Attachment of the new bulky ligand (Me3Si)2(Me2NMe2Si)C to Li, Hg, Al, Ga, and Sn. (see abstract)

Article abstract of DOI:10.1021/om980727k

The organolithium reagent [Li{C(SiMe₃)₂(SiMe₂NMe₂)(THF) ₂] (1) is readily obtained by reaction of the chloride (Me₃Si)₂(Me₂NMe₂Si)CCl with LiBu in THF (tetrahydrofuran) at low temperature. Reactions of 1 with HgBr₂, AlCl₃, GaCl₃, and SnCl₄ give [Hg{C(SiMe₃)₂-(SiMe₂NMe₂)} ₂] (2), [Al{C(SiMe₃)₂(SiMe₂NMe₂)}Cl ₂)] (3), Ga{C(SiMe₃)₂(SiMe₂NMe₂)}Cl ₂ (5), and [Sn{C(SiMe₃)₂(SiMe₂NMe₂)}Cl ₃] (6), respectively, and treatment of 3 with LiPh gives [Al{C(SiMe₃)₂(SiMe₂NMe₂)}Ph ₂] (4). Crystal structure determinations have shown that there is intramolecular coordination of the N atom to the metal M, with formation of a planar four-membered C-Si-N-M ring, in 1, 3, 4, and 5 (but not 2). Engagement of the lone pair on N in coordination with Al in 3 results in an exceptionally long Si-N bond length of 1.875-(2) A, some 0.16 ? longer than that in 2 and in simple silylamines generally; the Si-N bond is possibly shorter in 4 (1.851(2) ?) and 5 (1.858(4) ?), and is markedly so in 1 (1.796(4) ?), but still notably long. The lengths of the N - metal bonds in these compounds are similar to those between alkylamines and the metals in coordination compounds, indicating that at least in these systems the N atoms in the silylamines coordinate as strongly as those in the organic amines. Reaction of 6 with MeOH occurs exclusively at the Si-N bond to give [Sn-{C(SiMe₃)₂(SiMe₂OMe)}Cl₃], that of 2 with ICI or CF₃CO₂H gives [Hg{C(SiMe₃)₂(SiMe₂Cl)}₂] and [Hg{C(SiMe₃)₂(SiMe₂O₂CCF ₃)}₂], respectively, and that of 1 with ICH₂CH₂I gives the iodide (Me₃Si)₂(Me₂NMe₂Si)CI.

Full text of DOI:10.1021/om980727k

Organometallics 1999, 18, 45-52
45
Atta ch m en t of th e New Bu lk y Liga n d
(Me3Si)2(Me2NMe2Si)C to Li, Hg, Al, Ga , a n d Sn . Cr ysta l
Str u ctu r es of [Li{C(SiMe3)2(SiMe2NMe2)}(THF )2],
[Hg{C(SiMe3)2(SiMe2NMe2)}2],
[Al{C(SiMe3)2(SiMe2NMe2)}X2] (X ) Cl, P h ), a n d
[Ga {C(SiMe3)2(SiMe2NMe2)}Cl2]
Salih S. Al-J uaid, Colin Eaborn,* Salima M. El-Hamruni,
Peter B. Hitchcock, and J . David Smith*
School of Chemistry, Physics and Environmental Science, University of Sussex,
Brighton BN1 9QJ , U.K.
Received August 27, 1998
The organolithium reagent [Li{C(SiMe3)2(SiMe2NMe2)(THF)2] (1) is readily obtained by
reaction of the chloride (Me3Si)2(Me2NMe2Si)CCl with LiBu in THF (tetrahydrofuran) at
low temperature. Reactions of 1 with HgBr2, AlCl3, GaCl3, and SnCl4 give [Hg{C(SiMe3)2-
(SiMe2NMe2)}2] (2), [Al{C(SiMe3)2(SiMe2NMe2)}Cl2)] (3), Ga{C(SiMe3)2(SiMe2NMe2)}Cl2 (5),
and [Sn{C(SiMe3)2(SiMe2NMe2)}Cl3] (6), respectively, and treatment of 3 with LiPh gives
[Al{C(SiMe3)2(SiMe2NMe2)}Ph2] (4). Crystal structure determinations have shown that there
is intramolecular coordination of the N atom to the metal M, with formation of a planar
four-membered C-Si-N-M ring, in 1, 3, 4, and 5 (but not 2). Engagement of the lone pair
on N in coordination with Al in 3 results in an exceptionally long Si-N bond length of 1.875-
(2) Å, some 0.16 Å longer than that in 2 and in simple silylamines generally; the Si-N bond
is possibly shorter in 4 (1.851(2) Å) and 5 (1.858(4) Å), and is markedly so in 1 (1.796(4) Å),
but still notably long. The lengths of the N-metal bonds in these compounds are similar to
those between alkylamines and the metals in coordination compounds, indicating that at
least in these systems the N atoms in the silylamines coordinate as strongly as those in the
organic amines. Reaction of 6 with MeOH occurs exclusively at the Si-N bond to give [Sn-
{C(SiMe3)2(SiMe2OMe)}Cl3], that of 2 with ICl or CF3CO2H gives [Hg{C(SiMe3)2(SiMe2Cl)}2]
and [Hg{C(SiMe3)2(SiMe2O2CCF3)}2], respectively, and that of 1 with ICH2CH2I gives the
iodide (Me3Si)2(Me2NMe2Si)CI.
In tr od u ction
(Me2NMe2Si)3C to Li has given a linear polymeric
species with the polymer unit 7, in which the planar
carbanionic center is well removed from the planar
lithium ion center,5a and attachment of the ligand to
Mg has given the highly unusual Grignard reagent
Attachment of the very bulky ligand (Me3Si)3C (the
trisyl ligand) or the related ligand (PhMe2Si)3C to metal
centers has enabled us to isolate a substantial number
of novel types of organometallic compounds.1 Recently
the emphasis in our research has moved toward use of
ligands of the type (Me3Si)2(XMe2Si)C or (XMe2Si)3C
that provide comparable bulk around a metal center to
which they are attached but also contain donor groups
X capable of coordinating intra- or intermolecularly to
the metal. Those used previously include (Me3Si)2(XMe2-
Si)C with X ) OMe,2 SMe3 and (XMe2Si)3C with X )
OMe,4 NMe2.5,6 In particular, attachment of the ligand
(Me2NMe2Si)3CMgI, in which there is a planar carban-
(2) Eaborn, C.; Hitchcock, P. B.; Kowalewska, A.; Lu, Z.-R.; Smith,
J . D.; Stanczyk, W. A. J . Organomet. Chem. 1996, 521, 113.
(3) Antonov, D. A.; Eaborn, C.; Smith, J . D.; Hitchcock, P. B.; Molla,
E.; Rozenberg, V. I.; Stanczyk, W. A.; Kowalewska, A. J . Organomet.
Chem. 1996, 521, 109.
(4) Aigbirhio, F. I.; Buttrus, N. H.; Eaborn, C.; Gupta, S. H.;
Hitchcock, P. B.; Smith, J . D.; Sullivan, A. C. J . Chem. Soc., Dalton
Trans. 1992, 1015.
(5) (a) Farook, A.; Eaborn, C.; Hitchcock, P. B.; Smith, J . D. Chem.
Commun. 1996, 741. (b) Eaborn, C.; Farook, A.; Hitchcock, P. B.; Smith,
J . D. Organometallics 1997, 16, 503.
(6) A range of compounds of the type (Me3Si)2(XMe2Si)CLi, but not
any with X ) NR2, have been prepared in solution; some were isolated
as solids but not structurally characterized: Wiberg, N.; Preiner, G.;
Schieda, O. Chem. Ber. 1981, 114, 2087.
(1) For leading references see: (a) Eaborn, C.; Izod, K.; Smith, J .
D. J . Organomet. Chem. 1995, 500, 89. (b) Eaborn, C.; Smith, J . D.
Coord. Chem. Rev. 1996, 154, 125. (c) Eaborn, C.; Clegg, W.; Hitchcock,
P. B.; Hopman, M.; Izod, K.; O’Shaughnessy, P. N.; Smith, J . D.
Organometallics 1997, 16, 4728. (d) Eaborn, C.; Hitchcock, P. B.; Izod,
K.; Lu, Z.-R.; Smith, J . D.; Organometallics 1996, 15, 4783.
10.1021/om980727k CCC: $18.00 © 1999 American Chemical Society
Publication on Web 12/09/1998

46 Organometallics, Vol. 18, No. 1, 1999
Al-J uaid et al.
ionic center apparently without specific interaction with
the Mg atom.5b We have now made available the ligand
(Me3Si)2(Me2NMe2Si)C by preparation of the organo-
lithium reagent 1 and, in order to demonstrate the
utility of the latter, have used it to make the organo-
mercury compound 2, the organoaluminum compound
3 (and hence the corresponding diphenyl compound 4),
the organogallium compound 5, and the organotin
compound 6. Crystal structure determinations have
F igu r e 1. Molecular structure of [Hg{C(SiMe3)2(SiMe2N-
Me2)}2] (2).
Ta ble 1. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for [Hg{C(SiMe3)2(SiMe2NMe2)}2] (2)
Hg-C1
C1-Si1
C1-Si2
C1-Si3
2.161(4)
1.899(4)
1.881(4)
1.891(4)
Si1-N
1.721(4)
1.456(8)
1.441(8)
1.890(3)
N-C4
N-C5
Si-Me (mean)
Hg-C1-Si1
Hg-C1-Si2
Hg-C1-Si3
Si1-C1-Si2
Si1-C1-Si3
104.9(2)
107.4(2)
104.2(2)
113.2(2)
114.3(2)
Si2-C1-Si3
C2-Si1-C3
Si1-N-C4
111.9(2)
105.2(3)
123.5(4)
124.9(5)
110.9(5)
105.7(7)
shown that there is internal coordination of the NMe2
group to the metal in the lithium, aluminum, and
gallium compounds but not in the mercury compound.
Spectroscopic data suggest that there is similar internal
coordination in the tin compound.
Si1-N-C5
C4-N-C5
Me-Si-Me (mean)
there is a planar geometry at the nitrogen atom, as is
usual in the latter species. However, as a consequence
of the crowding, the Me-N-Me angle is lowered to
110.9(5)° and the Si1-N-Me angles are correspondingly
raised to 124.9(4) and 123.5(4)°. The other relevant
geometrical data for 2, viz. the C-Hg and C1-Si
distances and the mean Si-C-Si angle (113.1(4)°), are
essentially identical with those in Hg{C(SiMe3)3}29 and
Hg{C(SiMe3)2(SiMe2OMe)}2.7
There are marked changes in some of the geometrical
features of the (Me3Si)2(Me2NMe2Si)C ligand on going
to the aluminum compound 3 (see Figure 2 and Table
2), in which the N atom is strongly coordinated to the
Resu lts a n d Discu ssion
The ligand precursors (Me3Si)2(Me2NMe2Si)CH and
(Me3Si)2(Me2NMe2Si)CCl were respectively made by
reaction of (Me3Si)2(BrMe2Si)CH or (Me3Si)2(BrMe2Si)-
CCl with an excess of NMe2H in light petroleum. The
solvated organolithium reagent 1 was obtained by
treatment of (Me3Si)2(Me2NMe2Si)CH with MeLi at
room temperature or of (Me3Si)2(Me2NMe2Si)CCl with
LiBu in THF at low temperature. Reaction of 1 with
HgBr2 in THF gave the expected derivative 2, and
similar reactions with AlCl3 (in toluene), GaCl3 (in
toluene), or SnCl4 (in THF) gave 3, 5, and 6, respec-
tively. Treatment of 3 with LiPh in toluene gave the
diphenylaluminum compound 4.
Cr ysta l Str u ctu r es of Com p ou n d s 1-5. The crys-
tal structures of compounds 1-5 were determined by
X-ray diffraction studies. It is convenient to consider
first the mercury compound 2, in which the amino group
is not involved in coordination. The structure is shown
in Figure 1, and relevant bond lengths and angles are
given in Table 1. The form of the molecule is very
similar to that observed for the corresponding methoxy
compound Hg{C(SiMe3)2(SiMe2OMe)}2, with the NMe2
group, like the OMe group in the latter, pointing
outward away from the metal.7 (In contrast, in the
corresponding MeO-containing Zn and Cd compounds
the OMe groups point inward toward the metal.7) The
most important feature in the present context is that
the Si-N bond length of 1.721(4) Å falls in the normal
range of ca. 1.71-1.72 Å for trialkylaminosilanes,8 and
Al atom to give a near-planar Si-N-Al-C ring, the sum
of the internal angles being 358.2° and the fold angle
being 14°. The angle at Si, viz. 95.13(7)°, is significantly
larger than those at N, Al, and C, viz. 87.42(7), 88.28-
(7), and 87.33(7)°, respectively. The Si-N bond length
(1.875(2) Å) is, as far as we can ascertain, the longest
such bond ever observed for silicon attached to an amine
center, although it is not much longer than the Si-
NHBut bond (1.861(2) Å) in the four-membered-ring
species 8.10 The corresponding bond, Si-NMe2(AlCl3),
in the acyclic species 9 is, at 1.832(5) Å,11 markedly
shorter (but still much longer than the Si-NMe2 bonds
(8) Lukevics, E.; Pudova, O.; Sturkovich, R. Molecular Structure of
Organosilicon Compounds, Ellis Horwood: Chichester, U.K., 1989; pp
93-95.
(9) Glockling, F.; Hosmane, N. S.; Mahale, V. B.; Swindall, J . J .;
Magos, L.; King, T. J .; J . Chem. Res., Synop. 1977, 116; J . Chem. Res.,
Miniprint 1977, 1201.
(10) Veith, M.; Lange, H.; Recktenwald, O.; Frank, W. J . Organomet.
Chem. 1985, 294, 273.
(7) Aigbirhio, F. I.; Al-J uaid, S. S.; Eaborn, C.; Habtemariam, A.;
Hitchcock, P. B.; Smith, J . D. J . Organomet. Chem. 1991, 405, 149.
(11) Cowley, A. H.; Cushner, M. C.; Riley, P. E. J . Am. Chem. Soc.
1980, 102, 624.

Attachment of (Me3Si)2(Me2NMe2Si)C to Metals
Organometallics, Vol. 18, No. 1, 1999 47
Ta ble 2. Selected Bon d Len gth s (Å) a n d An gles (d eg) for [M{C(SiMe3)2(SiMe2NMe2)}Cl2] (M ) Al (3),
Ga (5))
M ) Al
M ) Ga
M ) Al
M ) Ga
M-Cl(1)
M-Cl(2)
M-C1
2.134(1)
2.145(1)
1.987(2)
1.975(2)
1.902(2)
1.894(2)
2.197(1)
2.200(1)
2.000(4)
2.057(4)
1.905(4)
1.895(5)
C1-Si3
1.865(2)
1.875(2)
1.491(2)
1.498(2)
1.878(1)
1.859(2)
1.870(5)
1.858(4)
1.489(6)
1.484(6)
1.877(3)
1.854(5)
N-Si3
N-C10
N-C11
Si-C in SiMe3 (mean)
Si-C in SiMe2 (mean)
M-N
C1-Si2
C1-Si1
C1-M-N
88.28(7)
87.33(7)
95.13(7)
86.4(2)
88.3(2)
96.4(2)
Cl1-M-Cl2
Cl1-M-C1
Cl2-M-C1
Cl1-M-N
106.74(3)
122.20(6)
118.47(5)
113.17(5)
105.49(5)
118.21(12)
112.83(12)
106.44(9)
109.15(9)
107.5(2)
105.63(5)
124.70(13)
119.73(13)
112.09(12)
104.68(11)
116.5(3)
112.5(3)
107.1(2)
109.0(2)
108.1(4)
M-C1-Si3
C1-Si3-N
Si3-N-M
C8-Si3-N
C9-Si3-N
M-C1-Si1
M-C1-Si2
Si1-C1-Si2
Si1-C1-Si3
Si2-C1-Si3
87.42(7)
87.0(2)
106.44(9)
109.15(9)
109.86(8)
114.13(8)
109.99(8)
120.70(9)
113.10(9)
107.1(2)
109.0(2)
108.6(2)
112.5(2)
110.4(2)
121.3(2)
113.5(2)
Cl2-M-N
M-N-C10
M-N-C11
N-Si3-C8
N-Si3-C9
C10-N-C11
Me-Si-Me (mean)
105.5(8)
105.8(9)
significantly larger than that (106°) in the 1,3-disilacy-
clobutane 10.14 In both 3 and 10 one Me group (C2 and
C7 in 3) of each Me3Si points in toward the ring and
the other two point outward. (There is an analogous
disposition in neutral species M{C(SiMe3)3}2.1a,b) It was
concluded in the case of the disilacyclobutane 10 that
widening of the Me3Si-C-SiMe3 angle is inhibited by
interactions between the inward-pointing Me groups
and the substituents on the ring atoms (the distance
between the inward-pointing Me groups and the Me
groups of the SiMe2 fragment is 3.4 Å) that force the
Me3Si groups together,14 and the analogous interactions
between C2 and C8 (C‚‚‚C 3.27 Å) and to a lesser extent
between C7 and C9 (C‚‚‚C 3.67 Å) as well as between
C2 and Cl2 or C7 and Cl1 (C‚‚‚Cl ) 3.65 and 3.64 Å,
respectively) appear to do the same in 3. However, the
sum of these interactions is evidently smaller than that
in 10, allowing the Me3Si-C-SiMe3 angle to be some
4° larger than in the latter. Other close contacts,
reflecting the inevitable crowding about a four-mem-
bered ring, are as follows: C8‚‚‚C10, 3.09 Å; C9‚‚‚C11,
3.17 Å; Cl1‚‚‚C11, 3.49 Å.
F igu r e 2. Molecular structure of [Al{C(SiMe3)2(SiMe2N-
Me2)}Cl2] (3).
from Si to the uncoordinated N atoms; mean 1.679(2)
Å). The length of the Si-N bond in 3 indicates that the
Other features of the structure of 3 are as follows.
(a) The Al-N bond length of 1.975(2) Å is fairly close to
that of 1.96 Å in, for example, the trialkylamine deriva-
tive Me3N‚AlCl316 and is significantly shorter than that
of 2.02 Å in Me3N‚AlMe2I.17 It is also significantly
shorter than that of the Al-NHtBuSi bond (1.994(2) Å)
in 8.10 The mean Al-Cl bond length of 2.139(1) Å
compares with the mean value of 2.138 Å for the Al-Cl
bonds in 8 and 2.116(4) Å for those in 9.11 (b) To
minimize interaction between the SiMe3 groups and the
Cl atoms, the Al-Cl bonds lie over toward the NMe2
group to give a mean C1-Al-Cl angle of ca. 120° and a
lone pair on the nitrogen atom is very firmly engaged
in bonding to Al. The increase of ca. 0.15 Å over the
(normal) Si-N bond length of 1.721(4) Å in 2 is
(13) (a) Fjeldberg, T.; Seip, R.; Lappert, M. F.; Thorne, A. J . J . Mol.
Struct. 1983, 99, 295. (b) Beagley, B.; Pritchard, R. G. J . Mol. Struct.
1982, 84, 129. Antipin, M. Yu.; Chernega, A. N.; Struchkov, Yu. T.;
Romanenko, V. D. Metallorg. Khim. 1991, 4, 358.
comparable to that of 0.14 Å for the Si-O bond on going
+ 12
to the protonated species But SiOH2
and raises the
3
(14) Eaborn, C.; Smith, J . D.; Hitchcock, P. B.; So¨zerli, S. E. J . Chem.
Res., in press.
(15) (a) Brain, P. T.; Mehta, M.; Rankin, D. W. H.; Robertson, H.
E.; Eaborn, C.; Smith, J . D.; Webb, A. D. J . Chem. Soc., Dalton Trans.
1995, 349. (b) Al-J uaid, S. S.; Eaborn, C.; Gorrell, I. B.; Hawkes, S.
A.; Hitchcock, P. B.; Smith, J . D. J . Chem. Soc., Dalton Trans. 1998,
2411.
Si-N distance to that corresponding to the sum (1.87
Å) of the covalent radii of Si and N.
The Me3Si-C-SiMe3 angle (110.0(1)°) is notably
small relative to the corresponding angles of 123.2° in
(Me3Si)2CH2 and 114.4(2)° in (Me3Si)3CH,13b but it is
13a
(16) Grant, D. F.; Killean, R. C. G.; Lawrence, J . L. Acta Crystallogr.,
Sect. B 1969, 25, 377.
(17) Atwood, J . L.; Milton, P. A. J . Organomet. Chem. 1973, 52, 275.
(12) Xie, Z.; Bau, R.; Reed, C. A. J . Chem. Soc., Chem. Commun.
1994, 2519.

48 Organometallics, Vol. 18, No. 1, 1999
Al-J uaid et al.
F igu r e 3. Molecular structure of [Ga{C(SiMe3)2(SiMe2N-
Me2)}Cl2] (5).
F igu r e 4. Molecular structure of [Al{C(SiMe3)2(SiMe2N-
Me2)}Ph2] (4).
Ta ble 3. Selected Bon d Len gth s (Å) a n d An gles
mean Cl-Al-N angle of ca. 109°. (c) The endocyclic Si-
C1 bond, 1.865(2) Å, is significantly shorter than the
exocyclic Si-C1 bonds (mean 1.898(2) Å); there is a
similar shortening of the intra-ring Si-C1 bond in 4
(1.857(3) Å), compared with a mean of 1.890(2) Å for
the other two Si-C1 bonds. No such shortening of the
C-SiMe2NMe2 bond is observed in the acyclic compound
2, and in the case of the cyclic lithium compound 1 (see
below) the intra-ring C1-Si1 bond, while clearly shorter
than the C1-Si3 bond, is not significantly shorter than
the C1-Si2 bond. (d) The Si-Me bonds in the SiMe3
groups (mean 1.878(1) Å) are longer than those in the
SiMe2 group (mean 1.859(2) Å); this is true also for
compound 5 and probably for compound 4, although in
this case the observed difference is within the limits
implied by the estimated standard deviations. (There
is no such effect in compounds 1 and 2.) (e) The mean
of the Si-C1-Si angles (114.6°) and the angle of 113.10-
(9)° between the Si3-C1 and Si2-C1 bonds are similar
to those in a (Me3Si)3C group attached to Al,15 but the
involvement of Si3 in the four-membered ring leads to
a large difference between the Si1-C1-Si3 and Si2-
C1-Si3 angles, which are 109.99(8) and 120.70(9)°,
respectively. The Al-C bond lengths are normal.
The structure of the gallium compound 5 is shown in
Figure 3, and relevant bond lengths and angles are
given in Table 2 alongside those for 3. The compound
is closely isomorphous with its aluminum analogue 3,
and so the comments made above on the structure of
the latter apply equally to that of 5. It is noteworthy,
however, that the metal-C bond lengths are not sig-
nificantly different in the two compounds but the
metal-N and metal-Cl bonds are slightly longer in 5.
The ring angle at the metal in 5 (86.4(2)°) is slightly
smaller than that in 3 (88.28(7)°). The other parameters
are virtually identical in the two compounds; the sum
of the ring angles is 358.1° in 5 and 358.8° in 3.
(d eg) for [Al{C(SiMe3)2(SiMe2NMe2)}P h 2] (4)
Al-C12
Al-C18
Al-C1
Al-N
C1-Si1
C1-Si2
1.984(3)
2.000(3)
2.057(3)
2.038(2)
1.857(3)
1.887(3)
C1-Si3
1.893(3)
1.851(2)
1.494(4)
1.484(3)
1.879(2)
1.866(3)
N-Si1
N-C2
N-C3
Si-C in SiMe3 (mean)
Si-C in SiMe2 (mean)
C1-Al-N
85.20(10)
87.38(11)
96.75(11)
C12-Al-C18
C12-Al-C1
C18-Al-C1
C12-Al-N
C18-Al-N
Al-N-C2
104.26(12)
125.57(11)
119.35(11)
109.04(11)
110.99(11)
110.7(2)
Al-C1-Si1
C1-Si1-N
Si1-N-Al
C4-Si1-N
C5-Si1-N
Al-C1-Si2
Al-C1-Si3
Si1-C1-Si2
Si1-C1-Si3
Si2-C1-Si3
88.13(10)
106.73(13)
108.61(13)
110.40(12)
115.20(12)
120.46(14)
113.30(13)
108.86(12)
Al-N-C3
120.2(2)
N-Si1-C4
N-Si1-C5
C2-N-C3
106.73(13)
108.61(13)
106.8(2)
Me-Si-Me (mean)
104.6(8)
fact that the Si-N bond length is, at 1.851(2) Å,
somewhat shorter than that in 3 is consistent with the
suggestion that as electron withdrawal from Al by Ph
is weaker than that by Cl, the resulting N-Al coordina-
tion is slightly weaker. Other features of the structure
are closely similar to those in 3 and require no further
comment.
As can be seen from Figure 5, there is also coordina-
tion of the N atom to the metal in the lithium compound
1, bond lengths and angles for which are given in Table
4. The four-membered ring is again almost planar, the
sum of the internal angles being 358.8° and the fold
angles across the N/C1 and Si1/Li axes being 13 and
11°. These fold angles differ because the endocyclic Li-C
and Li-N bonds (2.287(9) and 2.162(8) Å, respectively)
are substantially longer than the Si-C and Si-N bonds
(1.796(4) and 1.806(4) Å, respectively). The same effect
allows the endocyclic angle at Si (108.1(2)°) to be
markedly larger than that in 3 or 4.
The structure of 4 is shown in Figure 4, and relevant
bond lengths and angles are given in Table 3. The four-
membered ring is a little further from planarity than
that in 3, the sum of the internal angles being 357.5°
and the fold angle being 17°. The Me3Si-C-SiMe3 angle
(108.9(1)°) is slightly smaller than that in 3, probably
because the larger size of the substituents on Al slightly
increases the overall crowding around the ring in 4. The
There are striking differences between the geometry
of the (Me3Si)2C system in 1 and that in the aluminum
compound 3 (and so also in 4 or 5): the C1-Si bonds
(mean 1.819 Å) are markedly shorter, the mean Si-C1-
Si angle (116.9°) is markedly larger, and the mean Me-
Si-Me angle (103.6°) is significantly smaller than those
in 3 (1.878 Å, 114.6°, and 105.5°, respectively), and these
are attributed to the greater carbanionic character at

Attachment of (Me3Si)2(Me2NMe2Si)C to Metals
Organometallics, Vol. 18, No. 1, 1999 49
bond length of 1.796(4) Å is ca. 0.08 Å shorter than that
in 3, perhaps implying a somewhat weaker N-metal
coordination than in the latter; however, it is still
markedly longer than that in 2 or those in R3SiNR′2
compounds.8
Th e Com p ou n d Sn {C(SiMe3)2(SiMe2NMe2)}Cl3
(6). Reaction of the lithium reagent 1 with SnCl4 in THF
at -12 °C gave after workup a white solid which was
shown from its analysis and spectroscopic data to have
the formula Sn{C(SiMe3)2(SiMe2NMe2)}Cl3. Good crys-
tals were obtained from heptane, but they proved to be
cubic, with a ) 12.95 Å, the cell volume indicating that
the compound is monomeric. Unfortunately the struc-
ture could not be resolved, possibly because of extensive
disorder. However, the position of the signal in the 119Sn
NMR spectrum, at δ -182 for a solution in C6D6, is more
consistent with five- than four-coordinate tin,19 again
pointing to N-Sn coordination. (The position of the 15N
NMR signal is considered below.)
F igu r e 5. Molecular structure of [Li{C(SiMe3)2(SiMe2N-
Me2)}(THF)2] (1).
Treatment of 5 with MeOH in Et2O gave, as colorless
crystals, the methoxy derivative Sn{C(SiMe3)2(SiMe2-
OMe)}Cl3, identical with a sample that had been made
previously from [Li{C(SiMe3)2(SiMe2OMe)(THF)2] and
SnCl4.20
Ta ble 4. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for [Li{C(SiMe3)2(SiMe2NMe2)}(THF )2] (1)
Li-O1
Li-O2
Li-C1
Li-N
N-Si1
C1-Si1
1.980(8)
1.980(8)
2.287(9)
2.162(8)
1.796(4)
1.806(4)
C1-Si2
1.815(4)
1.835(4)
1.469(6)
1.468(6)
1.886(3)
C1-Si3
N-C4
Rea ction s of th e Mer cu r y Der iva tive 2. Treat-
ment of compound 2 with ICl in THF gave a moderately
good yield of the chloro derivative Hg{C(SiMe3)2(SiMe2-
Cl)}2 without any observable attack on the C-Hg bond.
Treatment with 2 mol equiv of CF3CO2H in the hope of
obtaining the ammonium salt [Hg{C(SiMe3)2(SiMe2-
NMe2H)}2][CF3CO2]2 gave the bis(trifluoroacetate) Hg-
{C(SiMe3)2(SiMe2O2CCF3)}2, the zinc analogue of which
was obtained earlier by reaction of Zn{C(SiMe3)2-
(SiMe2I}2 with CF3CO2H and Ag2O in CCl4.21
N-C5
Si-Me (mean)
C1-Li-N
Li-N-Si1
N-Si1-C1
Si1-C1-Li
O1-Li-O2
O1-Li-N
O2-Li-N
O1-Li-C1
O2-Li-C1
81.8(3)
86.4(2)
108.1(2)
82.5(2)
Si1-C1-Si2
Si1-C1-Si3
Si2-C1-Si3
C4-N-C5
117.4(2)
119.2(2)
114.0(2)
108.3(4)
96.5(3)
131.0(4)
119.8(3)
98.6(3)
95.7(3)
Li-N-C4
110.4(4)
119.8(4)
129.8(4)
120.8(4)
Li-N-C5
Si2-C1-Li
Si3-C1-Li
Me-Si-Me (mean)
103.2(5)
Th e Iod id e (Me3Si)2(Me2NMe2Si)CI. Treatment of
1 with ICH2CH2I gave the iodide (Me3Si)2(Me2NMe2Si)-
CI, which has the potential to react directly with appro-
priate metals to give the corresponding organometallic
iodides; compare the reaction of (Me2NMe2Si)3CI with
the C1 center in the lithium compound.1b,15a Especially
noteworthy is that the Me3Si-C-SiMe3 angle in 1
(114.0(2)°) is larger than that in 3 (110.0(1)°), and in
view of the discussion above of cross-ring Me‚‚‚Me
interactions in 3 it is appropriate to consider why the
angle in 1 can open so far. As in 3, and neutral M{C-
(SiMe3)3}2 compounds, one Me group of each Me3Si lies
toward the center of the molecule. However, because the
plane through the Si2, C1, and Si3 atoms lies well away
from perpendicularity to that through Si1, C1, and Li
(the Li-C1-Si2 and Li-C1-Si3 angles are 119.8(3) and
98.6(3)°, respectively) and the plane through the C5, N,
and C4 atoms similarly lies well away from perpendicu-
larity to the Si1, N, Li plane (the Li-N-C4 and Li-
N-C5 angles being 96.5(3) and 131.0(4)°, respectively),
inward-pointing Me groups at C6 and C11 are well
removed (by >5 Å) from the Me groups at C4 and C5.
The closest nonbonding Me‚‚‚Me contacts around the
ring are C2‚‚‚C4 (3.14 Å) and C3‚‚‚C5 (3.05 Å), and other
close contacts are C4‚‚‚O2 (3.34 Å), Si2‚‚‚C2 (3.50 Å),
and Si3‚‚‚C3 (3.56 Å); all of these contacts involve near-
eclipsed substituents in 1,2-dispositions in the four-
membered ring.
Mg to give (Me2NMe2Si)3CMgI5b and that of (Me3Si)2-
(MeOMe2Si)CI with Yb or Mg to give Yb{C(SiMe3)2-
1d
(SiMe2OMe)}2‚OEt2 or Mg{C(SiMe3)2(SiMe2OMe)}2.2
NMR Sp ectr a . Some significant chemical shift data
for solutions in C6D6 of the RX compounds with R )
(Me3Si)2(Me2NMe2Si)C are given in Table 5 for com-
pounds 1-5 and the compounds RH, RCl, and RI. The
features are as follows. (i) Neither the 29Si data for the
SiMe3 groups nor the 13C data appear to show any
systematic variation that might help in indicating
whether the nitrogen atom of the NMe2 group is coor-
dinated to a metal in relevant compounds in solution.
The relatively large negative value of the chemical shift
for 29Si of the SiMe3 group in the lithium compound can
be associated with the high carbanionic character of the
central carbon; compare the corresponding shift of δ
-16.8 for the 29Si nuclei in the salt [Li(THF)4][C(SiMe2-
The Li-N bond length of 2.162(8) Å in 1 (cf. 2.094(7)
and 2.133(11) Å in the unit 7) is not significantly longer
than that of 2.125(9) Å in [Li(TMEDA)2]+.18 The Si-N
(19) Davies, A. G.; Smith, P. J . In Comprehensive Organometallic
Chemistry; Wilkinson, G., Stone, F. G. A., Abel, E. W., Eds.; Perga-
mon: Oxford, U.K., 1982; Vol. 2, pp 527-529.
(20) So¨zerli, S. E. D. Phil. Thesis, University of Sussex, 1998.
(21) Al-J uaid, S. S.; Eaborn, C.; Habtemariam, A.; Hitchcock, P. B.;
Smith, J . D. J . Organomet. Chem. 1992, 437, 41.
(18) Eaborn, C.; Lu, Z.-R.; Hitchcock, P. B.; Smith, J . D. Organo-
metallics 1996, 15, 1651.

50 Organometallics, Vol. 18, No. 1, 1999
Al-J uaid et al.
Ta ble 5. NMR Da ta : Selected Ch em ica l Sh ifts in
C6D6 for Com p ou n d s Con ta in in g th e Liga n d
(Me3Si)2(Me2NMe2Si)C (R)a
Exp er im en ta l Section
Air and moisture were excluded as rigorously as possible
by use of Schlenk techniques, flame-dried glassware, and argon
as blanket gas. Solvents were dried by standard procedures
and distilled immediately before use. C, H analyses were by
Medac Ltd.
δ(Si)
δ(C)
compd
RH
RCl
RI
RLi‚2THF -10.6
R2Hg
RAlC12
RAlPh2
RGaC12
RSnCl3
SiMe3
SiNMe2 NMe2 SiMe3 SiMe2 δ(N)
-1.5
2.7
3.2
4.9
3.4
38.3
39.5
39.9
38.8
40.0
41.1
42.5
41.5
42.6
3.3
1.0
3.2
8.1
6.6
2.4
7.8
6.5
5.6
1.6
0.18
3.0
3.3
5.6
2.5
3.5
2.4
4.8
-380
-378
a
Sp ectr a . Unless otherwise stated, the NMR spectra were
determined for solutions in C6D6. The frequencies (MHz) used
for the various nuclei were as follows: 1H, 300.1; 13C, 125.8;
29Si, 99.4; 119Sn, 186.6; 7Li, 194.5; 199Hg, 89.5; 15N 50.7.
Chemical shifts are relative to SiMe4 for H, C, and Si, to SnMe4
for Sn, to HgMe2 for Hg, and to aqueous LiCl for 7Li. Signals
from quaternary 13C and from 29Si and 15N were enhanced by
polarization transfer. Mass spectra were obtained by EI at 70
eV; m/z values refer to 28Si, 35Cl, 120Sn, and 202Hg. It is
noteworthy that in the case of compounds 3, 4, and 5 the base
peak was that at m/z 230, corresponding to the ion produced
by loss of Me from the silene Me2SidC(SiMe2NMe2)SiMe3 or
an isomer.
3.5
7.0
2.3
30.0
29.0
31.8
18.3
-373
-378
-373
a
-5.1
-2.4
-3.5
-1.1
-0.04
a
-335
a
Not recorded.
C6H4Me-o)3]22 and δ -10.8 for the SiMe3 groups in the
cyclic anion [CH2SiMe2C(SiMe3)2LiC(SiMe3)2SiMeCH2]-.18
(ii) In contrast, the 29Si shifts for the SiMe2NMe2 groups
do show a clear separation between those in the range
δ 2-5 for the compounds in which there can be no
N-metal coordination and those in the range δ 29-32
for the Al and Ga compounds in which there is such
coordination in the solid state, and this strongly sug-
gests that in these compounds the coordination persists
in solution. The shift of δ 18.3 for the tin compound 6,
although distinctly smaller than those for the Al and
Ga compounds, also strongly favors the presence of such
coordination. The shift for the lithium compound at first
sight may seem anomalous, but in the absence of
coordination a substantial negative value would be
expected and the observed positive shift of δ 7.0 can be
attributed to persistence of the N-metal coordination
in solution in this case also. (iii) With one exception the
15N shifts lie within a remarkably narrow range, but
this is perhaps not surprising, since even protonation
of amines normally results in only small upfield shifts.23
In this light it seems likely that the change in the shift
from δ -378 to -380 for the compounds in which there
can be no coordination to the δ -373 observed for RLi
and RAlC12 reflects the persistence of the coordination
in these cases, but the effect is too small to be regarded
as diagnostic. The exceptional shift is that of δ -335
for the tin compound 6, and we are unable to account
for it, but we note that a shift of δ -357 was recorded
for the related compound Sn{C(SiMe2NMe2)3}Cl3 (com-
pared with δ -380 for the corresponding aluminum
(Me3Si)2(Me2NMe2Si)CCl. Dimethylamine (1.0 g, 22 mmol)
was added dropwise with stirring to a stirred solution of (Me3-
Si)2(BrMe2Si)CCl (3.7 g, 13 mmol)7 in light petroleum (bp 40-
60 °C, 40 mL) at -117 °C. The mixture was allowed to warm
to room temperature and the solvent then removed under
vacuum to leave a white solid, which was extracted with light
petroleum (3 × 25 mL). The extract was filtered and the
solvent evaporated from the filtrate to leave a white solid,
which was sublimed at 60 °C/0.05 mmHg to give (Me3Si)2(Me2-
NMe2Si)CCl (3.0 g, 92%), mp 95 °C. Anal. Calcd for C11H30
-
ClNSi3: C, 44.6; H, 10.2; Cl, 12.0; N, 4.7. Found: C, 44.0; H,
10.1; Cl, 11.2; N, 4.6. 1H NMR: δ 0.20 (s, 18H, SiMe3), 0.29 (s,
6H, SiMe2), 2.40 (s, 6H, NMe2). 13C NMR: δ 0.18 (SiMe2), 1.0
(SiMe3), 39.5 (NMe2), 44.2 (1J (CSi) 37 Hz, CSi3). 15N NMR
(C6D6): δ -378. 29Si NMR: δ 2.7 (SiMe3), 3.4 (SiMe2). MS: m/z
295 (15, M+), 280 (25, M - Me), 237 (30), 187 (10, Me2SidC-
(SiMe2H)SiMe2), 129 (25, Me2SidCHSiMe2), 102 (100, SiMe2-
NMe2].
(Me3Si)2(Me2NMe2Si)CH. Dimethylamine (0.70 g, 15 mmol)
was added dropwise with stirring to a stirred solution of (Me3-
Si)2(BrMe2Si)CH (2.3 g, 8.0 mmol) in light petroleum (bp 40-
60 °C, 40 mL) at -120 °C. The mixture was stirred at -120
°C for a further 1 h and then for an additional 2 h without
cooling. The solvent was removed under vacuum, and the
residue was extracted with light petroleum. The extract was
filtered, the solvent evaporated, and the residue distilled to
give (Me3Si)2(Me2NMe2Si)CH (bp 62-65 °C at 0.01 mmHg;
1.84 g, 82%). 1H NMR: δ -0.56 (s, Si3CH), 0.11 (s, 18H, SiMe3),
0.12 (s, 6H, SiMe2), 2.30 (s, 6H, NMe2). 13C NMR: δ 1.6 (SiMe2),
3.3 (SiMe3), 5.05 (CSi3), 38.3 (NMe2). 15N NMR (C6D6): δ -380.
29Si NMR: δ -1.5 (SiMe3), 4.9 (SiMe2). MS: m/z 261 (25, M+),
246 (100, M - Me), 102 (100, SiMe2NMe2), 73 (95, SiMe3), 59
(65, SiMe2H). The spectra indicated that traces of other species
were present in the product, and so it was not sent for analy-
sis but used directly in the reaction with MeLi as described
below.
compound Al{C(SiMe2NMe2)3}2).24
Con clu d in g Com m en ts. An important feature of the
results described above is that the lengths (and so
presumably the strengths) of the SiMe2N-M bonds in
the cyclic species with M ) Li, Al, Ga are not ap-
preciably different from those between organic amines
and these metals, which is somewhat surprising in view
of the fact that silylamines are much less basic than
alkylamines.25
[Li{C(SiMe3)2(SiMe2NMe2)(THF)2] (1). (a) Fr om (Me3Si)2-
(Me2NMe2Si)CCl. A solution of BuLi (1.06 mmol) in hexane
(0.43 mL) was added dropwise to a stirred solution of (Me3-
Si)2(Me2NMe2Si)CCl (0.25 g, 0.85 mmol) in THF (10 mL) at
-78 °C. The mixture was stirred for a further 2 h at -78 °C,
and the solvent was then removed under vacuum and the
residue crystallized from THF to give colorless crystals of 1
(0.20 g, 87%). Anal. Calcd for C19H46LiNO2Si3: C, 55.4; H, 11.3;
N, 3.4. Found: C, 53.8; H, 10.9; N, 3.8. (Better analytical data
could not be obtained because of the sensitivity of the
compound.) 1H NMR: δ 0.34 (s, 18H, SiMe3), 0.36 (s, 6H,
SiMe2), 1.3 (s, 8H, THF), 2.2 (s, 6H, NMe2), 3.4 (s, 8H, THF).
13C NMR: δ 3.3 (1J (CSi) 53.5 Hz, SiMe2), 3.8 (1J (CSi) 54 Hz,
CSi3), 8.1 (1J (CSi) 47.8 Hz, SiMe3), 25.4 (THF), 38.8 (NMe2).
68.5 (THF). 29Si NMR: δ -10.6 (1J (CSi) 47.8 Hz, SiMe3), 7.0
(22) Almansour, A. I.; Eaborn, C.; Hawkes, S. A.; Hitchcock, P. B.;
Smith, J . D. Organometallics 1997, 16, 6035.
(23) Witanowski, M.; Stefaniak, L.; Webb, G. A. Annu. Rep. NMR
Spectrosc. 1986, 18, 1.
(24) (a) Farook, A. D. Phil. Thesis, University of Sussex, 1998. (b)
Eaborn, C.; Farook, A.; Hitchcock, P. B.; Smith, J . D. Organometallics
1998, 17, 3135.
(25) Bassindale, A. R.; Taylor, P. G. In The Chemistry of Organic
Silicon Compounds; Patai, S., Rappoport, Z., Eds.; Wiley, Chichester,
U.K., 1989; pp 819-822.

Attachment of (Me3Si)2(Me2NMe2Si)C to Metals
Organometallics, Vol. 18, No. 1, 1999 51
(1J (CSi) 53.5 Hz, SiMe2). 7Li NMR: δ 0.48. 15N NMR: δ -373.
The identity of the product was confirmed by an X-ray
diffraction study.
[Ga {C(SiMe3)2(SiMe2NMe2)}Cl2] (5). A solution of the
lithium reagent 1 (1.10 g, 3.00 mmol) in toluene (35 mL) was
added dropwise to a stirred solution of GaCl3 in toluene (15
mL) at -15 °C and the mixture was allowed to warm to room
temperature. The solution was then filtered and the solvent
removed under vacuum to leave an off-white solid which was
recrystallized from heptane to give colorless crystals of 5 (0.95
g, 58%), mp 269-274 °C. Anal. Calcd for C11H30GaC12NSi3:
(b) F r om (Me3Si)2(Me2NMe2Si)CH. A solution of MeLi (5.0
mmol) in diethyl ether (3.7 mL) was added dropwise to a
stirred solution of (Me3Si)2(Me2NMe2Si)CH (1.04 g, 4.0 mmol)
in THF (30 mL) at room temperature. The mixture was stirred
for a further 5 h at room temperature, and the solvent was
then slowly removed under vacuum at 0 °C to deposit colorless
crystals. These were washed three times with light petroleum
(bp 40-60 °C) and shown to be those of 1 (0.95 g, 59%), with
spectroscopic data essentially identical with those presented
above.
Hg{C(SiMe3)2(SiMe2NMe2)}2 (2). A solution of the lithium
reagent 1 was made at -78 °C from (Me3Si)2(Me2NMe2Si)CCl
(2.4 g, 8.1 mmol) in THF (30 mL) and LiBu (10.2 mmol) in
hexane (4.1 mL) by the procedure described above and then
added dropwise with stirring to a suspension of HgBr2 (1.60
g, 4.1 mmol) in THF (20 mL) at -110 °C. The mixture was
allowed to warm to room temperature, and the solvents were
removed under vacuum to leave a solid, which was extracted
with light petroleum. The extract was filtered and evaporated
and the residue recrystallized from heptane to give 2 (2.9 g,
51%; mp 209-213 °C). Anal. Calcd for C22H60HgN2Si6: C, 36.6;
H, 8.4; N, 3.9. Found: C, 37.6; H, 8.8; N, 3.9. 1H NMR: δ 0.35
(s, 36H, SiMe3), 0.37 (s, 12H, SiMe2), 2.48 (s, 12H, NMe2). 13C
NMR: δ 5.6 (1J (CSi) 55 Hz, SiMe2), 6.6 (1J (CSi) 41 Hz, SiMe3),
40.0 (NMe2), 43.5 (1J (HgC) 332 Hz, 1J (CSi) 40.2 Hz (SiMe3)
and 34.6 Hz (SiMe2), Si3C). 29Si NMR: δ -5.1 (SiMe3), 2.3
(SiMe2); 199Hg NMR: δ - 531. MS: m/z 722 (1, M+), 707 (1, M
- Me), 635 (1), 520 (30), 504 (70), 477 (30), 462 (20), 201 (95),
129 (70), 102 (100, SiMe2NMe2], 73 (95).
1
C, 32.9; H, 7.5; N, 3.5. Found: C, 32.3, H, 7.5; N, 2.9 H NMR:
δ - 0.01 (s, 6H, SiMe2), 0.34 (s, 18H, SiMe3), 2.00 (s, 6H,
NMe2). 13C NMR: δ 2.4 (SiMe2), 6.5 (SiMe3), 18.8 (CSi3), 41.5
(NMe2). 29Si NMR: δ -1.1 (SiMe3), -32.3 (SiMe2). MS: m/z
401 (5%, M) 386 (35, M - Me), 366(50, M - Cl), 230 (100, Me2-
SidC(SiMe2NMe2)SiMe2), 102 (20, SiMe2NMe2], 73 (65%,
SiMe3), 59 (50, SiMe2H).
Sn {C(SiMe3)2(SiMe2NMe2)}Cl3 (6). A solution of the lithium
reagent 1 was made at -78 °C from (Me3Si)2(Me2NMe2Si)CCl
(1.1 g, 3.7 mmol) in THF (30 mL) and LiBu (4.6 mmol) in
hexane (1.9 mL) by the procedure described above and then
added dropwise with stirring to a solution of SnCl4 (0.98 g,
3.7 mmol) in THF (10 mL) at -12 °C. The mixture was allowed
to warm to room temperature, and the solvents were removed
under vacuum to leave a solid, which was extracted with light
petroleum (bp 40-60 °C). The solvent was evaporated from
the extract to leave a white solid, which was recrystallized
from heptane to give 6 (1.4 g, 78%; mp 247-250 °C). Anal.
Calcd for C11H30Cl3NSi3Sn: C, 27.2; H, 6.2; N, 2.9. Found: C,
1
27.2; H, 6.3; N, 2.7. H NMR: δ 0.04 (s, 6H, SiMe2), 0.34 (s,
18H, SiMe3), 2.13 (s, 6H, NMe2). 13C NMR: δ 4.8 (SiMe2), 5.6
(SiMe3), 42.5(1J (C119Sn) 217, 1J (C117Sn) 207 Hz; 1J (CSi) 36 Hz
(SiMe2), 26 Hz (SiMe3), CSi3), 42.6 (NMe2). 29Si NMR: δ -0.04
(2J (Si119Sn) 87 Hz, SiMe3), 18.3 (2J (Si119Sn) 135 Hz, SiMe2).
119Sn NMR: δ -182. MS: m/z 485 (20, M+), 470 (35, M - Me),
450 (30, M - Cl), 221 (75), 102 (85, SiMe2NMe2), 73 (100).
[Al{C(SiMe3)2(SiMe2NMe2)}Cl2)] (3). A solution of the
lithium reagent 1 was made at -78 °C from (Me3Si)2(Me2NMe2-
Si)CCl (0.80 g, 2.7 mmol) in THF (30 mL) and LiBu (3.4 mmol)
in hexane (1.4 mL) by the procedure described above, and the
solvent was then removed. A solution of the residue in toluene
(25 mL) was added dropwise with stirring to a suspension of
AlCl3 (0.40 g, 2.7 mmol) in toluene (15 mL) at -15 °C. The
mixture was warmed to room temperature, and the solvents
were removed under vacuum to leave a solid, which was
extracted with light petroleum. The extract was filtered and
evaporated and the residue recrystallized from light petroleum
(bp 40-60 °C) to give colorless crystals of 3 (1.1 g, 91%; mp
249-254 °C). Anal. Calcd for C11H30AlC12NSi3: C, 36.8; H, 8.4;
N, 3.9. Found: C, 36.7; H, 8.3; N, 4.1. 1H NMR: δ -0.02 (s,
6H, SiMe2), 0.36 (s, 18H, SiMe3), 1.91 (s, 6H, NMe2). 13C
NMR: δ 2.5 (SiMe2), 7.0 (SiMe3), 41.3 (NMe2); the signal from
the quaternary carbon was not observed. 15N NMR: δ -373.
29Si NMR: δ -2.4 (SiMe3), 30.1 (SiMe2). 27Al NMR: δ 126 (∆ν1/2
1200 Hz). MS: m/z 342 (65, M - Me), 322 (15, M - Cl), 230
(100, Me2SidC(SiMe2NMe2)SiMe2), 102 (30, SiMe2NMe2) 75
(SiMe3).
(Me3Si)2(Me2NMe2Si)CI. A solution of LiBu (13 mmol) in
hexane (5 mL) was added dropwise with stirring to a solution
of (Me3Si)2(Me2NMe2Si)Cl (3.0 g, 10 mmol) in THF (40 mL) at
- 78 °C. The mixture was stirred at - 78 °C for a further 2 h;
then a solution of ICCH2CH2I (2.8 g, 10 mmol) in THF (30
mL) was added dropwise. The stirred mixture was kept at -78
°C for 3 h, and the solvents were then removed under vacuum
at -60 °C to leave a brown solid. This was extracted with light
petroleum, and the solvent was removed from the extract to
leave a white solid, which was recrystallized from MeOH to
give white crystals of the iodide (Me3Si)2(Me2NMe2Si)CI (3.1
g, 82%; mp 199-204 °C). Anal. Calcd for C11H30INSi3: C, 34.1;
H, 7.8; N, 3.6. Found: C, 34.7; H, 7.4; N, 3.9. 1H NMR: δ 0.28
(s, 18H, SiMe3), 0.38 (s, 6H, SiMe2), 2.45 (s, 6H, NMe2). 13C
NMR: δ 3.01 (SiMe2), 3.16 (SiMe3), 16.3 (1J (CSi) 34 Hz (SiMe3),
37 Hz (SiMe2), CSi3), 39.9 (NMe2). 29Si NMR: δ 3.2 (SiMe3),
3.5 (SiMe2). MS: m/z 387 (15, M+), 372 (20, M - Me), 329 (20,
M - SiMe2), 102 (100, SiMe2NMe2), 73 (30, SiMe3).
Hg{C(SiMe3)2(SiMe2Cl)}2. A solution of 2 (0.44 g, 0.60
mmol) in THF (20 mL) was added dropwise with stirring to a
solution of ICl (0.19 g, 1.20 mmol) at -78 °C. The mixture was
allowed to warm to room temperature, and the solvent was
removed under vacuum. The residual solid was extracted with
light petroleum (bp 40-60 °C) and the extract filtered. The
solvent was removed from the filtrate under vacuum to leave
a solid, which was recrystallized from heptane to give Hg-
{C(SiMe3)2(SiMe2Cl)}2 (mp 270-273 °C). Anal. Calcd for
[Al{C(SiMe3)2(SiMe2NMe2)}P h 2] (4). A solution of LiPh
(5.6 mmol) in C6H6/Et2O (3.1 mL) was added dropwise to a
stirred solution of 3 (1.0 g, 2.7 mmol) in toluene (30 mL) at
-3 °C. The mixture was stirred at -3 °C for a further 5 h and
then set aside at room temperature for 10 h. The solvents were
then removed under vacuum, and the sticky residue solid was
extracted with light petroleum. The extract was filtered and
the solvent removed to leave a white solid, which was
recrystallized from toluene to give 4 in ca. 50% yield. 1H
NMR: δ 0.20 (s, 6H, SiMe2), 0.31 (s, 18H, SiMe3), 2.10 (s, 6H,
NMe2), 7.15-7.30 (m, 6H, m- and p-H), 7.78 (d, 4H, o-H). 13C
NMR: δ 3.5 (SiMe2), 7.8 (SiMe3), 42.5 (NMe2), 127.2, 127.6.
128.5, 139.1 (all Ph). 29Si NMR: δ -3.5 (SiMe3), 28.6 (SiMe2).
27Al NMR: δ 142 (∆ν1/2 4000 Hz) MS: m/z 426.2042 (15, M -
Me, C22H37AlNSi3 calcd 426.2049), 364 (75, M - Ph), 287 (55,
M - 2Ph), 230 (50, Me2SidC(SiMe2NMe2)SiMe2), 102 (80,
SiMe2NMe2), 73 (100, SiMe3), 59 (80, SiMe2H).
C
18H48C12HgSi6: C, 30.7; H, 6.9. Found: C, 30.6; H, 6.9. 1H
NMR: δ 0.33 (s, 36H, SiMe3), 0.60 (s, 12H, SiMe2). 13C NMR:
δ 5.8 (SiMe3), 9.1 (SiMe2). 29Si NMR: δ -3.5 (SiMe3), 25.1
(SiMe2). 199Hg NMR: δ -522. MS: m/z 704 (1, M), 689 (15, M
- Me), 236 (75, Me2SidC(SiMe2Cl)SiMe2), 221 (35), 201 (100,
Me2SidC(SiMe3)SiMe2), 73 (65, SiMe3).
Hg{C(SiMe3)2(SiMe2O2CCF 3)}2. A solution of 2 (0.15 g, 2.1
mmol) in benzene (10 mL) was added dropwise with stirring
to a solution of CF3CO2H (0.032 mL, 4.2 mmol) in benzene (5

52 Organometallics, Vol. 18, No. 1, 1999
Ta ble 6. Su m m a r y of Cr ysta llogr a p h ic Da ta for 1-5
Al-J uaid et al.
2
1
3
4
5
empirical formula
fw
C
721.9
22H60HgN2Si6
C19H46LiNO2Si3
411.8
C11H30AlC12NSi3
358.5
C23H40AlNSi3
441.8
C11H30GaC12NSi3
401.3
cryst size (mm)
cryst syst
space group
a (Å)
b (Å)
c (Å)
0.4 × 0.4 × 0.2
triclinic
P1h (No. 2)
9.048(1)
9.102(1)
12.580(2)
69.25(1)
71.32(1)
60.49(1)
829.5(2)
1
1.45
370
4.87
2-25
0 e h e 10
-8 e k e 10
-13 e l e 14
2907
2907
2892
0.4 × 0.3 × 0.1
triclinic
P1h (No. 2)
9.270(7)
9.867(4)
15.479(6)
85.63(3)
86.73(5)
66.05(5)
1289.6(12)
2
1.06
456
0.20
2-25
0 e h e 11
-10 e k e 11
-18 e l e 18
4522
4522
3060
0.4 × 0.4 × 0.2
monoclinic
P21/c (No. 14)
8.941(2)
14.093(2)
15.789(2)
90
90.08(1)
90
1989.5(6)
4
1.20
768
0.54
2-30
0 e h < 12
0 e k e 19
-22 e l e 22
6114
5790 (Rint ) 0.01)
4803
0.3 × 0.2 × 0.2
triclinic
P 1h (No. 2)
8.906(2)
9.414(4)
15.956(3)
80.75(2)
75.66(2)
87.04(3)
1279.1(7)
2
1.15
480
0.23
2-28
0 < h < 11
-12 e k e 12
-19 < l e21
6160
6160
4420
0.2 × 0.24 × 0.1
monoclinic
P21/c (No. 14)
8.941(2)
14.038(4)
15.840(4)
90
90.22(2)
90
1988.1(9)
4
1.34
840
1.82
2-28
0 e h < 11
0 e k e 18
-20 e l e 20
5059
4777 (Rint ) 0.04)
2976
R (deg)
â (deg)
γ (deg)
V (Å3)
Z
dc (Mg m-3
F(000)
)
µ (mm-1
)
θ range (deg)
index range
no. of rflns collected
no. of unique rflns
no. of rflns with I > 2σ(I)
R1; wR2 (I > 2σ(I))
R1; wR2 (all data)
no. of data/restraints/
params
0.027, 0.070
0.027, 0.071
2907/0/142
0.070; 0.184
0.111; 0.216
4522/0/236
0.032; 0.086
0.043; 0.111
5790/0/163
0.049; 0.130
0.080; 0.162
6160/0/253
0.054; 0.100
0.109; 0.120
4777/0/163
GOF on F2
0.846
1.031
0.430
0.761
1.013
max shift/error
0.001
0.96, -1.67
1.00, 0.52
0.001
0.47, -0.45
not applied
0.001
0.32, -0.29
not applied
0.001
0.37, -0.36
not applied
0.001
0.68, -0.47
not applied
largest diff peak/hole (e Å-3
abs cor: Tmax; Tmin
)
mL) at 0 °C. The mixture was allowed to warm to room
temperature, and the solvent was removed under vacuum. The
residual solid was extracted with light petroleum (bp 40-60
°C), and the extract was filtered. The solvent was removed
from the filtrate under vacuum to leave a solid, which was
recrystallized from heptane to give colorless crystals of Hg-
{C(SiMe3)2(SiMe2O2CCF3)}2 (0.10 g, 56%; mp 135-137 °C).
Anal. Calcd for C22H48F6HgO4Si6: C, 30.7; H, 5.6. Found: C,
Cr ysta l Str u ctu r e Deter m in a tion s. Data were collected
at 173(2) K on an Enraf-Nonius CAD4 diffractometer using
Mo KR radiation (λ 0.710 73 Å) and corrected for Lorentz and
polarization effects; details are given in Table 6. The structures
were determined by direct methods, with SHELXS-86 and
SHELXL-93 programs used for structure solution and refine-
ment on F2 using all reflections. Non-hydrogen atoms were
anisotropic. The H atoms were refined in the riding mode with
1
30.8; H, δ 5.8. H NMR: δ 0.20 (s, 36H, SiMe3), 0.50 (s, 12H,
U
iso(H) ) 1.5Ueq(C).
SiMe2). 13C NMR: δ 5.2 (SiMe2), 5.6 (SiMe3), 38.6 (1J (CSi) 32
(SiMe3), 46.3 Hz (SiMe2), CSi3), 115.3 (q, 1J (CF) 287 Hz, CF3),
2
156.3 (q, J (CF) 42 Hz, CO). 29Si NMR: δ -3.6 (SiMe3), 26.0
Ack n ow led gm en t. We thank the Engineering and
(SiMe2).199Hg NMR: δ -531. 19F NMR -76.5. MS: 860 (1, M),
845 (15, M - Me), 747 (5, M - O2CCF3), 314 (100, CH-
(SiMe3)2(SiMe2COCF3)), 205 (45), 73 (60, SiMe3).
Physical Sciences Research Council for support of this
work, the Libyan Government for the award of a
postgraduate scholarship to S.M.El-H., the Saudi Ara-
bian Government for support for S.S.Al-J ., and Dr. A.
G. Avent for help with NMR spectra.
Rea ction of Sn {C(SiMe3)2(SiMe2NMe2)}Cl3 w ith MeOH.
Methanol (0. 40 mL, 9.9 mmol) was added to a stirred solution
of 5 (0.07 g, 1.4 mmol) in Et2O (10 mL) at -15 °C. The mixture
was allowed to warm to room temperature, and the solid
present was filtered off and judged from its spectroscopic
properties, which were essentially identical with those of an
authentic sample,20 to be Sn{C(SiMe3)2(SiMe2OMe)}Cl3. 1H
NMR: δ 0.14 (s, 6H, SiMe2), 0.29 (s, 18H, SiMe3), 3.0 (s, 3H,
OMe). MS: m/z 457 (35, M - Me), 437 (M - Cl), 237 (100),
129 (25), 59 (40).
Su p p or tin g In for m a tion Ava ila ble: Tables of crystal-
lographic data, atom coordinates, bond lengths and angles, and
anisotropic thermal parameters for 1-5 (15 pages). Ordering
information is given on any current masthead page.
OM980727K