (
b
) schema ic ep esen a ion o he monoanionic
1
.2 block. The bending o he ligand is
no shown in he figu e, only i s coo dina ion mode, o acili a e he unde s anding o he s uc u e.
In all he mononuclea moie ies, he phenol oxygen a oms o he ligand a e dep o-
ona ed, and he dianionic aminophenol ac s as a pen aden a e N
3
O
2
dono . In addi ion,
in agmen s
1
.1 and
1
.3, a wa e molecule and a chlo ide ligand also bind he me al ion,
leading o coo dina ion numbe 7. Fo agmen
1
.3, wo chlo ide anions and an e hanol
dono om he sol en o he eac ion a e also coo dina ed o he dysp osium a om, leading
o an oc acoo dina ed en i onmen .
These h ee mononuclea agmen s a e joined among hem and o Dy4 by means o
a ious b idges, comple ing hei coo dina ion sphe es. Acco dingly, Dy1 eachs coo dina-
In . J. Mol. Sci. 2023,24, 9061 5o 16
ion numbe 8 by binding o an O
2−
b idge (O1), while Dy3 eachs coo dina ion numbe 9
by also binding o O1 and o a phenola e oxygen a om (O11) o one o he ligand a ms o
uni
1
.1. The e o e, be ween uni s
1
.1 and
1
.3, he e is a double oxygen b idge (phenola e
O11 and oxo O1, Figu e 3), and his Dy2O2co e shows Dy-O-Dy angles close o 110◦.
Figu e 3.
Dy
4
co e en i onmen o
1
, showing only he oxygen b idges. The in e molecula dis ances
be ween b idged Dy a oms a e also shown.
Uni s
1
.1,
1
.2, and
1
.3 employ all hei phenolic oxygen a oms ha we e no p e iously
used in coo dina ed bonds ( wo in
1
.2 and
1
.3, and one in
1
.1, a o al o fi e) o bind he
ou h dysp osium ion Dy4 (Figu es 1and 3). This Dy4 cen e is u he bonded o he oxo
b idge O1 and o one e hanol ligand, hus eaching coo dina ion numbe 7. Acco dingly, as
a consequence o he desc ibed ea u es, as shown in Figu e 3, he pai s Dy1 and Dy4, and
Dy2 and Dy4, a e also double b idged, and he Dy
2
O
2
g oups show dis ances compa able o
hose ound be ween Dy1 and Dy3, wi h simila Dy-O-Dy angles. Howe e , Dy3 and Dy4
a e iple b idged by wo phenolic oxygen a oms and by an oxygen a om o he oxo g oup
(O1), which a his poin ac s as a
μ3
b idge, linking Dy1, Dy3, and Dy4. This iple b idged
Dy
2
O
3
co e, as would be expec ed, shows he sho es dis ance be ween dysp osium a oms
(Figu e 3), wi h much sho e Dy-O-Dy angles, be ween 96.3 and 98.3◦.
As a esul o he si ua ion desc ibed, he h ee [H
2
L
]
2−
ligands show wo di e en
coo dina ion modes. In all h ee cases, i ac s as pen aden a e, bu in one case (when he
ligand inse s Dy1 in i s N
3
O
2
pocke ) i is a b idging
μ2
dono , and in wo o he s (when i
inse s Dy2 o Dy3 in he pocke ), a μ3dono (Figu e 4).
Figu e 4. Coo dina ion modes o he pen aden a e aminophenol ligand in 1.
Acco ding o he discussed ea u es, he coo dina ion numbe s o dysp osium a oms
a e di e en : 8 o Dy1 and Dy2, 9 o Dy3, and 7 o Dy4. Calcula ions o he dis o ion o
he polyhed a wi h espec o he ideals o 8, 9, o 7 e ices wi h he SHAPE p og am [
43
]
(Table S3) show ha he geome y ha bes ep esen ed he en i onmen o Dy1 and Dy2
is a iangula dodecahed on, o Dy3 a “mu fin”, and o Dy4 a capped oc ahed on. All
dis ances and bond angles in hese polyhed a a e wi hin hei no mal ange [
10
,
13
,
14
] and
do no me i u he conside a ion.
Finally, i should be no ed ha one o he amine ni ogen a oms and one o he chlo ine
ligands pe e anuclea molecule a e in ol ed in a weak in e molecula hyd ogen bond,
which expands his e anuclea uni in o a zig-zag chain.
[Dy
5
(H
2
L)
2
(H
2.5
L)
2
(NO
3
)
4
(
μ3
-O
2
)
2
]
·
2H
2
O(
2·
2H
2
O). An ellipsoid diag am o
2
is
shown in Figu e 5, and hei main bond dis ances and angles a e lis ed in Table S4.
In . J. Mol. Sci. 2023,24, 9061 6o 16
Figu e 5.
Ellipsoids diag am (50% p obabili y) o [Dy
5
(H
2
L)
2
(H
2.5
L)
2
(NO
3
)
4
(
μ3
-O
2
)
2
]. Only me al
ions and hei co es o he asymme ic uni a e labeled, o cla i y.
The uni cell o
2·
2H
2
O con ains molecules o he neu al pen anuclea complex
[Dy
5
(H
2
L
)
2
(H
2.5
L
)
2
(NO
3
)
4
(
μ3
-O
2
)
2
], oge he wi h wa e as a sol a e. The asymme ic
uni o he c ys al con ains only hal o he complex molecule, he o he hal being gene -
a ed by an imp ope o a ion axis (
−
x+1,y,
−
z+
1
2
) passing h ough Dy3. Thus, each
molecule o his neu al complex can be unde s ood as wo dinuclea [Dy(H
2
L
)(NO
3
)(
μ2
-
O
2
)Dy(H
2.5
L
)(NO
3
)]
1.5−
blocks (Figu e 6), which join a fi h Dy
3+
ion (Dy3) be ween hem,
using ou phenola e g oups (one pe aminophenol ligand, O11 and O21), and he wo (one
pe block) pe oxide ligands (O1-O2), as shown in Figu e 7. This leads o he aminophenol
ac ing as a μ2b idge bu in a di e en way (μ2-κ5:κ1, Figu e 7) om1.
Figu e 6.
Balls and s icks ep esen a ion o a dinuclea block [Dy
2
(H
2
L
)(H
2.5
L
)(NO
3
)
2
(
μ2
-O
2
)]
1.5−
.
Only he me al ions and hei coo dina ion sphe es a e ep esen ed as balls o he shake o cla i y.
In . J. Mol. Sci. 2023,24, 9061 7o 16
Figu e 7.
(
Le
) Ball diag am showing he b idges be ween he Dy
3+
cen es. The
μ3
-
κ2
:
κ2
:
κ2
bond o
he pe oxide dono s be ween Dy1, Dy2, and Dy3 is shown, wi h dis ances d(Dy1
···
Dy2) = 4.2636(6)
Å; d(Dy1
···
Dy3) = 3.6317(4) Å and d(Dy2
···
Dy3) = 3.5923(4) Å. (
Righ
) Coo dina ion mode o he
aminophenol in 2. The flexion o he ligand is no ep esen ed o he shake o cla i y.
In u n, he espec i e dinuclea blocks can be conside ed cons uc ed om wo
mononuclea uni s, [Dy(H
2.5
L
)(NO
3
)]
0.5−
and [Dy(H
2
L
)(NO
3
)]
−
, which con ain Dy1 and
Dy2, espec i ely. The main di e ence be ween he uni s lies in he ac ha one o he
phenolic oxygen a oms (O12) is semi-p o ona ed in one o he uni s bu no in he o he .
A he same ime, in each mononuclea uni , he aminophenol ligand links a Dy
III
cen e
in i s N
3
O
2
pocke , as in
1
. Each me al cen e also binds a ni a e ligand, which ac s as a
biden a e chela e dono (Figu e 6).
In addi ion, bo h oxygen a oms o he pe oxide g oup (O1 and O2) a e coo dina ed in
side-on mode o he wo dysp osium a oms, wi h a pa ial coo dina ion mode
μ2
-
κ2
:
κ2
in
each dinuclea block (Figu e 6). Thus, in hese dinuclea en i ies, he dysp osium a oms
a e nonacoo dina ed, in N
3
O
6
en i onmen s. Calcula ions wi h he SHAPE p og am
(Table S3)
[
43
] indica e ha he geome y a ound he dysp osium a oms is sphe ical capped
squa e an ip ism.
The cen al dysp osium a om (Dy3, see Figu e 7) is in a highly dis o ed O
8
en i on-
men . This is achie ed by means o he ou men ioned b idging phenola e O-a oms, and
wo pe oxide ligands ac ing as
μ3
-
κ2
:
κ2
:
κ2
b idges, and acco ding o SHAPE measu emen s
(Table S3) [43], his en i onmen can be desc ibed as a biaugmen ed igonal p ism.
The coo dina ion mode o he O
22−
ligand is qui e common o lan hanoid complexes
wi h pe oxide as dono [
25
,
36
–
38
,
42
], and all he dis ances be ween his dono and he
pen aden a e ligand a e wi hin hei no mal anges [
10
,
13
,
14
,
36
–
38
,
42
]. In addi ion, he
dysp osium ions wi hin he dinuclea subuni s b idged by he O
22−
dono a e a dis ances
Dy1
···
Dy2 o 4.2636(6) Å, wi h Dy1-O
pe oxide
-Dy2 angles o ca. 129
◦
. A double hyd ogen
bond be ween one oxygen a om o he ni a e g oup joined o Dy1 and one amine ni ogen
a om joined o Dy2 and ice e sa (Figu e 6) also con ibu es o sho ening his dis ance.
Dy1
···
Dy3 and Dy2
···
Dy3 a e iple b idged by he pe oxide and one phenol oxygen a om
(Figu e 7). This leads o sho e Dy1
···
Dy3 and Dy2
···
Dy3 dis ances, ca. 3.6 Å, wi h
Dy-O-Dy angles in he ange 97.6–103.1◦.
[Ho
2
(H
2
L
)(H
3
L
)(NO
3
)
2
(H
2
O)
2
](NO
3
)
·
2
·
5H
2
O(
3·
2.5H
2
O). The uni cell o
3·
2.5H
2
O
con ains [Ho
2
(H
2
L
)(H
3
L
)(NO
3
)
2
(H
2
O)
2
]
+
ca ions, NO
3-
anions, and wa e as sol a e. An
ellipsoid diag am o
3
is shown in Figu e 8, and he p incipal bond dis ances and angles
a e lis ed in Table S5.
In . J. Mol. Sci. 2023,24, 9061 8o 16
Figu e 8.
Ellipsoids diag am (50% p obabili y) o he ca ion [Ho
2
(H
2
L
)(H
3
L
)(NO
3
)
2
(H
2
O)
2
]
+
in
3
.
Only me al ions and hei co es a e labeled, o cla i y.
The dinuclea ca ionic complex [Ho
2
(H
2
L
)(H
3
L
)(NO
3
)
2
(H
2
O)
2
]
+
can be conside ed
assembled om wo mononuclea blocks: ca ionic [Ho(H
3
L
)(NO
3
)(H
2
O)]
+
, which we
call
3
.1, and neu al [Ho(H
2
L
)(NO
3
)(H
2
O)], which we call
3
.2. Bo h blocks a e simila
(Figu e 9), he main di e ence being ha in
3
.1 one o he phenolic oxygen a oms is
p o ona ed, while in
3
.2 bo h a e dep o ona ed. Apa om his di e ence, in
3
.1 and
3
.2,
he pen aden a e ligand ac s as usual, using i s N3O2dono se o link he DyIII cen e .
Figu e 9.
Schema ic ep esen a ion o he blocks [Ho(H
3
L
)(NO
3
)(H
2
O)]
+
(
3
.1, R = H, n = 1) and
[Ho(H
2
L
)(NO
3
)(H
2
O)] (
3
.2, R does no exis , n = 0). The flexion o he ligand is no ep esen ed o
he shake o cla i y.
In he wo blocks, he holmium cen e addi ionally binds o one ni a e ligand in
a biden a e chela e mode and o one wa e molecule (Figu e 9). Uni s
3
.1 and
3
.2 join
each o he using each one o he blocks a dep o ona ed phenolic oxygen o ac as a b idge
be ween he Ho1 and Ho2 cen e s. Thus, he aminophenol ligands also ac s as
μ2
-
κ5
:
κ1
b idges, as in
2
. The e o e, his double phenola e b idge leads o a Ho
2
O
2
co e, wi h a
Ho···Ho dis ance o 3.8091(2) Å, and Ho-O-Ho angles close o 109.7◦(Figu e 8).
As a esul o he desc ibed si ua ion, he me al ions a e in bo h cases nonacoo dina e,
and calcula ions pe o med wi h he SHAPE p og am o see he deg ee o dis o ion wi h
espec o an ideal 9- e ex polyhed on show ha he geome y in he en i onmen o he
me al cen e s is somewha di e en . Thus, o Ho1, he en i onmen is close o a squa e
capped an ip ism, dis o ed owa d a sphe ical icapped igonal p ism, while o Ho2,
In . J. Mol. Sci. 2023,24, 9061 9o 16
he geome y is “mu fin” dis o ed owa d a squa e capped an ip ism. The dis ances and
bond angles o hese olyhed al a e wi hin hei no mal ange and do no me i u he
conside a ion [10].
Mo eo e , powde X- ay di ac ion s udies o c ude samples o
2·
2H
2
O and
3·
2.5H
2
O
(Figu es S5 and S6) p o e ha hese mic oc ys alline samples a e he same compounds
as he single c ys als. The powde di ac og am o
1·
5H
2
O was no eco ded, gi en
ha SQUEZZE was applied o he single c ys als, and hus he sol a es o he c ys als
o c ea ing a heo e ical di ac og am and hose o he c ude sample a e di e en , hus
p e en ing an accu a e compa ison o he expe imen al and heo e ical di ac og ams.
2.3. Magne ic P ope ies
Suscep ibili y magne ic measu emen s we e eco ded o
1·
5H
2
O-
3·
2.5H
2
O be ween 2
and 300 K. The χMT s. Tplo s o he h ee complexes a e shown in Figu e 10.
(a) (b)
(c)
Figu e 10. χMT s. T o : (a)1·5H2O; (b)2·2H2O; (c)3·2.5H2O. Inse s: M/NμB s. Ha 2K.
The
χM
T alues a 300 K a e 55.2 cm
3
Kmol
−1
o
1·
5H
2
O, 66.5 cm
3
Kmol
−1
o
2·
2H
2
O,
and 28.8 cm
3
Kmol
−1
o
3·
2.5H
2
O, which a e easonably close o he expec ed ones o
wo Ho
3+
(28.14 cm
3
Kmol
−1
), ou (56.68 cm
3
Kmol
−1
), o fi e (70.85 cm
3
Kmol
−1
)Dy
3+
uncoupled ions a oom empe a u e. Fo
1·
5H
2
O and
2·
2H
2
O, his cu e con inuously
dec eases wi h dec easing empe a u e, and he diminishmen o he
χM
Tp oduc is mo e
p onounced below 50 K. Fo holmium complex
3·
2.5H
2
O, he
χM
Tis nea ly cons an om
300 o 100 K and hen i dec eases un il 2 K, he diminishmen being also mo e p onounced
below 50 K. Acco dingly, he con inuous d op o he cu es o
1·
5H
2
O and
2·
2H
2
O and
he s ong diminishmen o he
χM
T o
3·
2.5H
2
O a low empe a u e a e a ibu ed in
all cases o he mal depopula ion o he exci ed M
J
le els, which leads o he exis ence o
conside able single ion aniso opy.
In . J. Mol. Sci. 2023,24, 9061 16 o 16
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Disclaime /Publishe ’s No e:
The s a emen s, opinions and da a con ained in all publica ions a e solely hose o he indi idual
au ho (s) and con ibu o (s) and no o MDPI and/o he edi o (s). MDPI and/o he edi o (s) disclaim esponsibili y o any inju y o
people o p ope y esul ing om any ideas, me hods, ins uc ions o p oduc s e e ed o in he con en .
