Unde s anding he Ligand In luence in he Mul is ep Reac ion o
Diazoalkanes wi h Palladium Complexes Leading o Ca bene-A yl
Coupling
F ancisco Villalba and Ana C. Albéniz*
Ci e This: O ganome allics 2025, 44, 394−402
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ACCESS Me ics & Mo e A icle Recommenda ions *
sı Suppo ing In o ma ion
ABSTRACT: The eac ion o diphosphino a yl complexes [Pd-
(C6F5)(L-L)(NCMe)](BF4) (L-L = dppe, dppp, dppb) wi h
diazoalkanes N2CHR (R=−CH�CHPh, Ph) leads o η3-allyl o
η3-benzyl palladium de i a i es ha a e he o ganome allic p oduc s
esul ing om ca bene-a yl coupling. The expe imen al end shows
ha he eac ion is a o ed o dppe > dppp > dppb. I in ol es
se e al consecu i e s eps, i.e., diazoalkane coo dina ion, ni ogen
ex usion o gi e a Pd-ca bene, and mig a o y inse ion, which a e
expe imen ally insepa able, bu hey can be s udied wi h he help o
DFT calcula ions. The bulkiness and bi e angle o he ligand exe a
la ge in luence in he ela i e a e o he s eps in ol ed in he
eac ion, and we ha e ound ha ca bene o ma ion by N2ex usion
is he s ep wi h he la ges ba ie o dppe. In con as , he
coo dina ion o he diazoalkane is he mos ene gy-demanding s ep o he la ge dppp and dppb diphosphines. Thus, ligand
subs i u ion con ols he a e, an impo an elemen al s ep a ely conside ed in mechanis ic s udies o ca bene c oss coupling
eac ions. Since diazoalkanes a e he mos common ca bene p ecu so s, ei he di ec ly o gene a ed om hyd azones, he choice o
ligand can be e y impo an o acili a e he en ance o he ca bene p ecu so in he ca aly ic cycle.
■INTRODUCTION
Palladium-ca alyzed c oss coupling eac ions ha use ca bene
p ecu so s as eagen s a e impo an p ocesses in he C−C
bond o ming eac ion oolbox. The ca bene agmen is
amenable o double unc ionaliza ion and cascade eac ions
lead o he o ma ion o wo C−C o C-X bonds, which builds
up molecula complexi y in a ewe numbe o syn he ic
s eps.
1,2
The key s ep in hese ans o ma ions is he 1,1-
inse ion (o mig a o y inse ion) o a ca bene agmen in o a
Pd−C bond in a me al ca bene in e media e (B) o med by
eac ion o he ca bene p ecu so and a palladium hyd oca byl
complex A. The de ailed expe imen al s udy o his speci ic
s ep (B o C,Scheme 1) is no easy because he p eceding
ca bene complex is usually di icul o de ec o isola e.
The e o e, i is no possible o collec expe imen al da a
pe aining he a e o he mig a o y inse ion s ep o he ac o s
ha a o i alone, since he obse ed ou come will be a
combina ion o se e al consecu i e s eps. Ve y ew isola ed
ca benes Bha e been shown o unde go a mig a o y inse ion
eac ion and hey a e s abilized monoamino ca benes (R1=
NR2, R2= alkyl, a yl, Scheme 1),
3
and N-he e ocyclic ca benes
(NHCs).
4
Fo ca benes wi h hyd oca byl subs i uen s o
alkoxo g oups he ca bene is oo uns able o be isola ed and
only he ans o ma ion A o Ccan be obse ed (Scheme
1).
3a,c,5−7
The mos common ca bene p ecu so s used in Pd-ca alyzed
coupling p ocesses a e diazoalkanes N2R1R2, whe e R1, R2= H,
hyd oca byl. They can be di ec ly used as eagen s o
gene a ed in si u ia he decomposi ion o osylhyd azones.
Using hese p ecu so s he ca bene in e media es Ba e oo
uns able o be de ec ed bu sui able subs i uen s in he
diazoalkane ha e allowed isola ion o he alkyl complex igh
a e he mig a o y inse ion (C,Scheme 1). Thus, we ha e
Recei ed: Oc obe 14, 2024
Re ised: Decembe 3, 2024
Accep ed: Decembe 27, 2024
Published: Janua y 10, 2025
Scheme 1. In e media es in he Ca bene-Hyd oca byl
Coupling om Ca bene P ecu so s
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epo ed ha using [Pd(C6F5)(dppe)(NCMe)](BF4) as
p ecu so complex Ai is possible o isola e de i a i es o
ype Cwhe e he alkyl g oup is s abilized by coo dina ion o a
C−C double bond (η3-allylic complex) o a phenyl ing (η3-
benzylic complex).
8
Wi h his sys em a hand, we decided o s udy he in luence
o he ligands in he o ma ion o he mig a o y inse ion
p oduc . In pa icula , we looked a he cis− ans s e eo-
chemis y o he complexes and he ligand bi e angle o
analogous chela ing phosphines. The in luence o he ligand
bulk and bi e angle on C−C bond o ma ion eac ions can be
used o modula e a ca alys eac i i y. Fo example, he
inc ease o he educ i e elimina ion a e upon in oducing
bulky ligands is known and has p o ed o be one o he mos
success ul s a egies o achie e e icien c oss-coupling
eac ions in milde condi ions o hose o eluc an subs a es
(i.e luo ina ed subs a es).
9,10
1,1-Mig a o y inse ion eac ions
o ca bon monoxide a e also a o ed by bulky ligands wi h
la ge bi e angles and his has been shown o he inse ion o
CO in o a Pd-alkyl bond. A se ies o well-de ined me hyl
Pd(II)-complexes wi h biden a e phosphines, we e examined
by B ookha e al. They obse ed ha he kine ic ba ie s o
he mig a o y inse ion o CO in o he Pd-me hyl bond
dec ease wi h inc easing he P−Pd−P bond angle o he
complex and he s e ic bulk o he ligand.
11
A la ge bi e angle
o he auxilia y ligand, b ings he g oups ha ha e o couple
close oge he (CO and Me in his case) and he ba ie o
each he h ee membe ed ansi ion s a e in he mig a o y
inse ion dec eases.
Al hough he mig a o y inse ion o CO and ca benes ha e
many analogies (bo h a e isolobal),
12
no s udy o he in luence
o he ligands on he coupling o a ca bene agmen and a Pd-
R moie y has been epo ed. We ha e examined he eac i i y
o palladium a yl complexes wi h di e en monoden a e and
biden a e phosphine ligands and diazoalkanes, leading o C−C
coupling complexes C. Because o he impossibili y o isola ing
he ele an palladium ca bene complex Band sepa a ing he
mig a o y inse ion s ep om he eac ion o Awi h he diazo
compound, bo h expe imen al and compu a ional wo k is
epo ed he e. The combined expe imen al and compu a ional
da a gi e in o ma ion on he in luence o he di e en s eps in
con olling he a e o he o e all ca bene-a yl coupling.
■RESULTS AND DISCUSSION
P epa a ion o he Palladium Phosphino P ecu so s.
Complexes [PdB (C6F5)(L-L)] (1-3), [Pd(C6F5)(L-L)-
(NCMe)](BF4) (4-6; L-L = dppe, dppp, dppb) (Scheme 2)
and [Pd(C6F5)(NCMe)(PPh3)2](BF4) (7) we e used as
models o e alua e he ligand-dependen eac i i y wi h
diazoalkanes N2CH−CH�CHPh (8) and N2CHPh (9).
These diazoalkanes ha e al eady p o ed o be sui able o
s abilizing he expec ed alkyl in e media e a e he mig a o y
inse ion s ep (C,Scheme1), by coo dina ion o he
unsa u a ed double bond o a yl g oup o he me al.
8
The
chosen phosphine ligands belong o he same amily o
diphosphines. Thei elec onic p ope ies a e e y simila , bu
he e he be ween he phospho us a oms and he e o e he
bi e angle (P-M-P) is di e en in each phosphine. The use o
pen a luo ophenyl as a model a yl moie y is con enien since i
allows he e y in o ma i e ollow up o he eac ions by 19F
NMR (see below), while showing analogous beha io o less
luo ina ed a yls in palladium-media ed C−C coupling
p ocesses.
13
The syn heses o complexes 1-3we e ca ied
ou using he same dime ic p ecu so (NBu4)2[Pd(μ-
B )2B 2(C6F5)2] in he p esence o he s oichiome ic amoun
o he chela ing ligand. Complex 1has been epo ed be o e,
14
and he molecula s uc u e o he dppp de i a i e 2was
de e mined by X- ay di ac ion. I shows a palladium squa e-
plana geome y and a cis a angemen o he C6F5and B
ligands (Figu e S5, Suppo ing In o ma ion). The P−Pd−P
and C−Pd−B angles a e 93.44°and 88.28° espec i ely, being
in he expec ed ange o o he simila molecula s uc u es o
[PdA (dppp)(X)] complexes epo ed in he li e a u e.
15
The
cis a angemen is also p esen in solu ion as clea ly shown by
he appea ance o wo inequi alen 31P NMR esonances (see
Expe imen al sec ion). A di e en beha io was obse ed o
dppb and he isola ed complex 3is a ans-species as shown by
he appea ance o only one 31P NMR esonance a 18.92 ppm.
In chlo o o m solu ion a oom empe a u e, 3isome izes o
gi e a ans:cis mix u e in a 0.8:1 mol a io a e 48 h (c .
Figu es S14−S17, Suppo ing In o ma ion). When he isola ed
complex ans-3is ea ed wi h AgBF4 o emo e he B ligand
in ace oni ile a oom empe a u e, complex 6was ob ained as
a mix u e o isome s ans:cis = 1:0.8 mol a io (Scheme 2).
This was obse ed by 19F and 31P NMR (Figu es S22, S23,
Suppo ing In o ma ion). This beha io is only obse ed o
he dppb ligand because o i s inhe en wide P−Pd−P angle in
compa ison o he dppe o dppp ligands. Fo he complexes
bea ing he la e ligands (1and 2) hei eac ion wi h AgBF4
a o ds he co esponding cis-sol en o ace oni ile de i a i es 4
and 5(Scheme 2). Complex ans-[Pd(C6F5)(NCMe)-
(PPh3)2](BF4) (7) was p epa ed in he same way om he
known ans-[PdB (C6F5)(PPh3)2] complex.
14
The diphosphine 1,1-bis(diphenylphosphino)me hane
(dppm), wi h he smalles bi e angle, was excluded om he
s udy since he pa en palladium complex o composi ion
“PdB (C6F5)dppm” was ob ained as a mix u e o he binuclea
[Pd(μ-dppm)B (C6F5)]2(58%) wi h a b idging dppm and he
monome ic [PdB (C6F5)dppm] (42%). The pe cen ages gi en
we e ob ained om he c ude eac ion mix u e by 19F and 31P
NMR in eg a ion. This beha io o dppm has been obse ed
be o e,
16
and he p esence o he b idging phosphine does no
allow o e alua e he in luence o he bi e angle p ope ly.
Scheme 2. Syn hesis o he P ecu so Model Complexes
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Reac ions o he Sol en o Palladium Complexes wi h
Diazo Compounds. The sol en o ace oni ile complexes
eadily eac wi h diazoalkanes 8and 9gi ing o ganome allic
η3-allylic complexes o η3-benzylic complexes espec i ely
(Scheme 3). They a e he esul o he a yl-ca bene coupling
and co espond o he s abilized alkyl de i a i e Cin Scheme
1. The eac ions we e ca ied ou unde he same condi ions
o all he complexes and he amoun s o coupling p oduc s
we e de e mined by in eg a ion o he co esponding 19F
signals in he NMR spec a o he eac ion mix u es a a ixed
eac ion ime (Scheme 3).
We ha e epo ed he o ma ion o complexes 10 and 11 by
eac ion he dppe de i a i e 4wi h he diazode i a i es in ull
con e sion a e 5 min a oom empe a u e (Scheme 3a) as
well as hei s uc u al cha ac e iza ion.
8
The cha ac e is ic 19F
NMR signals o he s a ing sol en o complex 4(Pd−C6F5,
Fo ho abou −120 ppm) disappea and a e eplaced by he
cha ac e is ic C−C6F5 esonances (Fo ho abou −140 ppm) o
he o ganome allic complexes ob ained a e he mig a o y
inse ion (Figu e S1, Suppo ing In o ma ion). The eac ion o
he analogous dppp sol en o complex 5wi h an equimola
amoun o diazoalkane 8a o ded 46% o he η3-allylic Pd
complex 12. An addi ional po ion o diazoalkane was added o
he same sample, and he eac ion p oceeded o each 83% o
12 and a 17% o he s a ing 5which emains un eac ed
(Scheme 3b). Cha ac e is ic signals o he mig a ion o he
C6F5g oup o he ca bene agmen we e obse ed in he 19F
NMR (Fo ho c.a −142 ppm, Figu e 1, b). The Fo ho signals a e
b oad showing a es ic ed o a ion o he C−C6F5bond a
oom empe a u e, p esumably caused by he la ge bi e angle
and inc eased s e ic hind ance o he dppp ligand. The
molecula s uc u e o he η3-allyl complex 12 was de e mined
by X- ay di ac ion and i shows ha bo h a yl-subs i uen s o
he η3-allylic agmen a e in a syn a angemen (Figu e 2).
The eac ion o 5wi h he diazoalkane 9(Pd:9= 1:1.5 mol
a io) leads o he η3-benzylic palladium complex 13, as a
mix u e o he syn pen a luo ophenyl complex and a small
amoun o a en a i ely assigned an i-C6F5complex as collec ed
in Scheme 3b and shown in Figu e 1c.
As i was men ioned abo e he eshly p epa ed complex 6is
a mix u e o ans:cis isome s (Scheme 2). This in oduces a
new ac o ha can dis o he obse ed expe imen al esul s
since he mig a o y inse ion equi es a cis a angemen o he
ca bene and hyd oca byl agmen s. The eac ion o 6wi h
diazoalkane 8a o ded only 8% o he η3-allyl-palladium
complex 14 (Scheme 3c). The emaining s a ing complex 6is
a mix u e o he ans:cis isome s in a di e en a io o ha
obse ed minu es be o e i s in si u p epa a ion (Figu e S3,
Suppo ing In o ma ion). This means ha he cis- ans
equilib ium, p esumably slow, was no es ablished a he
beginning o he eac ion. The analysis o he inal eac ion
mix u e indica es ha he cis-6isome is he majo one, so he
poo o ma ion o he η3-allyl-palladium complex 14 is no
go e ned by he lack o cis-6, al hough i can ce ainly be
in luenced by he lowe concen a ion o his isome in he
s a ing mix u e o complexes.
Scheme 3. Complexes Fo med upon Reac ion o 4-6 wi h
he Diazoalkanes
Figu e 1. 19F NMR spec a (470.17 MHz, CH3CN, (CD3)2SO
capilla y) o : a) complex 5; b) he eac ion o 5wi h diazoalkane 8, o
gi e complex 12 (Pd:8= 1:2 mol a io); c) he eac ion o 5wi h
diazoalkane 9 o gi e 13 as a mix u e o syn (depic ed) and an i
isome s.
Figu e 2. X- ay molecula s uc u e o 12. Sol en molecules (CHCl3)
and he BF4
−anion a e omi ed o cla i y. Selec ed bond leng hs (Å)
and angles (deg): Pd1−P2, 2.3035(17); Pd1−P1, 2.3057(16); Pd1−
C9, 2.229(6); Pd1−C8, 2.196(6), Pd1−C7, 2.226(7); C7−C8,
1.406(10); C8−C9, 1.397(10).
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The eac ion o 6and he diazoalkane 9leads o wo new
o ganome allic species (30% o he o al amoun o C6F5in 19F
NMR) which ha e been en a i ely assigned o he an i:syn
isome s o he η3-benzyl-o ganome allic p oduc 15, in an
almos equimola a io (Figu es S4, S39 and S40, Suppo ing
In o ma ion). The syn-isome shows cha ac e is ic chemical
shi s in he 19F NMR analogous o he da a o complex 11
(syn) ha has been unequi ocally cha ac e ized (Fo ho
esonances a abou −137 ppm (syn) s −140 ppm (an i)).
8
As can be seen in Scheme 3, he syn a angemen in he η3-
benzylic complexes is p e e ed o he an i a angemen bu he
la e gains impo ance as he bulkiness o he ligands inc ease.
This is con i med by DFT calcula ions which show ha he syn
isome is mo e s able o he dppe de i a i e by 1.62 kcal
mol−1, bu he ene gy di e ence is almos he same o bo h
isome s in he case o he mo e s e ically demanding dppp and
dppb, in ag eemen wi h he expe imen al obse a ions (Figu e
S41, Suppo ing In o ma ion).
T ans-[Pd(C6F5)(NCMe)(PPh3)2](BF4) (7) eac s wi h he
diazoalkanes o gi e almos no a yl mig a ion species (eq 1).
When a mix u e o 7and he diazode i a i e 8was analyzed,
we could no iden i y any o ganome allic p oduc om he
mig a o y inse ion o a ansien palladium ca bene complex
in o he Pd−C6F5bond and jus small amoun s o C6F5-
con aining o ganic p oduc s (5%) we e de ec ed by 19F NMR.
Only decomposi ion p oduc s o he diazo compound we e
obse ed by 1H NMR: 5-Ph-1H-py azole, o med by
cycliza ion o he diazoalkane 8, and 1,6-diphenylhexa-1,3,5-
iene, as esul o he dime iza ion o he ca bene agmen .
Simila esul s we e ob ained in he eac ion o 7and
diazoalkane 9whe e no o ganome allic mig a o y inse ion
p oduc s could be de ec ed by 19F NMR. Benzaldehyde, cis/
ans s ilbene and he azine Ph−CH = N−N = CH-Ph we e
de ec ed by NMR as decomposi ion p oduc s o he
diazoalkane 9. Fo he monoden a e phosphine p ecu so ,
he pu a i e palladium ca bene gene a ed would be a ansien
ans-[Pd(C6F5)(PPh3)2(ca bene)]+and in his a angemen
he mig a o y inse ion canno occu . Thus, he esul s
ob ained a e consis en wi h a scena io whe e he isome -
iza ion p ocess o a o d a cis complex is slowe han he
decomposi ion o bo h he ee diazoalkane and he me al
ca bene.
DFT Calcula ions on he Ca bene Fo ma ion and
Mig a o y Inse ion S eps. The na u e o he auxilia y
ligand and he di e en numbe o ca bons in he backbone o
he diphosphine ligands exe a ele an in luence in he
ou come o he eac ion wi h diazoalkanes. Fo he chela ing
diphosphines he eac i i y o de ha can be ex ac ed om
Scheme 3 oughly ollows he end: dppe > dppp > dppb. In a
simpli ied way, he s eps in ol ed in he eac ions o sol en o
ace oni ile Pd(II) complexes wi h diazoalkane 8a e depic ed
in Scheme 4.
Only he η3-allylic p oduc s a e mig a o y inse ion we e
de ec ed, so he coo dina ion o he diazoalkane, he o ma ion
o he in e media e palladium ca bene and he mig a o y
inse ion eac ion canno be expe imen ally s udied sepa a ely.
A emp s a de ec ing in e media e species a low empe a u e
(−90 °C) we e epo ed be o e o he dppe p ecu so wi h no
success.8Fo his eason, DFT calcula ions we e employed o
gain insigh in o he s eps ha a e esponsible o he
di e ences obse ed. We modeled and compa ed he ene gy
p o iles o he eac ions o dppe, dppp and dppb wi h
diazoalkane 8using he M06 unc ional and including sol a ion
(MeCN) h ough he SMD implici sol en me hod (see
compu a ional de ails in he Expe imen al pa ). Fi s , we
analyzed he ni ogen ex usion and mig a o y inse ion s eps.
Figu e 3 shows a gene al p o ile o he h ee phosphines and
he ene gy alues o he in e media es and ansi ion s a es
( o ull speci ic ene gy p o iles o each phosphine, see he
Suppo ing In o ma ion, sec ion 4).
The ac i a ion ba ie s o he mig a o y inse ion s ep, i.e.
ΔGTS‑MI−ΔGI2‑ca b, ollow he end: dppe (6.1 kcal mol−1) >
dppp (5 kcal mol−1)≥dppb (4.6 kcal mol−1). As he bi e angle
o he phosphine inc eases he ba ie sligh ly dec eases. This is
mo e no iceable on going om dppe o dppp and i is he same
end obse ed o he mig a o y inse ion eac ion o CO.
11
Scheme 4. Reac ion Pa hway Leading o A yl-Ca bene
Coupling P oduc s
Figu e 3. Gibbs ene gy p o ile o he N2ex usion and mig a o y
inse ion s eps (ene gies in kcal mol−1).
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The angle C(C6F5)−Pd−C(ca bene) in he ca bene in e -
media e (I2-ca b) is indeed smalle as he bi e angle o he
phosphine inc eases and his geome ical pa ame e is close o
he small angle equi ed in he ansi ion s a e (see Table S5,
Suppo ing In o ma ion).
The ba ie s o ni ogen ex usion a e highe han hose o
he mig a o y inse ion s ep, as has also been ound o a ew
o he calcula ed sys ems.
17
As shown in Figu e 3, he ease o
ca bene o ma ion (I2-ca b) om he coo dina ed diazo
compound (I1-κ1-C) o he h ee diphosphines ollow he
same end ound o he mig a o y inse ion s ep, i.e.
ΔGTS−I1‑I2−ΔGI1‑κ
1−C: dppe (11 kcal mol−1) > dppp (10.2
kcal mol−1) > dppb (8.9 kcal mol−1). These esul s do no i
wi h hose obse ed expe imen ally. The e iciency in he
o ma ion o he mig a o y inse ion p oduc s, i.e. dppe > dppp
> dppb ollows he opposi e end o ha expec ed om he
ba ie s in Figu e 3. The e o e, we decided o explo e he o he
s ep ha is also in ol ed in he eac ion, i.e. he coo dina ion
o he diazoalkane o he palladium cen e o gi e in e media e
I1-κ1-C.
Diazoalkane Coo dina ion. Diazoalkanes a e ambiden-
a e ligands ha can coo dina e o he me al using he e minal
N (κ1-N) o he C (κ1-C) as dono a oms. Bo h in e media es
we e calcula ed o dppe and dppp, and hey a e close in
ene gy al hough only he κ1-C coo dina ed diazoalkane e ol es
o he o ma ion o he ca bene complex (Figu es S42−S43,
Suppo ing In o ma ion).
Bo h an associa i e subs i u ion, whe e he ansi ion s a e is
a pen acoo dina ed igonal-bipy amidal species, o a dis-
socia i e pa hway, ia a h ee-coo dina ed in e media e by
dissocia ion o ace oni ile, could be possible (see he
Suppo ing In o ma ion, sec ion 4.3, o he dppe complexes).
Howe e , he eac ion o he dppp complex 5wi h diazoalkane
8is in o ma i e and a o s one o hese pa hways. Scheme 3
shows ha he o ma ion o he mig a o y inse ion p oduc 12
was no comple e when he eac ion was ca ied ou wi h a
Pd:8= 1:1 mol a io o 5 min. Howe e , he addi ion o
ano he po ion o diazoalkane 8 o he same sample inc eased
he amoun o 12. To es he diazoalkane concen a ion
dependence, h ee sepa a e eac ions wi h he same ini ial
concen a ion o he sol en o ace oni ile complex 5([5] =
28.4 mM) and di e en Pd:8mol a ios we e ca ied ou .
Figu e 4 shows he o ma ion o 12 (%) when diazoalkane 8
was added in a Pd:8= 1, 2, and 3 mol a io a e 5 min a oom
empe a u e. The alues depic ed in he plo show an inc ease
o he eac ion a e upon diazoalkane concen a ion and his
poin s o an associa i e pa hway, which was he one modeled
o he sys em.
Figu e 5 shows he ene gy p o iles o he diazoalkane
coo dina ion o palladium as well as he N2-ex usion s ep o
gene a e he palladium ca bene. The coo dina ion o he
diazoalkane becomes mo e ene gy demanding on going om
dppe o he bulkie dppp and dppb. This e ec is impo an
and in ac , Figu e 5 shows ha he a e-con olling s ep o he
o e all ca bene-a yl coupling in he dppe complex is he N2
ex usion o o m he palladium ca bene (ene gy ba ie 14
kcal mol−1). In con as , he p ocess o he bulkie phosphines
is con olled by he coo dina ion o he diazoalkane o gi e
in e media e I1-κ1-C (ene gy ba ie a ound 16−17 kcal
mol−1). Acco ding o his, he expec ed eac i i y end
wouldbe dppe (N2-ex ussion) > dppp ≥dppb (diazoalkane
coo dina ion), consis en wi h he expe imen al end.
These esul s show he impo ance o he diazoalkane
coo dina ion and how his s ep can be easily a ec ed by he
s e ic bulk o he ligand, he e o e con olling he o e all
eac ion a e. Many ca aly ic c oss-coupling eac ions use
hyd azones ha slowly decompose o diazoalkanes p o iding a
usually low concen a ion o he la e in he eac ion medium.
Unde hese condi ions, he choice o ligands and he s udy o
he ligand subs i u ion s ep can be c ucial o a oid a oo
demanding diazoalkane coo dina ion and o ensu e an e icien
ca alysis. Fo example, Dingwall e al. ca ied ou an
expe imen al mechanis ic s udy on he Pd-ca alyzed c oss
coupling o a diazoalkane wi h benzyl b omide and de e mined
ha he palladium ca bene o ma ion, i.e. he o e all eac ion
o he diazoalkane wi h a palladium benzyl complex, is
u no e limi ing in a Pd-phosphine sys em. The diazo
coo dina ion could be esponsible o his, bu he ligand
subs i u ion s ep was no calcula ed sepa a ely.
18
Figu e 4. Amoun o complex 12 o med by eac ion o 5([5]0= 28.4
mM) and di e en Pd:8mol a ios a e 5 min a oom empe a u e.
Figu e 5. Gibbs ene gy p o ile o he diazoalkane coo dina ion and
N2ex usion s eps (ene gies in kcal mol−1).
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■CONCLUSIONS
The eac ion o diazoalkanes and palladium-hyd oca byl
complexes is in ol ed in many ca aly ic p ocesses ha lead
o ca bene-hyd oca byl c oss-coupling p oduc s. The eac ion
is a mul is ep p ocess ha in ol es se e al elemen al eac ions
(diazoalkane coo dina ion, ni ogen ex usion o gi e a Pd-
ca bene, and mig a o y inse ion) whose a es can be
in luenced by he auxilia y ligands.
The expe imen al end o he ease o o ma ion o ca bene-
a yl coupling p oduc s in he eac ion o he sol en o
complexes [Pd(C6F5)(P−P)(NCMe)]BF4wi h diazoalkanes
o di e en ancilla y diphosphine ligands is P−P = dppe >
dppp > dppb. Since he elec onic ea u es o hese phosphines
a e simila , he obse ed di e ences in he o ma ion o he
mig a o y inse ion o ganome allic complexes can be a ibu ed
p ima ily o he ligand backbone. DFT calcula ions show ha
he end in ene gy ba ie s o ni ogen ex usion and
mig a o y inse ion do no mi o he expe imen al ou come,
since he bulkie phosphines show lowe eac ion ba ie s. The
expe imen al di e ences can be explained conside ing he a es
o coo dina ion o he diazoalkane o palladium. We ha e
ound ha he coo dina ion o he diazoalkane 8 o he
palladium complex bea ing a dppe ligand has a low ac i a ion
ene gy and he ni ogen ex usion in a κ1-C coo dina ed
diazoalkane is he a e con olling s ep o he eac ion. In
con as , he dppp and dppb complexes show a highe
ac i a ion ba ie o he coo dina ion o he diazoalkane, ia
an associa i e pa hway. The e o e, he coo dina ion o he
diazoalkane is con olling he o e all eac ion a e o la ge bi e
angle phosphines.
The coo dina ion o he diazoalkane is o en o e looked in
mechanis ic s udies on ca bene-hyd oca byl couplings ca a-
lyzed by palladium complexes, which usually concen a e on
he ca bene o ma ion by N2ex usion and mig a o y inse ion
o explain ei he a e o selec i i y, o bo h. The impo ance o
ligand subs i u ion eac ions in ca alysis canno be unde -
es ima ed and he esul s he e show ha his is also he case in
ca bene-hyd oca byl couplings.
The eac ion o ans-[Pd(C6F5)(NCMe)(PPh3)2]BF4wi h
diazoalkanes does no lead o ca bene-a yl coupling. This ac
clea ly e idence ha he ans a angemen hampe s he
mig a o y inse ion p ocess and ha he equi ed isome iza ion
o a cis complex can be slowe han he decomposi ion
pa hways o he diazoalkane and he ans-palladium ca bene
species.
■EXPERIMENTAL SECTION
Gene al Me hods. 1H, 13C{1H} 31P{1H} and 19F NMR spec a
we e eco ded on an Agilen MR-500 spec ome e a he Labo a o io
de Tecnicas Ins umen ales (LTI) o he UVa. Chemical shi s (in δ
uni s, ppm) we e e e enced o SiMe4(1H and 13C), CFCl3(19F) and
H3PO4(85%, 31P). The spec al da a we e eco ded a 298 K unless
o he wise no ed. Homonuclea (1H−COSY) and he e onuclea
(1H−13C HSQC and HMBC) NMR expe imen s we e used o help
wi h he signal assignmen s. Elemen al analyses we e ca ied ou in a
Ca lo E ba 1108 mic oanalyze (a he Vigo Uni e si y, Spain). All
eac ions we e conduc ed unde a N2a mosphe e. Sol en s we e d ied
using a sol en pu i ica ion sys em SPS PS-MD-5 (e he , hexane, THF
and CH2Cl2) o dis illed om app op ia e d ying agen s unde
ni ogen p io o use and s o ed o e 3 o 4 Å molecula sie es
(ace oni ile and ace oni ile-d3). All comme cial eagen s and
sol en s we e used as ecei ed unless o he wise indica ed. Complexes
(NBu4)2[Pd(μ-B )2B 2(C6F5)2],14 [PdB (C6F5)(dppe)] (1),14 [Pd-
(C6F5)(dppe)(NCMe]BF4(4),8and [PdB (C6F5)(PPh3)2]14 we e
p epa ed acco ding o he li e a u e me hods. Complexes 10 and 11
ha e been epo ed and cha ac e ized be o e.
8
The syn heses o he
diazo compounds we e ca ied ou acco ding o he li e a u e
me hods.
19
The diazoalkanes we e p epa ed and kep as dichlo o-
me hane solu ions o no longe han 10 days unde a ni ogen
a mosphe e a −28 °C in he da k. The concen a ions o hese
solu ions we e de e mined by 1H NMR using CF3CH2I as in e nal
s anda d.
Syn hesis o [PdB (C6F5)(dppp)] (2). 1,3-Bis-
(diphenylphosphino)p opane (dppp) (110.87 mg, 0.268 mmol) was
added o a solu ion o (NBu4)2[Pd(μ-B )2B 2(C6F5)2] (176.5 mg,
0.130 mmol) in ace one (30 mL). The mix u e was s i ed a oom
empe a u e o 1 h. Du ing his ime he o ange solu ion became
pale-yellow. The sol en was e apo a ed o d yness and he yellow oil
was i u a ed wi h cold E OH un il he o ma ion o a pale-yellow
solid ha was il e ed, washed wi h cold E OH and ai -d ied. Yield:
165 mg (83%). C ys als sui able o X- ay analyses we e ob ained by
slow e apo a ion o a solu ion o 2in CHCl3.1H NMR (499.73 MHz,
δ, CDCl3): 7.78−7.73 (m, 4H, Ha om), 7.50−7.42 (m, 6H, Ha om),
7.41−7.33 (m, 6H, Ha om), 7.17 ( d, J = 5.5 Hz, 2.4 Hz, 4H, Ha om),
2.66 (m, 2H, CH2), 2.33 (m, 2H, CH2), 2.03 (m, 2H, CH2). 13C{1H}
NMR (125.67 MHz, δ, CDCl3): 138.3 (d, JC−P= 11.2 Hz, Ca om),
133.4 (d, JC−P= 10.6 Hz, Ca om), 132.7 (d, JC−P= 11.0 Hz, Ca om),
131.1 (d, JC−P= 2.6 Hz, Cpa a), 130.8 (d, JC−P= 2.5 Hz, Cpa a), 130.4
(d, J1C−P= 45.7 Hz, Cipso), 130.1 (d, J1C−P= 54.7 Hz, Cipso), 128.7 (d,
JC−P= 10.3 Hz, Ca om), 25.8 (dd, J = 29.2, 7.3 Hz, CH2), 25.4 (dd, J =
25.2, 7.4 Hz, CH2), 18.9 (s, CH2).*19F NMR (470.17 MHz, δ,
CDCl3): −116.92 (m, 2F, Fo ho), −161.77 ( , J= 20.1 Hz, 1F, Fpa a),
−162.85 (m, 2F, Fme a). 31P{1H} NMR (202.31 MHz, δ, CDCl3):
13.60 (d , J = 42.4 Hz, 6.4 Hz, 1P), −5.82 (m, 1P). Anal. Calcd o
C33H26B F5P2Pd: C, 51.76%; H, 3.42%. Found: C, 51.60%; H, 3.26%.
*The 13C signals o he C6F5g oup, hea ily coupled o 19F, could no
be obse ed.
Syn hesis o ans-[PdB (C6F5)(dppb)] ( ans-3). 1,4-Bis-
(diphenylphosphino)bu ane (dppb) (111.55 mg, 0.256 mmol) was
added o a solu ion o (NBu4)2[Pd(μ-B )2B 2(C6F5)2] (173.0 mg,
0.128 mmol) in ace one (30 mL). The mix u e was s i ed a oom
empe a u e o 1 h. Du ing his ime he o ange solu ion became
pale-yellow. The sol en was e apo a ed o d yness and he yellow oil
was i u a ed wi h cold E OH un il he o ma ion o a pale-yellow
solid ha was il e ed, washed wi h cold E OH and ai -d ied. Yield:
175 mg (88%). 1H NMR (499.72 MHz, δ, CDCl3): 7.43 (m, 9H,
Ha om), 7.27 ( , J = 7.2 Hz, 4H, Ha om), 7.21 (m, 7H, Ha om), 2.63 (m,
4H, CH2), 2.01 (m, 4H, CH2). 13C{1H} NMR (125.67 MHz, δ,
CDCl3): 132.9 (b , Ca om), 131.4 (d, J1C−P= 47.1 Hz, Ca om), 130.2
(b , Ca om), 128.1 (b , Ca om), 27.5 (m, 4C, CH2). 19F NMR (470.17
MHz, δ, CDCl3): −116.19 (m, 2F, Fo ho), −161.59 ( , J= 19.7 Hz,
1F, Fpa a), −162.22 (m, 2F, Fme a). 31P{1H} NMR (202.31 MHz, δ,
CDCl3): 18.92 (s, 2P). Anal. Calcd o C34H28B F5P2Pd: C, 52.36%;
H, 3.62%. Found: C, 52.56%; H, 3.68%. When a solu ion o complex
ans-3was kep a oom empe a u e o 48 h in CDCl3a mix u e o
isome s ( ans:cis = 0.8:1) was o med. cis-3:19F NMR (470.17 MHz,
δ, CDCl3): −117.15 (m, 2F, Fo ho), −161.99 ( , J= 19.9 Hz, 1F,
Fpa a), −162.83 (m, 2F, Fme a). 31P{1H} NMR (202.31 MHz, δ,
CDCl3): 40.72 (d, J = 32.5 Hz, 1P), −1.40 (m, 1P).
Cha ac e iza ion o [Pd(C6F5)(dppp)(NCMe)](BF4) (5). [PdB -
(C6F5)(dppp)] (13.4 mg, 0.017 mmol) and AgBF4(3.4 mg, 0.017
mmol) we e mixed in d y MeCN (0.6 mL) and s i ed o 15 min a
oom empe a u e unde ni ogen. The suspension was il e ed
h ough Kieselguh o emo e he AgB and he esul ing colo less
solu ion was cha ac e ized by NMR. Upon isola ion a emp s some
eo ganiza ion o he a yl g oups occu s by ansme ala ion and he
solids ob ained we e ine i ably con amina ed by small amoun s o
“Pd(C6F5)2” de i a i es. The e o e, he complexes we e usually
syn hesized in si u and used in solu ion.
1H NMR (499.73 MHz, δ, CH3CN/(CD3)2SO capilla y): 7.94−
7.83 (m, 10H, Ha om), 7.71−7.64 (m, 6H, Ha om), 7.52 (m, 4H, Ha om),
3.18 (m, 2H, CH2), 2.98 (m, 2H, C’H2).*19F NMR (470.17 MHz, δ,
CH3CN,(CD3)2SO capilla y): −117.87 (m 2F, Fo ho), −151.42
(BF4), −161.10 ( , J = 19.2 Hz, 1F, Fpa a), −162.99 (m, 2F, Fme a).
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31P{1H} NMR (202.31 MHz, δ, CH3CN, (CD3)2SO capilla y): 16.50
(d , J = 39.7, 7.2 Hz, 1P), −4.39 (m, 1P). *One CH2 om dppp is
o e lapped wi h he NCCH3signal.
Cha ac e iza ion o [Pd(C6F5)(dppb)(NCMe)](BF4) (6). [PdB -
(C6F5)(dppb)] (52.0 mg, 0.066 mmol) and AgBF4(13.0 mg, 0.066
mmol) we e mixed in d y MeCN (0.6 mL) and s i ed o 15 min a
oom empe a u e unde ni ogen. The suspension was il e ed
h ough Kieselguh o emo e he AgB and he esul ing colo less
solu ion was cha ac e ized by NMR. The esul ing complex is a
mix u e o ans:cis = 1:0.8 isome s. 1H NMR (499.73 MHz, δ,
CH3CN/(CD3)2SO capilla y; cis-6 + ans-6): 7.92 (m, 1H, Ha om),
7.85 (m, 3H, Ha om), 7.80 (m, 2H, Ha om), 7.77−7.69 (m, 10H, Ha om),
7.66 (m, 2H, Ha om), 7.57 ( d = J = 7.8, 2.9 Hz, 2H, Ha om). The CH2
signals o he dppb ligand a e o e lapped wi h he NCCH3signal. cis-
6:19F NMR (470.17 MHz, δ, CH3CN,(CD3)2SO capilla y): −118.58
(m 2F, Fo ho), −151.11 (BF4), −161.04 ( , J = 19.2 Hz, 1F, Fpa a),
−162.78 (m, 2F, Fme a). 31P{1H} NMR (202.31, MHz, δ, CH3CN,
(CD3)2SO capilla y): 40.60 (d , J = 30.8, 7.2 Hz, 1P), 7.26 (m, 1P).
ans-6:19F NMR (470.17 MHz, δ, CH3CN,(CD3)2SO capilla y):
−116.85 (m 2F, Fo ho), −151.11 (BF4), −160.18 ( , J = 19.6 Hz, 1F,
Fpa a), −161.98 (m, 2F, Fme a). 31P{1H} NMR (202.31, MHz, δ,
CH3CN,(CD3)2SO capilla y): 17.60 (s).
Syn hesis o [Pd(C6F5)(NCMe)(PPh3)2](BF4) (7). Equimola
amoun s o [PdB (C6F5)(PPh3)2] (184.3 mg, 0.210 mmol) and
AgBF4(41 mg, 0.210 mmol) we e mixed in d ied CH3CN (10 mL)
and s i ed o 15 min a oom empe a u e unde ni ogen. The
suspension was il e ed h ough Kieselguh and he il a e was
e apo a ed o d yness. The esul ing yellow oil was i u a ed wi h n-
hexane un il he o ma ion o a pale-yellow solid ha was il e ed,
washed wi h n-hexane and ai -d ied. Yield: 118 mg, (60%). 1H NMR
(499.73 MHz, δ, CD3CN): 7.62 (m, 6H, Hpa a PPh3) 7.60−7.50 (m,
24H, Hme a,o ho PPh3). 13C{1H} NMR (125.67 MHz, δ, CD3CN):
144.3 (m, 1JC−F= 230.5 Hz, Co ho, C6F5), 138.2 (m, 1JC−F= 250 Hz,
Cpa a, C6F5), 136.3 (m, 1JC−F= 248 Hz, Cme a, C6F5), 133.7 ( , JC−P=
6.5 Hz, Co ho PPh3), 131.9 (Cpa a PPh3), 129.2 ( , JC−P= 5.3 Hz, Cme a
PPh3), 127.5 ( , JC−P= 25.5 Hz, Cipso PPh3). 19F NMR (470.17 MHz,
δ, CD3CN): −118.40 (m, 2F, Fo ho), −151.70 (BF4), −161.63 ( , J =
19.0, 2.4 Hz, 1F, Fpa a), −162.34 (m, 2F, Fme a). 31P{1H} NMR
(202.29, MHz, δ, CD3CN): 23.12 ( d, J = 6.8, 2.2 Hz). Anal. Calcd
o C44H33BF9NP2Pd: C, 57.08%; H, 3.59%; N, 1.51%. Found: C,
56.68%; H, 3.44%; N, 1.40%. *The 13C signals o he Cme a and Cipso
(C6F5g oup) could no be obse ed.
Cha ac e iza ion o [Pd(dppp)(η3-Ph−CH−CH−CH-C6F5)]-
(BF4) (12). [Pd(B )(C6F5)(dppp)] (13.4 mg, 0.017 mmol) and
AgBF4(3.4 mg, 0.017 mmol) we e mixed in d y MeCN (0.6 mL) and
s i ed o 15 min a oom empe a u e unde ni ogen. The
suspension was il e ed h ough Kieselguh o emo e he AgB .
Addi ion o a dichlo ome hane solu ion o he diazo compound
N2CH−CH�CHPh (2- old mola amoun in wo po ions, 87 μL,
0.4 M, o al o 0.046 mmol) a o ded an in ense yellow solu ion,
which was s i ed a oom empe a u e o 5 min. Then, he solu ion
was cha ac e ized by NMR. The c ude yield was de e mined by
in eg a ion o he 19F NMR signals in he mix u e, (83%). C ys als
sui able o X- ay analyses we e ob ained by slow di usion o n-
hexane laye ed on o a solu ion o he complex 12 in CHCl3a −28
°C. 1H NMR (499.73 MHz, δ, CH3CN/(CD3)2SO capilla y): 7.72−
7.36 (m, 25H, Ha om), 6.86 ( , J = 12.7 Hz, 1H, Hallyl), 5.36 ( , J = 11.2
Hz, 1H, Hallyl), 4.87 ( , J = 11.2 Hz, 1H, Hallyl).*19F NMR (470.17
MHz, δ, CH3CN, (CD3)2SO capilla y): −141.99 (b , 2F, Fo ho),
−151.53 (BF4), −158.04 ( , J = 20.5 Hz, 1F, Fpa a), −164.00 (m, 2F,
Fme a). 31P{1H} NMR (202.31, MHz, δ, CH3CN, (CD3)2SO
capilla y): AB sys em. νA: 8.50 (d, J = 83.2 Hz, 1P), νB: 7.06 (d, J
= 83.2 Hz, 1P). *The CH2signals o he dppp ligand a e o e lapped
wi h he NCCH3signal.
The analogous eac ions o he dppb and PPh3de i a i es we e
ca ied ou in he same way using an equimola amoun o he
diazocompound. The o ma ion o [Pd(dppb)(η3-Ph−CH−CH−
CH-C6F5)](BF4) (14) was obse ed in 8% yield. 1H NMR (499.73
MHz, δ, CH3CN/(CD3)2SO capilla y): 6.59 ( , J = 12.6 Hz, 1H,
Hallyl), 5.52 ( , J = 11.5 Hz, 1H, Hallyl), 4.91 ( , J = 11.5 Hz, 1H,
Hallyl).*19F NMR (470.17 MHz, δ, CH3CN, (CD3)2SO capilla y):
−140.31 (b , 1F, Fo ho), −143.12 (b , 1F, Fo ho), −151.64 (BF4). The
Fpa a and Fme a as well as he 31P NMR signals ha e no been assigned
due o he e y low concen a ion o η3-allyl-complex in he eac ion
medium.
Cha ac e iza ion o [Pd(dppp)(η3-Ph−CH-C6F5)](BF4) (13).
[Pd(B )(C6F5)(dppp)] (17.7 mg, 0.023 mmol) and AgBF4(4.5 mg,
0.023 mmol) we e mixed in d y MeCN (0.6 mL) and s i ed o 15
min a oom empe a u e unde ni ogen. The suspension was il e ed
h ough Kieselguh o emo e he AgB . The addi ion o a
dichlo ome hane solu ion o he diazo compound N2CHPh (0.0345
mmol, 128 μL, 0.27 M) a o ded an in ense yellow solu ion, which
was s i ed a oom empe a u e o 5 min. Then, he solu ion was
cha ac e ized by NMR. Two isome s we e obse ed, syn:an i = 89:11,
The c ude yield was de e mined by in eg a ion o he 19F NMR
signals in he c ude mix u e (85%). syn-13:1H NMR (499.73 MHz, δ,
CH3CN/(CD3)2SO capilla y): 6.97 (m, 2H, H2, H6), 4.28 (d, JH−P=
4.28 Hz, 1H, Hα).*19F NMR (470.17 MHz, δ, CH3CN, (CD3)2SO
capilla y): −137.02 (m 2F, Fo ho), −151.72 (BF4), −158.84 (m, 1F,
Fpa a), −164.04 (m, 2F, Fme a). 31P{1H} NMR (202.31, MHz, δ,
CH3CN, (CD3)2SO capilla y): 17.29 (d , J = 81.2, 8.2 Hz, 1P), 4.94
(d, J = 81.2 Hz, 1P). an i-13:19F NMR (470.17 MHz, δ, CH3CN,
(CD3)2SO capilla y): −140.16 (m 2F, Fo ho), −150.59 (m, 1F, Fpa a),
−151.72 (BF4), −162.87 (m, 2F, Fme a). *The emaining signals
could no be assigned.
The eac ion o he dppb and PPh3de i a i es we e ca ied ou in
he same way. Complex 15 (dppb) was obse ed in 30% c ude yield.
syn-15:1H NMR (499.73 MHz, δ, CH3CN/(CD3)2SO capilla y):
6.96 (m, 2H, H2, H6), 4.17 (d, J = 11.9 Hz, 1H, Hα).*19F NMR
(470.17 MHz, δ, CH3CN,(CD3)2SO capilla y): −137.02 (m 2F,
Fo ho), −151.66 (BF4), −158.02 (m, 1F, Fpa a), −163.94 (m, 2F,
Fme a). 31P{1H} NMR (202.31, MHz, δ, CH3CN,(CD3)2SO capilla y):
36.55 (d , J = 64.0 Hz, 1P), 11.31 (d, J = 64.0 Hz, 1P). an i-15:1H
NMR (499.73 MHz, δ, CH3CN/(CD3)2SO capilla y): 6.64 (m, 2H,
H2, H6), 4.72 (m, 1H, Hα).*19F NMR (470.17 MHz, δ, CH3CN,
(CD3)2SO capilla y): −140.02 (m 2F, Fo ho), −151.14 (m, 1F, Fpa a),
−151.66 (BF4), −160.67 (m, 2F, Fme a). 31P{1H} NMR (202.31,
MHz, δ, CH3CN,(CD3)2SO capilla y): 28.35 (d, J = 44.9 Hz, 1P),
14.95 (d, J = 44.9 Hz, 1P). *The emaining signals could no be
assigned.
Expe imen s o he Fo ma ion o Complex 12 a Di e en
Diazoalkane Concen a ions. [Pd(C6F5)(dppp)(NCMe)]BF4
(0.028 mmol) and 0.5 mL o d y CH3CN ([Pd]0= 56 mM) we e
added in o an NMR ube along wi h a sealed glass capilla y illed wi h
(CD3)2SO as NMR lock signal unde a ni ogen a mosphe e.
Addi ion o a dichlo ome hane solu ion o he diazo compound
N2CH−CH�CHPh (8) (Pd:8= 1:1, 1:2 and 1:3 mol a io o each
o he h ee expe imen s) a o ded an in ense yellow solu ion, which
was s i ed a oom empe a u e o 5 min. Then, he solu ion was
checked by 19F NMR. The c ude yield o 12 was de e mined by
in eg a ion o he 19F NMR signals in he mix u e: Pd:8= 1:1; 30%.
Pd:8= 1:2; 64%. Pd:8= 1:3; 80%. See Figu e 4.
Compu a ional Me hods. All calcula ions we e pe o med using
he DFT app oach wi h he me a-hyb id GGA M06 unc ional,
20,21
using Gaussian09 as p og am package.
22
The selec ed basis se was 6-
31+G(d) o C, N, F and H,
23,24
and LANL2TZ( ) o Pd
25,26
(Basis
se I). Sol a ion was in oduced in all he op imiza ions, equency
calcula ions and po en ial ene gy e inemen h ough he SMD model,
whe e we applied he expe imen al sol en , ace oni ile (ε= 37.5, a
25 °C). All geome y op imiza ions we e ca ied ou in solu ion wi h
no symme y es ic ions. F ee ene gy co ec ions we e calcula ed a
298.15 K and 105Pa p essu e, including ze o-poin ene gy co ec ions
(ZPE), and he ene gies we e con e ed o 1 M s anda d s a e in
solu ion (adding/sub ac ing 1.89 kcal/mol o nonunimolecula
p ocesses). Vib a ional equency calcula ions we e pe o med o
es ablish he s a iona y poin s we e minima (wi hou imagina y
equencies) o ansi ion s a es (wi h one imagina y equency).
Connec i i y o he ansi ion s a e s uc u es we e con i med by
elaxing he ansi ion s a e geome y owa d bo h he eac an and
he p oduc . Final po en ial ene gies we e e ined by pe o ming
O ganome allics pubs.acs.o g/O ganome allics A icle
h ps://doi.o g/10.1021/acs.o ganome .4c00439
O ganome allics 2025, 44, 394−402
400
addi ional single-poin ene gy calcula ions (also in solu ion), Pd was
s ill desc ibed wi h LANL2TZ( ) basis se , and he emaining a oms
we e ea ed wi h 6- 311++G(d,p) basis se (Basis se II). All epo ed
ene gies in he manusc ip co espond o Gibbs ene gies in solu ion,
ob ained om po en ial ene gies (including sol a ion) wi h basis se
II plus Gibbs ene gy co ec ions wi h basis se I and a e gi en in kcal
mol−1.
■ASSOCIATED CONTENT
*
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.o ganome .4c00439.
Addi ional expe imen al da a, selec ed spec a, compu a-
ional da a including calcula ed po en ial ene gies (PDF)
Coo dina es o he calcula ed s uc u es (XYZ)
Accession Codes
Deposi ion Numbe s 2390734 and 2390743 con ain he
supplemen a y c ys allog aphic da a o his pape . These
da a can be ob ained ee o cha ge ia he join Camb idge
C ys allog aphic Da a Cen e (CCDC) and Fachin o ma ions-
zen um Ka ls uhe Access S uc u es se ice.
■AUTHOR INFORMATION
Co esponding Au ho
Ana C. Albéniz −IU CINQUIMA/Química Ino gánica,
Uni e sidad de Valladolid, Valladolid 47071, Spain;
o cid.o g/0000-0002-4134-1333; Email: [email p o ec ed]
Au ho
F ancisco Villalba −IU CINQUIMA/Química Ino gánica,
Uni e sidad de Valladolid, Valladolid 47071, Spain
Comple e con ac in o ma ion is a ailable a :
h ps://pubs.acs.o g/10.1021/acs.o ganome .4c00439
Au ho Con ibu ions
The manusc ip was w i en h ough con ibu ions o all
au ho s. All au ho s ha e gi en app o al o he inal e sion o
he manusc ip .
No es
The au ho s decla e no compe ing inancial in e es .
■ACKNOWLEDGMENTS
We acknowledge he inancial suppo o he Spanish MICIU
(AEI, g an PID2022-142100NB-I00), he join suppo o he
EU/MICINN/JCyL (C17.I01.P01.S21, H2Me Amo), and he
MEC (FPU-17/04559 ellowship o F. V.).
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