Synthesis and characterisation of bis(amino)silylene-nickel(0), -palladium(II), -platinum(0), -platinum(II) and copper(I) complexes

Article abstract of DOI:10.1016/S0022-328X(03)00560-6

The bis(amino)silylene Si[(NCH₂^tBu)₂ C₆H₄-1,2] (≡ SiNN) behaved as a ligand in displacing COD or PPh₃ from [Ni(COD)₂], [Pt(PPh₃)₄] or [CuI(PPh₃)₃], yielding the crystalline d¹⁰ complexes [Ni(SiNN)₄] (crystallised from Et₂O as the 1:1-adduct 2), [Pt(PPh₃)(SiNN)₃] (5) or [CuI(PPh₃) ₂(SiNN)] (6). Under the same conditions (in C₆ H₆ at ambient temperature), SiNN and [MCl₂ (PPh₃)₂] yielded the crystalline (i) d⁸ complex trans-[M{SiNN(Cl)}₂(SiNN)₂] [M=Pt (3), Pd (4)] or (ii) the d¹⁰ complexes [Ni(PPh₃) _4-n(SiNN)_n] (n=4 (2) or 3 (1), depending on stoichiometry; with Cl₂SiNN as co-product). The X-ray structures of 2, 4, 5 and 6 are presented; those of 1 and 3 appeared in a preliminary communication. Compound 3 was shown to undergo three fluxional processes in CDCl₃ solution, as shown by detailed variable temperature NMR spectroscopic experiments. These involved in order of increasing energy (a) two conformers of 3, (b) one of these and the cis -isomer, and (c) Si→Si 1,3-shifts of Cl^-. These results are placed into the context of related published silylenemetal chemistry.

Full text of DOI:10.1016/S0022-328X(03)00560-6

Journal of Organometallic Chemistry 686 (2003) 321ꢀ331
/
www.elsevier.com/locate/jorganchem
Synthesis and characterisation of bis(amino)silyleneꢀ
/
nickel(0),
ꢀ
/
palladium(II), ꢀplatinum(0), ꢀplatinum(II) and copper(I) complexes
/
/
Anthony G. Avent, Barbara Gehrhus, Peter B. Hitchcock, Michael F. Lappert *,
Hieronim Maciejewski 1
The Chemistry Laboratory, University of Sussex, Brighton, BN1 9QJ, UK
Received 7 May 2003; received in revised form 11 June 2003; accepted 16 June 2003
Abstract
The bis(amino)silylene Si[(NCHt2Bu)2C6H4-1,2] (ꢀ
/
SiNN) behaved as a ligand in displacing COD or PPh3 from [Ni(COD)2],
[Pt(PPh3)4] or [CuI(PPh3)3], yielding the crystalline d10 complexes [Ni(SiNN)4] (crystallised from Et2O as the 1:1-adduct 2),
[Pt(PPh3)(SiNN)3] (5) or [CuI(PPh3)2(SiNN)] (6). Under the same conditions (in C6H6 at ambient temperature), SiNN and
[MCl2(PPh3)2] yielded the crystalline (i) d8 complex trans-[M{SiNN(Cl)}2(SiNN)2] [Mꢁ
[Ni(PPh3)4ꢂn(SiNN)n] (nꢁ
and 6 are presented; those of 1 and 3 appeared in a preliminary communication. Compound 3 was shown to undergo three fluxional
/
Pt (3), Pd (4)] or (ii) the d10 complexes
/4 (2) or 3 (1), depending on stoichiometry; with Cl2SiNN as co-product). The X-ray structures of 2, 4, 5
processes in CDCl3 solution, as shown by detailed variable temperature NMR spectroscopic experiments. These involved in order of
Si 1,3-shifts of Clꢂ. These results are
increasing energy (a) two conformers of 3, (b) one of these and the cis-isomer, and (c) Si0
/
placed into the context of related published silylenemetal chemistry.
# 2003 Elsevier B.V. All rights reserved.
Keywords: Nickel; Palladium; Platinum; Copper; Silylene complexes; Silyl complexes
1. Introduction
the trapping of a transient silylene SiX2 at a transition
metal led to the complex [Pt(PR3)2(SiMes2)] (Rꢁi
Pr, c-
C6H11; MesꢁC6H2Me3-2,4,6), obtained by irradiating
a mixture of [Pt(PR3)3] and SiMes2(SiMe3)2 [7].
/
There are several early reviews dealing with silylene-
transition metal complexes LnM-SiXX? (X and X? being
a monodentate anionic ligand); these were generally
required to be stabilised by the incorporation of a
/
A new chapter in SiX2 chemistry was inaugurated in
1994 with the discovery by Denk, West, Haaland and
their collaborators of the synthesis and gas phase
structure of the first robust silylene Si[N(tBu)CH]2
(abbreviated as SiN1N1) [8], which was followed shortly
thereafter by the synthesis and X-ray structure of the
crystalline Si[(NCH2t Bu)2C6H4-1,2] (SiNN) [9]. These
two bis(amino)silylenes SiN1N1 and SiNN, as well as
Si[N(tBu)CH2]2 (SiN2N2), have been shown to have an
extensive chemistry, as summarised in recent reviews
[10,11]. Like bis(amino)-carbenes [12,13], -germylenes
[14], -stannylenes [14] and -plumbylenes [14], each is
capable of behaving as a ligand. This was first demon-
strated in 1994 by the isolation (from [Ni(CO)4] and
SiN1N1) and X-ray structure of [Ni(CO)2(SiN1N1)2] [15]
and later of [Fe(CO)4(SiN1N1)] [16]. We showed in 1997
that the silylene SiNN was capable of displacing a
tertiary phosphine or an alkene from [NiCl2(PPh3)2] or
neutral donor ligand D, as in LnMÃ
The first base-free silylenemetal complex [RuCp*(P-
Me3){Si(SR)2}][BPh4] (Cp*ꢁ RꢁEt,
h5-C5Me5,
C6H4Me-4) was reported by Tilley and co-workers in
1990 [4]. Further examples of cationic silylene complexes
of Ru(II) and Pt(II) followed [5]. Each was obtained
/
Si(XX?)D [1ꢀ3].
/
/
/
from a silylmetal precursor LnMÃSiX2(X?) by abstrac-
/
tion of X?ꢂ. Their stability was attributed mainly to p-
donation from the heteroatom (e.g. S) bound to silicon
[6]. The first, and thus far we believe the sole, instance of
* Corresponding author. Tel.: ꢃ
6777196.
E-mail address: m.f.lappert@sussex.ac.uk (M.F. Lappert).
/
44-1273-678316; fax: ꢃ44-1273-
/
1
Present address: A. Mickiewicz University, 60-780 Poznan,
Poland.
0022-328X/03/$ - see front matter # 2003 Elsevier B.V. All rights reserved.
doi:10.1016/S0022-328X(03)00560-6

322
A.G. Avent et al. / Journal of Organometallic Chemistry 686 (2003) 321ꢀ331
/
[Ni(COD)2], respectively, in generating the crystalline
silylene complexes [Ni(PPh3)(SiNN)3] and [Ni(SiNN)4]
[17]. Now almost thirty such compounds are known, as
summarised in Section 3.
briefly alluded to in our review [11]. Previously we also
reported that SiNN formed crystalline 1:1-adducts with
[LnCp3] (Lnꢁ/Y or Yb), which in toluene-d8 readily
dissociated (Yꢀ/Yb) [18].
As had earlier been demonstrated for stannylenes
such as Sn[N(SiMe3)2]2 [14], the role of a bis(amino)me-
tallene in transition metal chemistry is not limited to
that of functioning as a ligand: it may insert into a
2.1. Ligation reactions of the bis(amino)silylene SiNN
transition metal MÃ
/
X (e.g. XꢁCl) bond, or alterna-
/
The reactions of SiNN with the appropriate Ni(0),
Pt(0) or Cu(I) complex in the molar ratio 4:1, 3:1 or
1.5:1, respectively, gave in good yield the crystalline
bis(amino)silylenemetal complex 2, 5 and 6, respectively,
as summarised in Scheme 2. Each experiment was
carried out in benzene at ambient temperature, demon-
strating that in these systems the silylene SiNN readily
displaced cycloocta-1,5-diene or triphenylphosphine
from the appropriate d10 metal centre.
tively act as a reducing agent. For the bis(amino)silylene
SiNN the insertion reaction was illustrated by the
conversion of [PtCl2(PPh3)2] with SiNN into trans-
[Pt{SiNN(Cl)}2(SiNN)2]; while the reduction was estab-
lished by the dechlorination of [NiCl2(PPh3)2] by SiNN
to give [Ni(PPh3)(SiNN)3] and SiCl2[(NCHt2Bu)2C6H4-
1,2] [17]. The three types of SiX2 behaviour are
illustrated schematically in Scheme 1. The insertion
and reduction reactions of SiX2 have not yet been
widely explored; two complexes of the former are cited
in Section 3.
2.2. Reactions of the bis(amino)silylene involving
ligation and concomitant insertion
2. Results and discussion
Using reaction conditions identical to those of Section
2.1, treatment of [MCl2(PPh3)2] with four equivalents of
SiNN gave the crystalline trans-bis(chlorosilyl)bis(sily-
In a preliminary publication we showed that the
bis(amino)silylene SiNN (four equivalents) with one
equivalent each of [NiCl2(PPh3)2], [Ni(COD)2], or
[PtCl2(PPh3)2] afforded the crystalline complexes
[Ni(PPh3)(SiNN)3] (1), [Ni(SiNN)4] (2), or trans-
[Pt{SiNN(Cl)}2(SiNN)2] (3), while from SiNN (five
equivalents) and [NiCl2(PPh3)2] the product was 2; the
X-ray structures of 1 and 3 were presented [17]. In this
paper we provide (i) full details of these syntheses and
extensions to those of trans-[Pd{SiNN(Cl)}2(SiNN)2]
(4), [Pt(PPh3)(SiNN)3] (5) and [CuI(PPh3)2(SiNN)] (6),
(ii) X-ray structural information on 2, 4, 5 and 6, and
(iii) detailed multinuclear NMR spectral data on each of
lene)metal(II) complex 3 (Mꢁ
/
Pt) or 4 (MꢁPd), as
/
summarised in Scheme 3. It is evident that in the
formation of these d8 metal complexes, the bis(ami-
no)silylene behaved not only as a ligand but also a
coordinatively unsaturated moiety gaining coordinative
saturation by inserting into the appropriate MÃ
/Cl bond.
It is likely that the formation of the coordinated
bis(amino)(chloro)silyl ligand proceeded via intermedi-
ates having M bound to mutually cisoid SiNN and Clꢂ
ligands. Whether the triphenylphosphine is first dis-
placed generating labile complexes MCl2(PPh3)2ꢂn
-
(SiNN)n (nꢁ1 or 2) remains an open question. These
/
1ꢀ6 (which leads us to revise our original view as to the
/
insertion/ligation reactions may be compared with the
behaviour of [{PtCl(m-Cl)(PEt3)}2], which with an excess
of Sn[N(SiMe3)2]2 or Sn[CH(SiMe3)2]2 gave [{Pt{Sn-
(N(SiMe3)2)2Cl}(m-Cl)(PEt3)}2], (cis- and trans-; trans-
on heating) or trans-[PtCl{Sn(CH(SiMe3)2)2Cl}-
(PEt3){Sn(CH(SiMe3)2)2}] (trans-Sn/Sn?), respectively
[19].
structure of 3 in CDCl3); some of these results were
Scheme 1.
Scheme 2.

A.G. Avent et al. / Journal of Organometallic Chemistry 686 (2003) 321ꢀ
/331
323
Scheme 3.
2.3. Reactions of the bis(amino)silylene involving
ligation and concomitant reduction
bond angles close to the sp3 value (110.79
others much more acute (102.79
Si(1) close to the sp2 value at 119.77(6)8, Fig. 1. Selected
geometrical parameters are in Table 1. Two of the SiÃNi
/
2.58), two
/
1.88), and Si(4)Ã
/
NiÃ
/
Under reaction conditions identical to those of
Sections 2.1 and 2.2, treatment of [NiCl2(PPh3)2] with
four or five equivalents of SiNN gave the crystalline
bis(amino)silylenenickel(0) complexes 1 or 2, respec-
tively; likewise NiCl2 was a ready source of 2. These
data are summarised in Scheme 4. By NMR experiments
it was established that the reductive dechlorination of
the d8 Ni(II) substrate was accompanied by the con-
comitant oxidation of the silylene to yield the silane
SiCl2[(NCHt2Bu)2C6H4-1,2] [20]. The contrast between
the behaviour of [NiCl2(PPh3)2] and its heavier d8
/
bonds are significantly shorter than those to Si(1) or
Si(4), and these may be compared (see Section 3) with
those in 1 [17], [Ni(SiN1N1)3] and [Ni(SiN2N2)3] [22,23]
and [Ni(CO)2(SiN1N1)2] [15,23]. The silicon atom of
˚
each SiNN ligand in 2 is 0.35ꢀ0.52 A out of the
/
appropriate NiN2 plane, and each silylene ligand has
the neopentyl ligands arranged cis to one another.
The labile compounds Pd(SiN1N1)3 (d[29Si]ꢁ
/
113.6)
and Pd(SiN2N2)3 were believed to be intermediates
along the pathway to [{Pd(PtBu3)(m-SiN1N1Ã
Si or m-
SiN2N2ÃSi)}2] from Pd(PtBu3)2 and SiN1N1 or SiN2N2
[24]; a related tetravalent silicon compound, [{Pd(PPh3)-
Si)}2], was made from [Pd(PPh3)4] and
/
congeners [MCl2(PPh3)2] (Mꢁ
/
Pd, Pt) (Scheme 3) is
/
noteworthy. That a Pt(II) chloride was more resistant to
reductive dechlorination than an isoleptic Pd compound
was previously demonstrated: [MCl2(COD)] with an
excess of Sn[N(SiMe3)2]2 gave [Pd{Sn(N(SiMe3)2)2}3]
(m-SiN1N1Ã
/
SiN1N1 [25]. However, the centrosymmetric crystalline
d8 complex 4 is the first crystallographically charac-
terised palladium complex containing a silylene ligand
free of neutral donor stabilisation, and is isomorphous
for Mꢁ/Pd but cis-[Pt{Sn(N(SiMe3)2)2Cl}2(COD)] for
MꢁPt [21].
/
2.4. The X-ray structures of the crystalline compounds 2,
4, 5 and 6
The molecular structures of the compounds
[Ni(PPh3)(SiNN)3] 1 and trans-[Pt{SiNN(Cl)}2(SiNN)2]
3 have been published [17]. In summary; compound 1
lies on a crystallographic threefold axis, with the SiÃ
P angles of 106.4(1)8 narrower than the SiÃNiÃSi angles
of 112.4(1)8, the SiÃNi and PÃNi distances of 2.165(2)
and 2.210(4) A, respectively, and each silicon atom is
/
NiÃ
/
/
/
/
/
˚
˚
0.214 A out of the corresponding NiN2 plane. The
centrosymmetric compound 3 has PtÃSiNN and PtÃ
/
/
˚
SiNN(Cl) bond lengths of 2.266(1) and 2.426(1) A,
respectively, the silicon atom of each SiNN ligand is
only 0.048 out of the PtN2 plane, and in each silylene
ligand the neopentyl substituents are trans-disposed to
one another (cf., cis- in 1).
Crystalline 2 has the nickel atom at the centre of a
Fig. 1. Molecular structure of complex 2.
distorted NiSi4 tetrahedron, with three of the SiÃ
/
NiÃSi?
/
Scheme 4.

324
A.G. Avent et al. / Journal of Organometallic Chemistry 686 (2003) 321ꢀ331
/
Table 1
Table 2
˚
˚
Selected bond lengths (A) and angles (8) for 2
Selected bond lengths (A) and angles (8) for 4
Bond lengths
Bond lengths
NiÃ
NiÃ
Si(1)Ã
Si(2)Ã
Si(3)Ã
Si(4)Ã
/
Si(1)
2.215(2)
2.119(2)
1.754(4)
1.714(4)
1.722(4)
1.734(4)
NiÃ
NiÃ
Si(1)Ã
Si(2)Ã
Si(3)Ã
Si(4)Ã
/
Si(2)
2.110(2)
2.196(2)
1.757(4)
1.760(4)
1.777(4)
1.762(4)
PdÃ
Si(1)Ã
Si(1)Ã
ClÃ
/
Si(1)
2.269(2)
1.713(5)
1.708(5)
2.105(2)
PdÃ
Si(2)Ã
Si(2)Ã
/
Si(2)
2.437(2)
1.758(5)
1.753(5)
/Si(3)
/Si(4)
/N(1)
/N(3)
/
N(1)
N(3)
N(5)
N(8)
/
N(2)
N(4)
N(6)
N(7)
/N(2)
/N(4)
/
/
/
Si(2)
/
/
Bond angles
/
/
Si(1)Ã
Si(2)Ã
N(2)Ã
N(1)Ã
N(2)Ã
N(3)Ã
N(4)Ã
/
PdÃ
PdÃ
Si(1)Ã
Si(1)Ã
Si(1)Ã
Si(2)Ã
Si(2)Ã
/
Si(1)?
Si(2)?
180.0
180.0
Si(1)Ã
Si(1)Ã
N(4)Ã
N(4)Ã
N(3)Ã
ClÃSi(2)Ã
/
PdÃ
PdÃ
Si(2)Ã
Si(2)Ã
Si(2)Ã
/
Si(2)
Si(2)?
90.79(7)
89.21(7)
89.7(2)
Bond angles
/
/
/
/
Si(2)Ã
Si(3)Ã
Si(3)Ã
N(1)Ã
N(3)Ã
N(1)Ã
N(2)Ã
N(5)Ã
N(6)Ã
/
NiÃ
NiÃ
NiÃ
/
Si(3)
Si(4)
Si(1)
113.16(6)
103.67(6)
110.74(6)
86.0(2)
Si(2)Ã
Si(2)Ã
Si(4)Ã
N(5)Ã
N(8)Ã
N(3)Ã
N(4)Ã
N(7)Ã
N(8)Ã
/
NiÃ
NiÃ
NiÃ
/
Si(4)
Si(1)
Si(1)
108.18(6)
101.64(6)
119.77(6)
92.1(2)
/
/N(1)
92.6(2)
131.6(2)
135.6(2)
125.3(2)
123.7(2)
/
/
N(3)
Cl
/
/
/
/
/
/Pd
/
/
109.6(2)
108.0(2)
99.94(8)
/
/
/
/
/
/Pd
/
/
Cl
/
Si(1)Ã
Si(2)Ã
Si(1)Ã
Si(1)Ã
Si(3)Ã
Si(3)Ã
/
N(2)
N(4)
Ni
/
Si(3)Ã
Si(4)Ã
Si(2)Ã
Si(2)Ã
Si(4)Ã
Si(4)Ã
/
N(6)
N(7)
Ni
/
/Pd
/
/
Pd
/
/
91.5(2)
/
/
86.4(2)
/
/Pd
/
/
136.1(2)
136.4(2)
133.0(2)
133.39(14)
/
/
132.7(2)
132.46(14)
134.25(14)
136.9(2)
Symmetry transformations used to generate equivalent atoms: ꢂ
/
x,
/
/Ni
/
/
Ni
ꢂ/y, ꢂz.
/
/
/Ni
/
/
Ni
/
/Ni
/
/
Ni
with the isoleptic platinum(II) complex 3, Fig. 2 and
SiNN(Cl) bond lengths
Table 2. The PdÃ
/
SiNN and PdÃ
/
˚
of 2.269(2) and 2.437(2) A, respectively, are closely
similar to those in 3; and the latter is in the upper range
˚
previously found (2.33ꢀ
/
2.43 A) for Pdꢀ/silyl distances
[26,27]. As in 3, the neopentyl substitutents in each
silylene ligand are trans to one another, probably in
order to accommodate the mutually trans chlorine
atoms on the adjacent silyl ligands.
The crystalline d10 platinum(0) complex 5 lies on a
threefold symmetry axis; it is isomorphous with the
isoleptic Ni(0) complex 1. The structure is shown in Fig.
3 and selected geometrical parameters are in Table 3.
The disparity between the SiÃ
/
PtÃ
/
P and SiÃ
/
PtÃSi?
/
angles of 105.21(9) and 113.38(7)8 is somewhat greater
than in the nickel analogue 1. The discrepancy between
Fig. 3. Molecular structure of complex 5.
Table 3
˚
Selected bond lengths (A) and angles (8) for 5
Bond length
PtÃ
PtÃ
SiÃ
/
Si
2.261(3)
2.320(5)
1.724(10)
SiÃ
PÃC(17)
/
N(2)
1.737(10)
1.839(12)
/P
/
/N(1)
Bond angles
SiÃ
SiÃ
N(1)Ã
/
PtÃ
/
Si?
113.38(7)
105.21(9)
89.5
N(1)Ã
N(2)Ã
/
SiÃ
/
Pt
135.1(4)
131.3(4)
/
PtÃ
/P
/
SiÃ
/Pt
/
SiÃN(2)
/
Symmetry transformations used to generate equivalent atoms: y, z,
x.
the SiÃ
/
Pt and PÃ
/
Pt bond lengths of 2.261(3) and
˚
2.320(5) A, respectively, is ca. 3%; while for 1, the
corresponding bond lengths to the nickel atom vary by
˚
ca. 2%. Each silicon atom is 0.22 A out of the
Fig. 2. Molecular structure of complex 4.

A.G. Avent et al. / Journal of Organometallic Chemistry 686 (2003) 321ꢀ
/331
325
contiguous PtN2 plane and, as in 1, each silylene ligand
has the neopentyl substituents cis to one another.
Crystalline 6 has the d10 copper(I) atom at the centre
of a distorted tetrahedron, with two of the angles at Cu
Table 4
˚
Selected bond lengths (A) and angles (8) for 6
Bond lengths
CuÃ
CuÃ
SiÃ
/
I
2.641(2)
2.317(3)
1.716(9)
CuÃ
CuÃ
SiÃ
/
Si
2.289(4)
2.297(3)
1.736(9)
near to the sp2 value [P(2)Ã
118.29
1.68], two close to sp3 [P(2)Ã
Si, 109.190.58] and the mean of the remaining two [SiÃ
CuÃI and P(1)ÃCuÃI] is 99.690.68, Fig. 4 and Table 4.
The CuÃI and the CuÃP distances are unexceptional,
but slightly shorter than in [CuI(PPh3)3], 2.669(13) and
/
CuÃ
/
Si and P(2)Ã
/
CuÃ
/
P(1),
/P(1)
/P(2)
/
N(1)
/
N(2)
/
/
CuÃI and P(1)Ã
/
/
CuÃ
/
/
/
Bond angles
SiÃCuÃP(2)
P(2)ÃCuÃ
P(2)ÃCuÃ
N(1)ÃSiÃ
N(2)ÃSiÃ
/
/
119.80(12)
116.60(12)
109.16(9)
91.1(4)
SiÃ
SiÃ
P(1)Ã
N(1)Ã
/
CuÃ
/
P(1)
108.70(13)
100.22(9)
98.98(9)
/
/
/
/
/
/
I
/
CuÃ
/I
/
/
/
/I
/
CuÃ
/I
/
/
N(2)
Cu
/
SiÃCu
/
131.2(3)
˚
2.355(8) A, respectively; in the latter each bond angle
/
/
131.9(3)
subtended at Cu is close to the sp3 value [28]. The silicon
˚
atom in 6 is 0.26 A out of the CuN2 plane and, as in 1, 2
and 3, the two neopentyl groups are mutually cisoid.
processes, which have been studied by variable tempera-
ture multinuclear (1H, 29Si{1H}, 195Pt{1H}), as well as
1H saturation transfer (at 213 and 333 K) and 2D EXSY
(at 243 K) NMR spectroscopy.
2.5. Selected NMR spectral data for compounds 1ꢀ6
/
1
At 213 K, The H, 29Si (Fig. 6) and 195Pt (Fig. 5)
The 29Si{1H}-NMR spectral chemical shift for a
solution of a transition metal silylene complex is
invariably at higher frequency than in the parent
silylene: SiNN, d 96.9 [9]; SiN1N1, d 78.3 [8]; SiN2N2,
d 119 [16]. These data are summarised in Table 5, not
spectra showed the presence of three species, two major,
3a and 3b, and one minor, 3c. The three 195Pt chemical
shifts were within the narrow range of ca. 80 ppm (d ꢂ
/
5474, ꢂ5497 and ꢂ
/
/
5539). The 29Si spectrum showed
that for 3a and 3b there were two sets of peaks: one in
only for compounds 1ꢀ6 but also for the 23 others
/
the region of the coordinated silylene (d 142.5 and
1
reported to date. The 29Si{1H} signal for the
[SiNN(Cl)]ꢂ ligand was at much lower frequency than
that for the SiNN ligand in the Pt(II) complex 3, see
below. For the Cu(I) complex 6 in C6D6 at ambient
temperature, a 29Si{1H} signal was not detected, which
we attribute to a fast (on the NMR time scale)
dissociative equilibrium (in CDCl3 solution the complex
decomposed). For the Pd(II) complex 4 in C6D6 at
ambient temperature, a reductive elimination process
leading to Cl2SiNN is indicated by the 29Si{1H}-NMR
spectral data, see below. The 195Pt- and 29Si-NMR
spectra of the silyl(silylene)platinum(II) complex 3
showed that in CDCl3 solution 3 underwent fluxional
146.9, with J(29SiÃ
/
195Pt)ꢁ
2265 and 2259 Hz, respec-
/
tively) and the other in the region of the coordinated
chlorosilyl ligand (d 57.3 and 53.7, with
1J(29SiÃ195Pt)ꢁ
957 and 934 Hz, respectively). From
/
/
1
the H-NMR spectrum in the NCH2 region it is evident
that one of 3a/3b was symmetric giving just two AB
quartets, while the other showed four AB quartets.
These sets of signals from the major isomers are
assigned as arising from the symmetric (3a) and unsym-
metric (3b), trans- and cis-square planar d8 Pt(II)
complexes, respectively.
The minor isomer 3c showed two 29Si signals, both in
the coordinated SiNN region (d 143.0 and 146.5); there
were none which could unambiguously be assigned to
coordinated [SiNN(Cl)]ꢂ. In the NCH2 region of the
1H-NMR spectrum, four AB quartets were observed
which were in the low frequency region attributable to
the ligand [SiNN(Cl)]ꢂ; hence, we deduce that the 29Si
signals of this ligand were unresolved and thus unde-
tected.
Dynamic NMR spectral experiments at 213 K (Fig. 7)
showed that the lowest energy process is an exchange
between the minor isomer 3c and the trans-isomer 3a
only; this, and the close similarity of the chemical shifts
for 3a and 3c, particularly d(195Pt), indicates that 3a and
3c are two versions of the trans-isomer which differ only
in the conformation of their ligands. One possibility
Fig. 4. Molecular structure of complex 6.

326
A.G. Avent et al. / Journal of Organometallic Chemistry 686 (2003) 321ꢀ331
/
Table 5
Silylene complexes of d- and f-block metals
Si) (A) d[29Si]
Ref. Complex
/
Si) (A) d[29Si] Ref.
˚
l(MÃ
˚
Complex
l(MÃ
/
[Ycp2(SiNN)]
3.038(2)
2.329
2.326
119.5 at 188 K [18] [Ni(CO)2(SiN1N1)]
2.07(2)
2.165(2)
2.180 av.
2.152
97.5
[15,16]
a
trans-[Cr(CO)4(SiN1N1)2]
trans-[Cr(CO)4(SiN2N2)2]
trans-[Mo(CO)4(SiN1N1)2]
trans-[Mo(CO)4(SiN2N2)2]
cis-Mo(CO)4(SiNN)2
136.9
170.3
119.3
155.3
153.7
156.5
139.3
182
[23] [Ni(PPh3)(SiNN)3] (1)
[23] [Ni(SiNN)4] (2)
[23] [Ni(SiN1N1)3]
[23] [Ni(SiN2N2)3]
[34] Pd(SiN1N1)3
136.2
145.9
110.6
144.6
a
2.471
2.480
[22,23]
[22,23]
[24]
2.158
113.6
c
a
trans-[Mo(CO)4(SiNN)2]
[MoCp2(SiN1N1)]
2.4472(6)
2.4125(13)
2.288(2)
2.471
[34] trans-[Pd{SiNN(Cl)}2(SiNN)2] (4)
[29] trans-[Pt{SiNN(Cl)}2(SiNN)2] (3)
[33] [Pt(PCy3)2(SiMes2)]
[23] Pt(i PPr)2(SiMes2)
2.269(2) b
2.266(1) b
2.210(2)
c
a
[MoCp*(H)(dmpe){Si(Cl)Mes}]
trans-[W(CO)4(SiN1N1)2]
trans-W(CO)4(SiN2N2)2
trans-[Fe(CO)3(SiN1N1)2]
358
367
[7]
[7]
97.8
a
137.1
111.6
110.2
105.7
112
[23] [Pt(PPh3)(SiNN)3] (5)
[23] [CuI(PPh3)2(SiNN)] (6)
2.261(3)
2.289(4)
3.1910(1)
2.984(2)
108.4
c
a
2.196
2.330
2.228 av.
trans-[Ru(CO)3(SiN1N1)2]
[23] [SmCp2(SiN N )]
[30] [YbCp2(SiNN)]
[31]
[32]
[18]
1
1
ꢄ
ꢂ
ꢁ
ꢃ
/
[RuClfCH(CH2PCy2)2g(SiN1N1)]
RuCp*(Cl)(SiN1N1)
a
This work (see also [17] for 1 and 3).
b
c
This refers to MÃ
/
Si(NN).
See Section 2.5.
also would be expected to have NMR spectral para-
meters very different from those of 3a). In summary, the
structure of 3c has (i) the expected two 29Si signals, while
(ii) the single 29SiNN(Cl) signal is assumed to be
overlapping with that for 3a; and (iii) the anticipated
four AB quartets, one for each of the SiNN and
SiNN(Cl) ligands.
A second, but slower, dynamic process observed for
complex 3 in CDCl3 sets in at ca. 243 K, as illustrated by
1
the H-NMR 2D EXSY spectrum in the NCH2 region,
Fig. 8. It is attributed to the trans X cis isomerisation,
Eq. (1). This may be catalysed by a trace of free silylene,
implicating a five-coordinate stereochemically non-rigid
platinum(II) complex Pt{SiNN(Cl)}2(SiNN)3} inter-
mediate; a similar postulate is often proposed for the
tertiary phosphine-catalysed cis Xtrans isomerisation of
various d8 [PtX2(PPh3)2] complexes [37].
Fig. 5. 195Pt{1H}-NMR spectrum of 3 at 213 K.
ð1Þ
1
At 333 K a spin saturation H-NMR spectral experi-
ment showed that there was exchange between the
methylene protons of the SiNN and [SiNN(Cl)]ꢂ
ligands, Fig. 9. Thus, the third, and slowest of three
dynamic processes, is a Si0
/
Si 1,3-shift of Clꢂ, illu-
Fig. 6. 29Si{1H}-NMR spectrum of 3 at 213 K.
strated in Eq. (2) for 3c.
would be the rotamers of Scheme 5. (In our preliminary
communication [17], we suggested that 3c was a six-
coordinate Pt(II) complex; we now conclude that this is
unlikely, because a six-coordinate, 20-electron Pt(II)
complex would not only probably be paramagnetic but
ð2Þ
Upon changing the solvent from CDCl3 to thf-d8,
there was a marked shift in the cis Xtrans equilibrium,
presumably in favour of the more polar cis-isomer.

A.G. Avent et al. / Journal of Organometallic Chemistry 686 (2003) 321ꢀ
/331
327
consistent with the notion that the reductive elimination
is irreversible.
3. Conclusion
We have shown that the bis(amino)silylene
SiNN) can behave towards
Si[(NCHt2Bu)2C6H4-1,2] (ꢀ
a transition metal M substrate in diverse fashions: (i) it
may displace CO, PR3 or an alkene and form a complex
/
having one or more MÃ
formation may be accompanied by an MÃ
reaction yielding a product having one or more MÃ
SiNN(X) bonds, and (iii) MÃSiNN bond formation
/SiNN bonds, (ii) such bond-
/X insertion
/
/
may be supplemented by a reduction at the metal centre.
Type (i) reactions are illustrated here by the isolation
of the d10 complexes 1, 2, 5 and 6 of Ni(0), Pt(0) and
Cu(I), respectively. This type of behaviour is now widely
established, as summarised in Table 5. With four
exceptions, each of the listed compounds was made
from a bis(amino)silylene and an appropriate transition
metal substrate; those not mentioned in Sections 1 and 2
are [MoCp2(SiN1N1)] from [MoCp2(PEt3)] [29],
[RuCl{CH(CH2PCy2)(CH2CH2PCy2)}(SiN1N1)] from
[RuCl(L)(m-Cl)3RuL(N2)] [Lꢁ
/
Cy2P(CH2)4PCy2] [30],
[RuCp*(Cl)(SiN1N1)] from [{RuCp*Cl}4] [31], and
1
1
ꢄ
[SmCp2(SiN N )] [32]. The exceptions are [MoCp*(H)-
(dmpe){Si(Cl)Mes}], obtained from [MoCp*(h3-
CH2Ph)(dmpe)] and SiH2(Cl)Mes [33]; the crystalline
trans-[Mo(CO)4(SiNN)2] (in equilibrium in solution
with the cis-isomer), formed by heating 7, with
[Mo(CO)3{h-[C(tBu)P]3}] as coproduct [34]; and the
[Pt(PR3)2(SiMes2)] [7] complexes mentioned in Section
1.
Fig. 7. 1H-NMR spectra of the saturation transfer study (213 K) of 3
(methylene proton region).
The palladium(II) complex 4 in C6D6 solution is
evidently (and not unexpectedly [24]) more labile than
its isoleptic Pt(II) analogue 3. Thus, the 29Si{1H}-NMR
spectrum of 4 in C6D6 at 298 K showed three signals in
the NNSi-metal region (at d 132.1, 133.6 and 134.7, in
an intensity ratio of ca. 1:2:1) and one at d 24.1, which
corresponds to the literature value for Cl2SiNN [20].
The formation of the latter is indicative of a reductive
elimination of 4, yielding a mixture of (or a single)
silylene-Pd(0) complexes of as yet unknown composi-
tion. One possible interpretation of the three signals is
that two are from trans- and cis-[Pd{SiNN-
(Cl)}2(SiNN)2] (although a signal characteristic of
{SiNN(Cl)}ꢂ was not observed) and the third due to
Pd(SiNN)n. Several attempts to recrystallise 4 failed,
The type (ii) reactions are exemplified here by the
isolation of the crystalline d8 Pt(II) (3) and Pd(II) (4)
complexes, with the former more robust than the latter;
complex 3 has been shown to undergo three distinct
fluxional processes in solution. It appears that only two
other examples of insertion reactions have been re-
ported, Eq. (3) (MꢁMo, W), but they differ from (ii) in
/
that they relate to the conversion of a silylene into a
silylmetal product [29].
[MCp2H2 ꢃSiN1N1 MꢁM0o or [MH(Cp)2fSiN1N1(H)g] (3)
W
Nevertheless, we predict that many more MÃ
insertion reactions remain to be discovered, e.g., invol-
ving a d8-(m-Cl)2M2 precursor [Mꢁ
Rh(I) or Pt(II)].
/X/SiX2
/

328
A.G. Avent et al. / Journal of Organometallic Chemistry 686 (2003) 321ꢀ
/331
Scheme 5.
Fig. 9. 1H-NMR spectra of the saturation transfer study (333 K).
complexes, data for only one series are available, namely
trans-[Mo(CO)4(SiX2)2] in which d[29Si] decrease in the
sequence SiNN]
/
SiN2N2ꢁSiN1N1; the relative posi-
/
tion of SiN1N1 and SiN2N2 complexes is also main-
tained for appropriate Cr(0), W(0) and Ni(0) series [23].
The crystalline homoleptic d10 bis(amino)silylene-
nickel(0) complexes have a four-(SiNN) (2) or three-
(SiN1N1 or SiN2N2) coordinate metal environment,
whence it appears [23] that the non-benzenoid ligands
with the NtBu substituent are sterically the more
crowded.
Fig. 8. 1H-NMR 2D EXSY spectrum of 3 (243 K, methylene proton
region).
Type (iii) reactions are revealed here in the formation
of the d10 Ni(0) complexes 1 and 2 from the d8 precursor
[NiCl2(PPh3)2] or NiCl2, the SiNN acting not only as a
ligand but also a dechlorinating reagent, Cl2SiNN being
the coproduct. Other examples are not yet in the
literature, but readily reducible d-metal chlorides or
heavier halides are likely targets, e.g., an appropriate
Ti(IV) chloride or a Pd(II) bromide.
The MÃ
probably has a predominant s-component, with only a
rather weak contribution. This is consistent with
/SiX2 bond for bis(amino)silylene ligands
The bis(amino)silylenemetal complexes have 29Si
chemical shifts (Table 5) at higher frequency than in
the parent SiNN (d 96.9), SiN1N1 (d 78.3) and SiN2N2
(d 119), but at significantly lower frequency than in
(i) comparative IR and NMR spectral data for carbo-
nylmetal silylene complexes [23], (ii) molecular orbital
calculations on model compounds ClÃ
/
MÃ
/
SiN3N3 (Mꢁ
Si[N(H)CH]2) [35], (iii) compar-
/
Cu, Ag, Au; SiN3N3ꢁ
isons with related triarylphosphine-, E[N(SiMe3)2]2
/
[Pt(PR3)2(SiMes2)] (Rꢁi
/
Pr, Cy); although the other
ꢂ
ꢂ
a-amino-free silylenemetal complex [MoCp*(H)(dm-
pe){Si(Cl)Mes}] has the relatively low frequency
d[29Si] value of 182 ppm [33]. As for relative values of
(EꢁGe or Sn) and C[N(Me)CH2]2 [36] metal com-
/
plexes, and (iv) the observation that in each of 1ꢀ6 the
silicon atom of the silylene ligand is out of the MN2
plane.
/
d[29Si] in related MÃ
/
SiNN, MÃ
/
SiN1N1 and MÃ
/
SiN2N2

A.G. Avent et al. / Journal of Organometallic Chemistry 686 (2003) 321ꢀ
/331
329
Finally, we note that the neopentyl substituents at the
SiNN moieties are disposed cis in 1, 2, 5
and 6, but trans in 3 and 4.
C, 66.5; H, 9.06; N, 8.68. Found: C, 64.4; H, 8.57; N,
8.27%.
nitrogen of MÃ
/
4.4. Reaction of SiNN with [Ni(cod)2]
4. Experimental
A solution of SiNN (0.85 g, 3.1 mmol) in benzene (20
ml) was added to a solution of [Ni(cod)2] (0.21 g, 0.76
mmol) in benzene (20 ml) and stirred for several hours.
After removal of the solvent in vacuo the residue was
recrystallised from hexane yielding yellow crystals of 2
(0.81 g, 92%).
4.1. Materials and procedures
All operations and manipulations were carried out
under purified argon, by conventional Schlenk techni-
ques. Solvents were dried and degassed before use. The
NMR spectra were recorded in C6D6 or CDCl3 using
Bruker Instruments: Bruker DPX 300 (1H at 300 MHz,
13C at 75.5 MHz and 31P at 121.5 MHz) and AMX 500
(1H at 500 MHz and 29Si at 49.7 MHz), and referenced
internally to residual solvent resonances in the case of
1H- and 13C-spectra, or externally to H3PO4 or SiMe4
for 31P and 29Si, respectively; data in d. Microanalyses
were carried out by Medac Ltd. (Brunel University).
Melting points were taken in sealed capillaries and are
uncorrected. The yield of the products were not
optimised. The inorganic starting materials, with one
exception, were purchased from STREM, while
Si[(NCHt2Bu)2C6H4-1,2] [9] and [CuI(PPh3)3] [28] were
prepared as described in the literature.
4.5. Reaction of SiNN with NiCl2
A solution of SiNN (0.84 g, 3.08 mmol) in benzene (20
ml) was added to a suspension of an excess of NiCl2 (0.2
g, 1.54 mmol). After stirring for several hours the
mixture was filtered and the solvent was removed in
vacuo. Crystallisation from hexane at ꢂ25 8C gave
/
yellow crystals of 2 (0.47 g, 66%).
4.6. Reaction of SiNN with [PdCl2(PPh3)2]
A solution of SiNN (0.59 g, 2.15 mmol) in benzene (20
ml) was added to a solution of [PdCl2(PPh3)2] (0.3 g,
0.43 mmol) in benzene (20 ml). After stirring the mixture
for several hours a small amount of crystalline solid
formed. The solution was stored at 15 8C to complete
crystallisation; this yielded bright orange crystals of 4
4.2. Reaction of SiNN with [NiCl2(PPh3)2] (ratio 4:1)
A solution of SiNN (0.38 g, 1.4 mmol) in benzene (20
ml) was added to a solution of [NiCl2(PPh3)2] (0.23 g,
0.35 mmol) in benzene (20 ml) and stirred for several
hours. After removal of the solvent in vacuo the residue
(0.44 g, 80%), m.p. 115ꢀ
see text. Anal. Calc. for C64H104Cl2N8PdSi4×
67.8; H, 8.11; N, 6.73. Found: C, 67.1; H, 7.92; N, 7.4%.
/
117 8C (dec.). For NMR data
/5C6H6: C,
was dissolved in pentane and cooled to ꢂ
/
25 8C to
4.7. Reaction of SiNN with [PdCl2(cod)]
afford yellow crystals of 1 (0.27 g, 68%), m.p. 105ꢀ
/
1
108 8C (dec.). H-NMR (C6D6): d 0.78 (s, 54H, CH3),
A solution of SiNN (0.70 g, 2.55 mmol) in benzene (20
ml) was added to a solution of [PdCl2(cod)] (0.15 g, 0.51
mmol) in benzene (20 ml) and stirred for several hours.
Orange crystals of 4 (0.59 g, 91%), were obtained.
3.26 (s, 12H, CH2), 6.96 (m, 21H, phenyl) and 7.70 (m,
6H, phenyl). 13C{1H}-NMR (C6D6): d 29.46 (CMe3),
34.08 (CMe3), 52.47 (CH2), 110.99, 117.52 and 141.22
(phenyl). 31P{1H}-NMR (C6D6): d 47.31 (s). 29Si{1H}-
NMR (C6D6):
d
136.19. Anal. Calc. for
4.8. Reaction of SiNN with [PtCl2(PPh3)2]
C66H93N6NiPSi3: C, 69.3; H, 8.19; N, 7.34; Found: C,
68.9; H, 8.43; N, 7.41%.
A solution of SiNN (0.3 g, 1.0 mmol) in benzene (20
ml) was added to a solution of [PtCl2(PPh3)2] (0.16 g, 0.2
mmol) in benzene (20 ml). After removal of the solvent
4.3. Reaction of SiNN with [NiCl2(PPh3)2] (ratio 5:1)
in vacuo the residue was crystallised at ꢂ
hexane to afford orange crystals of 3 (0.16 g, 58%), m.p.
158ꢀ161 8C (dec.). X-ray-suitable crystals were obtained
/
25 8C from
Using the procedure in Section 4.2, but with SiNN
(0.40 g, 1.5 mmol) and [NiCl2(PPh3)2] (0.19 g, 0.3 mmol)
/
and crystallisation from hexane afforded at ꢂ
yellow crystals of 2 (suitable crystals for X-ray from
Et2O) (0.23 g, 66%), m.p. 84ꢀ
86 8C (dec.). 1H-NMR
/
25 8C
from benzene. For NMR data see text. Anal. Calc. for
C64H104Cl2N8PtSi4: C, 56.4; H, 7.69; N, 8.21. Found: C,
58.5; H, 7.42; N, 7.22%.
/
(C6D6): d 0.87 (s, 72H, CH3), 3.76 (s, 16H, CH2), 6.96
(m, 8H, phenyl) and 7.08 (m, 8H, phenyl). 13C{1H}-
NMR (C6D6): d 29.94 (CMe3), 34.32 (CMe3), 52.96
(CH2), 110.84, 118.06 and 141.30 (phenyl). 29Si{1H}-
NMR (C6D6): d 145.9. Anal. Calc. for C64H104N8NiSi4:
4.9. Reaction of SiNN with [PtCl2(cod)]
A solution of SiNN (0.52 g, 1.9 mmol) in benzene (20
ml) was added to a solution of [PtCl2(cod)] (0.14 g, 0.38

330
A.G. Avent et al. / Journal of Organometallic Chemistry 686 (2003) 321ꢀ331
/
mmol) in benzene (20 ml) and stirred for several hours.
After removal of the solvent in vacuo the residue was
crystallised from hexane yielding orange crystals of 3
(0.46 g, 89%).
134.53 (d) and 135.33 (d) (PPh3). Anal. Calc. for
C52H56CuIN2P2Si: C, 63.1; H, 5.70; N, 2.83. Found:
C, 62.9; H, 6.01; N, 2.77%.
4.10. Reaction of SiNN with [Pt(PPh3)4]
4.12. X-ray structure determinations for the complexes 2,
4, 5 and 6
A solution of SiNN (0.21 g, 0.75 mmol) in benzene (10
ml) was added to a solution of [Pt(PPh3)4] (0.18 g, 0.15
mmol) in benzene (10 ml) and stirred for 16 h. The
solvent was removed in vacuo. The residue was ex-
tracted with hexane, which led to the precipitation of
PPh3. After filtration and removal of the solvent in
vacuo the residue was crystallized from diethyl ether at
Data for the crystal structure determinations were
collected on an Enraf-Nonius CAD4 diffractometer at
173(2) K using monochromated MoꢀKa radiation (l
/
˚
0.71073 A). The structures were solved by direct
methods using SHELXL-86 [38] and refined by full-matrix
least squares on F2 using SHELXL-93 [39] for 2, 4 and 5,
or SHELXL-97 [40] for both structure solution and
refinement for 6, with all non-H atoms anisotropic;
ꢂ
25 8C yielding a few orange crystals of 5 (0.09 g). 1H-
/
NMR (C6D6): d 0.84 (s, 54H, CH3), 3.25 (vbr s, 12H,
CH2), 6.93 (m, 21H, phenyl) and 7.63 (m, 6H, phenyl).
31P{1H}-NMR (C6H6): d 22.85 (1JP,Si 1587 Hz).
29Si{1H}-NMR (C6D6): d 108.4.
H’s were included in riding mode with Uiso(H)ꢁ1.2
/
Ueg(C) or 1.5 Ueq(C) for methyl groups. Crystal data
and refinement details are listed in Table 6.
4.11. Reaction of SiNN with [CuI(PPh3)3]
A solution of SiNN (0.37 g, 1.35 mmol) in benzene (20
ml) was added to a solution of [CuI(PPh3)3] (0.88 g, 0.9
mmol) in benzene (20 ml) and stirred for 16 h. After
removal of the solvent in vacuo the residue was
extracted into diethyl ether. The extract was filtered
and after ca. 1/2 h some white precipitate had formed;
the mixture was filtered again. The filtrate was stored at
5. Supplementary material
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data centre, CCDC no. 207542 for compound 2, CCDC
no. 207543 for compound 4, CCDC no. 207544 for
compound 5, and CCDC no. 207545 for compound 6.
Copies of this information may be obtained free of
charge from The Director, CCDC, 12 Union Road,
Cambridge CB2 1EZ, UK (Fax: ꢃ44-1223-336033;
e-mail: deposit@ccdc.cam.ac.uk or www: http://
www.ccdc.cam.ac.uk).
ambient temperature for several days to afford yellow
1
crystals of 6 (0.65 g, 73%), m.p. 189ꢀ
/
190 8C. H-NMR
(C6D6): d 0.91 (s, 18H, CH3), 3.78 (s, 4H, CH2), 6.98 (m,
22H, phenyl) and 7.58 (m, 12H, phenyl). 13C{1H}-NMR
(C6D6): d 28.73 (CMe3), 33.47 (CMe3), 53.91 (CH2),
111.25, 118.85 and 140.48 (phenyl), 128.63 (d), 129.47,
/
Table 6
Crystal data and refinement for complexes 2, 4, 5 and 6
2
4
5
6
Formula
M
C
1230.7
64H104N8NiSi4×
/
(C4H10O) C64H104Cl2N8PdSi4×
/
5(C6H6) C66H93N6PPtSi3
C52H46CuIN2PSi×
1016.4
Triclinic
/0.5(C4H10O)
1665.75
Triclinic
1280.8
Cubic
Pa3 (No. 205)
24.026(4)
24.026(4)
24.026(4)
90
Crystal system
Space group
Orthorhombic
Pbca (No. 61)
20.780(4)
26.188(7)
26.922(6)
90
¯
P/1 (No. 2)
¯
P1 (No. 2)
/
˚
a (A)
13.757(7)
13.874(5)
13.982(5)
85.35(3)
61.02(3)
77.34(3)
2277(2)
1
13.409(6)
14.083(6)
15.308(14)
87.340(5)
78.680(6)
62.710(14)
2516(3)
2
˚
b (A)
˚
c (A)
a (8)
b (8)
g (8)
90
90
90
90
3
˚
U (A )
Z
Unique reflections collected 12 823
14 651(6)
8
13 869(4)
8
2828
6313
6142
Reflections with I ꢀ
Data/restraints/parameters
Goodness-of-fit on F2
/
2s(I)
7448
12 822/0/739
1.015
4048
6313/0/490
1.054
1787
2828/0/232
1.421
3953
6142/0/568
1.008
Final R indices [I ꢀ
R indices (all data)
/
2s(I)] R1ꢁ
/
0.070, wR2ꢁ
/
0.152
0.190
R1ꢁ
/
0.059, wR2ꢁ
/
0.097
R1ꢁ
/
0.056, wR2ꢁ
/
0.141 R1ꢁ
/
0.071, wR2ꢁ
/
0.158
0.187
R1ꢁ
/
0.138, wR2ꢁ
/
R1ꢁ
/
0.117, wR2ꢁ
/
0.120
R1ꢁ
/
0.101, wR2ꢁ
/
0.156 R1ꢁ
/
0.126, wR2ꢁ
/

A.G. Avent et al. / Journal of Organometallic Chemistry 686 (2003) 321ꢀ
/331
331
[19] T.A.K. Al-Alaf, C. Eaborn, P.B. Hitchcock, M.F. Lappert, A.
Pidcock, J. Chem. Soc. Chem. Commun. (1985) 548.
[20] B. Gehrhus, P.B. Hitchcock, M.F. Lappert, J. Heinicke, R. Boese,
Acknowledgements
We thank the Royal Society for the award of a R.S.-
NATO fellowship for H.M. and the EPSRC for a
fellowship and since 01.12.99 for an EPSRC Advanced
Fellowship for B.G.
D. Blaser, J. Organomet. Chem. 521 (1996) 211.
¨
[21] P.B. Hitchcock, M.F. Lappert, M.C. Misra, J. Chem. Soc. Chem.
Commun. (1985) 863.
[22] T.A. Schmedake, M. Haaf, B.J. Paradise, D. Powell, R. West,
Organometallics 19 (2000) 3263.
[23] T.A. Schmedake, M. Haaf, B.J. Paradise, A.J. Millevolte, D.R.
Powell, R. West, J. Organomet. Chem. 636 (2001) 17.
[24] W.A. Herrmann, P. Harter, W.K. Gstottmayer, F. Bielert, N.
References
¨
¨
Seeboth, P. Sirsch, J. Organomet. Chem. 649 (2001)
141.
[25] A. Furstner, H. Krause, C.W. Lehmann, Chem. Commun. (2001)
¨
[1] T.D. Tilley, in: S. Patai, Z. Rappoprt (Eds.), The Chemistry of
Organic Silicon Compounds, Wiley, New York, 1989, p. 1415.
[2] C. Zybill, Top. Curr. Chem. 160 (1992) 1.
[3] P.D. Lickiss, Chem. Soc. Rev. (1992) 271.
[4] D.A. Straus, S.D. Grumbine, T.D. Tilley, J. Am. Chem. Soc. 112
(1990) 7801.
2372.
[26] Y. Tanaka, H. Yamashita, S. Shimada, M. Tanaka, Organome-
tallics 16 (1997) 3246.
[27] M. Murakami, T. Yoshida, S. Kawanami, Y. Ito, J. Am. Chem.
Soc. 117 (1995) 6408.
[5] S.R. Klei, T.D. Tilley, R.G. Bergman, J. Am. Chem. Soc. 122
(2000) 1816.
[28] P.F. Barron, J.C. Dyason, P.C. Healy, L.M. Engelhardt, C.
Pakawatchai, V.A. Patrick, A.H. White, J. Chem. Soc. Dalton.
Trans. (1987) 1099.
[6] S.D. Grumbine, T.D. Tilley, F.P. Arnold, A.L. Rheingold, J. Am.
Chem. Soc. 115 (1993) 7884.
[29] S.H.A. Petri, D. Eikenberg, B. Neumann, H.-G. Stammler, P.
Jutzi, Organometallics 18 (1999) 2615.
[7] J.D. Feldman, G.P. Mitchell, J.O. Nolte, T.D. Tilley, J. Am.
Chem. Soc. 120 (1998) 11184.
[8] M. Denk, R. Lennon, R. Hayashi, R. West, A.V. Belyakov, H.P.
Verne, A. Haaland, M. Wagner, N. Metzler, J. Am. Chem. Soc.
116 (1994) 2691.
[30] D. Amoroso, M. Haaf, G.P.A. Yap, R. West, D.E. Fogg,
Organometallics 21 (2002) 534.
[31] J.M. Dysard, T.D. Tilley, Organometallics 19 (2000) 4726.
[32] W.J. Evans, J.M. Perotti, J.W. Ziller, D.F. Moser, R. West,
Organometallics 22 (2003) 1160.
[9] B. Gehrhus, M.F. Lappert, J. Heinicke, R. Boese, D. Blaser, J.
¨
Chem. Soc. Chem. Commun. (1995) 1931.
[10] M. Haaf, T.A. Schmedake, R. West, Acc. Chem. Res. 33 (2000)
704.
[33] B.V. Mork, T.D. Tilley, Angew. Chem. Int. Edit. 42 (2003)
357.
[11] B. Gehrhus, M.F. Lappert, J. Organomet. Chem. 617 (2001) 209.
[12] W.A. Herrmann, C. Kocher, Angew. Chem. Int. Ed. Engl. 36
(1997) 2163.
[34] S.B. Clendenning, B. Gehrhus, P.B. Hitchcock, D.F. Moser, J.F.
Nixon, R. West, J. Chem. Soc. Dalton. Trans. (2002) 484.
[35] C. Boehme, G. Frenking, Organometallics 17 (1998) 5801.
[36] M.F. Lappert, J. Organomet. Chem. 358 (1988) 185.
[37] F.R. Hartley, The Chemistry of Platinum and Palladium, Applied
[13] A.J. Arduengo, R. Krafczyk, Chem. Unserer Zeit 32 (1998) 6.
[14] M.F. Lappert, R.S. Rowe, Coord. Chem. Rev. 100 (1990) 267.
[15] M. Denk, R.K. Hayashi, R. West, J. Chem. Soc. Chem.
Commun. (1994) 33.
Science Publishers Ltd, London, 1973, pp. 313ꢀ
/315.
[38] G.M. Sheldrick, SHELXS-86, Program for the Solution of Crystal
Structures, University of Gottingen, Germany, 1985.
[16] R. West, M. Denk, Pure Appl. Chem. 68 (1996) 785.
[17] B. Gehrhus, P.B. Hitchcock, M.F. Lappert, H. Maciejewski,
Organometallics 17 (1998) 5599.
¨
[39] G.M. Sheldrick, SHELXL 93, Program for Crystal Structure
Refinement, University of Gottingen, Germany, 1993.
¨
[40] G.M. Sheldrick, SHELXL 97, Program for Crystal Structure
Refinement, University of Gottingen, Germany, 1997.
¨
[18] X.P. Cai, B. Gehrhus, P.B. Hitchcock, M.F. Lappert, Can. J.
Chem. Rev. Can. Chim. 78 (2000) 1484.