Heteroleptic organostannylenes and an organoplumbylene bearing phosphorus-containing pincer-type ligands - Structural variations and insights into the configurational stability

Article abstract of DOI:10.1002/zaac.201000387

The syntheses of the arylphosphonic esters 3-Br-5-tBu-1-{P(O)(OiPr) ₂}C₆H₃ (1), 5-tBu-1,3-{P(O)(OiPr) ₂}₂C₆H₃ (2), of the heteroleptic intramolecularly coordinated organostannyle

Full text of DOI:10.1002/zaac.201000387

ARTICLE
DOI: 10.1002/zaac.201000387
Heteroleptic Organostannylenes and an Organoplumbylene Bearing
Phosphorus-Containing Pincer-Type Ligands – Structural Variations and
Insights into the Configurational Stability
Markus Henn,[a] Vajk Deáky,[a] Stefan Krabbe,[a] Markus Schürmann,[a]
Marc H. Prosenc,[b] Sonja Herres-Pawlis,[a] Bernard Mahieu,[c] and Klaus Jurkschat*[a]
In Memory of Professor Herbert Schumann
Keywords: Organostannylenes; Organoplumbylenes; Density functional calculations; Arylphosphonic esters;
Pincer-type ligands
Abstract. The syntheses of the arylphosphonic esters 3-Br-5-tBu-1- substituted analogue. Variable-temperature and concentration-depend-
1
ent H and 31P NMR spectra reveal, on the respective time scales, the
tin atom in compound 3 to be configurationally unstable and those in
compounds 6 and 8 to be configurationally stable. DFT calculations
support a chlorido-bridged dimer to account for the configurational in-
stability in compound 3. Surprisingly and in contrast to compounds
3 and 6, the organobromido- and organoiodidostannylenes 4 and 5,
respectively, show intermolecular Sn···Sn distances of 3.6809(4) and
3.5953(4) Å being shorter than twice the van der Waals radius of tin
(2.20 Å). Quantum chemical calculations were performed on mono-
meric and dimeric model compounds, which revealed a weak Sn···Sn
bonding interaction for dimer 3 (16 kJ·mol–1) as well as for dimer 5
(20 kJ·mol–1) whereas the hypothetical model compound p-tBuC6H4SnI
showed an iodido-bridged dimer rather than a Sn···Sn bonding interac-
{P(O)(OiPr)2}C6H3 (1), 5-tBu-1,3-{P(O)(OiPr)2}2C6H3 (2), of the het-
eroleptic intramolecularly coordinated organostannylenes [4-tBu-2,6-
{P(O)(OiPr)2}2C6H2]SnX (3, X = Cl; 4, X = Br; 5, X = I; 6, X = SPh),
the organoplumbylene [4-tBu-2,6-{P(O)(OiPr)2}2C6H2]PbCl (7), and
the transition metal complex [4-tBu-2,6-{P(O)(OiPr)2}2C6H2]Sn(Cl)-
1
Cr(CO)5 (8) are reported. The compounds were characterized by H,
13C, 31P, 31P MAS (3), 119Sn, and 119Sn MAS (3) NMR spectroscopy,
electrospray ionization mass spectrometry (3), Mössbauer spectroscopy
(3–5, 8) and single-crystal X-ray diffraction analyses (2, 3–5, 6–8). In
contrast to its ethoxy-substituted analogue [4-tBu-2,6-{P(O)-
(OEt)2}2C6H2]SnCl, compound 3, like the thiophenolate derivative 6,
is monomeric in solution as well as in the solid state. This difference
is also manifested by the Mössbauer as well as solid state NMR spectro-
scopic data. On the other hand, the corresponding organoplumbylene
7 shows a similar chlorido-bridged polymeric structure as its ethoxy- tion.
of organotin(IV) compounds of type RR'SnXY (R' = organic
Introduction
substituent; Y = halogen).[2] Moreover, they are precursors for
the syntheses of organotin(I) compounds, RSnSnR,[3] the for-
mal tin analogues of alkynes, and of compounds such as
RSnW(PR3)4Cl[4] and RSnM(Cp)(CO)3 (M = Cr, Mo, W)[5]
with the former containing a formal tin–transition metal triple
bond. Only recently, RSnX-type compounds (X = Cl, H) have
been employed, in combination with SnCl2, for the synthesis
of the spectacular heptanuclear organotin cluster [Sn7{C6H3-
2,6-(C6H3-2,6-iPr2)2}2].[6]
Among the class of low-valent tin compounds heteroleptic
organostannylenes of type RSnX (R = organic substituent with
or without donor functionality, X = F, Cl, Br, I, N(SiMe3)2,
SC(S)C6H2-tBu3-2,4,6, Si(SiMe3)3, Sn(SiMe3)3) have attracted
increasing interest over the last two decades.[1] Compounds of
this type are used for the synthesis of novel unsymmetrically
substituted diorganostannylenes of type RR'Sn[1b,s] as well as
* Prof. Dr. K. Jurkschat
Heteroleptic organotin(II) halides, RSnX (X = Cl, Br, I), with
the R group containing an intramolecularly coordinating donor
function are usually monomeric both in solution and in the solid
state with the exception of [Sn{C6H3(NMe2)2-2,6}Cl][7] and
[Sn{CH(SiMe3)C9H6N-8}Br][8] each showing head-to-tail di-
merization via intermolecular N→Sn (3.204(4) Å) and Br→Sn
(3.420 Å) coordination, respectively. For those RSnCl type
compounds containing bulky substituents R monomers as well
as dimers (via intermolecular Sn–Cl···Sn bridges) were reported
for the solid state, to the extent that for [2,6-{2,4,6-
(iPr)3C6H2}2C6H3SnCl both monomer and dimer coexist in one
Fax: +49-231-7555048
E-Mail: klaus.jurkschat@tu-dortmund.de
[a] Lehrstuhl für Anorganische Chemie II
Technische Universität Dortmund
Otto-Hanh-Str. 6
44227 Dortmund, Germany
[b] Institut für Anorganische und Angewandte Chemie
Universität Hamburg
20146 Hamburg, Germany
[c] Laboratoire de Chimie Structurale (CSTR)
Université de Louvain
1348 Louvain-la-Neuve, Belgium
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/zaac.201000387 or from the
author.
Z. Anorg. Allg. Chem. 2011, 637, 211–223
© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
211

K. Jurkschat et al.
ARTICLE
unit cell.[1p] Notably, among the crystallographically character- organoplumbylene [4-tBu-2,6-{P(O)(OiPr)2}2C6H2]PbCl were
ized heteroleptic organotin(II) halides RSnX there are only two also determined. Notably, in the latter, the isopropoxy substitu-
examples with X = Br[8,9] and two examples with X = I,[1l,p] ents at the phosphorus atoms do not change the solid-state
respectively.
structure as compared to the ethoxy-substituted analogue.
1
The H NMR spectra of both (2,6-Me2NCH2)2C6H3SnCl,[1b]
o-C5H4NC(SiMe3)2SnX (X
=
Cl, N(SiMe3)2)[1d] and 8-
Results and Discussion
Syntheses and Molecular Structures in the Solid State
C9H6NCH(SiMe3)SnX (X = Cl, Br)[8] were reported to be tem-
perature-dependent. For the former compound, at –70 °C, both
the methylene and methyl protons are diastereotopic and indi-
cate the lone pair at the tin atom to be stereochemically active.
Coalescence phenomena of the CH2 and NMe2 proton resonan-
ces above –65 °C were interpreted in terms of intramolecular
rearrangement processes such as Sn–N dissociation/association
and inversion of configuration at the tin atom. However, no
attempts were made to distinguish between these two
alternatives.[1b] Later on and based on a more detailed study
including concentration dependence of coalescence tempera-
tures, however, inversion of configuration at the tin atom was
favored.[10] Nevertheless, for the two latter compounds, the co-
alescence phenomena observed for the methyl proton resonan-
ces were discussed in terms of combined N→Sn bond dissoci-
ation and rotation about the Sn–C bond.[1d,8]
The NiBr2-catalyzed reaction of triisopropyl phosphite,
P(OiPr)3, with the aryl dibromide 1,3-Br2-5-tBuC6H3 gave, de-
pending on the stoichiometry of the reagents, the arylphos-
phonic ester 3-Br-5-tBu-1-{P(O)(OiPr)2}C6H3 (1) and the
aryldiphosphonic ester 5-tBu-1,3-{P(O)(OiPr)2}2C6H3 (2) in
good yields (Scheme 1). Compound 1 is a colorless oil
whereas compound 2 is a colorless crystalline material.
For some years we have been interested in the application of
phosphorus-containing O,C,O-coordinating pincer-type ligands
to the synthesis of a variety of organoelement compounds.[11]
In course of these studies we also prepared the heteroleptic
organostannylene [4-tBu-2,6-{P(O)(OEt)2}2C6H2]SnCl and
noticed a considerable difference of the 119Sn NMR chemical
shifts in solution (δ = –100) and in the solid state (δ = –
160).[1o] Moreover, addition of [(Ph3P)2N]+Cl– to a solution
of [4-tBu-2,6-{P(O)(OEt)2}2C6H2]SnCl in CD2Cl2 caused low-
frequency shift of the 119Sn resonance to δ = –163, a value
being close to that of the chemical shift in the solid state.[1o]
The results were interpreted in terms of [4-tBu-2,6-
{P(O)(OEt)2}2C6H2]SnCl being monomeric in solution but, via
chlorido bridges, dimeric (or oligomeric) in the solid state, like
Scheme 1. Synthesis of compounds 1and 2.
The molecular structure of compound 2 is shown in Figure 1
together with selected structural parameters.
the
corresponding
organoplumbylene
[4-tBu-2,6-
{P(O)(OEt)2}2C6H2]PbCl.[11g] Unfortunately, no single crystals
of [4-tBu-2,6-{P(O)(OEt)2}2C6H2]SnCl suitable for X-ray dif-
fraction analysis could be obtained to verify this interpretation.
Bearing in mind the superior crystallization properties of or-
ganoelement compounds containing the isopropoxy- instead of
the ethoxy-substituted pincer-type ligand we decided to synthe-
size [4-tBu-2,6-{P(O)(OiPr)2}2C6H2]Sn(L)X (X = Cl, Br, I; L =
lone pair, Cr(CO)5) and to study their structures in solution as
Figure 1. Molecular structure of compound 2. Selected interatomic
well as in the solid state. We also prepared [4-tBu-2,6- distances /Å: P(1)–O(1) 1.469(3), P(1)–O(1') 1.565(3), P(1)–O(1'')
{P(O)(OiPr)2}2C6H2]SnSPh which is, to the best of our knowl-
edge, the first structurally characterized organotin(II) thiolate.
1.582(3), P(2)–O(2) 1.468(3), P(2)–O(2') 1.570(3), P(2)–O(2'')
1.586(3), O(1)···H(3) 2.65(4), O(2)···H(5) 2.68(4). Selected interatomic
angles /deg: C(1)–C(2)–P(1) 120.0(3), C(1)–C(6)–P(2) 120.5(3), O(1)–
We learned that the structures of these compounds in the solid
state depend indeed on the identity of the substituents at the
phosphorus atom as well as on the X atom even though the
former are remote from the tin atom. Moreover, we found that
the configurational stability in solution of the tin atom in intra-
molecularly coordinated heteroleptic organostannylenes of
type RSn(L)X depends on the identity of X and L. For the
sake of comparison, the molecular structures of the protonated
P(1)–O(1') 117.7(2), O(1)–P(1)–O(1'') 114.6(2), O(1')–P(1)–O(1'')
102.5(2), O(1)–P(1)–C(2) 113.4(2), O(1')–P(1)–C(2) 100.7(2), O(1'')–
P(1)–C(2) 106.3(2), O(2)–P(2)–O(2') 117.9(2), O(2)–P(2)–O(2'')
114.2(2), O(2')–P(2)–O(2'') 102.1(2), O(2)–P(2)–C(6) 113.2(2), O(2')–
P(2)–C(6) 100.3(2), O(2'')–P(2)–C(6) 107.6(2). Selected torsion an-
gles /deg: O(1)–P(1)–C(2)–C(3) 17.6(4), O(2)–P(2)–C(6)–C(5)
11.1(4).
¯
Compound 2 crystallized in the triclinic space group P1 with
ligand 5-tBu-1,3-{P(O)(OiPr)2}2C6H3 and of the heteroleptic two molecules per unit cell.
212 www.zaac.wiley-vch.de
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Heteroleptic Organostannylenes with Pincer-Type Ligands
Like in its ethoxy-substituted analogue 5-tBu-1,3-
{P(O)(OEt)2}2C6H3,[11h] both P=O oxygen atoms O(1) and
O(2) point away from the hydrogen atom H(1), but in contrast
to the latter they are only slightly displaced from the aromatic
plane. There are intramolecular O(1)···H(3) and O(2)···H(5)
distances of 2.65(4) and 2.68(4) Å, respectively, that are
shorter than the van der Waals distances[12] of oxygen (1.50 Å)
and hydrogen (1.20–1.45 Å). Somewhat longer but still in the
range of the sum of the van der Waals radii are the O(1'')···H(1)
and O(2'')···H(1) distances of 2.70(4) and 2.87(4) Å, respec-
tively. Associated with this are slightly longer P(1)–O(1'') and
P(2)–O(2'') distances of 1.582(3) and 1.586(3) Å, respectively.
It is still a matter of controversial debate[13] whether or not
weak C–H···O interactions in the order of magnitude of 0.5–
2.0 kcal·mol–1 influence the molecular structure that is actually
observed in the solid state. One has to be aware that these low
energy effects can be superimposed by crystal packing forces.
The reaction of the in situ-generated organolithium salt
[4-tBu-2,6-{P(O)(OiPr)2}2C6H2]Li with tin(II) halides, SnX2,
and lead dichloride, PbCl2, provided the heteroleptic organo-
stannylenes [4-tBu-2,6-{P(O)(OiPr)2}2C6H2]SnX, (3, X = Cl;
4, X = Br; 5, X = I) and the organoplumbylene [4-tBu-2,6-
{P(O)(OiPr)2}2C6H2]PbCl (7), respectively, in good yields
(Scheme 2). The reaction of the organochloridostannylene 3
with sodium thiophenolate and in situ-generated chromium-
pentacarbonyl tetrahydrofurane, Cr(CO)5(thf), gave the orga-
notin(II)thiophenolate [4-tBu-2,6-{P(O)(OiPr)2}2C6H2]SnSPh
(6), and the chromiumpentacarbonyl organostannylene com-
plex [4-tBu-2,6-{P(O)(OiPr)2}2C6H2]Sn(Cl)Cr(CO)5 (8), re-
spectively (Scheme 2). Compounds 3 and 6 are colorless
whereas 4, 5, 7, and 8 are yellow and green, respectively, crys-
talline solids that are well-soluble in common organic solvents
such as benzene, THF, and dichloromethane.
Figure 2. Molecular structure of compound 3.
Figure 3. Molecular structure of compound 5.
Scheme 2. Synthesis of the organostannylenes 3–6, the transition metal
complex 8, and of the organoplumbylene 7.
The molecular structures of the chlorido-, iodido-, and thio-
phenolato-substituted compounds 3, 5 and 6, respectively, are
shown in Figure 2, Figure 3, and Figure 4, and that of the bro-
mido-substituted derivative 4 is depicted in the Supporting In- Figure 4. Molecular structure of compound 6.
Z. Anorg. Allg. Chem. 2011, 211–223
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213

K. Jurkschat et al.
ARTICLE
Table 1. Selected bond lengths /Å, bond angles, and torsion angles /deg for compounds 3–7.
3 (M = Sn, X = Cl) 4 (M = Sn, X = Br) 5 (M = Sn, X = I) 6 (M = Sn, X = S) 7 (M = Pb, X = Cl)
M(1)–C(1)
M(1)–X(1)
M(1)–X(1A)
M(1)–O(1)
M(1)–O(2)
P(1)–O(1)
P(2)–O(2)
2.244(2)
2.237(2)
2.233(2)
2.231(3)
2.512(1)
2.334(4)
2.836(1)
2.879(1)
2.560(2)
2.4708(8)
2.6286(3)
2.8544(3)
2.430(2)
2.427(2)
1.489(2)
1.483(2)
2.463(2)
2.420(2)
1.484(1)
1.490(2)
2.473(2)
2.408(2)
1.487(2)
1.491(2)
2.478(2)
2.434(2)
1.485(2)
1.485(2)
1.485(2)
C(1)–M(1)–X(1)
O(1)–M(1)–O(2)
C(1)–C(2)–P(1)
94.23(6)
152.01(6)
115.8(2)
115.1(2)
93.73()
94.92(6)
152.23(6)
116.8(2)
115.5(2)
89.38(8)
152.48(7)
114.9(2)
116.9(3)
100.4(1)
90.5(1)
151.94()
117.34(16)
115.55()
147.1(1)
117.6(2)
C(1)–C(6)–P(2)
M(1)–X(1)–C(11)
X(1)–M(1)–M(1A)
X(1)–M(1)–X(1A)
M(1)–X(1A)–M(1A)
170.38(1)
166.96(1)
176.4(1)
126.8(1)
C(1)–Sn(1)–Sn(1A)–C(1A)
X(1)–Sn(1)–Sn(1A)–X(1A)
M(1)–C(1)–C(2)–C(3)
O(1)–P(1)–C(2)–C(3)
180.0(1)
180.0(1)
–177.0(1)
–179.9(1)
180.0(9)
180.0(1)
174.9(2)
179.1(2)
172.8(2)
175.2(2)
–174.3(2)
171.9(2)
171.2(2)
–165.4(3)
174.0(3)
173.5(2)
–170.0(2)
O(2)–P(2)–C(6)–C(5)
formation (Figure S1). Selected geometric parameters are col- of 3.6809(4) (4) and 3.5953(4) Å (5) that are shorter than twice
lected in Table 1.
the van der Waals radius of tin (2.20 Å). To the best of our
knowledge, this is unprecedented for heteroleptic organostan-
nylenes of type RSnX (X = halogen) for which RSn–X···Sn(X)R
rather than R(X)Sn···Sn(X)R bridges are to be expected. Thus,
Leung and co-workers reported the structure of intramolecu-
larly coordinated 8-NC9H6(Me3Si)CHSnBr[8] that forms a
head-to-tail dimer through a SnBrSnBr four-membered ring.
However, a rather similar Sn···Sn distance of 3.639(1) Å was
reported for one out of two modifications of [2,4,6-
(CF3)3C6H2]2Sn.[14]
Compound 3 crystallizes in the orthorhombic space group
P212121 with four molecules in the unit cell. The compounds
4 and 5 are isostructural and crystallize like compound 6 mon-
oclinically in the space group P21/c with four molecules per
unit cell as well. Both compounds 3 and 6 are essentially mon-
omeric; the shortest intermolecular Sn···Sn and Sn···Cl distan-
ces of 8.2966(2) and 7.2568(8) Å, respectively, being beyond
the sum of the van der Waals radii[12] of the respective atoms.
By contrast, the organobromido- and organoiodidostannylenes
4 and 5, respectively, reveal intermolecular Sn···Sn distances
[14]
Figure 5. Schematic representation of the molecular structures of compound 5 (left) and of [{2,4,6-(CF3)3C6H2}2Sn]2 (right). For compound
5 the isopropyl and tert-butyl groups, and for [{2,4,6-(CF3)3C6H2}2Sn]2 the CF3 group in 4-position are omitted for clarity.
214
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Heteroleptic Organostannylenes with Pincer-Type Ligands
The difference between the latter compound and the heter- ligand 5-tBu-1,3-{P(O)(OiPr)2}2C6H3 (2, 1.469(3)/1.468(3) Å)
oleptic stannylenes 4 and 5 is (i) the formal replacement of and fall into the range between 1.483(2) (3) and 1.491(2) (5).
one aryl substituent by a bromine respectively iodine atom and Associated with this is the decrease of the ν(P=O) for 3 (1189,
(ii) the presence of two strong intramolecular P=O→Sn inter- 1162 cm–1), and 6 (1193, 1180 cm–1) with respect to the proto-
actions. The consequence of this is that there are dramatic dif- nated ligand 2 (1250 cm–1). The Sn(1)–Cl(1) distance in com-
ferences in both the bond and torsion angles as it is illustrated pound 3 amounts to 2.4708(8) Å and is comparable with the
in Figure 5.
Sn–Cl
distances
in
[2,6-(Me2NCH2)2C6H3]SnCl
The Mössbauer spectra of the organohalogenidostannylenes (2.488(3) Å),[1b] [2,6-Trip2C6H3]SnCl·Py (2.448(2) Å),[1p] and
3 (I.S. 2.93 mm·s–1; Q.S. 3.30 mm·s–1), 4 (I.S. 3.02 mm·s–1; {2-[C(SiMe3)2]C5H4N}SnCl (2.440(5) Å).[1d] The Sn–Br dis-
Q.S. 3.32 mm·s–1), and 5 (I.S. 3.07 mm·s–1; Q.S. 3.23 mm·s–1) tance of 2.6286(3) Å (4) is shorter than the corresponding dis-
confirm the divalent nature of the tin atoms in these com- tance
in
intramolecularly
N→Sn
coordinated
pounds. Notably, the data for compound 3 differ considerably [Sn{CH(SiMe3)C9H6N-8}Br] (2.679(1) Å),[8] whereas the Sn–
from those measured for the ethoxy-substituted analogue [4- I distance of 2.8544(3) (5) Å is longer than the corresponding
tBu-2,6-{P(O)(OEt)2}2C6H2]SnCl (I.S. 3.24 mm·s–1, Q.S. distance reported for [Sn(I){C6H3-2,6-Trip2}] (2.766(2) Å)[1l]
3.51 mm·s–1)[1o] and underline the structural difference be- with the tin atom of the latter being two-coordinate. The
tween both compounds. The same statement holds for the 119Sn Sn(1)–S(1) bond length in compound 6 of 2.512(1) Å resem-
MAS chemical shift of δ = –96 (3) vs. δ = –160 ([4-tBu-2,6- bles the corresponding Sn–S distances of 2.532–2.552 Å in the
{P(O)(OEt)2}2C6H2]SnCl).[1o] On the other hand, the Möss- trithiophenolato stannates [Ph4E][Sn(SPh)3] (E = P,[16] As[17a]).
bauer data are not sensitive toward the structural differences
For both compounds 3 and 6, the Sn(1), O(1), and O(2) at-
between the organochloridostannylene 3 (monomeric) on the oms are only slightly displaced from the plane defined by the
one hand and the organobromido- and organoiodidostannyl- aromatic carbon atoms (see torsion angles in Table 1).
enes 4 and 5, respectively, (Sn···Sn approach) on the other
The molecular structure of the organochloridoplumbylene 7
hand. Notably, the I.S.’s for SnCl2 (4.06 mm·s–1),[15a] SnBr2 is shown in Figure 6. Selected bond lengths and bond angles
(3.95 mm·s–1),[15b] and SnI2 (3.90 mm·s–1)[15c] are larger and are given in Table 1.
show the opposite trend with the biggest value found for
In contrast to the corresponding organochloridostannylene 3,
SnCl2. However, the I.S.-differences between 3 and 5 compound 7 shows almost the same μ-chlorido-bridged poly-
(0.14 mm·s–1) and between SnCl2 and SnI2 (0.16 mm·s–1) are meric structure like its ethoxy-substituted analogue.[11g] Minor
rather similar.
differences between both structures are the slightly shorter
O(1)–Pb(1) distance of 2.518(2) Å and the more symmetric
Pb–Cl···Pb bridge with Pb(1)–Cl(1) and Pb(1)–Cl(1A) distan-
ces of 2.836(1) and 2.879(1) Å, respectively, for compound
7. A notable feature in the structure of compound 7 is the
intramolecular H(14)···Cl(1) distance of 2.759(1) Å that is
shorter than the sum of the van der Waals radii of chlorine
(1.70–1.90 Å) and hydrogen (1.20–1.45 Å), which seems to
influence the conformation of the P–O–CH(CH3)3 moiety.
The molecular structure of the organochloridostannylene
chromiumpentacarbonyl complex 8 is shown in Figure 7. Se-
The Sn(1) atoms in the organostannylenes 3–5 and 6 exhibit
ψ-trigonal bipyramidal configurations with C(1), X(1) (3–5,
X = Cl, Br, I; 6, X = S), and the lone pair occupying the equato-
rial, and O(1), O(2) occupying the axial positions. The stereo-
chemical activity of the lone pair at Sn(1) is especially mani-
fested in the C(1)–Sn(1)–X(1) bond angles ranging between
94.9(1)°(5) and 89.4(1)° (6). The former is close to that re-
ported for 2,6-(Me2NCH2)2C6H3SnCl (95.0(3)°)[1b] and the lat-
ter is the smallest value found among related derivatives con-
taining a CSnX fragment; the biggest value of 101.6(4)° being
reported for [2-{C(SiMe3)2}C5H4N]SnCl.[1d] The C(1)–Sn(1)–
X(1) angles found for 3–5 and 6 hint at high s-character of the
lone pair at Sn(1) in these compounds. The O(1)–Sn(1)–O(2)
angles fall into the narrow range of 151.9(1) (4) and 152.5(1)°
(6). They are similar to the corresponding angle in [4-tBu-2,6-
{P(O)(OEt)2}2C6H2]SnSiPh3 (151.0(1)°)[1o] and are mainly the
result of ligand constraint. The intramolecular Sn(1)–O(1)/
O(2) distances are rather similar and vary between 2.427(2)
(3) and 2.478(2) Å (6). The two phosphorus atoms in 3–5 and
6 are crystallographically nonequivalent and, exemplarily, for
compound 3 this is nicely reflected by a 31P{1H}MAS NMR
(161.98 MHz) spectrum showing two equally intense resonan-
ces at δ = 33.2 and 34.4. The C(1)–C(2)–P(1)/C(1)–C(6)–P(2)
angles (α/α' angles)[11h] between 114.9(2) (6) and 117.3(2)° (4)
support the idea that the Sn–O interactions are attractive. Simi-
lar angles (114.9(5)/114.5(3)°) were observed for the diorgano-
tin dichloride [4-tBu-2,6-{P(O)(OEt)2}2C6H2]SnPhCl2.[11o] As
a result of the O→Sn coordination, the P(1)–O(1)/P(2)–O(2)
distances in 3–5 and 6 are longer than those of the protonated Figure 6. Molecular structure of compound 7.
Z. Anorg. Allg. Chem. 2011, 211–223
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215

K. Jurkschat et al.
ARTICLE
lected bond lengths and angles are given in the Figure caption. O(2) atoms occupying the axial, and the C(1), Cl(1) and Cr(1)
The molecular structure of compound 8 strongly resembles atoms occupying the equatorial positions. Most remarkably,
that of its ethoxy-substituted analogue [4-tBu-2,6- the intramolecular P=O→Sn interactions in compound 8
{P(O)(OEt)2}2C6H2]Sn(Cl)Cr(CO)5.[1o] The tin atom shows a (O(1)–Sn(1) 2.316(2), O(2)–Sn(1) 2.347(2) Å) are stronger
distorted trigonal bipyramidal configuration with the O(1) and than in the parent stannylene 3 (O(1)–Sn(1) 2.430(2), O(2)–
Sn(1) 2.427(2) Å) and indicate an enhanced Lewis acidity of
the tin atom in the transition metal complex 8.
DFT Calculations
The unusual tin–tin interaction in the solid state of two RSnX
molecules (4, X = Br; 5, X = I) raises the question for its energy
and the factors that influence the latter. To probe alternative
bonding modes we considered first the geometry optimization
of the monomeric compounds RSnX (3c, X = Cl; 5c, I),
(Scheme 3).
Optimized geometric parameters of complexes 3c and 5c are
listed in Table 2. The calculated distances d(Sn–X) of 2.524 Å
(3c) and of 2.935 Å (5c), d(Sn)–C and d(Sn–O1), d(Sn–O2)
and calculated angles of C–Sn–Cl of 90.7° and C–Sn–I of
92.9° are in good agreement with those obtained by X-ray dif-
fraction analysis. The most predominant feature of the struc-
ture of both 3c and 5c is a bend of the halogenido ligand to-
wards the aryl substituent due to the inert electron pair effect
at the tin atom.
Figure 7. Molecular structure of compound 8. Selected interatomic
distances /Å: Sn(1)–C(1) 2.177(2), Sn(1)–Cl(1) 2.403(1), Sn(1)–Cr(1)
Table 2. Selected bond lengths /Å, bond angles, and torsion angles /
2.5783(4), Sn(1)–O(1) 2.316(2), Sn(1)–O(1) 2.347(2). Selected intera-
deg for calculated monomeric (3c and 5c) and dimeric structures 3cd
tomic angles /deg: C(1)–Sn(1)–Cl(1) 97.54(6), C(1)–Sn(1)–Cr(1)
and 5cd.
141.24(6), Cl(1)–Sn(1)–Cr(1) 121.14(2), O(1)–Sn(1)–O(2) 155.82(6),
C(1)–C(2)–P(1) 115.2(2), C(1)–C(6)–P(2) 115.1(2). Selected torsion
angles /deg: Sn(1)–C(1)–C(2)–C(3) 179.1(2), O(1)–P(1)–C(2)–C(3) –
176.5(2), O(2)–P(2)–C(6)–C(5) –176.8(2).
3c (X = Cl) 5c (X = I) 3cd (X = Cl) 5cd (X = I)
Sn–Sn
3.758
3.704
2.935
1.661
2.277
92.9
2.485
2.491
152.0
2.535
2.672
1.513
1.513
Sn–X
2.509
2.902
X1–Sn–Sn
Sn–C
1.718
2.280
90.7
2.510
2.480
152.0
2.670
2.650
1.513
1.511
2.295
90.2
2.508
2.488
151.2
2.293
92.4
2.495
2.490
151.2
X–Sn–C
Sn–O1
Sn–O2
O–Sn–O
H1–O1
H2–O2
P1–O1
P2–O2
1.510
1.510
1.510
1.510
For the calculation of the dimers two putative structures were
taken into account. A dichlorido-bridged four-membered ring
A (Scheme 3) and a geometry B (Scheme 3) with a tin–tin
bridge actually found in the solid state for compounds 4 and
5. The geometry optimization of the A type dimer with chlo-
rido bridges resulted in Sn–Cl···Sn bond dissociation and for-
mation of two monomeric complexes 3c.
We therefore considered the B type dimers 3cd and 5cd as
the most likely structure for the dimerization of two RSnX (X =
Cl, I) moieties. Geometry optimization revealed the geometry
parameters listed in Table 2 with calculated energies that are
16 and 20 kJ·mol–1 below the energy of two monomeric RSnCl
and RSnI species, respectively. Thus, the formation of dimers
3cd and 5cd is energetically favorable but apparently the bind-
ing energy is very low and, especially for the chlorido-substi-
Scheme 3. Schematic presentation of the different geometries for
which MO calculations were performed. The lone electron pairs for
3c, 5c, and (A)–(C) are omitted for clarity.
216
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Heteroleptic Organostannylenes with Pincer-Type Ligands
tuted compound 3, might be compensated for by interactions observed at room temperature upon dilution of the sample. The
with solvent molecules in solution and by packing forces in 1H NMR spectrum of a diluted sample (1 mg/0.6 mL
the solid state.
[D8]toluene) measured at 599.83 MHz even showed complete
To gain further insights into the unusual Sn···Sn bonding we de-coalescence into four equally intense doublets for the
analyzed the orbital contributions from each RSnX fragment. methyl protons of the isopropoxy groups. Addition of tetra-
A molecular orbital analysis revealed an interaction diagram phenylphosphonium chloride, Ph4PCl, to this solution again
for two monomeric compounds 3c to a dimer 3cd (Supporting caused coalescence of the four doublets into two doublets.
Information, Figure S3). The main interaction results from two
The 119Sn NMR spectrum (149.21 MHz, [D8]toluene) of
filled fragment orbitals which can be assigned as lone pairs of compound 3 showed a triplet resonance at δ = –99 (J(119Sn–
the SnII fragment. The interaction of the two occupied orbitals 31P) 121 Hz) which, upon cooling of the solution to –85 °C,
results in a 2-center-4-electron repulsion which is stabilized by broadened and shifted to δ = –114 (ν1/2 500 Hz). Addition of
a mixing from the empty antibonding Sn–X orbitals. The de- one molar equivalent of Et4NCl caused no change of the chem-
gree of mixing depends on the electronegativity of the substitu- ical shift, neither at room temperature nor at –85 °C. The 31P
ent X. It is slightly larger for X = I than for X = Cl. Thus, NMR spectrum (161.98 MHz) is virtually temperature- and
the Sn–Sn bonding interaction becomes stronger for X = I. In solvent-independent and displayed resonances at δ = 37.5
addition, a short C–H···O interaction of 2.395(2) Å between (J(31P–119Sn) 120 Hz, [D8]toluene, T = 25 °C), δ = 38.3
the methine proton of one of the isopropoxy substituents and (J(31P–119Sn) 114 Hz, [D8]toluene, T = –85 °C), and δ = 38.1
the Sn–O–P bridging oxygen atom was found in the solid-state (J(31P–119Sn) 117 Hz, [D8]THF, T = –85 °C), respectively.
1
structure of complex 5 as determined by single crystal X-ray
In contrast to the organochloridostannylene 3, the H NMR
diffraction analysis as well as in the optimized structure of spectrum ([D8]toluene, 599.83 MHz) of the thiophenolato-sub-
complex 5cd (2.507 Å). This interaction might contribute to stituted derivative 6 does not show coalescence phenomena
the stability of the dimer in complex 3cd as well as 5cd.
upon variation of temperature and/or concentration. Thus, at
Interestingly, the availability of the antibonding Sn–X orbit- ambient temperature four doublets at δ = 0.95 (3J(1H–1H)
als also depends on the presence of intramolecular P=O→Sn 6.0 Hz), 1.05 (3J(1H–1H) 6.0 Hz), 1.16 (3J(1H–1H) 6.0 Hz),
interaction. Thus, the DFT calculation-based geometry optimi- and 1.33 (3J(1H–1H) 6.0 Hz) were observed for the methyl pro-
zation for the hypothetical model compound p-tBuC6H4SnI in tons of the isopropoxy groups, and two multiplet signals cen-
which the two phosphonyl moieties, P(O)(O–iPr)2, had been tered at δ = 4.46 and 5.23, respectively, for the methine (CH)
removed revealed an iodido-bridged dimer (Figure S2, Sup- protons. The 31P and 119Sn NMR spectra each displayed a sin-
porting Information) rather than a Sn···Sn interaction.
gle resonance at δ = 35.3 (J(31P–119Sn) 98 Hz) and δ = –2
(J(119Sn–31P) 98 Hz), respectively.
These results indicate the dynamic process to account for the
coalescence phenomena in the H NMR spectra of compound
1
Structures in Solution
3 to take place at the tin rather than at the phosphorus atom
and to involve the equilibria shown in Scheme 4 (for absence
of additional chloride ions) and Scheme 5 (presence of addi-
tional chloride ions).
In solution, the aryldiphosphonic ester 2 as well as the organ-
1
ostannylenes 3–5 and 6 are essentially monomeric. The H
NMR spectrum (C6D6, 599.83 MHz) of compound 2 showed
a singlet resonance for the tert-butyl protons, a multiplet for
the methine protons, AA'XX' and AB2X2 resonances for the aro-
matic protons and most importantly, two doublet resonances of
equal integral at δ = 1.02 (3J(1H–1H) 6.3 Hz) (a) and δ = 1.17
(3J(1H–1H) 6.3 Hz) (b) that are assigned to nonequivalent
methyl protons of the isopropoxy groups. NOE experiments
reveal the low-frequency shifted doublet (a) to belong to those
methyl protons being close to the aromatic protons.
1
The H NMR spectrum (C6D6 or [D8]toluene, 599.83 MHz)
of the organochloridostannylene 3 is both concentration- and
temperature-dependent. Thus, at room temperature the spec-
trum of
a medium-concentrated sample (12 mg/0.6 mL
Scheme 4. Schematic view along the P···Sn axis (above) and the equi-
librium that accounts for the concentration dependence of the coales-
cence phenomena (below).
[D8]toluene) is similar to that of compound 2, except that there
is no AB2X2-type resonance and that the doublet at δ = 1.25 is
slightly broadened in comparison to that at δ = 0.97. At –17 °C
the signal at δ = 1.25 de-coalesced into two equally intense
For the organothiophenolatostannylene 6 the equilibrium
doublets at δ = 1.34 (3J(1H–1H) 6.1 Hz) and 1.16 (3J(1H–1H) (Scheme 4) is slow (or even absent) on the 1H NMR time scale
6.1 Hz), respectively, whereas the doublet at δ = 0.97 (3J(1H– and consequently, the α-, β-, γ-, and δ-methyl protons are non-
1H) 6.0 Hz) remained virtually unchanged. Simultaneously, the equivalent (Scheme 4). For the organochloridostannylene 3,
signal for the methine protons de-coalesced into two broad and the equilibrium (Scheme 4) is fast at ambient temperature and/
equally intense resonances at δ = 4.90 and 5.36, respectively. or at high concentration. The α- and γ-, and the β- and δ-
Most importantly, the same de-coalescence phenomena were methyl protons become equivalent resulting in observation of
Z. Anorg. Allg. Chem. 2011, 211–223
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217

K. Jurkschat et al.
ARTICLE
Scheme 5. Proposed mechanism that accounts for the configurational instability of compounds 3 (L = lone pair) and 8 [L = Cr(CO)5] in presence
of chloride anion.
two equally intense doublets. At low concentration and/or low ents. Apparently, for this compound, like for the organothio-
1
temperature the equilibrium becomes slow on the H NMR phenolatostannylene 6, any association is precluded by steric
time scale giving rise to de-coalescence of the α- and γ-methyl hindrance. However, coalescence of these four doublet reso-
proton resonances into two equally intense doublets. DFT cal- nances into one doublet at δ = 1.18 (J(1H–1H) 6.0 Hz) and a
culations reveal that the monochlorido-bridged dimer C rather broad (ν1/2 67 Hz) signal at δ = 0.95 (just coalescing),
(Scheme 3) lies in a thermodynamic minimum (in contrast to and a broadening (pre-coalescence) of the two methine reso-
the dichlorido-bridged dimer A in Scheme 3) being only nances was achieved by addition of tetraphenylphosphonium
5.4 kJ·mol–1 higher in energy than two separate monomers.
chloride, Ph4PCl. It clearly indicates the mechanism shown in
In the presence of additional chloride anions, the equilibrium Scheme 5 to be operative.
according to Scheme 5 is fast even at rather low concentration.
Finally, direct evidence for the absence of a dissociative
Important to notice is that the concentration of both the dimer mechanism for the configurational lability of the tin atom in
(equilibrium shown in Scheme 4) and the organodichloridos- intramolecularly coordinated organostannylenes of the type [4-
tannite (D) (equilibrium shown in Scheme 5) is rather low and tBu-2,6-{P(O)(OiPr)2}2C6H2]SnX (X = electronegative substit-
contributes only negligibly to the 119Sn NMR chemical shift uent such as halogen, alkoxide, thiolate, amide) stems from the
actually observed. Formation of an organotin(II) cation (E) by 19F and 119Sn NMR spectra of the organofluoridostannylene
loss of chloride ion (Scheme 3, Scheme 5) would also cause [4-tBu-2,6-{P(O)(OiPr)2}2C6H2]SnF that was prepared in situ
coalescence. However, DFT calculations show that this process by the reaction of the organotin(II) amide [4-tBu-2,6-
requires much more energy (517 kJ·mol–1) than formation of {P(O)(OiPr)2}2C6H2]SnN(iPr)2 with ammonium fluoride,
the organodichloridostannite D (133 kJ·mol–1, Scheme 3, NH4F. The 19F and 119Sn NMR spectra displayed a singlet res-
Scheme 5). With respect to these calculations it is worth men- onance at δ –138.4 (1J(19F–117/119Sn) 3051/3194 Hz) and a
tioning that the electrospray mass spectrum (positive mode) of doublet of triplet resonance at δ –202 (1J(119Sn–19F) 3191,
the organochloridostannylene 3 showed a mass cluster centered J(119Sn–31P) 108 Hz), respectively. The 1J(119Sn–19F) coupling
at
m/z
581
that
corresponds
to
[4-tBu-2,6- constant is close to that recently reported for LSnF [L =
{P(O)(OiPr)2}2C6H2]Sn+ whereas in the negative mode no HC(CMeNAr)2, Ar = 2,6-iPr2C6H3).[1s] Details for the synthe-
mass cluster corresponding to the organodichloridostannite an- sis of [4-tBu-2,6-{P(O)(OiPr)2}2C6H2]SnF will be presented in
–
ion [4-tBu-2,6-{P(O)(OiPr)2}2C6H2]SnCl2 was detected. Ap- a forthcoming paper.
parently, under ESI-MS conditions cations show up more eas-
ily than anions do.
Conclusions
In this work we report the syntheses and structures in solu-
The equilibrium shown in Scheme 4 gets support from (i)
the 31P NMR spectrum of an equimolar mixture of the organo-
chloridostannylene 3 (δ = 37.8) and the organoiodidostannyl- tion and in the solid state of a series of intramolecularly coordi-
ene 5 (δ = 36.9) to show one broad resonance at δ = 37.2 nated heteroleptic organostannylenes of the type [4-tBu-2,6-
indicating fast exchange, and (ii) the 31P NMR spectrum of an {P(O)(OiPr)2}2C6H2]Sn(X)L (X = Cl, Br, I, SPh; L = lone pair,
equimolar mixture of 3 and the organothiophenolatostannylene Cr(CO)5) and of the organoplumbylene [4-tBu-2,6-
6 to show two resonances at δ = 37.8 and δ = 35.4, respec- {P(O)(OiPr)2}2C6H2]PbCl. We learned that the tin atom in the
tively, indicating slow (or no) exchange. Furthermore, the organochloridostannylene 3 (X = Cl, L = lone pair) is configu-
chromiumpentacarbonyl-substituted organostannylene
8 is rationally not stable whereas the thiophenolato-substituted de-
1
configurationally stable and shows in its H NMR spectrum rivative 6 (X = SPh, L = lone pair) and the chromiumpentacar-
regardless of the concentration four equally intense doublet bonyl complex 8, under the same conditions, do not show
resonances for the methyl protons of the isopropoxy substitu- exchange of configuration at the tin atom. NMR spectroscopy
218
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Heteroleptic Organostannylenes with Pincer-Type Ligands
ples being maintained at 90 +/– 2 K. The data were treated with a
least-square iterative program deconvoluting the spectrum into a sum
of lorentzians.
at variable temperature and concentration as well as DFT cal-
culations make an associative mechanism to account for the
configurational lability of compound 3 very likely, rather than
a dissociative one. This supports the interpretation made by
van Koten et al. for the dynamic behavior of the organostannyl-
ene (2,6-Me2NCH2)2C6H3SnCl,[1b,10] the findings by Lappert
et al. on the halide exchange in β-diketiminatotin(II)
The electrospray mass spectra were recorded on a Thermoquest-Finni-
gan instrument using CH3CN as the mobile phase. The samples were
introduced as solution in CH3CN via a syringe pump operating at a
rate of 0.5 μL·min–1. The capillary voltage was 4.5 kV while the cone
halides[17b] and our previous results on the ethoxy-substituted skimmer voltage varied between 50 and 250 kV. Identification of the
expected ions was assisted by comparison of experimental and calcu-
lated isotope distribution patterns. The m/z values reported correspond
to those of the most intense peak in the corresponding isotope pattern.
Elemental analyses were performed with a LECO-CHNS-932 analyzer.
heteroleptic
organostannylene
[4-tBu-2,6-
{P(O)(OEt)2}2C6H2]SnCl.[1o]
Most importantly, the association behavior in the solid state
of [4-tBu-2,6-{P(O)(OR)2}2C6H2]SnX (R = Et, iPr; X = Cl, Br,
I, SPh) depends on the identity of both R and X. Whereas the
ethoxy-substituted organochloridostannylene (R = Et, X = Cl)
is more likely a chlorido-bridged dimer or polymer, its isoprop-
oxy-substituted analogue 3 (R = iPr, X = Cl) is a monomer. On
the other hand, the bromido (R = iPr, X = Br) and iodido (R =
iPr, X = I) substituted derivatives 4 and 5 are dimers with weak
tin–tin interactions. As suggested by MO calculations, the lat-
ter are made possible by participation of empty Sn–X (X = Cl,
I) σ* orbitals the availability of which is higher for X = I than
X = Cl, and which is influenced by the presence of intramolec-
X-ray Crystallography
Intensity data for the colorless crystals were collected with a Nonius
KappaCCD diffractometer with graphite-monochromated Mo-Kα
(0.71073 Å) radiation at 173(1) K. The data collection covered almost
the whole sphere of reciprocal space with two (3), three (2, 4, 6, 7),
four (8), and five (5) sets at different κ-angles with 317 (2), 194 (3),
288 (4), 395 (5), 234 (6), 230 (7), and 418 (8) frames via ω-rotation
(Δ/ω = 1°) at two times 10s (8), 20s (4, 5), 30s (3), 90s (2), 125s (7),
and 150s (6) per frame. The crystal-to-detector distance was 3.4 cm
ular donor–acceptor interactions such as P=O→Sn in com- (2, 4–8) and 4.0 cm (3). Crystal decay was monitored by repeating the
pounds 3–6, and CF3→Sn in [2,4,6-(CF3)3C6H2]2Sn.[14] The
initial frames at the end of data collection. The data were not corrected
weak secondary bond thus formed between two SnII atoms is
for absorption effects. Analyzing the duplicate reflections there was no
indication for any decay. The structure was solved by direct methods
supported by nonbonding interactions as well as weak van der
SHELXS97[18] and successive difference Fourier syntheses. Refine-
Waals interactions.
ment applied full-matrix least-squares methods SHELXL97.[19]
Notably, it appears that the concept can be generalized for
weak interactions between organo compounds of low-valent
Only the positions of H(1), H(3), and H(5) in compound 2 were refined
whereas all other hydrogen atoms were placed in geometrically calcu-
heavy elements. Thus, recently Beckmann et al. reported the
solid-state structures of the organotellurium compounds 2,4,6- lated positions using a riding model with isotropic temperature factors
tBu3C6H2TeCl[17c] and 8-Me2NC10H6TeCl[17d] that have a
constrained at 1.2 for non-methyl and at 1.5 for methyl groups times
Ueq of the carrier carbon atom.
rather similar substituent pattern but differ by the absence re-
spectively presence of an intramolecular N→Te interaction.
In 3 isopropoxy and tert-butyl groups are disordered over two sites
The former compound is a chlorido-bridged polymer whereas
with occupancies of 0.4 (C(8'), C(9') C(10'), C(15'), C(16')), of 0.5
the latter compound shows a weak Te···Te interaction at a dis-
(C(12), C(13), C(12'), C(13'), C(25), C(26), C(25'), C(26')), and 0.6
tance of 3.87(1) Å.
(C(8), C(9) C(10), C(15), C(16)) and in 8 an isopropoxy group with
occupancies of 0.4 (C(23') and 0.6 (C(23)). The solvent molecule tolu-
ene in 8 was refined with an occupancy of 0.5 and a set of restraints
to aid in modeling the disorder (AFIX 66 for aromatic rings and DFIX
1.540(1) for methyl aryl distances).
Experimental Section
General: All solvents were dried and purified by standard procedures.
All reactions were carried out in an atmosphere of dry argon. Varian
INOVA 600, Bruker DRX400, Bruker DRX500 and Bruker DPX-300
spectrometers were used to obtain 1H, 13C, 31P, and 119Sn NMR spectra.
1H, 13C, 31P, and 119Sn NMR chemical shifts are given in ppm and
were referenced to Me4Si, H3PO4 (85 %, 31P) and Me4Sn (119Sn). The
31P CP-MAS and 119Sn CP-MAS spectra were recorded with a Bruker
Avance 400 spectrometer at room temperature. CP/MAS (cross-polari-
zation/magic angle spinning) experiments were used with repetition
delays of 8 s (31P) and 10 s (119Sn), and the contact times were set at
7 ms (31P) and 10 ms (119Sn). Three spinning rates (3000, 5000,
8000 Hz, 31P; 6000, 7000, 9000 Hz, 119Sn) were used to identify the
isotropic chemical shift. The 31P and 119Sn chemical shifts were cali-
brated using H3PO4 (85 %) and tetracyclohexyltin (δ = –97.35), re-
spectively. The IR spectra were recorded with a Bruker IFS 28 spec-
trometer. The Mössbauer spectra were recorded in constant-
acceleration mode with a home-made instrument, designed and built
Atomic scattering factors for neutral atoms and real and imaginary
dispersion terms were taken from International Tables for X-ray
Crystallography.[20] The figures were created by SHELXTL.[21] Crys-
tallographic data are given in Table 3.
Crystallographic data for the structure reported in this paper have been
deposited with the Cambridge Crystallographic Data Centre as supple-
mentary material publications no. CCDC-801082 (2), -801081 (3),
-801085 (4), -801086 (5), -801084 (6), -801087 (7), -801083 (8). Cop-
ies of the data can be obtained free of charge on application to CCDC,
12 Union Road, Cambridge, CB2 1EZ, UK (Fax: +44-1223-336033;
E-Mail: deposit@ccdc.cam.ac.uk).
Computational Details
by the Instituut voor Kern- en Stralingsfysica (IKS), Leuven. The iso- For all calculations on the density functional theory level, the Program
mer shifts refer to a source of Ca119mSnO3 from Amersham, UK, sam- Turbomole was used.[22] Energies and geometries were developed on
Z. Anorg. Allg. Chem. 2011, 211–223
© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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219

K. Jurkschat et al.
ARTICLE
Table 3. Crystallographic data for compounds 2–8.
2
3
4
5
6
7
8
formula
fw
C22H40O6P2
462.48
C22H39ClO6P2Sn
615.61
C22H39BrO6P2Sn
660.07
monoclinic
0.24 × 0.20 × 0.20
P21/c
C22H39IO6P2Sn
707.06
C28H44O6P2SSn
689.32
C22H39ClO6P2Pb
704.11
orthorhombic
0.10 × 0.10 × 0.06
Pnma
C27H39ClCrO11P2Sn·0.5C7H8
853.73
cryst syst
cryst size /mm
space group
a /Å
triclinic
orthorhombic
monoclinic
monoclinic
triclinic
0.08 × 0.08 × 0.05 0.13 × 0.10 × 0.10
0.22 × 0.22 × 0.20 0.05 × 0.05 × 0.05
P21/c
0.20 × 0.20 × 0.18
¯
¯
P1
P212121
10.6527(2)
16.4053(3)
17.0227(3)
90
P21/c
P1
9.5782(4)
11.3408(4)
13.2396(7)
79.841(2)
89.141(2)
66.130(2)
1292.0(1)
2
13.2715(5)
12.5282(7)
18.3363(7)
90
13.4089(6)
12.5379(6)
18.4434(7)
90
19.7239(9)
9.8231(4)
18.1094(8)
90
10.2171(4)
18.886(1)
15.1732(9)
90
10.8903(2)
11.2655(2)
16.3422(3)
86.1897(7)
84.5212(8)
78.5213(7)
1953.55(6)
2
b /Å
c /Å
α /deg
β /deg
90
90
105.180(3)
90
105.136(2)
90
107.344(2)
90
90
90
γ /deg
V /Å3
2974.90(9)
4
2942.4(2)
4
2993.1(2)
4
3349.2(3)
4
2927.8(3)
4
Z
ρcalcd. /Mg·m–3
μ /mm–1
F(000)
1.189
1.374
1.490
1.569
1.367
1.597
1.451
0.200
1.086
2.366
2.022
0.956
5.994
1.118
500
1264
1336
1408
354
1392
870
θ range /deg
index ranges
2.96 to 27.55
–12 ≤ h ≤ 12
–12 ≤ k ≤ 14
–17 ≤ l ≤ 17
12924
3.13 to 27.48
–13 ≤ h ≤ 13
–21 ≤ k ≤ 21
–22 ≤ l ≤ 22
18250
2.92 to 27.47
–17 ≤ h ≤ 17
–16 ≤ k ≤ 16
–23 ≤ l ≤ 22
26849
2.91 to 27.48
–17 ≤ h ≤ 17
–16 ≤ k ≤ 16
–23 ≤ l ≤ 23
37446
2.98 to 25.35
–23 ≤ h ≤ 22
–11 ≤ k ≤ 11
–21 ≤ l ≤ 21
23080
2.63 to 27.48
–13 ≤ h ≤ 13
–24 ≤ k ≤ 24
–19 ≤ l ≤ 19
21374
2.02 to 27.48
–14 ≤ h ≤ 14
–13 ≤ k ≤ 14
–20 ≤ l ≤ 21
25780
no. of reflns collcd
completeness to θmax 98.0
99.2
6617 / 0.031
3780
99.8
6734 / 0.033
4007
99.8
6844 / 0.036
4161
99.6
6100 / 0.065
3314
99.9
3454 / 0.041
1855
99.4
8901 / 0.034
6060
no. of indep reflns/Rint 5843 / 0.077
no. of reflns obsd
2849
with [I > 2σ(I)]
no. of refined Params 291
370
0.709
300
0.773
300
0.834
354
0.801
173
0.657
448
0.913
GooF (F2)
0.992
R1 (F) [I > 2σ(I)]
wR2 (F2) (all data)
(Δ/σ)max
0.0771
0.2229
0.001
0.0249
0.0400
0.001
0.0279
0.0422
<0.001
0.504 / –0.821
0.0273
0.0427
0.001
0.0352
0.0556
0.001
0.0248
0.0380
0.001
0.0354
0.0582
0.001
largest diff. peak/hole / 0.875 / –0.401
0.337 / –0.364
0.575 / –1.287
0.561 / –0.453
1.058 / –1.775
0.532 / –0.477
e·Å–3
the nonlocal level of theory. For geometry optimization the energies (60 mL, 240 mmol) was added to a magnetically stirred suspension of
were corrected for nonlocal exchange according to Becke[23,24] and for 1,3-dibromo-5-tert-butylbenzene (30,0 g, 102 mmol) and NiBr2 (4,5 g,
nonlocal correlation according to Perdew (BP-86)[25] in the self-con- 21 mmol). The dark brown suspension thus obtained was kept at
sistent procedure. The TZVPPP-split valence base set was used for 160 °C for additional 2 hrs during which the isopropyl bromide formed
chlorine, bromine, phosphorus, oxygen, carbon and hydrogen (17.8 g, 145 mmol) was condensed into a dry ice-cooled trap. After
atoms.[26,27] For tin and iodine we used an effective core potential base the crude reaction product had been pre-purified by column chroma-
set (ECP-28-mwb) with triple-zeta functions for the valence region and tography (silica gel/chloroform) it was distilled in vacuo to give 31,0 g
an additional d polarization function supplied by the program. For the (67 %) 5-tBu-1,3-[P(O)(O-iPr)2]2C6H31as colorless viscous oil that im-
Jij term approximation an additional auxiliary base set was used.[22,28] mediately solidified (m.p. 64–65 °C). H NMR (400.13 MHz, C6D6):
3
All stationary points were checked by second derivative calculations δ = 1.02 (d, 12 H, CH(CH3)(CH3)', J(1H–1H) = 6.3 Hz), 1.06 (s, 9 H,
3
revealing no imaginary frequency for the minima.
C(CH3)3), 1.17 (d, 12 H, CH(CH3)(CH3)', J(1H–1H) = 6.3 Hz), 4.68
(unresolved multiplet, 4 H, CH(CH3)2), 8.32 (AA'XX', 2 H, H4, H6),
8.59 (t, 1 H, 3J(31P–1H) = 20.5 Hz, H2). 13C{1H} NMR (100,63 MHz,
CDCl3): δ = 23.8 (s, CH(CH3)(CH3)'), 24.1 (s, CH(CH3)(CH3)'), 31.2
(s, C(CH3)3), 35.1 (s, C(CH3)3), 70.9 (s, CH(CH3)2), 130.2 (dd, C1,
For inclusion of dispersion (van der Waals) effects in the investigation
of the Sn···Sn dimers single-point calculations using the functional
B97-d[29] were employed on previously optimized geometries. For the
calculation of the species C, D and E, a TZVPP-split valence basis set
was used.[30]
C3, J(13C–31P) = 188.6, J(13C–31P) = 14.6 Hz), 132.1–132.6 (com-
1
3
plex pattern, C2, C4/6), 151.6 (t, C5, J(13C–31P) = 26.2 Hz). 31P{1H}
2
NMR (161.98 MHz, CDCl ): δ = 17.3. IR (KBr): ν (P=O) =
˜
3
1250 cm–1. Elemental analysis: C22H40P2O6 (462.23 g·mol–1); C 57.2
Syntheses
(calcd. 57.13); H 8.5 (8.72)%.
1-Bromo-3-diisopropoxyphosphonyl-5-tert-butylbenzene (1): 1,3-
Dibromo-5-tert-butylbenzene (39.6 g, 140 mmol) and nickel bromide,
NiBr2, (1.7 g, 7.8 mmol) were heated at 165 °C. Triisopropyl phos-
phite, P(O-iPr)3, (35 mL, 140 mmol) was added dropwise within
30 min and the reaction mixture was kept at 165 °C for another
180 min, during which it turned black. The crude product was purified
by column chromatography (silica, diethyl ether) to give 16.4 g (32 %)
of compound 1 as brown oil. 1H NMR (300.13 MHz, CDCl3): δ =
1.20 (d, 3J(1H–1H) = 6.2 Hz, 6 H), 1.29 (s, 9 H, C(CH3)), 1.34 (d,
3J(1H–1H) = 6.2 Hz, 6 H), 4.66 (doublet of septets, 3J(1H–1H) = 6,
3J(1H–31P) = 9 Hz, 2 H, CH(CH3)2), 7.62–7.73(complex pattern, aro-
matic H, 4 H). 31P{1H} NMR (121.49 MHz, CDCl3): δ = 16.1. No
elemental analysis was performed.
{[2,6-Bis(diisopropoxyphosphonyl)-4-tert-butyl]phenyl}tin(II) chlo-
ride, {4-tBu-2,6-[P(O)(O-iPr)2]2C6H2}SnCl (3): A 0.75 m solution
(36 mL, n-hexane/diethyl ether: 1/0.8) of lithium diisopropyl amide
(27.5 mmol) was added dropwise within 20 min and at –60 °C to a
solution of 4-tBu-2,6-[P(O)(O-iPr)2]2C6H3 (10.3 g, 22.2 mmol) in
THF (80 mL). After stirring the reaction mixture for 7 h at –40 °C,
within 30 min, SnCl2 (4.7 g, 24.8 mmol) was added in small portions.
The reaction mixture was allowed to warm to room temperature over-
night. After evaporating the solvents in vacuo the residue was extracted
with hot n-hexane (3 × 100 mL) to provide 11.1 g (81 % yield) of
compound 3 as colorless crystals of mp. 132 °C, suitable for X-ray
diffraction analysis. 1H NMR (300.13 MHz, C6D6): δ = 1.04 (d, 12
H, CH(CH3)2, 3J(1H–1H) = 6.2 Hz), 1.17 (s, 9 H, C(CH3)3, 1.30 (d, 12
5-tBu-1,3-bis(diisopropoxyphosphonyl)benzene, 5-tBu-1,3-[P(O)- H, CH(CH3)2, J(1H–1H) = 5.9 Hz), 4.90 (m, 4 H, CH(CH3)2, J(1H–
3
3
(O-iPr)2]2C6H3 (2): Within 2.5 h and at 160 °C, triisopropyl phosphite 1H) = 6.1, 3J(1H–31P) = 7.3 Hz), 8.08 (d, 2 H, H3/5, 3J(31P–1H) =
220
www.zaac.wiley-vch.de
© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2011, 211–223

Heteroleptic Organostannylenes with Pincer-Type Ligands
13.0 Hz). 1 3 C{1 H} NMR (75.47 MHz, C6 D6 ):δ = 23.4 (d, (J(31P–117/119Sn) = 112/117 Hz). 119Sn{1H} NMR (111.92 MHz,
CH(CH3)(CH3)', J(13C–31P) = 5.4 Hz), 23.8 (d, CH(CH3)(CH3)', C6D6): δ = –22 (J(31P–119Sn) = 117 Hz). Mössbauer spectroscopy:
J(13C–31P) = 3.6 Hz), 30.7 (s, C(CH3)3), 34.5 (s, C(CH3)3), 72.1 (s, I.S. 3.07 mm·s– 1, Q.S. 3.23 mm·s– 1. Elemental analysis:
CH(CH3)2), 131.6 (dd, C3/5, 2J(13C–31P) = 16.7, 4J(13C–31P) = 4.4 Hz), C22H39IO6P2Sn (707.10 g·mol–1); C 37.1 (calcd. 37.37); H 5.9
132.6 (dd, C2/6, 1J(13C–31P) = 192.2, 3J(13C–31P) = 23.6 Hz), 150.9 (5.56) %.
3
2
(t, C4, J(13C–31P) = 12.5 Hz), 186.7 (t, C1, J(13C–31P) = 36.3 Hz).
31P{1H} NMR (121.49 MHz, C6D6): δ = 37.8 (J(31P–117/119Sn) = 113/
119 Hz). 31P MAS NMR (161.98 MHz): δ = 34.4, 33.2. 119Sn{1H}
NMR (111.92 MHz, C6D6): δ = –99 (J(119Sn–31P) = 119 Hz.
119Sn{1H}MAS NMR (149.21 MHz): δ = –96. Mössbauer spectro-
scopy: I.S. 2.93 mm·s–1, Q.S. 3.30 mm·s–1. Elemental analysis:
{[2,6-Bis(diisopropoxyphosphonyl)-4-tert-butyl]phenyl}tin(II) thio-
phenolate, [4-tBu-2,6-{P(O)(OiPr)2}2C6H2]SnSPh (6): Under mag-
netically stirring and at room temperature, sodium thiophenolate,
PhSNa, (0,055 g, 0,42 mmol) was added to a solution of {4-tBu-2,6-
[P(O)(O-iPr)2]2C6H2}SnCl (3) (0,251 g, 0,41 mmol) in THF (20 mL).
After the reaction mixture had been stirred for 24 h, the precipitate of
sodium chloride was filtered. The solvent of the filtrate was removed
in vacuo to give a solid residue. The latter was recrystallized from
toluene (10 mL) to afford 187 mg (66 %) of compound 6 as colorless
crystals (m.p. 124–126 °C). 1H NMR (400.13 MHz, [D8]toluene): δ =
0.95 (d, 6H, CH(CH3)(CH3)', 3J(1H–1H) = 6.3 Hz), 1.05 (d, 6H,
C
22H39ClO6P2Sn (615.65 g·mol–1); C 42.8 (calcd. 42.92); H 6.3
(6.39) %.
[2,6-Bis(diisopropoxyphosphonyl)-4-tert-butyl]phenyl}tin(II) bro-
mide, {4-tBu-2,6-[P(O)(O-iPr)2]2C6H2}SnBr (4): A 0.75 m solution
(n-hexane/ethyl ether: 1/0.8) of lithium diisopropyl amide (36 mL,
27.5 mmol) was added dropwise within 20 min to a solution of 4-tBu-
2,6-[P(O)(O-iPr)2]2C6H3 10.3 g, 22.2 mmol) in THF (80 mL). After
stirring the reaction mixture for 7h at –40 °C, SnBr2 (4.7 g,
24.8 mmol) was added in small portions within 30 min at –30 °C. The
reaction mixture was allowed to warm to room temperature overnight.
After removing of the solvents in vacuo the residue was extracted with
hot n-hexane (3 × 100 mL) to give 8.9 g (61 %) of compound 4 as
pale yellow crystals, mp. 111 °C that were suitable for X-ray diffrac-
tion analysis. 1H NMR (300.13 MHz, C6D6): δ1.05 (d, 12 H,
3
CH(CH3)(CH3)', J(1H–1H) = 6.0 Hz), 1.15 (s, 9H, C(CH3)3), 1.16 (d,
6H, CH(CH3 )(CH3 )', 3 J(1 H–1 H) = 6.0 Hz), 1.33 (d, 6 H,
3
CH(CH3)(CH3)', J(1H–1H) = 6.0 Hz), 4.44–4.49 (unresolved multip-
let, 2H, CH(CH3)2), 5.20–5.25 (unresolved multiplet, 2H, CH(CH3)2),
6.94–7.14 (complex pattern, 3H, CHSPh), 7,95–7,99 (complex pattern,
4H, CHSPh + CHaryl3/5). 13C{1H} NMR (100.63 MHz, [D8]toluene):
δ = 23.2–23.8 (complex pattern, CH(CH3)2), 30.6 (s, C(CH3)3), 34.2
(s, C(CH3)3), 71.2 (d, CH(CH3)2, J(13C–31P) = 5.3 Hz), 71.8 (d,
CH(CH3)2, J(13C–31P) = 3.9 Hz), 127.9 (s, CSPh–meta), 128.7 (s,
2
4
3
C
SPh–ortho), 131.2 (dd, C3/5, J(13C–31P) = 16.5, J(13C–31P) = 4.4 Hz),
CH(CH3)(CH3)', J(1H–1H) = 6.2 Hz), 1.17 (s, 9 H, C(CH3)3, 1.30 (d,
133,1 (s, CSPh–para), 133,5 (dd, C2/6, 1J(13C–31P) = 192,4, 3J(13C–31P) =
23,8 Hz), 142,9 (s, CSPh–ipso), 150.2 (t, C4, 3J(13C–31P) = 12.6 Hz),
12 H, CH(CH3)(CH3)', J(1H–1H) = 5.9 Hz), 4.92 (m, 4 H, CH(CH3)2,
3J(1H–1H) = 6.0, 3J(1H–31P) = 7.5 Hz), 8.10 (d, 2 H, H3/5, 3J(31P–
1H) = 13.5 Hz). 13C{1H} NMR (75.47 MHz, C6D6):δ = 23.5 (d,
CH(CH3)(CH3)', J(13C–31P) = 4.8 Hz), 23.8 (d, CH(CH3)(CH3)',
J(13C–31P) = 3.9 Hz), 30.7 (s, C(CH3)3), 34.4 (s, C(CH3)3), 72.1 (d,
182.9 (t, C1, J(13C–31P) = 35.2 Hz). 31P{1H} NMR (161.98 MHz,
2
[D8]toluene): δ = 35.3 (J(31P–119/117Sn) = 97 Hz). 119Sn{1H} NMR
(149,21 MHz, [D8]toluene): δ = –2 (J(31P–119/Sn) = 98 Hz). IR (KBr):
2
ν(P=O) = 1193 cm–1, 1180 cm–1. No elemental analysis was per-
CH(CH3)2, J(13C–31P) = 4.9 Hz), 131.6 (dd, C3/5, J(13C–31P) = 17.0,
˜
4J(13C–31P) = 4.4 Hz), 150.0 (t, C4, 3J(13C–31P) = 12.0 Hz), 174.2 (dd,
formed.
1
3
2
C2/6, J(13C–31P) = 54.1, J(13C–31P) = 4.7 Hz), 184.6 (t, C1, J(13C–
31P) = 35.3 Hz). 31P{1H} NMR (121.49 MHz, C6D6): δ37.6 (J(31P–
117/119Sn) = 114/118 Hz). 119Sn{1H} NMR (111.92 MHz, C6D6): δ–69
(J(31P–119Sn) = 118 Hz. Mössbauer spectroscopy: I.S. 3.02 mm·s–1,
Q.S. 3.32 mm·s– 1 . Elemental analysis: C2 2 H3 9 BrO6 P2 Sn
(660.10 g·mol–1); C 39.9 (calcd. 40.03); H 5.7 (5.96) %.
[2,6-Bis(diisopropoxyphosphonyl)-4-tert-butyl]phenyl}lead(II)
chloride, [4-tBu-2,6-{P(O)(OiPr)2}2C6H2]PbCl (7): At –60 °C, a
0.75 m solution (36 mL, n-hexane/ethyl ether: 1/0.8) of lithium diiso-
propyl amide (27.5 mmol) was added dropwise over a period of
20 min to a solution of 4-tBu-2,6-[P(O)(O-iPr)2]2C6H3 (10.3 g,
22.2 mmol) in THF (80 mL). After stirring the yellow reaction mixture
for 7h at –40 °C, within 30 min, lead dichloride, PbCl2 (6.9 g,
24.8 mmol) was added in small portions. The reaction mixture was
stirred for additional 12 h during which it warmed to room tempera-
ture. After evaporating all volatiles in vacuo the residue was extracted
three times with hot n-hexane (3 × 70 mL). The extracts were com-
bined and the solvents evaporated in vacuo to give a solid material.
This was recrystallized from hot n-hexane to afford 3.20 g (20 %) of
{[2,6-Bis(diisopropoxyphosphonyl)-4-tert-butyl]phenyl}tin(II) io-
dide, {4-tBu-2,6-[P(O)(O-iPr)2]2C6H2}SnI (5): A 0.75 m solution (n-
hexane/diethyl ether: 1/0.8) of lithium diisopropyl amide (27.5 mmol,
36 mL) was added dropwise within 20 min to a solution of 4-tBu-
2,6-[P(O)(O-iPr)2]2C6H3 (10.3 g, 22.2 mmol) in THF (80 mL). After
stirring the reaction mixture for 7 h at –40 °C, SnI2 (4.7 g, 24.8 mmol)
was added in small portions within 30 min at –30 °C. The reaction
mixture was allowed to warm to room temperature overnight. After
the solvents had been removed in vacuo, the residue was extracted
with hot n-hexane (3 × 100 mL) to afford 8.3 g (53 %) of compound
5 as deep yellow crystals of mp. 138 °C that were suitable for X-ray
diffraction analysis. 1H NMR (300.13 MHz, C6D6): δ = 0.96 (d, 12
1
compound 7 as colorless crystals of mp. 159 °C (decomposition). H
3
NMR (300.13 MHz, C6D6): δ = 1.06 (d, 6 H, CH(CH3)(CH3)', J(1H–
1H) = 6.0 Hz), 1.25 (d, 6 H, CH(CH3)(CH3)', 3J(1H–1H) = 6.0 Hz),
1.32 (s, 9 H, C(CH3)3, 1.35 (d, 6 H, CH(CH3)(CH3)', 3J(1H–1H) =
3
6.0 Hz), 1.41 (d, 6 H, CH(CH3)(CH3)', J(1H–1H) = 6.0 Hz), 4.66 (m,
3
3
2 H, CH(CH3)2, J(1H–1H) = 6.1, J(31P–1H) = 7.3 Hz), 4.86 (m, 2 H,
3
H, CH(CH3)(CH3)', J(1H–1H) = 6.2 Hz), 1.05 (s, 9 H, C(CH3)3, 1.19
3
CH(CH3)2, 3J(1H–1H) = 6.1, J(31P–1H) = 7.3 Hz), 8.06 (AXX', 2 H,
(d, 12 H, CH(CH3)(CH3)', J(1H–1H) = 6.0 Hz), 4.83 (m, 4 H,
CHaryl,
3J(31P–1H) = 13.0 Hz). 31P{1H} NMR (121.49 MHz, C6D6):
3
3
CH(CH3)2, J(1H–1H) = 6.0, J(31P–1H) = 7.5 Hz), 7.96 (d, 2 H, H3/
5, 3J(31P–1H) = 13.4 Hz). 13C{1H} NMR (75.47 MHz, C6D6):δ = 23.5
(d, CH(CH3)(CH3)', 3J(13C–31P) = 4.8 Hz), 23.8 (d, CH(CH3)(CH3)',
δ = 50.5 (J(3 1 P–2 0 7 Pb) = 125 Hz). Elemental analysis:
C22H39ClO6P2Pb (705.14); C 36.9 (calcd. 37.47); H 5.4 (5.57) %.
3J(13C–31P) = 3.9 Hz), 30.7 (s, C(CH3)3), 34.4 (s, C(CH3)3), 72.1 (d, {[2,6-Bis(diisopropoxyphosphonyl)-4-tert-butyl]phenyl}tin(II) chlo-
CH(CH3)2, 2J(13C–31P) = 4.9 Hz), 131.6 (dd, C3/5, 2J(13C–31P) = 16.4, ride tungsten pentacarbonyl, {{2,6-[P(O)(OiPr)2]2-4-tBu}C6H2}-
4J(13C–31P) = 4.2 Hz), 132.8 (dd, C2/6, J(13C–31P) = 192.7, J(13C– SnCl[Cr(CO)5] (8): A solution of the organostannylene {4-tBu-2,6-
31P) = 23.7 Hz), 151.1 (t, C4, 3J(13C–31P) = 12.2 Hz), 182.6 (t, C1, [P(O)(O-iPr)2]2C6H2}SnCl (3) (1,55 g, 2,5 mmol) and chromium hex-
2J(13C–31P) = 35.5 Hz). 31P{1H} NMR (121.49 MHz, C6D6): δ = 36.9 acarbonyl, Cr(CO)6 (0,55 g, 2,5 mmol) in THF (250 mL) was irradi-
1
3
Z. Anorg. Allg. Chem. 2011, 211–223
© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
221

K. Jurkschat et al.
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3511.
ated with UV light (Hg high pressure lamp, 150 W) until the formation
of carbon monoxide gas stopped. After removing the solvent in vacuo
the yellow-green residue was extracted with toluene (40 mL). The tol-
uene solution was concentrated in vacuo to one third of its volume and
stored at –30 °C to give 1.71 g (85 %) of compound 8, as its toluene
1
solvate 8·0.5 C7H8, as yellow crystals of m.p. 139–141 °C. H NMR
3
(400.13 MHz, C6D6): δ = 0.94 (d, 6 H, CH(CH3)(CH3)', J(1H–1H) =
6.0 Hz), 1.10 (s, 15 H, C(CH3)3 + CH(CH3)2, ν1/2 = 12 Hz), 1.24 (d,
6
H, CH(CH3)(CH3)', 3J(1H–1H)
=
7.5 Hz), 1.26 (d,
6
H,
3
CH(CH3)(CH3)', J(1H–1H) = 6.7 Hz), 4.74–4.96 (complex pattern, 4
H, CH(CH3)2), 8.06 (d, CHaryl, J(1H–31P) = 13.3 Hz). 13C{1H} NMR
3
(100.63 MHz, C6D6): δ = 21.0 (complex pattern, CH(CH3)(CH3)'),
21.3 (complex pattern, CH(CH3)(CH3)'), 21.5 (complex pattern,
CH(CH3)(CH3)'), 30.4 (s, C(CH3)3), 34.6 (s, C(CH3)3), 73.6–73.8
(complex pattern, CH(CH3)2), 131.8 (dd, C3/5,
2J(13C–31P) = 14.6,
4J(13C–31P) = 4.8 Hz), 131.8 (dd, C2/6
,
1J(13C–31P) = 188.1, 3J(13C–
3
31P) = 19.9 Hz), 153.7 (t, C4aryl, J(13C–31P) = 11.2 Hz), 171.7 (t, C1,
2J(13C–31P) = 25.8 Hz), 219.4 (s, COcis 2J(13C–119Sn) = 129.3 Hz),
,
225.7 (s, COtrans). 31P{1H} NMR (161.98 MHz, C6D6): δ = 30.4
(J(31P–117/119Sn) = 178 Hz). 119Sn{1H} NMR (149.21 MHz, C6D6): δ =
127.9 (J(119Sn–31P) = 182 Hz). IR (Nujol): ν(P=O) = 1182 cm–1,
˜
1155 cm–1; ν(CO) = 1932 cm–1, 2051 cm–1. Mössbauer spectro-
˜
scopy: IS = 2.01 mm·s–1, QS = 3.50 mm·s–1. Elemental analysis:
C27H39P2O11SnCrCl·0.5 C7H8 (853.84 g·mol–1); C 42.7 (calcd. 42.90);
H 5.0 (5.08) %.
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Supporting Information (see footnote on the first page of this article):
Molecular structure of 4 (Figure S1), calculated structure (BP86/def2-
TZVP) of the hypothetical compound p-t-BuC6H4SnI (Figure S2) and
molecular orbital interaction diagram of compound 3 (Figure S3).
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Acknowledgement
We thank Dr. G. Bradtmöller for recording the 31P and 119Sn MAS
NMR spectra and Professor B. Costisella for performing the NOE ex-
periments. Mrs. Sylvia Marzian is acknowledged for recording the
electrospray ionization mass spectra.
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Received: October 26, 2010
Published Online: December 29, 2010
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© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
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