Deprotonated iminophosphorane o-C6H4Ph2P double bond NSiMe3 as a novel ligand to stabilize a diarylstannylene and -plumbylene via side arm donation

Article abstract of DOI:10.1021/om0003988

Lithiation of triphenyl(trimethylsilylimino)phosphorane Ph₃P double bond NSiMe₃ with MeLi gives the ortho-metalated species [Li(o-C₆H₄PPh₂NSiMe₃)]₂·Et₂O (1). It has all the requirements of an organometallic ligand capable of side arm donation: the deprotonated ortho phenyl carbon atom leads to metal-carbon σ bonds in reactions with metal halides, and the Ph₂P double bond NSiMe₃ moiety donates an electron pair to that metal via the imine nitrogen atom. In reactions with SnCl₂ the Sn(II) organometallic complex [Sn(o-C₆H₄PPh₂NSiMe₃)₂] (2) was obtained, while with PbCl₂ a new example of the rare lead(II) organometallic complexes was obtained. In [Pb(o-C₆H₄PPh₂NSiMe₃)₂] (3) the lead(II) center is bonded to the two orthocarbon atoms and additionally stabilized by two Pb←N donor bonds. In all metal complexes the Ph₂P double bond NSiMe₃ unit acts as a side arm donating group via nitrogen.

Full text of DOI:10.1021/om0003988

3890
Organometallics 2000, 19, 3890-3894
Dep r oton a ted Im in op h osp h or a n e o-C6H4P h 2P dNSiMe3 a s
a Novel Liga n d To Sta bilize a Dia r ylsta n n ylen e a n d
-p lu m bylen e via Sid e Ar m Don a tion †
Stefan Wingerter,‡ Heinz Gornitzka,§ Ru¨diger Bertermann,‡ Sushil K. Pandey,|
J oa˜o Rocha, and Dietmar Stalke*,‡
Institut fu¨r Anorganische Chemie der Universita¨t Wu¨rzburg, Am Hubland,
D-97074 Wu¨rzburg, Germany, Laboratoire He´te´rochimie Fondamentale et Applique´e,
Universite´ Paul Sabatier, 118 Route de Narbonne, F-31062 Toulouse Cedex 04, France,
Department of Chemistry, University of J ammu, New Campus, J ammu-180006, India, and
Department of Chemistry, University of Aveiro, P-3800 Aveiro, Portugal
Received May 10, 2000
Lithiation of triphenyl(trimethylsilylimino)phosphorane Ph3PdNSiMe3 with MeLi gives
the ortho-metalated species [Li(o-C6H4PPh2NSiMe3)]2‚Et2O (1). It has all the requirements
of an organometallic ligand capable of side arm donation: the deprotonated ortho phenyl
carbon atom leads to metal-carbon σ bonds in reactions with metal halides, and the Ph2Pd
NSiMe3 moiety donates an electron pair to that metal via the imine nitrogen atom. In
reactions with SnCl2 the Sn(II) organometallic complex [Sn(o-C6H4PPh2NSiMe3)2] (2) was
obtained, while with PbCl2 a new example of the rare lead(II) organometallic complexes
was obtained. In [Pb(o-C6H4PPh2NSiMe3)2] (3) the lead(II) center is bonded to the two ortho-
carbon atoms and additionally stabilized by two PbrN donor bonds. In all metal complexes
the Ph2PdNSiMe3 unit acts as a side arm donating group via nitrogen.
In tr od u ction
nor contacts of methyl groups to the low-valent metal
center were not observed in [Sn{2,4,6-(Me3C)3C6H2}2]2.8
However, the 2,4,6-tris(trifluoromethyl)phenyl ligand
was recently successfully employed in the synthesis of
the first plumbylene dimer [Pb{2,4,6-(F3C)3C6H2}{Si-
Since the synthesis of the first dialkylstannylene [Sn-
{CH(SiMe3)2}2]2,1 a heavy carbene analogue that dimer-
izes in the solid state and exhibits a Sn-Sn distance of
2.764(2) Å,2 by Lappert et al., stannylenes and plum-
bylenes have attracted continued interest.3 After the
synthesis of the first dialkylplumbylene, [Pb{CH-
(SiMe3)2}2]2,2 another 15 years went by until the first
diarylplumbylene was synthesized and structurally
characterized.4 In the monomeric [Pb{2,4,6-(F3C)3C6H2}2]
molecule four short Pb‚‚‚F contacts supported the low-
coordinate lead(II) center. Apart from the steric bulk
of the 2,4,6-tris(trifluoromethyl)phenyl ligand it was
this feature that stabilized the monomeric stannylene
[Sn{2,4,6-(F3C)3C6H2}2]5 as well as the dimeric species
9
(SiMe3)3}]2 with a Pb‚‚‚Pb distance of 3.537(1) Å
(synthesis and structure of [Pb{Si(SiMe3)3}2] see ref 10).
The side arm donation concept has been applied to
stabilize Sn(II) centers by formation of SnrN donor
bonds. R-Metalated aryl ligands substituted with R2N-
(CH2)n amino groups make intramolecular complexation
possible (a in Chart 1).
Compounds such as [Sn{C6H4CH2NMe2-o}2],11 [Sn-
{C(SiMe3)2C5H4N-2}2]12 [Sn{C10H6NMe2}2],13 and [Sn-
{2,6-(NMe2)2C6H3}2]14 exhibit two Sn-C σ bonds and
two SnrN donor bonds, leaving the tin(II) center four-
coordinated. In general, side arm donation encourages
organotin compounds to be monomeric species.15 In the
6
[Sn{2,4,6-(F3C)3C6H2}2]2 with a long-range Sn‚‚‚Sn
interaction (3.639(1) Å). Short metal-fluorine distances
have already been observed in the starting material
[Et2O‚Li{2,4,6-(F3C)3C6H2}2]2.7 Potential additional do-
(7) Stalke, D.; Whitmire, K. H. J . Chem. Soc., Chem. Commun. 1990,
833.
(8) Weidenbruch, M.; Schlaefke, J .; Scha¨fer, A.; Peters, K.; von
Schnering, H. G.; Marsmann, H. Angew. Chem. 1994, 106, 1938;
Angew. Chem., Int. Ed. Engl. 1994, 33, 1846.
(9) Klinkhammer, K. W.; Fa¨ssler, T. F.; Gru¨tzmacher, H. Angew.
Chem. 1998, 110, 114; Angew. Chem., Int. Ed. 1998, 37, 124.
(10) Klinkhammer, K. W.; Schwarz, W. Angew. Chem. 1995, 107,
1448; Angew. Chem., Int. Ed. Engl. 1995, 34, 1334.
(11) Angermund, K.; J onas, K.; Kru¨ger, C.; Latten, J . L.; Tsay, Y.-
H. J . Organomet. Chem. 1988, 353, 17.
(12) (a) Engelhardt, L. M.; J olly, B. S.; Lappert, M. F.; Raston, C.
L.; White, A. H. J . Chem. Soc., Chem. Commun. 1988, 336. (b) J olly,
B. S.; Lappert, M. F.; Engelhardt, L. M.; White, A. H.; Raston, C. L. J .
Chem. Soc., Dalton Trans. 1993, 2653.
† Dedicated to Professor Max Schmidt on the occasion of his 75th
birthday.
‡ Institut fu¨r Anorganische Chemie der Universita¨t Wu¨rzburg.
§ Laboratoire He´te´rochimie Fondamentale et Applique´e.
| University of J ammu.
University of Aveiro.
(1) Davidson, P. J .; Lappert, M. F. J . Chem. Soc., Chem. Commun.
1973, 317.
(2) Davidson, P. J .; Harris, D. H.; Lappert, M. F. J . Chem. Soc.,
Dalton Trans. 1976, 2268.
(3) Recent review: Driess, M.; Gru¨tzmacher, H. Angew. Chem. 1996,
108, 900; Angew. Chem., Int. Ed. Engl. 1996, 35, 827.
(4) Brooker, S. A.; Buijink, J .-K.; Edelmann, F. T. Organometallics
1991, 10, 25.
(5) Gru¨tzmacher, H.; Pritzkow, H.; Edelmann, F. T. Organometallics
1991, 10, 23.
(13) J astrzebski, J . T. B. H.; van der Schaaf, P. A.; Boersma, J .; van
Koten, G.; Heijdenrijk, D.; Goubitz, K.; de Ridder, D. J . A. J .
Organomet. Chem. 1989, 367, 55.
(6) Lay, U.; Pritzkow, H.; Gru¨tzmacher, H. J . Chem. Soc., Chem.
Commun. 1992, 260.
(14) Drost, C.; Hitchcock, R. B.; Lappert, M. F.; Pierssens, L., J .-M.
J . Chem. Soc., Chem. Commun. 1997, 1141.
10.1021/om0003988 CCC: $19.00 © 2000 American Chemical Society
Publication on Web 08/18/2000

Deprotonated Iminophosphorane o-C6H4Ph2PdNSiMe3
Organometallics, Vol. 19, No. 19, 2000 3891
Ch a r t 1. Am in o Sid e Ar m Don a tion (a ) ver su s
Im in o Sid e Ar m Don a tion (b)
F igu r e 1. Solid state structure of [Sn(o-C6H4PPh2-
NSiMe3)2] (2); anisotropic displacement parameters are
depicted at the 50% probability level.
compounds discussed in this paper the R2N(CH2)n amino
group is formally replaced by a Me3SiNdPPh2 imino
group within the deprotonated triphenyl(trimethylsi-
lylimino)phosphorane Ph3PdNSiMe3 (b in Chart 1).
Lithiation and reactivity of the trimethyl(trimethylsi-
lylimino)phosphorane Me3PdNSiMe3 have been studied
earlier by Schmidbaur et al.,16 and the structure of the
[(LiCH2)Me2PdNSiMe3]4 tetramer was determined re-
cently by Dehnicke et al.17
lography were obtained within 3 days of storage of its
ether solution at room temperature. The blocks turned
colorless when exposed to traces of air. Data were
collected at -90 °C, because at slightly lower temper-
atures they cracked due to a destructive solid/solid
phase transition.
The structure of [Sn(o-C6H4PPh2NSiMe3)2] (2) dis-
plays two Sn-C σ bonds and two SnrN donor bonds in
the monomer (Figure 1). The two Sn-C distances of
2.243(3) and 2.232(3) Å (Table 1), respectively, fall in
the range covered by other Sn-C(aryl) bonds in di-
arylstannylenes (av 2.214(5) Å in [Sn{2,6-(NMe2)2-
C6H3}2],14 av 2.222(3) Å in [Sn{C6H4CH2NMe2-o}2],11
2.225(5) Å in [Sn{2,6-(Mes)2C6H3}2],19 2.261(4) Å in [Sn-
{2,4,6-(Me3C)3C6H2}2],8 and 2.281(5) Å in [Sn{2,4,6-
(F3C)3C6H2}2]5). The SnrN bonds in 2 of 2.495(2) and
2.575(2) Å differ significantly, as in the structure of [Sn-
{C6H4CH2NMe2-o}2]11 (2.516(3) and 2.660(3) Å). In [Sn-
{2,6-(NMe2)2C6H3}2]14 the two shortest Sn‚‚‚N distances
are 2.607(5) and 2.669(5) Å. The C-Sn-C angle of
86.88(9)° in 2 is remarkably acute, and to our knowledge
it is the smallest ever observed in a diorganostannylene.
They range from 95.3° in SnMe220, 98.3(1)° in [Sn{2,4,6-
(F3C)3C6H2}2],5 100.5(1)° in [Sn{C6H4CH2NMe2-o}2],11
103.6(1)° in [Sn{2,4,6-(Me3C)3C6H2}2],8 112° in [Sn{CH-
(SiMe3)2}2]2,2 to 114.7(2)° in [Sn{2,6-(Mes)2C6H3}2].19
This small value even below 90° is in accordance with
the electronic configuration of a 1σ2 singlet carbene
homologue at Sn with the lone pair in a spherical s
orbital and both bonding electrons in orthogonal p
orbitals each.3,15b Normally the ideal 90° angle is
expected to be widened by steric repulsion between the
substituents. In 2, however, it is squeezed below 90° due
to parallel orientation of the bonded phenyl rings and
NSiMe3/phenyl repulsion of both substituents across the
metal. Because of the limited bite of the ligand the
NfSnrN angle of 164.05(7)° is bent from linearity
toward the bisection of the C-Sn-C angle.
Resu lts a n d Discu ssion
P r ep a r a tion of 1-3. Lithiation of triphenyl(trim-
ethylsilylimino)phosphorane Ph3PdNSiMe3 with MeLi
gives [Li(o-C6H4PPh2NSiMe3)]2‚Et2O (1) according to eq
1.18 The C2 symmetric dimer contains a tetrahedrally
coordinated and a trigonal planar coordinated lithium
atom. We embarked on the synthesis of organometallic
compounds using the lithiated triphenyl(trimethylsi-
lylimino)phosphorane as a starting material, because
[Li(o-C6H4PPh2NSiMe3)]2‚Et2O (1) meets all the require-
ments of a ligand capable of side arm donation: the
deprotonated ortho phenyl carbon atom should lead to
metal-carbon σ bonds in transmetalation reactions, and
the Ph2PdNSiMe3 moiety should donate an electron
pair to that metal via the imine nitrogen atom. In a
reaction of Li(o-C6H4PPh2NSiMe3)]2‚Et2O (1) with SnCl2
the diorgano tin complex [Sn(o-C6H4PPh2NSiMe3)2] (2)
was obtained, while the reaction with PbCl2 gave the
diarylplumbylene [Pb(o-C6H4PPh2NSiMe3)2] (3) (eq 2).
Cr ysta l Str u ctu r e of [P b(o-C6H4P P h 2NSiMe3)2]
(3). [Pb(o-C6H4PPh2NSiMe3)2] (3) (Figure 2) is isostruc-
tural to 2, but the cell contains a single noncoordinating
lattice solvent molecule of toluene. The two Pb-C
distances in 3 of 2.319(5) and 2.331(6) Å (Table 1),
respectively, match those found in other diarylplumby-
lenes (2.296(4) Å in [Pb{2,4,6-(iPr)3C6H2}{Si(SiMe3)3}]2,21
(16) Schmidbaur, H.; J onas, G. Chem. Ber. 1967, 100, 1120.
(17) Mu¨ller, A.; Neumu¨ller, B.; Dehnicke, K. Chem. Ber. 1996, 129,
253.
Cr yst a l St r u ct u r e of [Sn (o-C6H 4P P h 2NSiMe3)2]
(2). Pale yellow crystals of 2 suitable for X-ray crystal-
(18) Steiner, A.; Stalke, D. Angew. Chem. 1995, 107, 1908; Angew.
Chem., Int. Ed. Engl. 1995, 34, 1752.
(19) Simons, R. S., Pu, L.; Olmstead, M. M.; Power, P. P. Organo-
metallics 1997, 16, 1920.
(15) For review see: (a) van Koten, G. Pure Appl. Chem. 1989, 61,
1681. (b) J astrzebski, J . T. B. H.; van Koten, G. Adv. Organomet. Chem.
1993, 35, 241.

3892 Organometallics, Vol. 19, No. 19, 2000
Wingerter et al.
Ta ble 1. Selected Bon d Len gth s (Å) a n d An gles (d eg) of 2 a n d 3
2, M ) Sn
2.232(3)
3, M ) Pb
M-C
2.243(3)
2.331(6)
2.633(4)
1.572(5)
1.802(6)
1.822(6)
2.319(5)
2.638(4)
1.567(5)
1.813(5)
M-N
2.575(2)
2.495(2)
P-N
1.572(2)
1.573(2)
P-C(C6H4M)
1.794(3)
1.801(3)
P-C(C6H5)
1.812(3)-1.813(3)
1.806(3)-1.812(3)
1.806(3)
86.88(9)
1.809(6)-1.814(6)
av P-C
1.814(6)
86.0(2)
1.628(2)
C-M-C
N-M-N
1.6405(7)
130.8(2)
P-N-Si
130.1(2)
109.3(2)
108.6(2)
120.5(2)
77.2(9)
130.2(3)
110.3(2)
109.1(2)
120.7(2)
76.1(2)
132.9(3)
N-P-C(C6H4)
M-N-P
109.1(2)
111.2(2)
118.0(2)
78.4(9)
110.7(2)
110.7(2)
116.1(2)
76.2(2)
M-N-Si
CR-M-N
C-C-C angle at themetalated C
116.2(2)
115.7(3)
115.3(5)
116.5(5)
deviation of
the metalated C from the C5H4-plane
the M from the C5H4-plane
0.01
0.034
0.006
0.098
0.012
0.089
0.017
0.073
covered by the range normally observed in iminophos-
phoranes (1.47-1.62 Å).25
The metalated phenyl ring atom in the ortho position
is partially sp3 rehybridized, as indicated by the acute
C-C-C angle of 116°.26 It is slightly displaced from the
best C5H4 plane. This leads to an even more pronounced
dislocation of the σ-bonded metal from the C5H4 plane
(Table 1).
NMR Sp ectr oscop ic In vestiga tion s. Although in
solution the two lithium sites in 1 at room temperature
gave rise to only one signal at δ 3.0 (LiCl ext.), the signal
broadened upon cooling and at -50 °C two signals could
be resolved at δ 3.4 and 2.2. Therefore, we expected to
F igu r e 2. Solid state structure of [Pb(o-C6H4PPh2-
NSiMe3)2] (3); anisotropic displacement parameters are
depicted at the 50% probability level. The single lattice
solvent molecule of toluene has been omitted.
7
resolve the two sites in the Li MAS NMR experiment
av 2.334(12) Å in [Pb{2,6-(Mes)2C6H3}2],19 2.366(4) Å in
[Pb{2,4,6-(F3C)3C6H2}2],4 and 2.369(7) Å in [Pb{2,4,6-
as well. This technique proved in the past to be a
valuable tool to monitor rearrangement processes in the
9
(F3C)3C6H2}{Si(SiMe3)3}]2 ). The PbrN bonds in 3 of
7
solid state either by Li MAS NMR spectroscopy27 or
2.633(4) and 2.638(4) Å are identical within estimated
standard deviations and are about 0.49 Å longer than
those in [Pb{N(SiMe3)}2].22 As anticipated, proceeding
toward the higher homologue, the C-Pb-C angle of
86.0(2)° in 3 is even more acute than that in 2. Because
of the bigger radius and longer M-C bonds of lead
compared to tin and the same bite of the ligand the
NfPbrN angle in 3 is only 162.8(2)°.
Str u ctu r a l Com p a r ison . The coordination geometry
in 2 and 3 is orbital controlled due to the ns2np2 electron
configuration of tin and lead. In contrast the coordina-
tion geometry of the central Zn2+ atom in the related
complex [Zn(o-C6H4PPh2NSiMe3)2]23 is governed by
electrostatics. The closed shell d10 configuration can be
considered as a point charge. The ligands arrange
themselves around that charge so as to maximize the
interatomic distances. The zinc atom is tetrahedrally
coordinated by both carbon and nitrogen atoms of the
two ligands (C-Zn-C, 129.3(3)°; NfZnrN, 116.1(2)°).
The PdN bonds of 1.57 Å on average in 2 and 3 are
only marginally longer than in the starting material [Li-
(o-C6H4PPh2NSiMe3)]2‚Et2O (1) (1.562(3) Å)18 and are
less than 0.03 Å longer than in the parent iminophos-
phorane Ph3PdNSiMe3 (1.542(2) Å).24 The distances are
7
by Li quadrupole nutation MAS NMR spectroscopy.28
The 7Li high-power proton-decoupled MAS NMR of 1
showed a broad structured signal, which could be
deconvoluted by line shape analysis with Lorentzian/
Gaussian curves. The isotropic shifts of the 1:1 signals
are δ 0.4 and 0.9, respectively.
The resonance for 2 in the 119Sn NMR spectrum in
toluene-d8 solution shows a doublet of a doublet centered
2
at δ 47.7 (Me4Sn ext.) with a J Sn-P coupling of 57.8 Hz
(confirmed in the 31P NMR experiment). This chemical
shift differs by more than a magnitude from that found
in non-donor-stabilized stannylenes such as [Sn{2,4,6-
(Me3C)3C6H2}2]8 (980 ppm), [Sn{2,4,6-(F3C)3C6H2}2]5
(723 ppm), or [Sn{2,6-(Mes)2C6H3}2]19 (635 ppm), but it
is closer to the area covered by stannylenes with two
additional SnrN donor bonds such as in [Sn{C(Si-
Me3)2C5H4N-2}2]12b (141 ppm), [Sn{C6H4CH2NMe2-o}2]11
(169 ppm), [Sn{C10H6NMe2}2]13 (178 ppm), or [Sn{2,6-
(24) Weller, F.; Kang, H.-C.; Massa, W.; Ru¨benstahl, T.; Kunkel, F.;
Dehnicke, K. Z. Naturforsch., B 1995, 50, 1050.
(25) Niecke, E.; Gudat, D. Angew. Chem. 1991, 103, 251; Angew.
Chem., Int. Ed. Engl. 1991, 30, 217.
(26) (a) Bohnen, F: M.; Herbst-Irmer, R.; Stalke, D. In Crystal-
lographic Computing G.; Flack, H. D., Parkanyi, L., Simon, K., Eds.;
IUCr/Oxford Science Publications: New York, 1993. (b) Domenicano,
A. In Accurate Molecular Structures; Domenicano, A., Hargittai, I.,
Eds.; IUCr/Oxford Science Publications: New York, 1992. (c) J ones,
P. G. J . Organomet. Chem. 1988, 345, 405.
(27) (a) Freitag, S.; Kolodziejski, W.; Pauer, F.; Stalke, D. J . Chem.
Soc., Dalton Trans. 1993, 3479. (b) Gornitzka, H.; Stalke, D. Angew.
Chem. 1994, 106, 695; Angew. Chem., Int. Ed. Engl. 1994, 33, 693.
(28) Pauer, F.; Rocha, J .; Stalke, D. J . Chem. Soc., Chem. Commun.
1991, 1477.
(20) Bleckmann, P.; Maley, H.; Minkwitz, R.; Neumann, W. P.;
Watta, B.; Olbrich, G. Tetrahedron Lett. 1982, 23, 4655.
(21) Stu¨rmann, M.; Saak, W.; Weidenbruch, M.; Klinkhammer, K.
Eur. J . Inorg. Chem. 1999, 579.
(22) Fjeldberg, T.; Hope, H.; Lappert, M. F.; Power, P. P.; Thorne,
A. J . J . Chem. Soc., Chem. Commun. 1983, 639.
(23) Wingerter, S.; Gornitzka, H.; Bertrand, G.; Stalke, D. Eur. J .
Inorg. Chem. 1999, 173.

Deprotonated Iminophosphorane o-C6H4Ph2PdNSiMe3
Organometallics, Vol. 19, No. 19, 2000 3893
(NMe2)2C6H3}2]14 (380 ppm). The considerable upfield
shift is certainly due to the presence of the phosphorus
and silicon atom next to the imino nitrogen atom. They
enhance the donor capacity of the new ligand compared
to alkyl-substituted amino groups.
Ta ble 2. Cr ysta l Da ta for 2 a n d 3
2
3
formula
CCDC no.
mol. mass
cryst size [mm]
space group
a [Å]
C42H46N2P2Si2Sn C42H46N2P2PbSi2‚0.5C7H8
143669
815.62
0.4 × 0.3 × 0.3
P1h
143670
950.19
0.3 × 0.3 × 0.2
P1h
11.079(2)
14.968(3)
15.756(3)
105.55(3)
108.69(3)
107.01(3)
2.1699(8)
2
Con clu sion
11.014(2)
12.238(2)
16.775(3)
69.87(3)
71.02(3)
82.35(3)
2.0070(7)
2
b [Å]
c [Å]
Transmetalation of the ortho-lithiated triphenyl(tri-
methylsilylimino)phosphorane [Li(o-C6H4PPh2NSiMe3)]2‚
Et2O (1) results in a side arm N-donating chelating
organometallic ligand. In the diarylstannylene [Sn(o-
C6H4PPh2NSiMe3)2] (2) and the diarylplumbylene [Pb-
(o-C6H4PPh2NSiMe3)2] (3) the smallest observed C-M-C
R [deg]
â [deg]
γ [deg]
V [nm3]
Z
temp [K]
183(2)
153(2)
1
angles (<90°) indicate a σ2 singlet carbene homologue
Fc [Mg/m3]
1.350
1.454
µ [mm-1
F(000)
]
0.807
4.049
electronic configuration at the heavy p-block metals with
the lone pair in a spherical s orbital and both bonding
electrons, each in orthogonal p orbitals.
840
954
2θ-range [deg]
no. of refln measd 8964
no. of unique reflns 5219
4-45
8-45
5904
5638
no. of restraints
ref param
0
448
0.0238
0.0555
91
512
Exp er im en ta l Section
R1a [I > 2σ(I)]
wR2b (all data)
g1; g2c
0.0321
0.0941
0.0523; 2.7435
-1.144; 1.336
All experiments were performed under a nitrogen atmo-
sphere either by using modified Schlenk techniques or in a
drybox. Solvents were freshly distilled from sodium-potassium
alloy prior to use. 1H, 13C, 29Si, and 31P NMR spectra were
recorded in THF-d8 or toluene-d8 solution by using a Bruker
AM 250 or a Bruker MSL 400 spectrometer. The solid state
7Li MAS NMR spectra were recorded on a Bruker MSL 400P
(wide-bore) spectrometer employing a 4 mm CP/MAS probe.
IR spectra were recorded as Nujol mulls on a Perkin-Elmer
180, 325, or 735 B spectrometer. Melting (decomposition)
points were determined by using a MEL TEMP II, laboratory
devices, melting point apparatus. EI mass spectra were
measured with Finnigan MAT 8230 or Varian MAT CH5
instruments. Elemental analyses were performed by the
analytical laboratory of the Department of Inorganic Chem-
istry at Go¨ttingen.
[Li(o-C6H4P P h 2NSiMe3)]2‚Et2O (1) was prepared by reac-
tion of Ph3PdNSiMe3 and MeLi in diethyl ether.18 The 7Li MAS
NMR of 1 was recorded at 155.5 MHz in a 4 mm bottom layer
ZrO2 rotor. It was accumulated at a spinning speed of 14 kHz
with proton high-power decoupling. The broad spectrum could
be deconvoluted with the following features: signal 1 {δ 0.4;
rel int 74.8; line width 471 Hz; ratio Lorentzian/Gaussian )
1; area 50.5%}; signal 2 {δ 0.9; rel int 25.0; line width 1800
Hz; ratio Lorentzian/Gaussian ) 0.28; area 49.5%}.
0.0183; 1.6124
resid electr density -0.310; 0.285
[e/Å3]; min/max
abs corr
semiempirical
semiempirical
0.6561; 1.0
min/max transmsn 0.8828; 0.9307
R1 ) ∑|Fo| - |Fc|/∑|Fo|. wR2 ) (∑w(Fo - Fc2)2/∑w(Fo2)2)1/2
.
a
b
2
c P ) (max(Fo2,0) + 2Fc2)/3.
3
room temperature, TMS): δ 5.0 (d, J C-P ) 2.7 Hz, SiMe3),
2
3
124.9-139.5 (m, Ph), 179.6 (dd, J C-P ) 27.0 Hz, J C-P ) 1.3
Hz, 2-C). 29Si NMR (toluene-d8, room temperature, TMS): δ
2
-1.55 (d, J Si-P ) 6.8 Hz). 31P NMR (toluene-d8, room tem-
perature, 85% H3PO4): δ 28.0 (dd, J P-Sn ) 56.7 Hz). 119Sn
2
(toluene-d8, room temperature, Me4Sn/C6D6): δ 47.7 (dd,
2J Sn-P ) 57.8 Hz). MS (70 eV); m/z (%): 816 (47) [M+], 468
(79) [PPh3NSiMe3Sn+], 334 (100) [PPh3NSiMe2+]. Anal. Calcd
for C42H46N2P2Si2Sn: C, 61.9; H, 5.68; N, 3.43. Found: C, 59.3;
H, 5.28; N, 3.33.
[P b(o-C6H4P P h 2NSiMe3)]2 (3). Et2O (30 mL) was added
to a mixture of [Li(o-C6H4PPh2NSiMe3)]2‚Et2O (1) (1.45 g, 1.85
mmol) and PbCl2 (0.51 g; 1.85 mmol) at -30 °C. The suspen-
sion was stirred for 3 days at room temperature. The solvent
was removed in a vacuum. THF (50 mL) was added to the
white residue and stirred overnight. The mixture was refluxed
for 12 h. The solid dissolved and the solution turned pale
yellow. The solvent was removed in a vacuum. Toluene (30
mL) was added to the solid residue, and the mixture was
stirred over the weekend. The unsolvated LiCl was separated
by filtration, and the volume of the mother liquor was reduced
until the product just started to precipitate. The solution was
filtered again to remove traces of LiCl. After storage at room
temperature for 5 days colorless crystals were obtained for the
X-ray diffraction experiment. After isolating the crystals the
solvent from the remaining solution was removed in a vacuum.
The residue was washed with pentane (30 mL) and dried in a
vacuum. Melting points and spectroscopic data of the crystals
(first batch) and the yellow precipitate (second batch) were
identical. Total yield: 0.78 g; 0.86 mmol; 47%. Mp: 202 °C.
IR (Nujol, KBr): ν [cm-1] 2920 (C-H aliphat.), 1445 (P-Ph),
[Sn (o-C6H4P P h 2NSiMe3)]2 (2). A mixture of [Li(o-C6H4-
PPh2NSiMe3)]2‚Et2O (1) (1.30 g, 1.65 mmol) and SnCl2 (0.31
g; 1.63 mmol) was dissolved in Et2O (20 mL) at -30 °C. The
pale yellow solution was stirred for 1 day at room temperature.
The solvent was removed in a vacuum. Toluene (30 mL) was
added to the solid residue, and the mixture was stirred
overnight. The unsolvated LiCl was separated by filtration,
and the volume of the yellow mother liquor was reduced until
further product just started to precipitate. The solution was
filtered again to remove traces of LiCl. After storage at room
temperature for 3 days yellow crystals were obtained for the
X-ray diffraction experiment. Further crystalline product was
obtained from the supersaturated filtered solution (about 0.3
g). After isolating the crystals the solvent from the remaining
solution was removed in a vacuum. The residue was washed
with pentane (30 mL) and dried in a vacuum. Melting points
and spectroscopic data of the crystals (first and second batch)
and the yellow precipitate (third batch) were identical. Total
yield: 0.90 g; 1.10 mmol; 65%. Mp: 218 °C. IR (Nujol, KBr):
ν [cm-1] 2900 (C-H aliphat.), 1440 (P-Ph), 1390 (CH3), 1261
(SiMe3), 1097 (PdN). 1H NMR (toluene-d8, room temperature,
TMS): δ 0.39 (s, 18H, SiMe3), 6.77 (mc, 4H, 5-H), 6.86 (mc,
4H, 4-H), 6.94 (mc, 4H, 6-H), 7.01 (mc, 4H, 9-H), 7.61 (mc, 8H,
1
1395 (CH3), 1256 (SiMe3), 1098 (PdN). H NMR (toluene-d8,
room temperature, TMS): δ 0.34 (s, 18H, SiMe3), 7.05 (mc,
3
18H, 4-,5-, 6-, 9-, 10-H), 7.63 (mc 8H, 8-H), 8.49 (d, J 3,4 ) 7.5
Hz, 2H, 3-H). 13C NMR (THF-d8, room temperature, TMS): δ
5.1 (d, 3J C-P ) 3.0 Hz, SiMe3), 124.0-146.7 (m, Ph), 224.5 (dd,
2J C-P ) 26.8 Hz, 3J C-P ) 1.0 Hz, 2-P). 29Si NMR (THF-d8, room
temperature, TMS): δ -3.7 (d, J Si-P ) 7.4 Hz). 31P NMR
2
8-H), 8.27 (d, J 3,4 ) 7.0 Hz, 4H, 3-H). 13C NMR (toluene-d8,
(toluene-d8, room temperature, 85% H3PO4): δ 31.7. MS (70
3

3894 Organometallics, Vol. 19, No. 19, 2000
Wingerter et al.
eV); m/z (%): 904 (3) [M+], 556 (52) [PPh3NSiMe3Pb+], 334
(100) [PPh3NSiMe2+]. Anal. Calcd for C42H46N2P2Si2Pb: C,
55.8; H, 5.13; N, 3.10. Found: C, 57.2; H, 5.34; N, 2.97. The
analytical data almost fit the additionally present half-toluene
molecule in the lattice.
Director of the Cambridge Crystallographic Data Centre, 12
Union Road, GB-Cambridge CB2 1EZ (fax: (+44)1223-336-
033; e-mail: deposit@ccdc.cam.ac.uk) by quoting the supple-
mentary publication no. (see Table 2).
Cr ysta llogr a p h ic Mea su r em en ts. Crystal data for struc-
tures 2 and 3 are presented in Table 2. Data of all structures
were collected at low temperatures using oil-coated shock-
cooled crystals29 on a Stoe-Siemens-AED diffractometer using
graphite-monochromated Mo KR radiation (λ ) 0.71073 Å).
Semiempirical absorption correction was applied. The struc-
tures were solved by Patterson or direct methods with SHELXS-
90.30 All structures were refined by full-matrix least-squares
procedures on F2, using SHELXL-93.31 All non-hydrogen atoms
were refined anisotropically, and a riding model was employed
in the refinement of the hydrogen atom positions. Further
details on structure investigation can be obtained from the
Ack n ow led gm en t. The authors thank the Deutsche
Forschungsgemeinschaft (D.S., S.W.), the Fonds der
Chemischen Industrie (D.S.), and the DAAD (PRO-
COPE German/French exchange program (D.S., S.W.,
H.G.) and INIDA German/Portuguese exchange pro-
gram (D.S., J .R., R.B.)) for financial support. D.S. kindly
acknowledges the support of Bruker axs-Analytical
X-ray Systems, Karlsruhe, and CHEMETALL, Frankfurt/
Main.
Su p p or tin g In for m a tion Ava ila ble: Tables of crystal
data, fractional coordinates, bond lengths and angles, aniso-
tropic displacement parameters, and hydrogen atom coordi-
nates of the structures 2 and 3. This material is available free
of charge via the Internet at http://pubs.acs.org.
(29) (a) Stalke, D. Chem. Soc. Rev. 1998, 27, 171. (b) Kottke, T.;
Lagow, R. J .; Stalke, D. J . Appl. Crystallogr. 1996, 29, 465. (c) Kottke,
T.; Stalke, D. J . Appl. Crystallogr. 1993, 26, 615.
(30) Sheldrick, G. M. Acta Crystallogr. Sect. A 1990, 46, 467.
(31) Sheldrick, G. M. SHELXL93, Program for Crystal Structure
Refinement; Universita¨t Go¨ttingen, Germany, 1996.
OM0003988