Synthesis and structures of 3-sila-β-diketiminato complexes of the coinage metals

Article abstract of DOI:10.1016/j.jorganchem.2007.07.012

The dimeric copper(I) 3-sila-β-diketiminate [Cu{(N(R)C(Ar))₂SiR}]₂ · (thf) (1) was obtained from CuI and [Li{(N(R)C(Ar))₂SiR}(thf)₂] (B) in toluene (R = SiMe₃, Ar = C₆H₃Me₂-2,6). When [CuI(PPh₃)₃] was used as a starting material, the LiI-containing compound [Cu{Si(R)(C(Ar)N(R))₂Li(μ-I)}(PPh₃)] (2) was isolated. The reaction of [MI(PPh₃)_n] (M = Ag, n = 3; M = Au, n = 2) with two equivalents of B in toluene gave the isomorphous silver and gold 3-sila-β-diketiminates [M{Si(R)(C(Ar)N(R))₂Li}₂(μ-I)] [M = Ag (3), Au (4)]. Each of 1-4 was characterised by the multinuclear NMR spectroscopy and single-crystal X-ray diffraction crystallography.

Full text of DOI:10.1016/j.jorganchem.2007.07.012

Journal of Organometallic Chemistry 692 (2007) 4953–4961
www.elsevier.com/locate/jorganchem
Synthesis and structures of 3-sila-b-diketiminato complexes
of the coinage metals
*
James D. Farwell, Peter B. Hitchcock, Michael F. Lappert , Andrey V. Protchenko
Department of Chemistry, University of Sussex, Brighton BN1 9QJ, UK
Received 23 May 2007; accepted 12 July 2007
Available online 18 July 2007
Abstract
The dimeric copper(I) 3-sila-b-diketiminate [Cu{(N(R)C(Ar))2SiR}]2 Æ (thf) (1) was obtained from CuI and [Li{(N(R)C(Ar))2-
SiR}(thf)2] (B) in toluene (R = SiMe3, Ar = C6H3Me2-2,6). When [CuI(PPh3)3] was used as a starting material, the LiI-containing com-
pound [Cu{Si(R)(C(Ar)N(R))2Li(l-I)}(PPh3)] (2) was isolated. The reaction of [MI(PPh3)n] (M = Ag, n = 3; M = Au, n = 2) with two
equivalents of B in toluene gave the isomorphous silver and gold 3-sila-b-diketiminates [M{Si(R)(C(Ar)N(R))2Li}2(l-I)] [M = Ag (3), Au
(4)]. Each of 1–4 was characterised by the multinuclear NMR spectroscopy and single-crystal X-ray diffraction crystallography.
ꢀ 2007 Elsevier B.V. All rights reserved.
Keywords: Copper; Silver; Gold; b-Diketiminates; Silyl complexes
1. Introduction
Scheme 1. X-ray structural data are available for
[Li{(N(R)@C(Ar))2SiR}(NCAr)2] [4], [Li{(N(R)@C(Ar))2-
SiR}(NCAr)] [7], C1 [6], C2 [7], D [6], E2 [7], E3 [7], E5 [7],
F [7] and H [8]. Two further crystalline magnesium 3-sila-b-
diketiminates have been reported: I from [Mg(SiR3)2(thf)2]
[9] and 2ArCN, and J from I and Me3SiOTf [8].
From these data, it will be evident that the 3-sila-b-dike-
timinato ligand operates as an Si-centred nucleophile in E1
to E5, F and G. By contrast, the alkali metal (B, C, D) and
Mg (H, I, J) complexes are zwitterionic, with the ligand
behaving in an N,N0-chelating (B, H, I, J), N,N0-chelating
and Si-bridging (C1, C2), or N,N0-bridging (D) fashion.
b-Diketiminato ligands, shown in A in p-delocalised
monoanionic form, feature extensively in the coordination
chemistry of nearly all the elements and in catalysis [1].
Most are b-diketiminates (R2 and R4 are alkyl, aryl or
silyl); only a few are b-dialdiminates (R2 = H = R4) [2].
The ligands A generally function as N,N0-centred nucleo-
philes in their coordination chemistry, either as chelates
or as bridges between two metal centres; but other ligating
modes (rarely C-centred [3]) have also been observed.
R3
R2
R1
R4
F3C
O
O
N
N
R5
R
R
R
R
R
R
Me
Me
Ar
Si
Ar
Si
Ar
Si
S
A
O
C
C
N
N
C
C
N
N
N
N
C
C
Mg
(thf)2
Mg
N
C
R
R
Mg
R
O
O
A 3-sila-b-diketiminato ligand was first obtained as the
lithium salt B (R = SiMe3, Ar = C6H3Me2-2,6) (Scheme
1) [4], prepared from [Li(SiR3)(thf)3] [5] and 2ArCN. Com-
pound B has been the source of the derivatives C1 [6], C2
[7], D [6], E1 to E5 [7], G [7] and H [8], as shown in
S
Ar
Ar
Ar
O
CF3
I
J
In this paper, we report extensions of our earlier studies
on metal b-diketiminates to the coinage metals (M) in the
+1 oxidation state. For comparison reference in made to
the literature data on MI diiminates. Until recently such
*
Corresponding author. Tel.: +44 1273 678316; fax: +44 1273 677196.
E-mail address: m.f.lappert@sussex.ac.uk (M.F. Lappert).
0022-328X/$ - see front matter ꢀ 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2007.07.012

4954
J.D. Farwell et al. / Journal of Organometallic Chemistry 692 (2007) 4953–4961
Ar
Ar
C
Ar
C
R
R
R
C
N
N
Si
R
R
R
R
R
Ar
Ar
R
Ar
R
N
K
N
K
C
C
N
C
N
Si
Si
M(L)
R
Mg
Si
R
N
N
Br
thf
Si
(L)
R
M
C
C
H
Ar
Ar
N
C
Ar
R
D
N
C
ii
vi
X = Br
R
Ar
C1 (L)M = Na
C2 (L)M = (ArCN)Rb
i
R
X
R
Si
Ar
Ar
R
Si
C
N
C
N
Ar
R
Ar
iii
C
N
C
N
R
R
Li
E1 X = H, E2 X = Cl
thf
thf
B
v
E3 X = Br, E4 X = SiMe3
E5 X = SnMe3
iv
R
OMe
Ar
Si
R
R
Ar
Ar
Ar
R
R
R
C
CH
C
N
N
R
N
N
C
C
N
N
Si
Si
Hg
H
R
C
R
G
Ar
Ar
F
Scheme 1. Reactions of the 3-sila-b-diketiminate B (R = SiMe3, Ar = C6H3Me2-2,6) [6–8]: i, MOBut (M = Na, Rb); ii, KOBut; iii, CpH (for E1),
[TiCp2Cl2] (for E2), HgBr2 or (CH2Br)2 (for E3), Me3SiCl (for E4), Me3SnCl (for E5); iv, Hg2Cl2; v, 2MeOH; and vi, Mg, Et2O/thf.
Group 11 metal complexes were restricted to those of CuII
2. Results and discussion
[1a] but since 2001 a few CuI compounds, including the
dialdiminates [Cu{(N(C6H2Me3-2,4,6)C(H))2CNO2}(L)]
[10a], [Cu{(N(Ar)C(H))2CPh}(L)] (L = NCMe [2a],PPh3
[2e]), and several diketiminates such as [Cu{(N(Ar)C-
(Me))2CH}(L)] (L = C2H4 [10b], Ge(NR2)2 [10c]) and
[Cu{N(Ar)C(Me)C(H)C(Me)N(C6H3Pri-2-CH2SMe-6)}]4
[10d] have been described. Data on the first AgI b-diimi-
nates appeared in 2005; these included the crystalline com-
plex K, obtained from H[{N(Ar)C(H)}2CH] and AgPF6
and NEt3 in MeOH, while from H[{N(Ar)C(Me)}2CH]
and the same reagents the product was the Ag-free C–C-
coupled compound [-C{C(Me)N(Ar)}{C(Me)N(Ar)H}]2
[11]. Three further AgI b-diketiminates, having N,N0-che-
lating (and bridging) ligands, including [Ag{(N(C6H3-
(CF3)2-3,5)C(CF3))2CH}(g2-C2H4)] have been obtained
from successively the parent diketimine and Ag2O in MeCN
and then C2H4 in benzene [12]. At the time we submitted
this paper, a gold b-diketiminate, as far as we were aware,
had not been described, but the product derived from AuCl
and Li[{N(Ar)C(Me)}2CH] was employed as a catalyst in
the aerobic oxidation of PhCH2OH to PhCHO [13].
2.1. The 3-sila-b-diketiminatocopper(I) complex 1
Treatment of copper(I) iodide with the lithium 3-sila-b-
diketiminate B in toluene, removal of volatiles and extrac-
tion of the residue with thf afforded (Scheme 2) the yellow
crystalline dimeric CuI 3-sila-b-diketiminate-thf solvate 1.
The 1H NMR spectrum of 1 in C6D6 showed the appropri-
ate integrated signals for 1, but even at ꢀ80 ꢁC in toluene-
d8 only a single SiMe3 resonance was observed, indicative
of a fast fluxional process, possibly due to weak N ! Cu
bonding and rapid
rotation. Compound 1 (like 2–
Cu Si
4) was labile in solution, slowly depositing metal; neverthe-
less the EI mass spectrum revealed the parent molecular
ion.
The X-ray molecular structure of crystalline 1 is shown
in Fig. 1. The core centrosymmetric molecule 1 is an eight-
membered CuNCSiCuNCSi puckered ring, with each
ligand bridging two copper atoms in an N,Si-bridging fash-
ion. The two puckered CuNCSiCu moieties are arranged in
a transoid fashion about the Cu–Cu0 vector. Similar eight-
membered CuNCXCuNCX rings, with short Cuꢁ ꢁ ꢁCu0
contacts have been reported in three dimeric CuI amidi-
nates (X = N) and an 1-azaallyl (X = C); selected endocy-
clic geometric parameters for these and 1 are listed in Table
1. Selected exocyclic ligand parameters for 1 are closely
similar to those for the mercury(II) 3-sila-b-diketiminate
ArN
Ag
ArN
NAr
Ag
NAr
K

J.D. Farwell et al. / Journal of Organometallic Chemistry 692 (2007) 4953–4961
4955
R
R
R
N
Ar
Ph 3P
N
Si
Ar
Ar
R
Cu
Cu
Ar
Cu
I
Si
R
R
Si
Ar
Ar
N
N
R
N
N
R
Li
2, orange, 87%
[crystallised from
toluene as 2 (0.5PhMe)]
CuI
PhMe
[CuI(PPh3)3]
pentane
R
1, yellow, 87%
[crystallised from thf as 1 (thf)]
R
Si
Ar
R
Ar
R
C
N
C
N
Li
thf
thf
[AgI(PPh3)3]
[AuI(PPh3)2]
PhMe
B [4]
PhMe
R
R
R
R
Ar
Ar
Ar
N
Si
Ag
Si
Ar
N
Si
Au
Si
Ar
R
Ar
R
Ar
Ar
R
N
N
N
N
N
N
R
R
R
R
Li
I
Li
Li
I
Li
R
4, yellow, 65%
3, green, 72%
Scheme 2. Synthesis of the crystalline Group 11 metal 3-sila-b-diketiminates 1–4 (R = SiMe3, Ar = C6H3Me2-2,6).
Fig. 1. ORTEP diagram of the molecular structure of 1 with thermal ellipsoids drawn at 20% probability level.
F [7], as illustrated in Table 2. The data of Tables 1 and 2
2.2. The 3-sila-b-diketiminatotris(triphenylphosphine)-
copper(I)–LiI adduct 2
support the view that there is little, if any, p-delocalisation
in the ligands of 1, consistent with its valence bond repre-
sentation in Scheme 2. The Cu–Si distance in 1 of
Addition of the lithium 3-sila-b-diketiminate B in pen-
tane to [CuI(PPh3)3] yielded (Scheme 2) complex 2 as a light
orange crystalline material from toluene at ꢀ5 ꢁC. A freshly
prepared sample of 2 in C6D6 gave 1H NMR spectral signals
˚
2.2728(8) A is closely similar to that in [Cu(SiR3){Sn-
(SiR3)(C6H3Mes2-2,6)}] which like 1 has the Cu and Si
atoms in two- and four-coordination, respectively [18].

4956
J.D. Farwell et al. / Journal of Organometallic Chemistry 692 (2007) 4953–4961
Table 1
Selected endocyclic geometric parameters for 1, four CuI amidinates and a CuI 1-azaallyl (R = SiMe3)
0
˚
˚
˚
Compound
Cuꢁ ꢁ ꢁCu (A)
Cu–N (A)
C–N (A)
Endocyclic angle at Cu (ꢁ)
Reference
1
2.4626(2)
2.414(1)
2.4031(6)
2.4571(2)
2.425
1.964(2)
1.869(1)
1.877(2)
1.880(2)
1.890
1.304(3)
1.329(2)
1.326(3)
1.336(2)
1.330
162.15(9)
176.4(1)
176.62(1)
175.37(2)
175.9
This work
[14a]
[14b]
[15]
[16]
[17]
[Cu{N(Pri)C(Me)N(Pri)}]2
[Cu{N(Bus)C(Me)N(Bus)}]2
[Cu{N(C6H3Me2-2,6)C(Ph)N(C6H3Me2-2,6)}]2
[Cu{N(R)C(Ph)N(R)}]2
[Cu{N(R)C(But)C(H)R}]2
2.499(2)
1.921(5)
1.309(8)
166.2(2)
Table 2
Selected exocyclic geometric parameters for 1 and Hg[Si(R){C(Ar)N(R)}2]2 (F) (R = SiMe3, Ar = C6H3Me2-2,6)
˚
˚
˚
˚
Compound
Si–Si (A)
Si–C (A)
C–N (A)
N–Si (A)
Me3Si–Si–
Si–C(Ar)–N
C(Ar)–N–
Reference
C(Ar) (ꢁ)
(ꢁ)
SiMe3 (ꢁ)
1
2.3741(11)
2.353(2)
1.926(3)
1.920(6),
1.923(6)
1.280(3)
1.275(7),
1.288(7)
1.745(2)
1.740(5),
1.753(5)
105.86(8)
106.3(2),
110.9(2)
113.2(2)
111.5(4),
114.4(5)
133.3(2)
132.1(4),
133.9(4)
This work
[7]
F
of appropriate relative intensities. However, as for 1, slow
decomposition with deposition of copper was observed
accompanied by formation of a benzene-soluble compound
having 1H NMR spectral characteristics of the ligand. Nev-
ertheless, the solid sample was adequately robust to furnish
satisfactory microanalytical data.
The X-ray molecular structure of crystalline 2 may be
regarded as a composite of its two precursors with loss of
2(PPh3 + thf). It is illustrated in Fig. 2 with selected geo-
metrical parameters. The six atoms Li, N(1), C(13), Si(1),
C(4) and N(2) of the Li[{N(R)C(Ar)}2SiR] moiety adopt
the boat conformation, as previously found for B [4], C1
[7], C2 [7], H [8] and [Li({N(R)C(Ar)}2SiR)(NCAr)] (L)
[7]. Its Si(1) and Li atoms act as a bridge to the Cu and I
atoms, respectively. The endocyclic parameters of the boat
are somewhat similar to those in L as shown by the follow-
ing data for L: Li–N(1) 1.954(5), Li–N(2) 1.950(5), N(1)–
C(13) 1.311(3), N(2)–C(4) 1.303(3), C(13)–Si(1) 1.881(2),
˚
C(4)–Si(1) 1.881(2) A; N(1)–Li–N(2) 111.4(2)ꢁ, Li–N(1)–
C(13) 105.3(2)ꢁ, Li–N(2)–C(4) 107.0(2)ꢁ, N(1)–C(13)–Si(1)
124.4(2)ꢁ, N(2)–C(4)–Si(1) 123.9(2)ꢁ, C(4)–Si(1)–C(13)
108.8(1)ꢁ; and the dihedral angles between the N(1)C(13)-
C(4)N(2) plane and the N(1)LiN(2) and C(13)Si(1)C(4)
planes are 53.7(1)ꢁ and 28.4(1)ꢁ, respectively [7], which
˚
Fig. 2. ORTEP diagram of the molecular structure of 2 with thermal ellipsoids drawn at 20% probability level. Selected bond lengths (A) and angles (ꢁ):
Li–N(1) 1.953(9), Li–N(2) 1.958(8), N(1)–C(13) 1.293(6), N(2)–C(4) 1.295(5), C(13)–Si(1) 1.931(4), C(4)–Si(1) 1.932(4), Si(2)–Si(1) 2.3666(17), Li–I
2.640(10), Cu–Si(1) 2.3298(12), Cu–I 2.6572(6), Cu–P 2.2523(12); N(1)–Li–N(2) 108.3(4), Li–N(1)–C(13) 109.8(4), Li–N(2)–C(4) 110.7(4), N(1)–C(13)–
Si(1) 120.9(3), N(2)–C(4)–Si(1) 120.4(3), C(4)–Si(1)–C(13) 105.13(18), N(1)–Li–I 116.9(4), N(2)–Li–I 118.3(4), Li–I–Cu 75.65(18); the dihedral angle
˚
between the P–I–Si(1) and N(1)–N(2)–I is 82.6(1)ꢁ; the Cu atom is 0.122(1) A out of the P–I–Si(1) plane.

J.D. Farwell et al. / Journal of Organometallic Chemistry 692 (2007) 4953–4961
4957
compares with 49.0(5)ꢁ and 37.3(2)ꢁ in 2. The Si(1) atom of
2 is in an approximately tetrahedral environment with
angles at Si(1) ranging from the Cu–Si(1)–C(13) at
102.60(13) to the Cu–Si(1)–Si(2) at 116.55(6)ꢁ. The three-
coordinate Cu atom of 2 is in a distorted trigonal planar
environment. The Cu–I and Li–I bond lengths of 2 are sig-
nificantly longer and somewhat shorter, respectively, com-
pared with those found in [(Et2O)2Li{(l-I)CuAr0}] [Ar0 =
expected from the molecular structure shown for crystalline
3.
The crystalline complexes 3 and 4 are isomorphous.
Their molecular structure is illustrated for the gold com-
plex 4 in Fig. 3. The framework tricyclic structure is shown
in Fig. 4. It is composed of a ten-membered C(1)–N(1)–
Li(2)–I–Li(1)–N(3)–C(28)–Si(5)–M–Si(1) (M = Ag, Au)
ring having [C(13)–N(2)] and [C(40)–N(4)] bridges to the
atom pairs [Si(1), Li(2)] and [Si(5), Li(1)], respectively. It
may be regarded as being an adduct of M-I and two
[Li{(N(R)C(Ar))2SiR}] moieties in which the Li(1) and
Li(2) atoms are bridged by an I atom, while the noble metal
atom M bridges the atoms Si(1) and Si(5). Average geomet-
rical parameters for these two moieties are listed in Table 3
together with corresponding data for [Li{(N(R)C(Ar))2-
i
C6H3(C6H2 Pr3-20,40,60)2-2,6] of 2.4512(8) and 2.690(11)
˚
A, respectively [19]. The Cu–P distance in 2, like its planar
environment, are unexceptional, being similar to those
found in crystalline [Cu{(N(Ar)C(H))2CPh}(PPh3)] in
˚
which d(Cu–P) = 2.1645(8) A [2e,20]. The Cu–Si bond
˚
length in 2 is similar to the 2.345 A found in [Cu(SiR3)-
(PPh3)2] [21] which like 2 has the Cu and Si atoms in a
3- and 4-coordination environment, respectively.
2.3. The noble metal(I) iodide-bridged bis(lithium 3-sila-b-
diketiminate) [M{Si(R)(C(Ar)N(R))2Li}2(l-I)]
[M = Ag (3), Au (4)]
The green (3) and the yellow (4) crystalline title com-
pounds were obtained (Scheme 2) from the appropriate
[MI(PPh3)n] (M = Ag, n = 3; M = Au, n = 2) and two
equivalent portions of the lithium compound B in toluene.
When the silver reaction was carried out using an equimo-
lar portion of the two reagents, approximately one half of
the unreacted [AgI(PPh3)3] was recovered. A freshly pre-
1
pared sample of 3 or 4 in C6D6 gave H NMR spectra
showing the appropriate relative intensities for signals cor-
responding to the ligand; and the 29Si spectra of 3 revealed
coupling of the 29Si nucleus to both 107Ag and 109Ag, as
Fig. 4. The core structure of complexes 3 and 4 (M = Ag, Au).
Fig. 3. ORTEP diagram of the molecular structure of 4 with thermal ellipsoids drawn at 20% probability level.

4958
J.D. Farwell et al. / Journal of Organometallic Chemistry 692 (2007) 4953–4961
Table 3
Selected geometric parameters for the [Li{(N(R)C(Ar))2SiR}] moiety of 3, 4 and [Li{(N(R)C(Ar))2SiR}(NCAr)] (L)
Compound
Average
(Li–N) (A)
Average
(N–C) (A)
Average
(C–Si) (A)
Average
(Si–Si) (A)
Average
(Li–N–C) (ꢁ)
Average
(N–C–Si) (ꢁ)
Average
(C–Si–Si) (ꢁ)
Reference
˚
˚
˚
˚
3
1.996
2.009
1.952
1.295
1.286
1.307
1.939
1.966
1.881
2.380
2.362
2.336
111.4, 106.2
110.7, 105.5
106.2
118.7, 122.1
118.6, 121.3
124.2
112.6
113.1
115.1
This work
This work
[7]
4
L
Table 4
Geometric parameters at the atoms I and M in 3 (M = Ag) and 4 (M = Au)
Compound Li(1)–I Li(2)–I M–Si(1) M–Si(5)
Mꢁ ꢁ ꢁI
(a) Bond distances (A)
˚
3
4
2.620(9)
2.626(12)
2.555(10)
2.549(12)
2.4827(13)
2.4044(17)
2.4883(13)
2.4072(17)
3.703(1)
4.083(1)
I–Li(1)–
N(3)
I–Li(1)–
N(4)
I–Li(2)–
N(1)
I–Li(2)–
N(2)
M–Si(1)–
C(1)
M–Si(1)–
C(13)
M–Si(1)–
Si(2)
M–Si(5)–
C(28)
M–Si(5)–
C(40)
M–Si(5)–
Si(6)
(b) Bond angles (ꢁ)
3
4
139.4(4)
116.0(4)
122.3(4)
122.4(6)
126.4(5)
132.7(6)
111.71(14)
121.01(19)
106.22(14)
108.76(19)
109.44(6)
106.90(8)
104.61(15)
105.84(19)
112.29(15)
112.61(19)
108.89(6)
106.77(8)
144.8(6)
115.7(5)
7
SiR}(NCAr)] (L) [7], while parameters associated with the
atoms I and Ag (3) or Au (4) are to be found in Table 4.
The Au–Si distance in 4 may be compared with the
116.2 MHz for Li and 121.5 MHz for 31P) or AMX 500
(99.4 MHz for 29Si, 194.3 MHz for 7Li) and referenced
1
internally to residual solvent resonances in the case of H
7
and 13C spectra. The Li, 29Si and 31P spectra were refer-
˚
2.356(2) A in [Au(SiR3)(PMePh2)] [22]; Ag–Si-containing
compounds were not found in the Cambridge Crystallo-
graphic Data Base [23]. The Li–I distances (see Table 4)
in 3 and 4 are very short with the Li(2)–I distance being
close to the value (2.54 A) reported for the gaseous mole-
cule [Li(l-I)]2 [24] and are much shorter than Li–I (bridging
enced externally to LiNO3 with D2O lock, SiMe4 and
H3PO4 (85% aqueous solution), respectively. Compounds
[MI(PPh3)3] (M = Cu, Ag) were prepared using stoichiom-
etric quantities of the appropriate MI and 3PPh3 in CH2Cl2
[28], while [AuI(PPh3)2] was obtained from H[AuCl4], KI
and 2PPh3 [30]; the synthesis of [Li{(N(R)C(Ar))2-
SiR}(thf)2] (B) was described previously [4,7]. Each of the
compounds 1–4 in benzene slowly decomposed yielding
a metallic precipitate; 1 and 2 were sufficiently robust to
be sent away for microanalysis (Medac Ltd., Brunel
University).
˚
or terminal) distances found in solvated lithium iodide
˚
(e.g., 2.822(6) and 2.840(6) A in [LiI(NEt3)]4 [25], 2.75(3)
˚
and 2.67(3) A in [LiI(pmdeta)] [26]). Slightly longer (appar-
ently due to the higher Li coordination number) Li–I dis-
˚
tances [2.635(10) and 2.721(10) A] have been found in the
copper imidosulfite cluster [Cu3{(NBut)3S}2{Li(thf)}2(l-
I)] [27]. The Agꢁ ꢁ ꢁI and Auꢁ ꢁ ꢁI distances in 3 and 4, respec-
tively, are clearly non-bonding, as evident from Table 4
and comparison with the M-I bond lengths in the starting
3.2. Preparation of [Cu{(N(R)C(Ar))2SiR}]2 Æ (thf) (1)
˚
compounds [AgI(PPh3)3] [2.855(1) and 2.864(1) A] [28] and
CuI (0.23 g, 1.21 mmol) was added to a stirred solution
of [Li{(N(R)C(Ar))2SiR}(thf)2] (B) (0.81 g, 1.22 mmol) in
toluene (30 cm3). The red mixture was stirred for 1 day,
resulting in a brown suspension. Solvent was removed in
vacuo. The solid was washed with pentane (ca. 5 cm3) to
leave a green residue, which was extracted into thf
(40 cm3). The orange extract was concentrated (to ca.
5 cm3) and stored at 5 ꢁC for 1 week to produce yellow
crystals of compound 1 (0.64 g, 87%). Anal. Calc. for
C58H98Cu2N4OSi8: C, 57.1; H, 8.10; N, 4.60. Found: C,
57.3; H, 8.19; N, 4.53%.
˚
[AuI(PPh3)2] [2.754(1) A] [29].
In conclusion, the synthesis and structures of the four crys-
talline CuI (1, 2), AgI (3) and AuI (4) 3-sila-b-diketiminato
complexes are described. Whereas in Group 11 metal-b-dik-
etiminates the negative charge of the ligand is p-delocalised,
in the [{N(SiMe3)C(C6H3Me2-2,6)}2Si(SiMe3)]ꢀ ligand of
1–4 (as in Li, Na, K, Rb, Mg andHgII analogues) the 3-silicon
atom carries the negative charge.
3. Experimental
1H NMR (C6D6): d 0.04 (s, 18H, NSiMe3), 0.56 (s, 9H,
SiSiMe3), 1.40 (4H, m, thf), 2.06 (s, 6H, C6H3Me2), 2.28 (s,
6H, C6H3Me2), 3.57 (m, 4H, thf), 6.55 (d, 2H, J = 7.6 Hz,
m-H), 6.60 (d, 2H, J = 7.6 Hz, m-H), 6.82 (t, 2H,
J = 7.6 Hz, m-H). 13C {1H} NMR (C6D6): d 1.75 (s, NSiM-
e3), 3.95 (s, SiSiMe3), 21.43 (s, 6H, C6H3Me2), 21.48 (s, 6H,
C6H3Me2), 25.96 (s, thf), 67.98 (s, thf), 127.0 (s, p-C),
132.71 (s, o-C), 133.12 (s, o-C), 147.05 (s, ipso-C);
3.1. General details
All manipulations were carried out under an inert atmo-
sphere using Schlenk techniques. Solvents were distilled
from appropriate drying agents and then degassed. The
NMR spectra were recorded at 298 K using a Bruker
DPX 300 (300.1 MHz for 1H, 75.5 MHz for 13C,

J.D. Farwell et al. / Journal of Organometallic Chemistry 692 (2007) 4953–4961
4959
29Si{1H} NMR (C6D6): d ꢀ28.0 (s, SiSiMe3), ꢀ10.3 (s,
SiSiMe3), 0.82 (s, NSiMe3); EI-MS (70 eV): m/z (%) 1146
(M+, 4), 1073 (M+ꢀSiMe3, 5).
(60 cm3). The mixture was stirred for 15 h. Volatiles were
removed in vacuo. The residue was washed with pentane
(ca. 5 cm3), then dissolved in toluene (ca. 10 cm3). The
green solution was concentrated (to ca. 3 cm3) and stored
at ꢀ30 ꢁC for 2 days. Grass-green crystals of compound
3.3. Preparation of [Cu{Si(R)(C(Ar)N(R))2Li(l-
I)}(PPh3)] (2)
1
3 (1.37 g, 72%) were isolated; H NMR (C6D6): d ꢀ0.25
(s, 9H, SiSiMe3), 0.13 (s, 18H, NSiMe3), 2.30 (s, 6H,
C6H3Me2), 2.42 (6H, s, C6H3Me2), 6.71 (d, 2H), 6.79 (d,
2H), 6.89 (t, 2H); 29Si{1H} NMR (C6D6): d 23.8 [q,
J(29Si107Ag) = 149.29, J(29Si109Ag) = 172.24 Hz, SiSiMe3],
0.80 (s, NSiMe3), ꢀ15.9 (d, J(SiAg) = 3.31 Hz, SiSiMe3).
The lithium 3-sila-b-diketiminate B (0.25 g, 0.38 mmol)
in pentane (20 cm3) was added to a stirred suspension of
[CuI(PPh3)3] (0.37 g, 0.38 mmol) in pentane (30 cm3). The
red mixture was stirred for 1 day. The reaction mixture
had turned yellow and a yellow precipitate had formed.
Volatiles were removed in vacuo. The residue was dissolved
in toluene (100 cm3); the solution was concentrated (to ca.
50 cm3) and stored at ꢀ5 ꢁC for 3 days, yielding light
orange crystals of compound 2 Æ (0.5C7H8) (0.35 g, 96%).
Anal. Calc. for C48.5H64CuILiN2PSi4: C, 57.4; H, 6.35;
N, 2.76. Found: C, 57.6; H, 6.65; N, 2.83%. 1H NMR
(C6D6): d ꢀ 0.29 (s, 9H, SiSiMe3), 0.09 (s, 18H, NSiMe3),
2.28 (s, 6H, C6H3Me2), 2.39 (s, 6H, C6H3Me2), 6.60–6.90
(m, 6H, C6H3Me2), 6.90–7.10 (m, 15H, PPh3);29Si {1H}
NMR (C6D6): d 32.6 [d, J(SiP) = 59.8 Hz, SiSiMe3],
ꢀ17.3 (s, SiSiMe3) ꢀ0.42 (s, NSiMe3); 31P{1H} NMR
(C6D6): d ꢀ0.43.
3.5. Preparation of [Au{Si(R)(C(Ar)N(R))2Li}2(l-I)]
(4)
[AuI(PPh3)2] (0.78 g, 0.92 mmol) was added to a stirred
solution of the lithium salt B (1.21 g, 1.83 mmol) in toluene
(60 cm3). The mixture was stirred for 15 h. Volatiles were
removed in vacuo. The residue was washed with pentane
(ca. 5 cm3), then dissolved in toluene (ca. 10 cm3). The yel-
low solution was concentrated (to ca. 3 cm3) and stored at
ꢀ30 ꢁC for 2 days. Yellow crystals of compound 4 (0.81 g,
65%) were isolated. 1H NMR (C6D6): d ꢀ0.17 (s, 9H,
SiSiMe3), 0.21 (s, 18H, NSiMe3), 2.13 (s, 6H, C6H3Me2),
2.67 (6H, s, C6H3Me2), 6.76 (d, 2H, J = 7.3 Hz, m-H),
6.86 (d, 2H, J = 7.3 Hz, m-H), 6.95 (t, 2H, J = 7.5 Hz, p-
H); 13C{1H} NMR (C6D6): d 1.32 (s, SiSiMe3), 1.46 (s,
NSiMe3), 21.7 (s, C6H3Me2), 23.6 (s, C6H3Me2), 127.6 (s,
p-C), 127.8 (s, m-C), 128.2 (s, m-C), 131.0 (s, o-C), 133.4
(s, o-C), 148.0 (s, ipso-C), 221.4 (N@C-Ar); 7Li{1H}
3.4. Preparation of [Ag{Si(R)(C(Ar)N(R))2Li}2(l-I)]
(3)
[AgI(PPh3)3] (1.53 g, 1.50 mmol) was added to a stirred
solution of the lithium salt B (1.98 g, 2.99 mmol) in toluene
Table 5
Crystallographic data and refinement parameters for complexes 1–4
Compound
1
2
3
4
Empirical formula
C
54H90Cu2N4Si8
C
45H60CuILiN2PSi4
C
54H90AgILi2N4Si8
C54H90AuILi2N4Si8
Æ (C4H8O)
1219.20
Æ 0.5(C7H8)
1015.73
Formula weight
Crystal size (mm)
Crystal system
Space group
1268.67
1357.77
0.25 · 0.25 · 0.10
Monoclinic
C2/c (No. 15)
0.4 · 0.4 · 0.3
Monoclinic
P21/n (No. 14)
0.4 · 0.2 · 0.2
Monoclinic
P21/c (No. 14)
0.4 · 0.3 · 0.3
Monoclinic
P21/c (No. 14)
Unit cell dimensions
˚
a (A)
25.5037(11)
14.2252(4)
20.1496(9)
111.005(2)
6824.4(5)
4
1.109
0.80
18780
17.7212(3)
11.8240(2)
25.1970(4)
90.374(1)
5279.55(15)
4
1.28
1.15
42833
21.7677(9)
16.2573(7)
20.5227(6)
110.619(2)
6797.4(5)
4
1.24
0.93
27486
21.6689(10)
16.2254(8)
20.6837(7)
110.760(2)
6800.0(5)
4
1.33
2.79
24591
˚
b (A)
˚
c (A)
b (ꢁ)
3
˚
V (A )
Z
Dcalc (Mg mꢀ3
)
Absorption coefficient (mmꢀ1
Reflections collected
)
Independent reflections (Rint
Reflections with [I > 2r(I)]
Data/restraints/parameter
Goodness-of-fit on F2
)
5993 (0.059)
4964
5993/0/349
1.033
15207 (0.046)
12482
15207/0/523
1.140
11877 (0.082)
9044
11877/30/562
1.029
14685 (0.057)
10496
14685/30/652
1.028
Final R indices [I > 2r(I)]
R1 = 0.043, wR2 = 0.106
R1 = 0.067, wR2 = 0.154
R1 = 0.060,
wR2 = 0.149
R1 = 0.082,
wR2 = 0.165
1.32 and ꢀ1.41
(near Ag)
R1 = 0.053,
wR2 = 0.112
R1 = 0.090,
wR2 = 0.130
1.08 and ꢀ2.21
(near Au)
R indices (all data)
R1 = 0.056, wR2 = 0.114
0.55 and ꢀ0.46
R1 = 0.082, wR2 = 0.160
1.27 and ꢀ1.06
Largest difference in peak and hole
ꢀ3
˚
(e A
)

4960
J.D. Farwell et al. / Journal of Organometallic Chemistry 692 (2007) 4953–4961
NMR (C6D6): d 2.54; 29Si{1H} NMR (C6D6): d 7.31 (s,
SiSiMe3), 2.18 (s, NSiMe3) ꢀ14.79 (s, SiSiMe3).
(b) Y. Cheng, P.B. Hitchcock, M.F. Lappert, M. Zhou, Chem.
Commun. (2005) 752;
(c) Y. Cheng, D.J. Doyle, P.B. Hitchcock, M.F. Lappert, Dalton
Trans. (2006) 4449;
(d) P.B. Hitchcock, M.F. Lappert, G. Li, A.V. Protchenko, Chem.
Commun. (2007) 846;
3.6. X-ray crystallographic studies
(e) X. Li, J. Ding, W. Jin, Y. Cheng, Inorg. Chim. Acta (2007),
doi:10.1016/j.ica.2007.06.024.
[3] (a) P.J. Ragogna, N. Burford, M. D’eon, R. McDonald, Chem.
Commun. (2003) 1052;
Diffraction data for compounds 1–4 were collected on
an Enraf-Nonius Kappa CCD diffractometer using mono-
˚
chromated Mo Ka radiation, k = 0.71073 A at 173(2) K.
Crystals were coated in oil and then directly mounted on
the diffractometer under a stream of cold nitrogen gas.
For 1 the Si(2)Me3 group is disordered and the thf mole-
cule is disordered across a twofold axis and was included
as isotropic C atoms without H atoms. For 2 there is a mol-
ecule of toluene solvate disordered across an inversion cen-
tre which was included with isotropic C atoms, distance
restraints, and H atoms omitted. For 4 the disordered
Si(8)Me3 group was refined with isotropic C atoms and dis-
tance constraints. The crystal 3 is isomorphous with 4.
Absorption corrections were applied using MULTISCAN and
refinement using SHELXL-97 [31]. Further details are given
in Table 5.
(b) P.B. Hitchcock, M.F. Lappert, J.E. Nycz, Chem. Commun.
(2003) 1142;
(c) N. Burford, M. D’eon, P.J. Ragogna, R. McDonald, M.J.
Ferguson, Inorg. Chem. 43 (2004) 734;
(d) D. Vidovic, Z. Lu, G. Reeske, J.A. Moore, A.H. Cowley, Chem.
Commun. (2006) 3501.
[4] P.B. Hitchcock, M.F. Lappert, M. Layh, Chem. Commun. (1998)
2179.
[5] K.W. Klinkhammer, Chem. Eur. J. 3 (1997) 1418.
[6] J.D. Farwell, P.B. Hitchcock, M.F. Lappert, Chem. Commun. (2002)
456.
[7] J.D. Farwell, P.B. Hitchcock, M.A. Fernandes, M.F. Lappert, M.
Layh, B. Omondi, Dalton Trans. (2003) 1719.
[8] J.D. Farwell, P.B. Hitchcock, M.F. Lappert, A.V. Protchenko,
Chem. Commun. (2005) 2271.
[9] J.D. Farwell, M.F. Lappert, C. Marschner, C. Strissel, T.D. Tilley, J.
Organomet. Chem. 603 (2000) 185.
[10] (a) S. Yokota, Y. Tachi, N. Ishiwaki, M. Ariga, Inorg. Chem. 40
(2001) 5316;
4. Note added in proof
(b) X. Dai, T.H. Warren, Chem. Commun. (2001) 1998;
(c) J.T. York, V.G. Young Jr., W.B. Tolman, Inorg. Chem. 45 (2006)
4191;
Two Au(I) b-dialdiminates, analogues of K, have
recently been reported by Dias and Flores [32].
(d) N.W. Aboelella, B.F. Gherman, L.M.R. Hill, J.T. York, N.
Holm, V.G. Young Jr., C.J. Cramer, W.B. Tolman, J. Am. Chem.
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Acknowledgements
[11] C. Shimokawa, S. Itoh, Inorg. Chem. 44 (2005) 3010.
[12] H.A. Chiong, O. Daugulis, Organometallics 25 (2006) 4504.
[13] B. Guan, D. Xing, G. Cai, X. Wan, N. Yu, Z. Fang, L. Yang, Z.
Shi, J. Am. Chem. Soc. 127 (2005) 8004.
[14] (a) B.S. Lim, A. Rahtu, J.-S. Park, R.G. Gordon, Inorg. Chem. 42
(2003) 7951;
We thank the BASF for financial support (J.D.F.). We
acknowledge the use of the EPSRC’s Chemical Database
Service at Daresbury.
(b) Z. Li, S.T. Barry, R.G. Gordon, Inorg. Chem. 44 (2005) 1728.
[15] X. Jiang, J.C. Bollinger, M.-H. Baik, D. Lee, Chem. Commun.
(2005) 1043.
Appendix A. Supplementary material
[16] S. Maier, W. Hiller, J. Stra¨hle, C. Ergezinger, K. Dehnicke, Z.
Naturforsch. B 43 (1988) 1628.
[17] P.B. Hitchcock, M.F. Lappert, M. Layh, Dalton Trans. (1998)
1619.
[18] J. Klett, K.W. Klinkhammer, M. Niemeyer, Chem. Eur. J. 5 (1999)
2531.
[19] C.-S. Hwang, P.P. Power, Organometallics 18 (1999) 697.
[20] The crystalline complex [Cu{(N(Ar)C(H))2CPh}(PPh3)] has been
made independently by Dr. M. Zhou; some data additional to those
of Ref. [2e] are to be found in Supplementary material.
[21] (a) Cited in Ref. [21b];
(b) K.W. Klinkhammer, J. Klett, Y. Xiong, S. Yao, Eur. J. Inorg.
Chem. (2003) 3417.
[22] J. Meyer, J. Willnecker, U. Schubert, Chem. Ber. 122 (1989) 223 (Au–
Si bond length).
[23] The United Kingdom Chemical Database Service: D.A. Fletcher,
R.F. McMeeking, D. Parkin, J. Chem. Inf. Comput. Sci. 36 (1996)
746.
[24] A.F. Wells, Structural Inorganic Chemistry, fifth ed., Clarendon
Press, Oxford, 1984, p. 444 (cited in Ref. [25]).
[25] C. Doriat, R. Ko¨ppe, E. Baum, G. Sto¨sser, H. Ko¨hnlein, H.
Schno¨ckel, Inorg. Chem. 39 (2000) 7951.
CCDC 648094, 648095, 648096 and 648097 contain the
supplementary crystallographic data for 1, 2, 3 and 4.
These data can be obtained free of charge via http://
www.ccdc.cam.ac.uk/conts/retrieving.html, or from the
Cambridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or
e-mail: deposit@ccdc.cam.ac.uk. Supplementary data asso-
ciated with this article (which also contains characterisa-
tion of [Cu{(N(Ar)C(H))2CPh}(PPh3)]). Supplementary
data associated with this article can be found, in the online
version, at doi:10.1016/j.jorganchem.2007.07.012.
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