Synthesis and reactions of l-t-butyldimethylsilyl- 2,3-diphenyl-1-aza-3-phosphaallyl lithium and potassium.

Article abstract of DOI:10.1016/S0022-328X(02)02116-2

Reaction of MP(Ph)SiMe₂Bu^t (M = Li, K) with an equivalent of PhCN afforded the 1-aza-3-phosphaallyllithium and -potassium complexes [M{P(Ph)C(Ph)NSiMe₂Bu^t}(L)]₂ (1, M = Li, L = THF; 2, M = K, L = Et₂O), respectively. After exposing 2 in vacuo at room temperature, the solvent-free complex [K{P(Ph)C(Ph) NSiMe₂Bu^t}] (3) was obtained. Treatment of 1 with SnCl₂ in a 2:1 ratio furnished the homoleptic tin(II) complex [Sn{P(Ph)C(Ph)NSiMe₂Bu^t}₂] (4). Compound 1 reacted with an equimolar amount of ClSnN (SiMe₃)₂ to give [P(Ph)C(Ph)=NSiMe₂Bu^t]₂ (5) via ligand coupling. Reaction of 3 with PhCN produced [K{P(Ph)C(Ph)NC(Ph)NSiMe₂Bu^t}] (6) by addition of the nitrogen atom to PhCN followed by a 1,3-N0→N′ migration of the SiMe₂Bu^t group. Structures of compounds 1, 2, 4 and 5 have been determined by single crystal X-ray diffraction techniques. The complexes 1 and 2 are dimeric and 4 is both monomeric, while 5 is the product of a ligand coupling with formation of new P-P bond.

Full text of DOI:10.1016/S0022-328X(02)02116-2

Journal of Organometallic Chemistry 665 (2003) 205Á213
/
www.elsevier.com/locate/jorganchem
Synthesis and reactions of 1-t-butyldimethylsilyl-2,3-diphenyl-1-aza-
3-phosphaallyl lithium and potassium. Crystal structures of
ꢀ
ꢂ
[
/
MfP(Ph)C(Ph)N
/
SiMe2But}(L)]2 (Mꢀ
/
Li, Lꢀ
/
THF; Mꢀ
/
K, Lꢀ
/
ꢀ
ꢂ
Et2O), [/
SnfP(Ph)C(Ph)N
/
SiMe2But}2] and [P(Ph)C(Ph)ꢃ
/
NSiMe2But]2
Zhong-Xia Wang a,*, Da-Qi Wang b, Jian-Min Dou b
a Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, People’s Republic of China
b Department of Chemistry, Liaocheng Normal University, Liaocheng, Sandong 252059, People’s Republic of China
Received 12 June 2002; accepted 21 October 2002
Abstract
Reaction of MP(Ph)SiMe2But (Mꢀ
/
Li, K) with an equivalent of PhCN afforded the 1-aza-3-phosphaallyllithium and -potassium
SiMe2But}(L)]2 (1, Mꢀ
Li, LꢀTHF; 2, MꢀK, LꢀEt2O), respectively. After exposing 2 in vacuo at
SiMe2But}] (3) was obtained. Treatment of 1 with SnCl2 in a 2:1 ratio
ꢀ
ꢂ
/
complexes [
/
MfP(Ph)C(Ph)N
/
/
/
/
ꢀ
ꢀ
ꢂ
/
room temperature, the solvent-free complex [
/
KfP(Ph)C(Ph)N
ꢂ
furnished the homoleptic tin(II) complex [
ClSnN(SiMe3)2 to give [P(Ph)C(Ph)ꢃ
NSiMe2But]2 (5) via ligand coupling. Reaction of
[K{P(Ph)C(Ph)NC(Ph)NSiMe2But}] (6) by addition of the nitrogen atom to PhCN followed by a 1,3-N0
SiMe2But group. Structures of compounds 1, 2, 4 and 5 have been determined by single crystal X-ray diffraction techniques. The
/
SnfP(Ph)C(Ph)N
/
SiMe2But}2] (4). Compound 1 reacted with an equimolar amount of
with PhCN produced
N? migration of the
/
3
/
complexes 1 and 2 are dimeric and 4 is both monomeric, while 5 is the product of a ligand coupling with formation of new Pꢄ
/P
bond.
# 2002 Elsevier Science B.V. All rights reserved.
Keywords: 1-aza-3-Phosphaallyl ligand; Lithium; Potassium; Tin; Complexes; Structures
1. Introduction
For
[N(SiMe3)C(Ph)ꢃ
bonding to lithium by the nitrogen atoms of the ligands
[5Á7], and the latter [7] also reveals a lithium-phospho-
rus contact of 2.924 A (see I and II);
example,
both
[N(H)C(Me)ꢃ
/
PPh]ꢁ
and
/
PPh]ꢁ act as monodentate ligands
P,N-chelating ligands have attracted increasingly
attention in recent years due to the presence of a ‘soft’
and a ‘hard’ reaction center [1]. One important property
of these ligands is that they can stabilize metal ions in a
variety of oxidation states and geometries. These ligands
also display quite different coordination modes com-
/
˚
pared with P,P and N,N ligands [2Á4]. Recently 1-aza-3-
/
phosphaallyl anions as mono and bidentate ligands have
been reported. The complexes of such ligands with
metals such as lithium, alkaline earth metals and even
platinum have been synthesized and characterized and
the unstable [Li{N(SiMe3)C(Ph)ꢃ
/
PSiMe3}] acts with
show interesting bonding character and reactivity [5Á9].
/
PhCN to afford lithium bis{(trimethylsilylimino)ben-
zoyl}phosphanide (Eq. (1)) [8]. However, known com-
plexes with this type of ligands are still rare. Here we
report synthesis of a novel 1-aza-3-phosphaallyl ligand,
its reactivity towards SnCl2, Sn(Cl)N(SiMe3)2 and
* Corresponding author. Tel.: ꢂ
363-1760
E-mail address: zxwang@ustc.edu.cn (Z.-X. Wang).
/
86-551-360-3301; fax: ꢂ86-551-
/
0022-328X/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.
PII: S 0 0 2 2 - 3 2 8 X ( 0 2 ) 0 2 1 1 6 - 2

206
Z.-X. Wang et al. / Journal of Organometallic Chemistry 665 (2003) 205Á213
/
ꢀ
ꢂ
ꢀ
ꢂ
/
PhCN and the crystal structures of [
SiMe2But}(L)]2 (Mꢀ
Li, LꢀTHF; Mꢀ
SiMe2But}2] and [P(Ph)C(Ph)ꢃ
/
MfP(Ph)C(Ph)N
/
KfP(Ph)C(Ph)N
2 in vacuo at room temperature, the solvent-free
SiMe2But}(OEt2)]2 (2). After exposing
/
/
/
K, LꢀEt2O),
/
ꢀ
ꢂ
/
ꢀ
ꢂ
/
complex [/
KfP(Ph)C(Ph)N
SiMe2But}] (3) was obtained.
[/
SnfP(Ph)C(Ph)N
/
NSi-
Me2But]2.
This proved that the diethyl ether molecules were loosely
bound in the complex. Treatment of complex 1 with
SnCl2 in a 2:1 ratio yielded the homoleptic tin(II)
ꢀ
ꢂ
/
complex [
/
SnfP(Ph)C(Ph)N
SiMe2But}2] (4) as yellow
ð1Þ
orange crystals in good yield. Attempts to prepare the
heteroleptic tin(II) complex by reaction of 1 with one
equivalent of SnCl2 were unsuccessful; only an oily
species was obtained and the 1H-NMR spectrum
showed it to be a mixture. Reaction of 1 with an
equimolar amount of ClSnN(SiMe3)2 in diethyl ether
furnished a yellow orange solution with white precipi-
tates. Filtration of the reaction mixture and concentra-
tion of the filtrate gave precipitates, which could not be
redissolved in organic solvents. The mother liquor was
left for about 4 weeks to give yellow crystals which
turned out by NMR spectroscopy and single crystal X-
ray diffraction to be the ligand coupling species,
2. Results and discussion
The synthesis of the new 1-aza-3-phosphaallyl lithium
and potassium and their reactions are summarized in
Scheme 1. Treatment of LiP(Ph)SiMe2But prepared
from PhP(H)SiMe2But and LiBun with an equivalent
of PhCN in THF gave a deep red solution. Removal of
the solvent and crystallization from diethyl ether
[P(Ph)C(Ph)ꢃ
proceeds through the heteroleptic tin(II) complex
[Sn{P(Ph)C(Ph)ꢃ
NSiMe2But}{N(SiMe3)2}], and the
/
NSiMe2But]2 (5). Presumably the reaction
ꢀ
ꢂ
/
/
afforded red orange crystals of [
/
LifP(Ph)C(Ph)N
SiMe2-
unstable complex further decomposed to form 5 and
other species. Reaction of 3 with PhCN in a 1:1 ratio
afforded [K{P(Ph)C(Ph)NC(Ph)NSiMe2But}] (6) as
yellow crystals, but their quality was not sufficient for
an X-ray structure analysis. Apparently the reaction
involved not only attack of the nitrogen atom of 3 to
PhCN but also a 1,3-silatropic migration. The addition
orientation is different from that of the reaction between
[Li{N(SiMe3)C(Ph)P(SiMe3)}] and PhCN which yielded
But}(THF)]2 (1) in high yield. The potassium analogue
of 1 was obtained similarly from KP(Ph)SiMe2But
(prepared by reaction of PhP(H)SiMe2But with potas-
sium metal) and PhCN as a diethyl ether adduct, [/
[LiP{C(Ph)ꢃ/NSiMe3}2] (Eq. (1)) [8]. Complex 6 can also
be obtained in a one-pot reaction from KP(Ph)SiMe2-
But and two equivalents of PhCN.
Each of the compounds 1 and 3Á6 was characterized
/
1
by elemental analysis, H, 13C{1H} and 31P{1H}-NMR
spectroscopy. For example, the 1H-NMR spectrum of 1
showed signals of the appropriate groups, and coordi-
nate THF molecules. The 13C{1H}-NMR spectrum
displayed the signal of the Pꢄ
/
Cꢄ/N fragment as a
doublet due to coupling with the phosphorus atom
and other corresponding signals. Complex 3 is not very
soluble in benzene, its NMR spectra were recorded in a
solvent mixture of C6D6 and C5D5N. The 1H and
13C{1H}-NMR spectra showed signals of the appro-
priate groups, consistent with the proposed structure.
However, its 31P chemical shift of 31.61 ppm was quite
Scheme 1. Syntheses and reactions of 1-t-butyldimethylsilyl-2,3-
diphenyl-1-aza-3-phosphaallyl lithium and potassium. Reagents and
conditions: (i) LiBun , THF, 0 8C to room temperature, 2 h; K, THF,
different from that of [K{N(Ph)C(But)PPh}] (d ꢁ
102
/
ppm) reported by Issleib and co-workers [9]. This can be
attributed to different bonding modes of the two
complexes. The 31P{1H}-NMR spectral signals of 4
appeared at 6.48 ppm with satellites due to coupling
with tin, which proved a bonding interaction between
room temperature, 15 h and reflux for 30 min; (ii) PhCN, ꢁ
room temperature, stirred overnight; (iii) exposing to vacuum, room
temperature, 30 min; (iv) 1/2 SnCl2, Et2O, ꢁ80 8C to room tempera-
ture, stirred overnight; (v) ClSnN(SiMe3)2, Et2O, ꢁ70 8C to room
temperature, stirred overnight; (vi) PhCN, ꢁ70 8C to room tempera-
ture, 6 h.
/50 8C to
/
/
/
1
the phosphorus and the tin atom. The H and 31P{1H}-

Z.-X. Wang et al. / Journal of Organometallic Chemistry 665 (2003) 205Á
/213
207
NMR spectra of 5 displayed two sets of equal intensity
signals. The reason is the coupling of the ligands
[P(Ph)C(Ph)NSiMe2But]ꢁ form two diastereomers [III
and IV (and its enantiomer)] which exhibit different
chemical shifts in the NMR spectra.
The structures of compounds 1, 2, 4 and 5 were
further confirmed by single crystal X-ray diffraction.
The complex 1 is a dimer bridged by the phosphorus
atoms and crystallizes with two dimeric molecules in the
unit cell. For one dimer only, however, an ORTEP
representation of the molecular structure is shown in
Fig. 1 and selected bond lengths and angles are listed in
Table 1. The skeletal structure is ladder-shaped. Due to
a center of inversion the central ring Li(1)P(1)P-
(1A)Li(1A) is planar with the angle at P smaller
[72.9(3)8] than that at Li [107.1(3)8]. Therefore, one of
the coordinating THF molecules is situated above the
four-membered and the other below. The P(1)C(1)N(1)
unit coordinates to the central Li atom in an h3 mode,
different from that found in [Li{NHC(Me)P-
Ph}(THF)2]2 and [Li{N(SiMe3)C(Ph)PPh}] (see I and
˚
P(1) distance of 2.641(9) A is
II) [5Á
/
7]. The Li(1)ꢄ
/
˚
P(1A) [2.592(7) A],
and the latter is close to those found in [{Li(THF)2}2-
slightly longer than that of Li(1)ꢄ
/
[K{P(Ph)C(Ph)NSiMe2But}] (3) has two nucleophilic
centers, the phosphorus and the nitrogen atom, respec-
tively. The reaction of 3 with PhCN has, in principle,
three possible paths (Scheme 2): (i) the phosphorus atom
of 3 attacks PhCN to form IV; (ii) the nitrogen atom of
3 attacks PhCN to yield V and (iii) the nitrogen atom of
3 attacks PhCN and then the SiMe2But group migrates
from N to N? affording VI. Experimentally, the
13C{1H}-NMR spectrum of 6 showed only one set of
˚
{PhPCH2CH2PPh}] (av. 2.56 A) [10] and [{Li(TME-
˚
DA)}2{C6H4(PPh)2-1,2}] (av. 2.58 A) [11]. The Li(1)ꢄ
/
˚
N(1) distance of 1.991(10) A is shorter than those found
˚
in I [2.031(8) and 2.090(8) A] [5] but remains in the usual
range. For example, the LiꢄN distances in [Li{CH-
(SiMe3)P(Ph)2ꢃNSiMe3}]2 vary from 1.898(10) to
/
/
˚
2.166(9) A [12], and in [Li{CH2P(Me)2ꢃ
/
NSiMe3}]4
˚
from 1.97(1) to 2.12(1) A [10]. The Li(1)ꢄ
/
C(1) distance
˚
of 2.499(10) A is longer than those in [Li{CH(SiMe3)P-
P-coupled Cꢃ
constant of 59.36 Hz; hence IV is ruled out. Compound
V contains a CꢃP double bond, while VI is a delocalized
system. From the reported spectral data, the 31P
chemical shifts for a CꢃP double bond normally appear
downfield compared with a corresponding delocalized
system, e.g. the 31P chemical shifts of PhPꢃ
C(Me)NH2
and PhPꢃC(Me)N(H)SiMe3 appear at 74.7 and 94.7
/N signals at 207.57 ppm with a coupling
˚
(Ph)2ꢃ
/
NSiMe3}]2 [2.122(9) and 2.190(9) A] [12] and
2.23(2)
[Li{h3-CH(CHSiMe2But)2}(TMEDA)] [2.11(2)Á
/
/
˚
A] [13], but comparable with those found in azaallyl
lithium compounds such as [Li{CH(SiMe3)C(But)-
˚
/
N(SiMe3)}]2 [2.43(1) and 2.44(1) A] [14]. Thus, the Liꢄ
/
C distance in complex 1 is within the usual range
/
˚
compared with relevant compounds [15]. At 1.759(5) A
the P(1)ꢄC(1) distance is in between a single and a
double bond. However, the 1.321(5) A of C(1)ꢄ
distance is near to a CꢄN double bond [5]. The Li(1)ꢄ
/
/
ppm, respectively, while those of delocalized [Li-
{NHC(Me)PPh}(THF)2]2 and [Li{N(SiMe3)C(Me)-
PPh}(THF)x] at 34.3 and 28.5 ppm, respectively [5].
The 31P{1H}-NMR signal of 6 was detected at 37.44
ppm, thus VI is the most plausible structure.
˚
/
N(1)
/
/
˚
Li(1A) distance of 3.110(17) A implies that it is too long
for bond [16].
Scheme 2.

208
Z.-X. Wang et al. / Journal of Organometallic Chemistry 665 (2003) 205Á213
/
Fig. 1. An ORTEP representation of the molecular structure of complex 1.
Table 1
3.32(7) [K(1)ꢄ
/
C(2)], 3.36(7) [K(1)ꢄ
/
C(3)], 3.42(8)
˚
Selected bond lengths (A) and angles (8) for complex 1 (only one
dimer)
˚
[K(1)ꢄ
/
C(8A)] and 3.34(7) A [K(1)ꢄ
/
C(9A)], comparable
with those found in [K{h4-N(SiMe2But)C(But)(CH)3-
SiMe2But}]ꢀ [17] and [K3(THF)2{PH(Mes)}3]ꢀ
Bond lengths
Li(1)ꢄN(1)
Li(1)ꢄP(1A)
Li(1)Á Á ÁLi(1A)
P(1)ꢄC(1)
1.991(10) Li(1)Á Á ÁC(1)
2.592(7)
Li(1)ꢄP(1)
3.110(17) N(1)ꢄC(1)
2.499(10)
2.641(9)
1.321(5)
1.717(4)
(Mesꢀ
/
2,4,6-Me3C6H2) [18]. The mean Kꢄ
/
P distance
of 3.48 A is longer than those observed for [KP(H)-
˚
C6H2But3-2,4,6]x ranging from 3.181(2) to 3.357(2) A
˚
1.759(5)
N(1)ꢄSi(1)
[19] and [KP(H)(DMP)]4 (DMPꢀ2,6-dimesitylphenyl)
˚
ranging from 3.043(2) to 3.438(2) A [20], but still falls
/
Bond angles
C(1)ꢄN(1)ꢄLi(1)
C(1)ꢄP(1)ꢄLi(1)
Li(1)ꢄP(1)ꢄLi(1A)
C(2)ꢄC(1)ꢄP(1)
C(1)ꢄN(1)ꢄSi(1)
Li(1)ꢄN(1)ꢄSi(1)
95.8(4)
65.7(2)
72.9(3)
N(1)ꢄLi(1)ꢄP(1A)
N(1)ꢄLi(1)ꢄP(1)
P(1)ꢄLi(1)ꢄP(1A)
C(1)ꢄP(1)ꢄLi(1A)
C(8)ꢄP(1)ꢄLi(1)
N(1)ꢄC(1)ꢄP(1)
131.6(5)
68.0(3)
into usual range. For example, the Pꢄ
/K distances in
107.1(3)
127.9(3)
133.2(3)
117.6(4)
ꢃ
[Cp2ZrP3K(THF)1.5] (Cp*ꢀ
/
C5Me5) vary from 3.37(1)
120.1(4)
133.5(4)
129.7(4)
˚
˚
to 3.61(1) A [21]. At 2.81(8) A the K(1)ꢄ
quite usual, too.
/N(1) distance is
Table 2
The molecular structure of 2 is presented in Fig. 2,
selected bond lengths and angles are listed in Table 2.
The crystalline 2 is also a dimer bridged by phosphorus
atoms and the K(1)P(1)K(1A)P(1A) ring is planar due
to a center of inversion. The 1-aza-3-phosphaallyl unit
˚
Selected bond lengths (A) and angles (8) for complex 2
Bond lengths
K(1)ꢄN(1)
K(1)ꢄC(2)
K(1)ꢄC(3)
K(1)ꢄP(1A)
K(1)ꢄK(1A)
N(1)ꢄC(1)
2.81(8)
3.32(7)
3.36(7)
3.48(7)
4.86(13)
1.33(4)
K(1)ꢄC(1)
K(1)ꢄC(9A)
K(1)ꢄC(8A)
K(1)ꢄP(1)
P(1)ꢄC(1)
3.13(7)
3.34(7)
3.42(8)
3.48(9)
1.85(3)
1.79(3)
binds to the potassium atom in an approximate h3-
˚
mode and at 3.13(7) A the K(1)ꢄ
/
C(1) distance is too
N(1)ꢄSi(1)
long for a bond. However, the P(1)ꢄ
/C(1) distance of
˚
Bond angles
1.85(3) A corresponds to a single bond and the N(1)ꢄ
/
˚
C(1) distance of 1.33(4) A approximates a double bond
C(1)ꢄN(1)ꢄSi(1)
P(1)ꢄC(1)ꢄN(1)
P(1)ꢄC(1)ꢄC(8)
C(1)ꢄP(1)ꢄC(2)
C(1)ꢄP(1)ꢄK(1)
136.9(9)
132.7(10)
107.4(19)
106.0(19)
63.6(18)
K(1)ꢄN(1)ꢄSi(1)
N(1)ꢄK(1)ꢄP(1A)
N(1)ꢄK(1)ꢄP(1)
P(1A)ꢄK(1)ꢄP(1)
C(1)ꢄP(1)ꢄK(1A)
118.9(17)
105.9(11)
54.1(6)
[5]. Each K atom also interacts with the carbon atoms of
two phenyl rings attached to the phosphorus atom of a
ligand and to the carbon atom of another ligand,
respectively. These KÁ Á ÁC contacts are as follows:
91.3(15)
90.1(19)

Z.-X. Wang et al. / Journal of Organometallic Chemistry 665 (2003) 205Á
/213
209
Fig. 2. An ORTEP representation of the molecular structure of complex 2.
The structure of complex 4 is shown in Fig. 3, and
selected bond lengths and angles are given in Table 3.
The structure reveals that the compound is monomeric
in the solid state. The coordination number of the
central Sn atom is four and the lone electron pair on tin
mean distance between tin and the carbon atom of the
PCN unit is too long for a bond [22]. Hence the 1-aza-3-
phosphaallyl unit behaves as a bidentate ligand. How-
ever, both the four membered rings Sn(1)P(1)C(7)N(1)
and Sn(1)P(2)C(26)N(2) are not planar, the torsion
˚
occupies an additional coordination site. At 2.896 A the
angles between the planes Sn(1)ꢄ
/
P(1)ꢄ
/
C(7) and P(1)ꢄ
/
Fig. 3. An ORTEP representation of the molecular structure of complex 4.

210
Z.-X. Wang et al. / Journal of Organometallic Chemistry 665 (2003) 205Á213
/
Table 3
three coordinate and the lone electron pair occupies the
˚
˚
P distance of 2.202(5) A
(Table 4) is comparable with those observed for single
Selected bond lengths (A) and angles (8) for complex 4
fourth coordination site. The Pꢄ
/
Bond lengths
˚
bonds in diphosphines [2.205(1)Á
/
2.260(1) A] [24]. The
C distance of 1.886(6) A agrees fairly well with the
value of a single bond and the CꢄN distance of 1.288(9)
Sn(1)ꢄN(1)
Sn(1)ꢄP(2)
N(1)ꢄC(7)
P(1)ꢄC(7)
N(1)ꢄSi(1)
P(1)ꢄC(1)
2.459(3)
Sn(1)ꢄN(2)
2.473(4)
2.6288(13)
1.330(6)
1.809(5)
11.781(4)
1.825(5)
˚
Pꢄ
/
2.6127(13) Sn(1)ꢄP(1)
1.296(5)
1.812(4)
1.758(4)
1.829(5)
N(2)ꢄC(26)
P(2)ꢄC(26)
N(2)ꢄSi(2)
P(2)ꢄC(20)
/
˚
A is indicative of a double bond [5]. The angles at atom
C(1) sum up to 3598, therefore, the atoms C(1), N(1),
P(1), C(8) lie in a plane.
Bond angles
N(1)ꢄSn(1)ꢄN(2)
N(2)ꢄSn(1)ꢄP(2)
N(2)ꢄSn(1)ꢄP(1)
C(7)ꢄN(1)ꢄSn(1)
C(7)ꢄP(1)ꢄC(1)
C(1)ꢄP(1)ꢄSn(1)
N(1)ꢄC(7)ꢄP(1)
C(20)ꢄP(2)ꢄC(26)
152.53(13) N(1)ꢄSn(1)ꢄP(2)
62.82(11) N(1)ꢄSn(1)ꢄP(1)
99.25(10) P(2)ꢄSn(1)ꢄP(1)
99.73(8)
61.90(9)
101.86(4)
94.8(3)
3. Experimental
95.5(2)
C(26)ꢄN(2)ꢄSn(1)
C(7)ꢄP(1)ꢄSn(1)
104.7(2)
78.78(14)
79.83(17)
109.73(15)
109.16(15) C(26)ꢄP(2)ꢄSn(1)
All experiments were performed under nitrogen using
standard Schlenk and vacuum line techniques. Solvents
were distilled under nitrogen over sodiumÁbenzophe-
113.9(3)
103.9(2)
C(20)ꢄP(2)ꢄSn(1)
/
none (THF, Et2O and n-hexane) or CaH2 (CH2Cl2) and
degassed prior to use. CDCl3, C5D5N and C6D6 were
purchased from Acros Organics, degassed and stored
C(7)ꢄ
and P(2)ꢄ
The mean Snꢄ
found in Sn(II) amide complexes [21], but is comparable
/
N(1) and between the planes Sn(1)ꢄ
C(26)ꢄN(2) are 29.1 and 26.58, respectively.
N distance of 2.466 A is longer than those
/
P(2)ꢄ
/
C(26)
/
/
˚
/
Table 4
˚
Selected bond lengths (A) and angles (8) for complex 5
˚
with that in Sn[{N(SiMe3)}2PPh2]2 [2.511(6) A] [23]. At
Bond lengths
˚
2.6208 A the mean Snꢄ
/
P distance is comparable with
N(1)ꢄC(1)
P(1)ꢄC(2)
P(1)ꢄP(1A)
1.288(9)
1.856(7)
2.202(5)
N(1)ꢄSi(1)
P(1)ꢄC(1)
C(1)ꢄC(8)
1.724(6)
1.886(6)
1.512(12)
those of Sn[C(PMe2)3]2 ranging from 2.598(2) to
˚
2.839(2) A. In addition, in each of the 1-aza-3-phos-
phaallyl units the NꢄC bond corresponds to a double
bond (av. 1.313 A) and the mean PꢄC distance of 1.811
A approximates roughly the value a single bond.
Compound 5 consists of centrosymmetric molecules
/
Bond angles
˚
/
C(2)ꢄP(1)ꢄC(1)
C(1)ꢄP(1)ꢄP(1A)
N(1)ꢄC(1)ꢄP(1)
C(1)ꢄN(1)ꢄSi(1)
98.5(3)
95.3(3)
C(2)ꢄP(1)ꢄP(1A)
N(1)ꢄC(1)ꢄC(8)
C(8)ꢄC(1)ꢄP(1)
101.7(3)
129.0(5)
109.5(5)
˚
121.5(4)
140.5(5)
with a Pꢄ
/P bond (Fig. 4). Each phosphorus atom is
Fig. 4. An ORTEP representation of the molecular structure of complex 5.

Z.-X. Wang et al. / Journal of Organometallic Chemistry 665 (2003) 205Á
/213
211
over activated molecular sieves (CDCl3 and C5D5N) or
Na/K alloy (C6D6). SnCl2 and LiBun (Acros Organics)
were used as received. PhCN was distilled over P2O5 and
degassed prior to use. PhP(H)SiMe2But [25] and
ClSnN(SiMe3)2 [26] were prepared according to the
literature. NMR spectra were recorded on a Bruker
AV400 or a Bruker DMX500 spectrometer at ambient
temperature. The chemical shifts of the 1H and 13C{1H}-
NMR spectra are referenced to internal solvent reso-
nances, the 31P{1H}-NMR spectra to external 85%
H3PO4. Elemental analyses were performed by the
Analytical Laboratory of Shanghai Institute of Organic
Chemistry and the Analytical Center of the University
of Science and Technology of China.
MHz, C6D6/C5D5N): d (ppm) ꢁ
/
0.09 (s, 6H, SiMe2),
1.11 (s, 9H, But), 6.91Á
/
6.99 (m, 6H, Ph), 7.53Á
4H, Ph). 13C{1H}-NMR (100.62 MHz, C6D6/C5D5N): d
(ppm) ꢁ
1.65 (SiMe2), 20.01 (But), 27.88 (But), 124.73,
127.68, 128.08, 128.38, 129.26 (d, Jꢀ16.40 Hz), 131.87,
132.69 (d, Jꢀ14.29 Hz), 150.92 (d, Jꢀ20.32 Hz) (Ph),
206.45 (d, Jꢀ
56.44 Hz, PCN). 31P{1H}-NMR (161.97
/7.63 (m,
/
/
/
/
/
MHz, C6D6/C5D5N): d (ppm) 31.61.
Single crystals were obtained by recrystallization of
ꢀ
ꢂ
/
[
/
KfP(Ph)C(Ph)N
identified crystallographically as [
Me2But}(OEt2)]2.
SiMe2But}] from diethyl ether and
ꢀ
ꢂ
/
/
KfP(Ph)C(Ph)N
Si-
ꢀ
ꢂ
/
3.3. Synthesis of [
/
SnfP(Ph)C(Ph)N
SiMe2But}2] (4)
ꢀ
ꢂ
/
3.1. Synthesis of [
(1)
/
LifP(Ph)C(Ph)N
SiMe2But}(THF)]2
To a stirred solution of 1 (0.63 g, 1.56 mmol) in 20 ml
of Et2O was added SnCl2 (0.15 g, 0.79 mmol) at ꢁ80 8C.
/
A solution of LiBun (1.32 ml of a 2.5M solution in
hexane, 3.30 mmol) was added to a stirred solution of
PhP(H)SiMe2But (0.74 g, 3.30 mmol) in 20 ml of THF
at 0 8C. The mixture was warmed to room temperature
(r.t.) and stirred for 2 h. The solution was cooled to
The mixture was warmed up to r.t. and stirred over-
night. The solvent was removed and the residue was
extracted with CH2Cl2. The extract was concentrated to
about 3 ml and an equal volume of Et2O was added.
Yellow orange crystals were obtained after 1 day (0.45 g,
75.0%), m.p.: 158Á160 8C. Anal. Found: C, 58.98; H,
/
ꢁ50 8C and PhCN (0.34 g, 3.30 mmol) was added using
/
6.33; N, 3.54. C38H50N2P2Si2Sn requires: C, 59.15; H,
6.53; N, 3.63%. 1H-NMR (400.13 MHz, C6D6): d (ppm)
a syringe. The mixture was allowed to come up to r.t.
and stirred overnight. The solvent was removed in vacuo
and the residual solid was washed with hexane. The
solid was dissolved in Et2O and filtered. Concentration
of the filtrate afforded red crystals of complex 1 (1.15 g,
ꢁ
/
0.16 (s, 12H, SiMe2), 0.86 (s, 18H, But), 6.81ꢁ
/
6.87
7.34 (m,
7.65 (m, 4H, Ph). 13C{1H}-NMR (100.61
MHz, C6D6): d (ppm) ꢁ
2.21 (b, SiMe2), 19.78 (But),
27.76 (But), 128.13, 128.60, 130.01, 137.73 (d, Jꢀ
Hz), 145.13 (d, Jꢀ15.22 Hz) (Ph), 213.06 (d, Jꢀ
(m, 8H, Ph), 6.97 (t, Jꢀ
4H, Ph), 7.61Á
/
7.44 Hz, 4H, Ph), 7.31Á
/
/
/
86.0%), melting point (m.p.): 166Á168 8C. Anal. Found:
/
/17.13
C, 67.88; H, 8.16; N, 3.63. C23H33LiNOPSi requires: C,
68.12; H, 8.20; N, 3.45%. 1H-NMR (500.13 MHz,
C6D6): d (ppm) 0.08 (s, 6H, SiMe2), 1.13 (s, 9H, But),
/
/27.04
Hz, PCN). 31P{1H}-NMR (161.97 MHz, C6D6): d
(ppm) 6.48 with satellites (Jꢀ777.29 Hz).
/
1.29Á
6.81Á
7.54 (m, 4H, Ph). 13C{1H}-NMR (125.77 MHz, C6D6):
d ꢁ
1.57 (SiMe2), 20.15 (But), 25.76 (THF), 27.77 (But),
69.28 (THF), 125.44, 127.79, 128.68, 136.06 (d, Jꢀ
13.21 Hz), 143.87 (d, Jꢀ30.94 Hz), 147.46 (d, Jꢀ
12.58 Hz) (Ph), 218.63 (d, Jꢀ36.22 Hz, PCN).
31P{1H}-NMR (161.97 MHz, C6D6): d 53.27.
/
1.32 (m, 4H, THF), 3.62Á
/
3.64 (m, 4H, THF),
/
6.87 (m, 1H, Ph), 6.97Á7.05 (m, 5H, Ph), 7.51Á
/
/
3.4. Reaction of 1 with ClSnN(SiMe3)2
/
/
A solution of ClSnN(SiMe3)2 (0.42 g, 1.34 mmol) in
/
/
10 ml of Et2O was added dropwise at ꢁ70 8C to a
/
/
stirred solution of 1 (0.53 g, 1.31 mmol) in 10 ml of
Et2O. The suspension formed was warmed up to r.t. and
stirring was continued overnight. White precipitates
were removed by filtration and the filtrate was concen-
trated to form insoluble products which could not be
redissolved in organic solvents. The mother liquor was
left for about 4 weeks to yield yellow crystals identified
ꢀ
ꢂ
/
3.2. Synthesis of [
/
KfP(Ph)C(Ph)N
SiMe2But}] (3)
To a suspension of small pieces of potassium (0.15 g,
3.84 mmol) in 20 ml of THF was added PhP(H)SiMe2-
But (0.67 g, 2.99 mmol) at r.t. The mixture was stirred
for 15 h and then refluxed for 30 min. After cooling to
r.t., the mixture was filtered to remove excess potassium.
as [P(Ph)C(Ph)ꢃ
114Á117 8C. Anal. Found: C, 69.63; H, 7.49; N, 4.46.
C38H50N2P2Si2 requires: C, 69.91; H, 7.73; N, 4.29%.
1H-NMR (400.13 MHz, C6D6): d (ppm) Á
0.31 to ꢁ0.08
(b, 6H, SiMe2), ꢁ0.02 to 0.15 (b, 6H, SiMe2), 1.00 (s,
9H, But), 1.25 (s, 9H, But), 6.61Á
7.09 (m, 14H, Ph),
7.30Á7.56 (m, 4H, Ph), 7.68Á
7.88 (b, 4H, Ph). 13C{1H}-
NMR (100.61 MHz, C6D6): d (ppm) ꢁ3.22, 3.09
(SiMe2), 18.49Á
19.22 (b), 27.25 (But), 127.09, 128.38,
128.86, 129.34, 136.41Á137.42 (m), 145.09 (d, Jꢀ16.60
/
NSiMe2But]2 (5) (0.17 g, 39.8%), m.p.:
/
PhCN (0.31 g, 3.01 mmol) was added at ꢁ
/
80 8C and
/
/
thereafter the solution was stirred for 14 h at r.t.
Volatiles were removed in vacuo, the residual solid
was recrystallized from Et2O and dried in vacuo to give
/
/
/
/
yellow orange solid (1.03 g, 94.3%). M.p.: 220Á
/
222 8C.
Anal. Found: C, 62.01; H, 6.70; N, 3.99. C19H25NKPSi
/
/
1
requires: C, 62.43; H, 6.89; N, 3.83%. H-NMR (500.13
/
/

212
Z.-X. Wang et al. / Journal of Organometallic Chemistry 665 (2003) 205Á213
/
Hz), 145.26 (d, Jꢀ
/
16.70 Hz) (Ph), 189.59 (Cꢃ
/
N).
31P{1H}-NMR (161.97 MHz, C6D6): d (ppm) 10.45,
16.44.
3.6. Crystal structure solution and refinement for
compounds 1, 2, 4 and 5
Crystals were mounted in Lindemann capillaries
under nitrogen. Diffraction data were collected on a
Siemens CCD area-detector with graphite-monochro-
˚
3.5. Reaction of 3 with PhCN
mated MoÁ
/
Ka radiation (lꢀ0.71073 A). A semi-
/
empirical absorption correction was applied to the
data. The structures were solved by direct methods
using SHELXS-97 [27] and refined against F2 by full-
matrix least-squares using SHELXL-97 [28]. Hydrogen
atoms were placed in calculated positions. Crystal data
and experimental details of the structure determinations
are listed in Table 5. Since the poor quality of the single-
crystal of complex 2, the quality of the X-ray structure
determination is low and that the standard deviations
are relatively high.
To a stirred solution of 3 (1.0 g, 2.74 mmol) in 20 ml
of THF was added PhCN (0.29 g, 2.82 mmol) at
ꢁ70 8C. The solution was warmed up to r.t. and stirred
/
for 6 h. Volatile compounds were removed in vacuo and
the residual solid was dissolved in Et2O. Filtration of the
solution and concentration of the filtrate afforded
yellow crystals of 6 (0.91 g, 71.0%), m.p.: 213Á215 8C.
/
Anal. Found: C, 67.03; H, 6.39; N, 5.76. C26H30N2PSiK
1
requires: C, 66.63; H, 6.45; N, 5.98%. H-NMR (400.13
MHz, C6D6/C5D5N): d (ppm) ꢁ
1.10 (s, 9H, But), 6.68Á
6.87 (m, 2H, Ph), 6.97Á
3H, Ph), 7.08Á7.20 (m, 5H, Ph), 7.61 (d, Jꢀ7.76 Hz,
3H, Ph), 8.39 (b, 2H, Ph). 13C{1H}-NMR (100.61 MHz,
C6D6ꢂC5D5N): d (ppm) ꢁ1.49 (SiMe2), 20.12, 27.99
(But), 123.41, 124.02, 127.20, 127.74, 129.25 (d, Jꢀ
9.36
Hz), 132.86 (d, Jꢀ14.99 Hz), 135.74, 136.07, 151.73 (d,
59.36
/
0.09 (s, 6H, SiMe2),
/
/
7.03 (m,
/
/
4. Supplementary material
/
/
/
Crystallographic data for the structural analysis have
been deposited at the Cambridge Crystallographic Data
/
Jꢀ
/
37.02 Hz) (Ph), 169.24 (NCN), 207.57 (d, Jꢀ
/
Center, CCDC no. 186908Á186911 for 1, 2, 4 and 5,
/
Hz) (PCN). 31P{1H}-NMR (161.97 MHz, C6D6/
C5D5N): d (ppm) 37.44.
respectively. Copies of this information can be obtained
from The Director, CCDC, 12 Union Road, Cambridge
Table 5
Details of the X-ray structure determinations of compounds 1, 2, 4 and 5
1
2
4
5
Empirical formula
Fw
C
46H66Li2N2O2P2Si2
C23H35KNOPSi
439.68
293(2)
Monoclinic
P21/n
C38H50N2P2Si2Sn
771.61
298(2)
C38H50N2P2Si2
652.92
293(2)
811.01
293(2)
Triclinic
Temperature T (K)
Crystal system
Space group
Triclinic
¯
Triclinic
¯
¯
P/
1
/
P/
1/
P/ /
1
˚
a (A)
11.861(3)
14.870(4)
15.096(4)
78.361(5)
74.194(4)
81.446(5)
2496.7(11)
2
14.1(4)
15.1(4)
14.1(4)
90
13.269(2)
13.969(3)
14.136(3)
100.541(3)
108.340(2)
117.781(2)
2023.9(7)
2
9.333(16)
10.96(2)
11.13(2)
66.96(2)
75.92(3)
69.54(3)
974(3)
˚
b (A)
˚
c (A)
a (8)
b (8)
g (8)
109.3(6)
90
3
˚
V (A )
Z
2824(145)
4
0.299
1
0.200
m (mmꢁ1
)
0.170
0.796
u Range for data collection (8)
Number of reflections collected
Number of independent reflections
1.79Á
10 904
6891 (Rintꢀ0.0603)
/
23.37
2.23Á
5815
3516 (Rintꢀ0.1702)
/
24.47
1.65Á
9967
6604 (Rintꢀ0.0252)
/
24.77
2.37Á
1723
1720 (Rintꢀ0.0017)
/
25.02
(Rint
)
Goodness-of-fit on F2
0.772
0.832
0.916
0.932
a
Final R indices [I ꢁ2s(I)]
R1ꢀ0.0575;
wR2ꢀ0.0892
R1ꢀ0.2090;
wR2ꢀ0.1251
0.197 and ꢁ0.133
R1ꢀ0.0664;
wR2ꢀ0.1028
R1ꢀ0.1539;
wR2ꢀ0.1295
0.202 and ꢁ0.168
R1ꢀ0.0444;
wR2ꢀ0.0872
R1ꢀ0.0779;
wR2ꢀ0.0979
0.963 and ꢁ0.855
R1ꢀ0.0583;
wR2ꢀ0.1181
R1ꢀ0.1353;
wR2ꢀ0.1541
0.113 and ꢁ0.131
R indices (all data)
Largest difference peak and hole
ꢁ3
˚
(e A
)
a
R1ꢀajjFojꢁjFcjj/ajFoj; wR2ꢀ[aw(F2oꢁFc2)2/aw(Fo4)]1/2
.

Z.-X. Wang et al. / Journal of Organometallic Chemistry 665 (2003) 205Á
/213
213
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Acknowledgements
We are grateful for financial support of this work
from NSFC (Project Code 20072035) and the Ministry
of Education, PRC.
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