Bulky Amidinate Complexes of Indium(III). Synthesis and Structure of [CyNC(tBu)NC]2InCl

Article abstract of DOI:10.1021/ic950943a

Reaction of 2 equiv of lithium dicyclohexylacetamidinate with InCl₃ affords the new species In[CyNC(Me)NCy]₂-Cl (Cy = cyclohexyl) (1). Compound 1 reacts with MeLi to yield In[CyNC(Me)NCy]₂CH₃ (2) and also reacts with a third equivalent of amidinate to yield In[CyNC(Me)NCy]₃ (3). Two new bulky amidinate ligands are prepared by the addition of ¹BuLi to CyN=C=NCy and Me₃SiN=C=CSiMe₃, respectively. Subsequent reactions with InCl₃ lead to the high-yield syntheses of In[CyNC(CMe₃)NCy]₂Cl (4) and [Me₃SiN(CMe₃)NSiMe₃]₂InCl (5). Spectroscopic and elemental analyses confirm the formulas of all of these new species. Compound 4 is further characterized by X-ray crystallography and shown to possess a distorted trigonal bipyramidal coordination geometry around the metal center with the chloride group in the equatorial position. Crystal data for 4: triclinic, P1?, a = 12.545(7) ?, b = 13.482(8) ?, c = 11.965(6) ?, α = 102.08(5)°, β= 92.00(5)°, γ = 64.36(4)°, Z = 2, R = 0.029, R_w = 0.045.

Full text of DOI:10.1021/ic950943a

2448
Inorg. Chem. 1996, 35, 2448-2451
Bulky Amidinate Complexes of Indium(III). Synthesis and Structure of
[CyNC(tBu)NCy]2InCl
Yuanlin Zhou and Darrin S. Richeson*
Department of Chemistry, University of Ottawa, Ottawa, Ontario, Canada K1N 6N5
ReceiVed July 27, 1995X
Reaction of 2 equiv of lithium dicyclohexylacetamidinate with InCl3 affords the new species In[CyNC(Me)NCy]2-
Cl (Cy ) cyclohexyl) (1). Compound 1 reacts with MeLi to yield In[CyNC(Me)NCy]2CH3 (2) and also reacts
with a third equivalent of amidinate to yield In[CyNC(Me)NCy]3 (3). Two new bulky amidinate ligands are
prepared by the addition of tBuLi to CyNdCdNCy and Me3SiNdCdCSiMe3, respectively. Subsequent reactions
with InCl3 lead to the high-yield syntheses of In[CyNC(CMe3)NCy]2Cl (4) and [Me3SiN(CMe3)NSiMe3]2InCl
(5). Spectroscopic and elemental analyses confirm the formulas of all of these new species. Compound 4 is
further characterized by X-ray crystallography and shown to possess a distorted trigonal bipyramidal coordination
geometry around the metal center with the chloride group in the equatorial position. Crystal data for 4: triclinic,
P1h, a ) 12.545(7) Å, b ) 13.482(8) Å, c ) 11.965(6) Å, R ) 102.08(5)°, â ) 92.00(5)°, γ ) 64.36(4)°, Z )
2, R ) 0.029, Rw ) 0.045.
Introduction
preparation of indium compounds. This family of ligands has
been important in preparing a variety of dinuclear transition
metal complexes,18 and a member of this class of ligands, the
triazenide anion, was recently used to stabilize unusual alumi-
num and indium alkyls.4,7,8 In particular, we have focused on
the use of amidinates, formamidinates, and triazenates (RNXNR-;
X ) CR′, CH, N) as ligands for In and Sn. Through
modification of the organic substituents on the nitrogen atoms
and at the bridge position, these ligands should present an ideal
system to explore the effects of steric bulk and electronic
features on the product compounds. For example, formamidi-
nate ligands are known to favor unusual structural features in
both transition metal and main group metal chemistry.17,19,20
Herein we report, as part of our ongoing investigation, the
synthesis and characterization, including preliminary reactivity,
of a novel family of monomeric five-coordinate InIII compounds
of the general formula In[RNC(R′)NR]2Cl (R ) cyclohexyl,
The recent resurgence of interest in the preparation of
inorganic and organometallic complexes of Al, Ga, and In stems
from their appearance in a variety of technologically important
electronic materials and from a more basic effort to clarify the
steric and electronic effects on both the structure and reactivity
of group 13 species.1 The latter endeavor is reflected by an
increasing number of reported complexes of these elements
having novel ligands and uncommon coordination geometries.2-17
Motivated by an interest in the effects of ligand geometry on
the coordination environments of post-transition elements in
general and of indium specifically, we began a systematic study
of the use of bidentate, three-atom bridging ligands for the
X Abstract published in AdVance ACS Abstracts, April 1, 1996.
(1) (a) For a summary of In organometallic chemistry, see: Tuck, D. G.
In ComprehensiVe Organometallic Chemistry; Wilkinson, G., Stone,
F. G. A., Abel, E. W., Eds.; Pergamon Press: Oxford, England, 1982;
Vol. 1, Chapter 7. (b) For a summary of In coordination chemistry,
see: Tuck, D. G. In ComprehensiVe Coordination Chemistry; Wilkin-
son, G., Gillard. D., McCleverty, J. A., Eds.; Pergamon Press: Oxford,
England, 1987; Vol. 3, Chapter 25.2.
t
t
SiMe3; R′ ) Me, Bu). The introduction of the Bu group at
the bridging position adds two new sterically demanding
members to the amidinate family of ligands. The complexes
within this series show substantial differences in reactivity with
respect to alkylation and formation of tris(ligand) complexes.
(2) Robinson, G. H.; Sangokoya, S. A. J. Am. Chem. Soc. 1987, 109,
6852.
(3) Healy, M. D.; Barron, A. R. J. Am. Chem. Soc. 1989, 111, 398.
(4) Leman, J. T.; Barron, A. R. Organometallics 1989, 8, 1828.
(5) Self, M. F.; Pennington, W. T.; Laske, J. A.; Robinson, G. H.
Organometallics 1991, 10, 36.
(6) Lee, B.; Pennington, W. T.; Robinson, G. H. Organometallics 1990,
9, 1709.
(7) Leman, J. T.; Roman, H. A.; Barron, A. R. Organometallics 1993,
12, 2986.
(8) Leman, J. T.; Roman, H. A.; Barron, A. R. J. Chem. Soc., Dalton
Trans. 1992, 2183.
(9) Schumann, H.; Just, O.; Seuss, T. D.; Weiman, R. J. Organomet. Chem.
1994, 472, 15.
(10) Schumann, H.; Seuss, T. D.; Just, O.; Weiman, R.; Hemling, H.;
Go¨rlitz, F. H. J. Organomet. Chem. 1994, 479, 171.
(11) Reger, D. L.; Knox, S. J.; Rheingold, A. L.; Haggerty, B. S.
Organometallics 1990, 9, 2581.
(12) Reger, D. L.; Mason, S. S.; Reger, L. B.; Rheingold, A. L.; Ostrander,
R. L. Inorg. Chem. 1994, 33, 1803.
(13) Reger, D. L.; Mason, S. S.; Rheingold, A. L.; Ostrander, R. L. Inorg.
Chem. 1994, 33, 1811.
Results and Discussion
Complexes of the [CyNC(Me)NCy]- Anion. Reaction of
the lithium salt of dicyclohexylacetamidinate, prepared by the
combination of dicylohexylcarbodiimide and MeLi, with InCl3
in a 2:1 stoichiometry afforded, the new species 1 (Scheme 1)
1
in 78% yield. The H NMR spectrum for 1 is consistent with
a single environment for the acetamidinate ligand. Elemental
analysis confirmed the formula of this species to be In[CyNC-
(Me)NCy]2Cl (Cy ) cyclohexyl). We propose the structure
shown in Scheme 1.7,17,20
Complex 1 undergoes a facile alkylation reaction with 1 equiv
of MeMgCl to yield the new organometallic species In[CyNC-
(Me)NCy]2CH3 (2). The spectroscopic features are consistent
our proposed composition of 2 as an organoindium species.
(14) Rettig, S. J.; Storr, A.; Trotter, J. Can. J. Chem. 1976, 54, 1278.
(15) Rettig, S. J.; Storr, A.; Trotter, J. Can. J. Chem. 1975, 53, 58.
(16) Khan, M.; Steevensz, R. C.; Tuck, D. G.; Noltes, J. G.; Corfield, P.
W. R. Inorg. Chem. 1980, 19, 3407.
(18) For a review, see: Cotton, F. A.; Walton, R. A. Multiple Bonds
Between Metal Atoms, 2nd ed.; J. Wiley & Sons: New York, 1982.
(19) Berno, P.; Hao, S.; Minhas, R.; Gambarotta, S. J. Am. Chem. Soc.
1994, 116, 7417 and references therein.
(17) Zhou, Y.; Richeson, D. S. Organometallics 1995, 14, 3558.
(20) Zhou,Y.; Richeson, D. S. Submitted for publication.
0020-1669/96/1335-2448$12.00/0 © 1996 American Chemical Society

Bulky Amidinate Complexes of Indium(III)
Inorganic Chemistry, Vol. 35, No. 9, 1996 2449
Table 1. Summary of Crystal Data for 4
Scheme 1
empirical formula
fw
In Cl N4 C34 H62
677.16
space group
a, Å
b, Å
c, Å
P1h
12.545(7)
13.482(8)
11.965(6)
102.08(5)
92.00(5)
64.36(4)
1780.3(16)
2
R, deg
â, deg
γ, deg
V, Å3
Z
no. of reflns for cell
24
1.263
0.74
-153
Mo KR (0.710 69)
0.029, 0.045, 4.50
D
calc, Mg‚m-3
µ, mm-1
T, °C
radiation (λ, Å)
R, Rw, GoFa
2
a R ) ∑||Fo| - |Fc||/∑|Fo|; Rw ) [∑w(|Fo| - |Fc|)2/∑wFo ]1/2; GoF
Scheme 2
) [(∑w(|Fo| - |Fc|)2)/(nreflns - nparams)]1/2
.
establish the monomeric nature, coordination geometry of the
metal center, and connectivity of the ligand for complex 4
(Figure 1 and following section).
The reactivity of complex 4 contrasts with the methyl analog,
1. So far, attempts to alkylate this material with Grignard and
lithium reagents have been unsuccessful. Both reaction of
complex 4 with Na/C10H8 and attempts to incorporate a third
equivalent of ligand to generate the analogous complex to 3
have resulted in a complex mixture of products, a fact which is
most clearly demonstrated by the appearance of several reso-
1
t
nances in the H NMR ascribed to Bu groups. We attribute
this difference in reactivity to the increased steric bulk of CyNC-
(CMe3)NCy compared to CyNC(Me)NCy.
t
A similar reaction of BuLi with 1,3-bis(trimethylsilyl)-
carbodiimide in ether generates Li[Me3SiN(CMe3)NSiMe3].
Reaction of this species with InCl3 in a 2:1 ratio yields the
corresponding bis(amidinato) chloro complex [Me3SiN(CMe3)-
NSiMe3]2InCl (5) (Scheme 2). The formulation and proposed
structure for 5 were confirmed by spectroscopic evidence,
microanalysis, and analogy with 4. Like complex 4 and in
contrast to 1, 5 does not react cleanly with alkylating or reducing
agents and will not incorporate a third amidinate ligand.
Crystal Structure of 4. Complex 4 crystallized in the
triclinic space group P1h with two molecules in the unit cell
(see Table 1). There are no anomalously short intermolecular
contacts. The molecular geometry and atom-numbering scheme
are shown in Figure 1.
The structural analysis revealed a molecular core with the
metal center in a distorted trigonal bipyramidal (TBP) environ-
ment consisting of the two amidinate anions with an equatorial
chloride group completing the coordination sphere.22 Tables
2-4 provide a summary of heavy atom postitions and selected
bond distances and angles for 4. The bonding parameters within
the two amidinate ligands are not dramatically different,
resulting in a molecular geometry that is of approximately C2
symmetry. The fact that the Cy groups are equivalent in the
1H and 13C NMR spectra indicates the possibility that complex
may be fluxional in solution.
Because bulky groups are known to stabilize a reduced In
center, we attempted the reduction of 1 with Na/C10H8 as shown
in Scheme 1.21 The product of this reaction, 3, possessed only
the NMR resonances for equivalent dicyclohexylamidinate
ligands. Microanalysis confirmed the formulation as the tris-
(acetamidinate) complex, In[CyNC(Me)NCy]3, which likely
arises through a disproportionation reaction from a reduced In
complex. We propose a six-coordinate structure on the basis
of the high-yield, independent synthesis of 3 from the reaction
of InCl3 with 3 equiv of Li[CyNC(Me)NCy], the spectroscopic
evidence, and the report of the six-coordinate complex In{2-
[N(CH2C6H5)]NC5H4}3 from our laboratory (Scheme 1).17
Complexes of the [RNC(CMe3)NR]- Anion (R ) Cy,
SiMe3). In an effort to extend this family of complexes as well
as to enlarge the range of available amidinate ligands, we have
been investigating the introduction of sterically demanding
groups into the bridge position. Our synthetic methodology is
based on the reaction of organolithium reagents with carbodi-
imide to generate the appropriate amidinate species. Complex
preparation is achieved by addition of a stoichiometric amount
of InCl3 to this solution.
t
The addition of BuLi to dicylohexylcarbodiimide proceeds
The metal center lies at the intersection of two planes: the
pseudoequatorial plane consisting of Cl1, N1, and N4 with the
pseudoaxial plane described by Cl1, N2, and N3. Planarity of
these groups is confirmed by the fact that the sum of the
appropriate angles is 360°. As expected for the trigonal
smoothly in ether at room temperature. Subsequent addition
of 0.5 equiv of InCl3 followed by recrystallization resulted in
isolation of an 86% yield of In[CyNC(CMe3)NCy]2Cl (4)
(Scheme 2). Spectroscopic characterization and microanalysis
confirmed the formula of the complex. However, a single-
crystal X-ray diffraction analysis was needed in order to
(22) References 6, 7, 9, 13, 14, and 16 present crystal structures of five-
coordinate gallium and indium complexes in distorted trigonal
bipyramidal coordination environments. The values for the angle along
the pseudoaxial vectors in these reports fall in the range 149.7-178.4°.
(21) Frazer, A.; Piggot, B.; Hursthouse, M. B.; Mazid, M. J. Am. Chem.
Soc. 1994, 116, 4127.

2450 Inorganic Chemistry, Vol. 35, No. 9, 1996
Zhou and Richeson
Table 3. Selected Bond Distances (Å) for 4
In1-Cl1
In1-N1
In1-N2
In1-N3
In1-N4
N1-C1
N1-C7
N2-C7
2.405(1)
2.198(3)
2.236(3)
2.239(3)
2.188(3)
1.459(5)
1.345(5)
1.347(5)
N2-C8
1.457(5)
1.456(5)
1.327(5)
1.341(5)
1.455(5)
1.561(5)
N3-C14
N3-C20
N4-C20
N4-C21
C7-C27
C20-C31
1.560(5)
Table 4. Selected Bond Angles in (deg) for 4
Cl1-In1-N1
Cl1-In1-N2
Cl1-In1-N3
Cl1-In1-N4
N1-In1-N2
N1-In1-N3
N1-In1-N4
N2-In1-N3
N2-In1-N4
N3-In1-N4
In1-N1-C1
In1-N1-C7
C1-N1-C7
In1-N2-C7
124.43(8)
99.25(8)
97.57(8)
123.74(8)
60.2(1)
109.7(1)
111.8(1)
163.2(1)
109.6(1)
59.8(1)
133.0(2)
95.1(2)
130.6(3)
93.3(2)
In1-N2-C8
C7-N2-C8
131.4(2)
129.4(3)
132.7(2)
93.3(2)
130.2(3)
95.2(2)
133.0(2)
130.4(3)
111.4(3)
122.3(3)
126.1(3)
111.7(3)
126.9(4)
121.2(3)
In1-N3-C14
In1-N3-C20
C14-N3-C20
In1-N4-C20
In1-N4-C21
C20-N4-C21
N1-C7-N2
Figure 1. Molecular structure and atom-numbering scheme for ClIn-
[C6H11NC(CMe3)NC6H11]2 (4). Hydrogen atoms have been omitted for
clarity.
N1-C7-C27
N2-C7-C27
N3-C20-N4
N3-C20-C31
N4-C20-C31
Table 2. Atomic Parameters x, y, z and Biso Values
x
y
z
Biso,a Å2
is likely due to the constraints imposed by the three-atom bite
of the ligand. Although direct comparisons are difficult due to
the lack of known In amidinate complexes, the In-N and In-
Cl bond lengths of 4 correlate favorably with the few reported
values for five-coordinate TBP complexes.7,9,16
In1
Cl1
N1
N2
N3
N4
C1
C2
C3
C4
C5
C6
C7
C8
C9
C10
C11
C12
C13
C14
C15
C16
C17
C18
C19
C20
C21
C22
C23
C24
C25
C26
C27
C28
C29
C30
C31
C32
C33
C34
0.85965(3)
1.0139(1)
0.7841(3)
0.7224(3)
0.9552(3)
0.7797(3)
0.7895(3)
0.7878(3)
0.7996(4)
0.9074(4)
0.9082(4)
0.8995(3)
0.7102(3)
0.6993(3)
0.7002(4)
0.6840(4)
0.7741(4)
0.7710(4)
0.7896(3)
1.0796(3)
1.1346(3)
1.2651(4)
1.3344(4)
1.2798(4)
1.1499(4)
0.8688(3)
0.6613(3)
0.6406(4)
0.5166(4)
0.4240(4)
0.4437(4)
0.5681(4)
0.6161(3)
0.6755(4)
0.5458(4)
0.5237(4)
0.8600(4)
0.7609(4)
0.9691(4)
0.8357(4)
0.15234(3)
-0.03710(9)
0.2443(2)
0.1202(2)
0.2361(2)
0.2551(2)
0.3414(3)
0.4249(3)
0.5261(3)
0.4895(3)
0.4076(3)
0.3064(3)
0.1964(3)
0.0211(3)
-0.0223(3)
-0.1304(3)
-0.2198(3)
-0.1775(3)
-0.0711(3)
0.2133(3)
0.1848(3)
0.1596(4)
0.0663(3)
0.0933(3)
0.1173(3)
0.2835(3)
0.3003(3)
0.2095(3)
0.2524(4)
0.3069(4)
0.3968(4)
0.3530(3)
0.2351(3)
0.2328(4)
0.1662(4)
0.3548(3)
0.3706(3)
0.4852(3)
0.3918(4)
0.3317(4)
0.28369(3)
0.2366(1)
0.4582(2)
0.3636(2)
0.2152(2)
0.1572(2)
0.5348(3)
0.4654(3)
0.5400(3)
0.6097(3)
0.6796(3)
0.6030(3)
0.4612(3)
0.3448(3)
0.2163(3)
0.1898(3)
0.2443(3)
0.3724(3)
0.3992(3)
0.2082(3)
0.3199(3)
0.3178(3)
0.2154(4)
0.1049(3)
0.1075(3)
0.1491(3)
0.1158(3)
0.0318(3)
-0.0083(4)
0.0901(4)
0.1726(4)
0.2148(3)
0.5625(3)
0.6774(3)
0.5579(4)
0.5557(4)
0.0772(3)
0.1362(4)
0.0706(4)
-0.0470(3)
1.9(1)
3.3(6)
1.8(2)
1.7(2)
1.8(2)
1.8(2)
1.8(2)
2.2(2)
2.5(2)
2.8(2)
2.3(2)
2.0(2)
1.8(2)
1.8(2)
2.4(2)
3.0(3)
3.3(3)
2.4(2)
2.1(2)
1.9(2)
2.3(2)
3.0(3)
3.2(3)
2.9(2)
2.5(2)
2.0(2)
2.0(2)
2.8(2)
4.0(3)
4.4(3)
4.2(3)
3.1(3)
2.2(2)
3.3(3)
3.5(3)
3.2(3)
2.6(2)
3.7(3)
4.3(3)
3.5(3)
Conclusion
Amidinate ligands have proven to be useful in the preparation
of a family of unusual In complexes. We have extended the
available amidinate ligands by demonstrating the synthesis and
reactivity of two new bulky anionic ligands, [Me3SiN(CMe3)-
NSiMe3]- and [CyNC(CMe3)NCy]-. A combination of X-ray
crystallographic and spectroscopic studies confirms the nature
of these compounds. The subsequent reactivity of these indium
species is dependent on the nature of the group bound to the
bridging C atom of the amidinate; at this stage, the acetamidinate
complexes appear to be more reactive toward substitution and
the ligand is sufficiently small to accommodate the 6-fold
coordination at the metal center. Our continuing investigations
are oriented toward discerning the steric and electronic features
that influence the formation and reactivity of high-coordination-
number indium compounds and toward extending this work to
other post-transition metals.
Experimental Section
General Procedures. All reactions were carried out either in a
nitrogen-filled drybox or under nitrogen using standard Schlenk-line
techniques. Diethyl ether, hexamethyldisiloxane, hexane, and benzene
were distilled under nitrogen from potassium. Deuterated benzene was
dried by vacuum transfer from potassium. MeLi (1.4 M in diethyl
t
ether), BuLi (1.7 M in hexane), dicyclohexylcarbodiimide, and 1,3-
bis(trimethylsilyl)carbodiimide were purchased from Aldrich and used
without further purification. InCl3 was sublimed prior to use.
Synthesis of ClIn[C6H11NC(Me)NC6H11]2 (1). A Schlenk flask was
charged with dicyclohexylcarbodiimide (0.93 g, 4.51 mmol), diethyl
ether (30 mL), and a stir bar. To this solution was added MeLi (3.2
mL, 1.4 M, 4.51 mmol) dropwise, and the mixture was stirred for 30
min, followed by the addition of InCl3 (0.50 g, 2.26 mmol). The
reaction mixture was stirred overnight. A white solid was removed
by filtration, and the solution was concentrated to ca. 8 mL and cooled
to -30 °C. The resulting white crystalline solid was collected by
filtration and dried under oil pump vacuum (1.05 g, 78%, 1.76 mmol);
mp (sealed) 158-160 °C. IR (Nujol, cm-1): 1502 (s). 1H NMR (C6D6,
ppm): 3.13 (m, C6H11, 4H); 1.96-1.16 (m, C6H11, 40H);1.50 (s, Me,
a Biso is the mean of the principal axes of the thermal ellipsoid.
bipyramidal geometry, the equatorial In-N bond lengths are
slightly shorter than the axial distances.23 These two planes
are not perpendicular (e.g. N1-In-N2 ) 60.2(1)° and N3-
In-N4 ) 59.8(1)°), as in a strict TBP geometry, a feature which
(23) Albright, T. A.; Burdett, J. K.; Whangbo, M. H. Orbital Interactions
in Chemistry; Wiley; New York, 1985; Chapter 14.

Bulky Amidinate Complexes of Indium(III)
Inorganic Chemistry, Vol. 35, No. 9, 1996 2451
6H). Anal. Calcd for C28H50ClInN4: C, 56.71; H, 8.50; N, 9.45.
Found: C, 57.11; H, 8.66; N, 9.53.
white crystalline solid was collected by filtration and dried under oil
pump vacuum (0.80 g, 86%, 1.19 mmol); mp (sealed) 189-194 °C
dec. IR (thin film, cm-1): 1487 (m), 1446 (s), 1427 (s). 1H NMR
(C6D6, ppm): 3.89 (m, C6H11, 4H); 2.13-1.15 (m, C6H11, 40H); 1.27
(s, CMe3, 18H). 13C NMR (C6D6, ppm): 174.4 (s, NC(C(Me)3)N);
56.1, 36.1, 26.2, 25.8 (4s, C6H11,); 39.5 (s, C(CH3)3); 30.1 (C(CH3)3).
Anal. Calcd for C34H62ClInN4: C 60.13; H, 9.23; N, 8.27. Found:
C, 59.71; H, 9.39; N, 8.39.
Synthesis of MeIn[C6H11NC(Me)NC6H11]2 (2). Complex 1 (0.50
g, 0.84 mmol) was dissolved in 10 mL of THF, and the solution was
cooled to -78 °C in a dry ice-acetone bath. MeMgCl (0.2 mL, 0.84
mmol, 3 M in diethyl ether) was added via syringe. The solution was
allowed to slowly warm to room temperature and then stirred overnight.
The THF was removed under oil pump vacuum, and the residue was
extracted with 15 mL of diethyl ether. After filtration, the solution
was concentrated to ca. 5 mL and cooled to -30 °C. The resulting
crystalline solid was collected by filtration and dried under oil pump
vacuum (0.35 g, 73%, 0.61 mmol); mp (sealed) 139-140 °C. IR
(Nujol, cm-1): 1520 (s). 1H NMR (C6D6, ppm): 3.21 (m, C6H11, 4H);
1.96-1.23 (m, C6H11, 40H); 1.63 (s, CMe, 6H); 0.32 (s, 3H, InMe).
13C NMR (C6D6, ppm): 166.5 (s, NC(Me)N); 55.8, 37.6, 26.3, 26.2
(4s, C6H11,); 11.92 (s, NC(Me)N) (InCH3). Anal. Calcd for C29H53-
InN4: C 60.73; H, 9.33; N, 9.78. Found: C, 60.39; H, 9.47; N, 9.80.
Synthesis of In[C6H11NC(Me)NC6H11]3 (3). Method A. A Schlenk
flask was charged with sodium (0.020 g, 0.84 mmol), naphthalene (0.11
g, 0.84 mmol), THF (15 mL), and a stir bar, and the resultant deep
green solution was stirred for 5 h at room temperature. The solution
was then cooled to -78 °C in a dry ice-acetone bath. To this solution
was added dropwise complex 1 (0.50 g, 0.84 mmol) dissolved in 5
mL of THF. The reaction mixture was allowed to warm to room
temperature and then stirred overnight. The THF was removed under
oil pump vacuum, and the residue was extracted with 20 mL of diethyl
ether. After filtration, the solution was concentrated to ca. 7 mL and
cooled to -30 °C. The resulting white solid was collected by filtration
and dried under oil pump vacuum (0.31 g, 0.39 mmol).
Method B. A Schlenk flask was charged with dicyclohexylcarbo-
diimide (0.57 g, 2.76 mmol), diethyl ether (15 mL), and a stir bar. To
this solution was added MeLi (2.0 mL, 1.4 M, 2.76 mmol) dropwise,
and the mixture was stirred for 30 min, followed by the addition of
InCl3 (0.20 g, 0.92 mmol). The reaction mixture was stirred overnight
and then filtered. The solution was concentrated to ca. 8 mL and cooled
to -30 °C. The resulting white solid was collected by filtration and
dried under oil pump vacuum (0.57 g, 80%, 0.74 mmol); mp (sealed)
248-251 °C. IR (Nujol, cm-1): 1516 (s). 1H NMR (C6D6, ppm):
3.25 (m, C6H11, 6H); 2.10-1.25 (m, C6H11, 60H); 1.71 (s, CMe, 9H).
13C NMR (C6D6, ppm): 164.5 (s, NC(Me)N); 56.6, 37.6, 35.5, 26.7,
26.6 (5s, C6H11,); 11.93 (Me). Anal. Calcd for C42H75InN6: C 64.76;
H, 9.71. Found: C, 64.59; H, 9.84.
Synthesis of ClIn[Me3SiN(CMe3)NSiMe3]2 (5). A Schlenk flask
was charged with 1,3-bis(trimethylsilyl)carbodiimide (0.71 g, 3.81
mmol), diethyl ether (20 mL), and a stir bar. To this solution was
added tBuLi (2.2 mL, 1.7 M in hexane, 3.81 mmol) dropwise, and the
mixture was stirred for 30 min, followed by the addition of InCl3 (0.42
g, 1.91 mmol). The reaction mixture was stirred overnight and then
filtered. The solution was removed under oil pump vacuum, the residue
was extracted with 10 mL of (Me3Si)2O, and the extract was cooled to
-30 °C. The resulting white crystalline solid was collected by filtration
and dried under oil pump vacuum (0.90 g, 74%, 1.41 mmol); mp
(sealed) 122-124 °C. 1H NMR (C6D6, ppm): 1.14 (s, CMe3, 18H);
0.46 (s, 36H, Me3Si). Anal. Calcd for C22H54ClInN4Si4: C 41.46; H,
8.54. Found: C, 41.08; H, 8.64.
X-ray Crystallography. Data were collected on a Rigaku diffrac-
tometer at -153 °C using the θ-2θ scan technique to a maximum 2θ
value of 50° for crystals mounted on glass fibers. Cell constants and
orientation matrices were obtained from the least-squares refinement
of 24 carefully centered high-angle reflections. Redundant reflections
were removed from the data set. The intensities of three representative
reflections were measured after every 150 reflections to monitor the
crystal and instrument stability. Data were corrected for Lorentz and
polarization effects but not for absorption. The structure was solved
by direct methods. The non-hydrogen atoms were refined anisotropi-
cally. Hydrogen atom positions were located in the difference Fourier
maps and refined isotropically in the cases of favorable observation/
parameter ratios. The final cycle of full-matrix least-squares refinement
was based on the number of observed reflections with [I > 2.5σ(I)].
Anomalous-dispersion effects were included in the Fc values. All
calculations were performed using the NRCVAX package. Details of
the data collection and structure refinement and final atomic coordinates
are reported in the Supporting Information.
Acknowledgment. This work was supported by the Natural
Sciences and Engineering Research Council of Canada.
Synthesis of ClIn[C6H11NC(CMe3)NC6H11]2 (4). A Schlenk flask
was charged with dicyclohexylcarbodiimide (0.57 g, 2.76 mmol), diethyl
Supporting Information Available: Tables of hydrogen atomic
positions, thermal parameters, crystallographic data, and bond distances
and angles for 4 (10 pages). Ordering information is given on any
current masthead page.
t
ether (20 mL), and a stir bar. To this solution was added BuLi (1.6
mL, 1.7 M in hexane, 2.76 mmol) dropwise, and the mixture was stirred
for 30 min, followed by the addition of InCl3 (0.31 g, 1.38 mmol). The
reaction mixture was stirred overnight and then filtered. The solution
was concentrated to ca. 8 mL and cooled to -30 °C. The resulting
IC950943A