Multiple bonds between Sn and S: Synthesis and structural characterization of (CyNC((t)Bu)NCy)2Sn=S and [(CyNC(Me)NCy)2Sn(μ-S)]2

Article abstract of DOI:10.1021/ja960350e

Two new sulfido complexes of tin have been prepared by the reaction of styrene sulfide with novel tin(II) amidinate complexes. These compounds exhibit two very different bonding modes for the sulfido ligand; in one case, S=Sn(CyNC((t)Bu)NCy)₂ (3), a terminal Sn=S moiety was found while in the other case, [(CyNC(Me)NCy)₂Sn(μ-S)]₂ (4), a bridging sulfido dimer is observed. The starting complexes were prepared by the reaction of 2 equiv of the appropriate lithium amidinate with SnCl₂ to yield the new species Sn(CyNC(R)NCy)₂ [Cy = cyclohexyl; R = Me (1); R = (t)Bu (2)]. This account represents the first report of (CyNC((t)Bu)NCy)^- and the coordination chemistry of this bulky ligand. Spectroscopic and elemental analyses confirmed the formulas of all of these new species. Compounds 2, 3, and 4 were further characterized by X-ray crystallography. Compound 2 possesses a coordination geometry based on a trigonal bipyramid with one equatorial vertex occupied by the stereochemically active lone pair of electrons. Crystal data for 2: monoclinic, P21/c, a = 18.944(5) A?, b = 10.604(2) A?, c = 19.423(2) A?, β = 95.99(1)°, Z = 4, R = 0.046, R(W) = 0.049. Crystal data for 3: orthorhombic, Cmcm, a = 12.3788(23) A?, b = 14.1977(15) A?, c = 20.670(3) A?, Z = 4, R = 0.057, R(W) = 0.070. Crystal data for 4: monoclinic, P2/n, a = 13.0395(2) A?, b = 13.0263(2) A?, c = 23.8856(2) A?, β = 95.719(3)°, R = 0.055, R(w) 0.044.

Full text of DOI:10.1021/ja960350e

10850
J. Am. Chem. Soc. 1996, 118, 10850-10852
Multiple Bonds between Sn and S: Synthesis and Structural
Characterization of (CyNC(tBu)NCy)2SndS and
[(CyNC(Me)NCy)2Sn(µ-S)]2
Yuanlin Zhou and Darrin S. Richeson*
Contribution from the Department of Chemistry, UniVersity of Ottawa,
Ottawa, Ontario, Canada K1N 6N5
ReceiVed February 5, 1996. ReVised Manuscript ReceiVed June 12, 1996X
Abstract: Two new sulfido complexes of tin have been prepared by the reaction of styrene sulfide with novel tin(II)
amidinate complexes. These compounds exhibit two very different bonding modes for the sulfido ligand; in one
case, SdSn(CyNC(tBu)NCy)2 (3), a terminal SndS moiety was found while in the other case, [(CyNC(Me)NCy)2Sn-
(µ-S)]2 (4), a bridging sulfido dimer is observed. The starting complexes were prepared by the reaction of 2 equiv
of the appropriate lithium amidinate with SnCl2 to yield the new species Sn(CyNC(R)NCy)2 [Cy ) cyclohexyl; R
) Me (1); R ) tBu (2)]. This account represents the first report of (CyNC(tBu)NCy)- and the coordination chemistry
of this bulky ligand. Spectroscopic and elemental analyses confirmed the formulas of all of these new species.
Compounds 2, 3, and 4 were further characterized by X-ray crystallography. Compound 2 possesses a coordination
geometry based on a trigonal bipyramid with one equatorial vertex occupied by the stereochemically active lone pair
of electrons. Crystal data for 2: monoclinic, P21/c, a ) 18.944(5) Å, b ) 10.604(2) Å, c ) 19.423(2) Å, â )
95.99(1)°, Z ) 4, R ) 0.046, Rw ) 0.049. Crystal data for 3: orthorhombic, Cmcm, a ) 12.3788(23) Å, b )
14.1977(15) Å, c ) 20.670(3) Å, Z ) 4, R ) 0.057, Rw ) 0.070. Crystal data for 4: monoclinic, P2/n, a )
13.0395(2) Å, b ) 13.0263(2) Å, c ) 23.8856(2) Å, â ) 95.719(3)°, R ) 0.055, Rw 0.044.
Introduction
taa]SndE (E ) S, Se) represent the only structurally character-
ized terminal chalcogenido complexes of tin.6b,7
Among the properties that are ascribed uniquely to the first-
row elements of the periodic table is the ability to form multiple
bonds. As one moves to the heavier congeners of these
elements, the appearance of multiply bonded species declines.
Recently, the challenge presented in preparing complexes with
multiple bonds between group 14 metals and the chalcogens
has occupied much attention. For example, isolation and
structural characterization of species possessing GedS and
GedSe moieties have been achieved through the kinetic
stabilization provided by steric congestion/protection of this
function (e.g. Tbt(Tip)GedS).1,2 Alternatively, thermodynamic
stability has been attained through the coordination of a base
to the group 14 center and was employed to stabilize [η3-{(µ-
tBuN)2(SiMeNtBu)2}]GeS.3 The examples of stable terminal
chalcogenides of Sn in solution include [tetra(aryl)porphyrin]-
SndE (E ) S, Se)4 and Tbt(Tip)SndE (E ) S, Se).5 Neither
of these species has been structurally characterized, and in fact,
the latter exhibits a dimeric chalcogenido-bridge structure, [Tbt-
(Tip)Sn(µ-E)]2, in the solid state. A versatile supporting ligand,
octamethyldibenzotetraaza[14]annulene (Me8taa2-), was recently
utilized for the preparation of precursors to tin and germanium
terminal chalcogenido complexes.6 The complexes [η4-Me8-
X Abstract published in AdVance ACS Abstracts, October 15, 1996.
(1) (a) Tokitoh, N.; Matsumoto, T.; Manmaru, K.; Okazaki, R. J. Am.
Chem. Soc. 1993, 115, 8855. (b) Tokitoh, N.; Matsuhashi, Y.; Shibata, K.;
Matsumoto, T.; Suzuki, H.; Saito, M.; Manmaru, K.; Okazaki, R. Main
Group Met. Chem. 1994, 17, 55. (c) Matsumoto, T.; Tokitoh, N.; Okazaki,
R. Angew. Chem., Int. Ed. Engl. 1994, 33, 2316. (d) Tokitoh, N.; Matsumoto,
T.; Ichida, H.; Okazaki, R. Tetrahedron Lett. 1991, 32, 6877.
(2) Tbt ) 2,4,6-[(SiMe3)2CH]3C6H2, Tip ) 2,4,6-[(CH3)2CH]3C6H3.
(3) Veith, M.; Becker, S.; Huch, V. Angew. Chem., Int. Ed. Engl. 1989,
28, 1237.
(4) Guilard, R.; Ratti, C.; Barbe, J.-M.; Dubois, D.; Kadish, K. M. Inorg.
Chem. 1991, 30, 1537.
(5) (a) Tokitoh, N.; Saito, M.; Okazaki, R. J. Am. Chem. Soc. 1993, 115,
2065. (b) Matsuhashi, Y.; Tokitoh, N.; Okazaki, R.; Goto, M. Organome-
tallics 1993, 12, 2573.
Tin amidinates display a rich coordination chemistry with
the metal in both the divalent and tetravalent oxidation states,
however, these results have been, by and large, limited to use
of the N-silylated benzamidinate.8-10 Through modification of
the organic substituents on the nitrogen atoms and at the bridge
position, these ligands present an ideal system to explore the
effects of steric bulk and electronic features on the coordinated
metal center. For example, formamidinate ligands are known
to favor unusual structural features in both transition metal and
main group metal chemistry.11,12 Our investigation of the
coordination chemistry of amidinate anions has relied on their
generation by the addition of alkyl anion equivalents to
carbodiimides. For example, we have synthesized and crys-
tallographically characterized complexes of the (CyNC(R)NCy)-
(6) (a) Kuchta, M. C.; Parkin, G. J. Chem. Soc., Chem. Commun. 1994,
1351. (b) Kuchta, M. C.; Parkin, G. J. Am. Chem. Soc. 1994, 116, 8372.
(7) Examples of structurally characterized polythioanions of tin which
have terminal Sn-S bonds include [Sn10O4S208-],7a [Sn2S64-],7b [SnS32-],7c,d
[Sn2S76-].7e (a) Schiwy, W.; Krebs, B. Angew. Chem., Int. Ed. Engl. 1975,
14, 436. (b) Krebs, B.; Pohl, S.; Schiwy, W. Z. Anorg. Allg. Chem. 1972,
393, 241. (c) Schiwy, W.; Blutau, C.; Ga¨thje, D.; Krebs, B. Z. Anorg. Allg.
Chem. 1975, 412, 1. (d) Olivier-Fourcade, J.; Philippot, E.; Ribes, M.;
Maurin, M. ReV. Chim. Miner. 1972, 9, 757. (e) Krebs, B.; Schiwy, W. Z.
Anorg. Allg. Chem. 1973, 398, 63.
(8) (a) Borgsen, B.; Dehnicke, K.; Fenske, D.; Baum, G. Z. Anorg. Allg.
Chem. 1991, 596, 133. (b) Appel, S.; Weller, F.; Dehnicke, K. Z. Anorg.
Allg. Chem. 1990, 583, 7. (c) Kidea, J. D.; Hiller, W.; Borgsen, B.; Dehnicke,
K. Z. Naturforsch. 1989, 44B, 889. (d) Ergezinger, C.; Weller, F.; Dehnicke,
K. Z. Naturforsch. 1988, 43B, 1621. (e) Dehnicke, K.; Ergezinger, C.;
Hartmann, E.; Zinn, A.; Ho¨sler, K. J. Organomet. Chem. 1988, 352, C1.
(9) Roesky, H. W.; Meller, B.; Noltemeyer, M.; Schmidt, H.-G.; Scholz,
U.; Sheldrick, G. M. Chem. Ber. 1988, 121, 1403.
(10) Edelmann, F. T. Coord. Chem. ReV. 1994, 137, 403.
(11) (a) Berno, P.; Hao, S.; Minhas, R.; Gambarotta, S. J. Am. Chem.
Soc. 1994, 116, 7417 and references therein. (b) Hao, S.; Berno, P.; Minhas,
R.; Gambarotta, S. Inorg. Chim. Acta 1996, 224, 37.
(12) (a) Zhou, Y.; Richeson, D. S. Inorg. Chem. 1996, 35, 1423. (b)
Zhou, Y.; Richeson, D. S. Inorg. Chem. 1996, 35, 2448.
S0002-7863(96)00350-2 CCC: $12.00 © 1996 American Chemical Society

Synthesis of Tin-Sulfido Complexes
J. Am. Chem. Soc., Vol. 118, No. 44, 1996 10851
Treatment of these two new species with styrene sulfide
followed the redox pathway outlined in Figure 1. In both cases
the reaction was rapid and complete (>90% yield). While
spectroscopic and microanalytical data for both products
provided formulas, a firm indication that 3 and 4 were not
isostructural was first indicated by the observation of a dramatic
difference in the 119Sn NMR chemical shifts for 3 and 4;
complex 3 exhibited a 119Sn resonance at -236.2 ppm relative
to SnMe4, while for complex 4, a signal at -484.4 ppm was
observed. For comparison, the Sn(II) starting materials, 1 and
2, exhibited 119Sn NMR signals at -272.0 and -223.0 ppm,
respectively. As a result, we undertook an investigation of the
structures of 3 and 4 by single-crystal X-ray diffraction.
Complex 3 crystallized in the orthorhombic space group
Cmcm with Z ) 4.16 From Figure 1 it is clear that the most
outstanding structural feature in this molecule is the terminal
SndS bond. The bond length, Sn1-S1, of 2.280(5) Å correlates
favorably with the only comparable report in the literature of
2.274(3) Å.6b The SndS bond in 3 is shorter than the terminal
sulfur linkages found for a series of polythioanions which span
a range of 2.325-2.381 Å.7 The distorted trigonal bipyramidal
Sn coordination geometry in this complex is similar to that of
the Sn(II) starting material (2) with the Sn-S vector residing
in the equatorial site previously occupied by the lone electron
pair and N1 and N1a in the pseudoaxial sites. Not surprisingly,
the Sn-N bonds for 3 are shorter than in the starting material
2. There are no striking differences between these complexes
for the structural parameters within the ligands.
Figure 1. Reaction sequence for the synthesis of complexes 1-4.
Molecular structure and atom numbering schemes for [CyNC(tBu)-
NCy]2Sn (2), [CyNC(tBu)NCy]2SndS (3), and {[CyNC(Me)NCy]2Sn-
(µ-S)}2 (4) (Cy ) cyclohexyl). Hydrogen atoms and solvent molecules
have been omitted for clarity.
(Cy ) cyclohexyl; R ) Me, tBu) and (Me3SiNC(tBu)NSiMe3)-
anions which were generated by the addition of appropriate
alkyllithium reagent to CyNdCdNCy, dicyclohexylcarbodi-
imide and Me3SiNdCdNSiMe3, bis(trimethylsilyl)carbodiim-
ide, respectively.12
In surprising contrast to 3, the structural analysis of 4 (see
Figure 1) revealed a dimeric [(C14H25N2)2SnS]2 complex with
a C2 axis perpendicular to the nearly square (Sn-µ-S)2 ring.17
The Sn atoms have pseudooctahedral coordination geometries
and the two Sn-S distances (2.434(2) Å, 2.476(2) Å) are, as
expected, significantly longer than in 3.
We report the synthesis of a unique family of tin-sulfido
complexes in which a change to a remote portion of the ligand
dramatically affects the stability of the terminal SndS bond.
The new bulky amidinate ligand, (CyNC(tBu)NCy)-, provided
the supporting environment for a structurally characterized ter-
minal SndS complex which is unique in the absence of macro-
Through changes to the substituent on the central carbon of
the NCN unit in two amidinate ligands, we have been able to
(14) Selected bond distances (Å) and bond angles (deg) for 2: Sn1-
N1, 2.363(5); Sn1-N2, 2.203(5); Sn1-N3, 2.394(5); Sn1-N4, 2.186(5);
N1-C1, 1.478(8); N1-C25, 1.327(8); N2-C7, 1.460(8); N2-C25, 1.329-
(8); N3-C13, 1.444(8); N3-C30, 1.341(8); N4-C19, 1.448(8); N4-C30,
1.368(8); N1-Sn1-N2, 57.1(2); N1-C25-N2, 110.9(5); N1-Sn1-N3,
144.3(3); N1-C25-C26, 126.0(6); N1-Sn1-N4, 98.3(2); N2-C25-C26,
122.9(6); N2-Sn1-N3, 96.1(2); N4-C19-C20, 110.3(5); N2-Sn1-N4,
95.0(2); N4-C19-C24, 110.6(5); N3-Sn1-N4, 57.7(2); N3-C30-N4,
110.0(5); N3-C30-C31, 128.7(6); Sn1-N1-C1, 124.9(4); N4-C30-C31,
121.3(6); Sn1-N1-C25, 92.0(4); C1-N1-C25, 127.0(5); Sn1-N2-C7,
133.7(4); Sn1-N2-C25, 99.3(4); C7-N2-C25, 127.0(5); Sn1-N3-C13,
130.0(4); Sn1-N3-C30, 91.1(4); C13-N3-C30, 128.5(5); Sn1-N4-C19,
130.9(4); Sn1-N4-C30, 99.7(4); C19-N4-C30, 129.5(5); N2-C7-C12,
110.3(5).
t
cyclic supporting ligation. By simply changing the Bu group
of the amidinate ligand to Me, a bridging mode for the sulfido
group was obtained. These results provide a unique example
for the structural characterization of these two bonding modes
of the chalcogenido ligand within one family of compounds.13
Results and Discussion
t
The in situ preparation of (CyNC(R)NCy)Li (R ) Me, Bu)
followed by addition of SnCl2 generated the Sn(II) complexes
1 and 2 in greater than 70% isolated yields (Figure 1). Both of
these compounds have been thoroughly characterized by
spectroscopic means, microanalysis and subsequent reactivity.
Compound 2 was further characterized through a single-crystal
X-ray diffraction study.14 As can be seen in Figure 1, 2
possesses a geometry derived from a distorted trigonal bipyramid
in which one equatorial vertex is occupied by a stereochemically
active lone pair of electrons and N1 and N3 are in pseudoaxial
positions.15 The amidinate rings are approximately planar with
the average axial Sn-N bonds (2.38 Å) and slightly longer than
the average equatorial Sn-N bonds (2.19 Å). The average of
these four bonds (2.287 Å) is slightly longer than that of the
structurally characterized Sn(IV) benzamidinate complex (2.143
Å).8d
(15) For a similar Sn(II) structure with the diiminophosphinate ligand
[Ph2P(NSiMe3)2-], see: Kilimann, U.; Noltemeyer, M.; Edelmann, F. T.
J. Organomet. Chem. 1993, 443, 35.
(16) Selected bond distances (Å) and bond angles (deg) for 3: Sn1-
N1, 2.19(1); Sn1-N2, 2.09(1); N1-C1, 1.47(2); N1-C5, 1.69(2); N2-
C5, 1.70(2); S1-Sn1-N1, 107.9(3); S1-Sn1-N2, 130.0(3); N1-Sn1-
N1a, 144.2(4); N1-Sn1-N2, 78.6(2); N2-Sn1-N2b, 100.0(5); N2-C10-
C11, 108.1(13); Sn1-N1-C1, 136.1(8); C5-N2-C10c, 113.0(11); Sn1-
N1-C5, 85.5(7); N1-C5-C6, 129.0(13); C1-N1-C5, 115.1(7); C5-C6-
C8, 105.9(14); Sn1-N2-C5, 88.5(8); Sn1-N2-C10, 157.5(7); N1-C5-
N2, 106.4(11); N2-C5-C6, 122.7(14); C5-C6-C7, 115.3(15).
(17) Selected bond distances (Å) and bond angles (deg) for 4: Sn1-
N1, 2.226(5); N1-C1, 1.456(7); Sn1-N2, 2.264(4); N1-C13, 1.315(7);
Sn1-N3, 2.215(4); N2-C7, 1.475(7); Sn1-N4, 2.226(4); N2-C13, 1.345-
(8); S1-Sn1a, 2.4757(16); N3-C15, 1.466(8); N4-C21, 1.466(7); N3-
C27, 1.322(8); N4-C27, 1.305(7); S1-Sn1-S1a, 88.95(5); N2-Sn1-N3,
143.1(2); S1-Sn1-N1, 157.1(1); N2-Sn1-N4, 93.17(2); S1-Sn1-N2,
98.6(1); N3-Sn1-N4, 59.1(2); S1-Sn1-N3, 107.9(1); Sn1-S1-Sn1a,
89.24(5); S1-Sn1-N4, 97.1(1); C1-N1-C13, 123.9(5); S1a-Sn1-N1,
93.6(1); Sn1-N2-C13, 92.7(3); S1a-Sn1-N2, 108.4(1); C7-N2-C13,
121.3(4); S1a-Sn1-N3, 97.6(1); Sn1-N3-C27, 94.0(3); S1a-Sn1-N4,
156.6(1); C15-N3-C27, 124.2(5); N1-Sn1-N2, 59.1(2); Sn1-N4-C27,
94.0(4); N1-Sn1-N3, 94.3(2); C21-N4-C27, 124.1(5).
(13) A similar example of both bridging and terminal bonding modes
for S atoms can be found in refs 1(a) and 1(d) where the replacement of a
ligand on the metal center results in the isolation of monomeric Tbt(Tip)-
GedS or dimeric [Tbt(Mes)Ge(µ-S)]2.

10852 J. Am. Chem. Soc., Vol. 118, No. 44, 1996
Zhou and Richeson
(sealed): 239-241 °C. IR (Nujol, cm-1): 1514 (s). 1H NMR (C6D6,
ppm): 3.37 (br, C6H11, 8H), 2.22-1.22 (m, C6H11, 80H), 1.72
(s, Me, 12H). 119Sn NMR (THF, ppm): -484.4. Anal. Calcd for
C56H100N8S2Sn2: C, 56.67; H, 8.49; N, 9.44. Found: C, 56.42; H,
8.69; N, 9.16.
prepare both terminal sulfido and µ-sulfido complexes of Sn.
X-ray crystallographic studies and spectroscopic parameters
confirm the features of these complexes. We suggest that the
fact that an alteration to a remote substituent of the amidinate
ligand leads to a profound change in the structure of the product
is due to the steric congestion of the tBu-substituted amidinate.
Formation of a monomeric species is favored by relaxation of
the ligand strain and interligand repulsions that would be present
in a dimeric framework. Our continuing investigations are
oriented at dissecting the steric and electronic features that
influence the formation and reactivity of these tin-sulfido
compounds and their germanium analogues.
[C6H11NC(CMe3)NC6H11]2SnS (4). Complex 2 (1.00 g, 1.55 mmol)
was dissolved in 15 mL of hexane followed by the addition of excess
styrene sulfide. The reaction mixture was stirred at room temperature
overnight. The resulting white solid was collected by filtration and
dried under oil pump vacuum (0.95 g, 90%, 1.40 mmol). Crystals were
obtained by cooling a concentrated THF/ether (1:1 vol.) solution of
complex 4 to -30 °C. Mp (sealed) 222-224 °C. Spectroscopic data:
IR (Nujol, cm-1): 1488 (m), 1456 (s), 1432 (s). 1H NMR (C6D6,
ppm): 3.90 (br, C6H11, 4H), 1.84-1.05 (m, C6H11, 40H), 1.18 (s, CMe3,
18H). 119Sn NMR (C6D6, ppm): -236.2. Anal. Calcd for C34H62N4-
SSn: C, 60.26; H, 9.22; N, 8.27. Found: C, 60.42; H, 9.39; N, 8.28.
X-ray Crystallography. Intensity data were collected on a Rigaku
diffractometer at -153 °C using the ω-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 25 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 and absorption (ψ scan). The structures
were solved by direct methods. The non-hydrogen atoms were refined
anisotropically. Hydrogen atom positions were located in the difference
Fourier maps and refined isotropically in the case of favorable
observation/parameter ratio. 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 Fcalc. All
calculations were performed using the NRCVAX package. Full details
of the data collection, refinement, and final atomic coordinates are
reported in the Supporting Information.
Experimental Section
General Procedure. All reactions were carried out either in a
nitrogen-filled drybox or under nitrogen using standard Schlenk-line
techniques. Diethyl ether, hexane, and THF were distilled under
nitrogen from potassium. Deuterated benzene was dried by vacuum
transfer from potassium. MeLi (1.4 M in diethyl ether), tBuLi (1.7 M
in hexane), SnCl2, and dicyclohexylcarbodiimide were purchased from
Aldrich and used without further purification.
Sn[C6H11NC(Me)NC6H11]2 (1). A Schlenk flask was charged with
dicyclohexylcarbodiimide (1.36 g, 6.60 mmol), diethyl ether (20 mL),
and a stir bar. To this solution was added MeLi (4.8 mL, 1.4 M, 6.60
mmol), and the mixture was stirred for an additional 30 min. In a
seperate Schlenk flask, SnCl2 was dissolved in 20 mL of THF (0.62 g,
3.30 mmol). The two Schlenk flasks were cooled to -78 °C in a dry
ice/acetone bath, and the SnCl2 solution was combined with the
amidinate solution Via cannula. The reaction mixture was stirred
overnight, and the reaction temperature was allowed to warm to room
temperature slowly. The solvent was removed under oil pump vacuum,
and the residue was extracted with 40 mL of hexane. The solution
was concentrated to ca. 15 mL, and the mixture was put in the freezer
for 3 days. The resulting white crystals of 1 were collected by filtration
and dried (1.44 g, 78%, 2.57 mmol). Mp (sealed): 147-149 °C. IR
(Nujol, cm-1): 1516 (s). 1H NMR (C6D6, ppm): 3.25 (br, C6H11, 4H),
1.95-1.15 (m, C6H11, 40H), 1.63 (s, Me, 6H). 13C NMR (C6D6,
ppm): 165.5 (s, NCN), 56.5, 36.3, 26.4, 26.2 (4s, C6H11), 12.6 (s, Me).
119Sn NMR (C6D6, ppm): -272.0. Anal. Calcd for C28H50N4Sn: C,
59.90; H, 8.98; N, 9.98. Found: C, 59.69; H, 9.20; N, 9.93.
Sn[C6H11NC(CMe3)NC6H11]2 (2). A Schlenk flask was charged
with dicyclohexylcarbodiimide (1.36 g, 6.60 mmol), diethyl ether (35
mL) and a stir bar. To this solution was slowly added tBuLi (3.9 mL,
1.7 M in hexane, 6.60 mmol) and the mixture was stirred for an
additional 30 min. SnCl2 (0.63 g, 3.30 mmol) was added and the
reaction mixture was stirred overnight. The solvent was removed under
oil pump vacuum, and the residue was extracted with 40 mL of hexane.
The hexane was removed under vacuum, and the pale yellow powder
was dissolved in 10 mL of ether. After the mixture was cooled to
-30 °C for 3 days, the resulting colorless crystals of 2 were collected
by filtration and dried (1.55 g, 72%, 2.40 mmol). Mp (sealed): 103-
105 °C. IR (thin film, cm-1): 2927 (vs), 2846 (s), 1594 (w), 1488
(m), 1446 (s), 1425 (s),1356 (s), 1342 (s). 1H NMR (C6D6, ppm): 4.07
(br, C6H11, 4H), 2.05-1.15 (m, C6H11, CMe3, 76H). 119Sn NMR (C6D6,
ppm): -223.0. Anal. Calcd for C34H62N4Sn: C, 63.26; H, 9.68; N,
8.68. Found: C 63.47; H, 9.86; N, 8.45.
Summary of Crystal Data. Complex 2: space group P21/c
(monoclinic); a ) 18.944(5) Å, b ) 10.604(2) Å, c ) 19.423(2) Å, â
) 95.99(1); Z ) 4; empirical formula C34H62N4Sn + (C4H10O); F(000)
) 1543.65; number of unique reflections ) 3997; R ) 0.046, Rw
0.049.
)
Complex 3: space group Cmcm (orthorhombic); a ) 12.3788(23)
Å, b ) 14.1977(15) Å, c ) 20.670(3) Å; Z ) 4; empirical formula
C34H62N4SnS; F(000) ) 1468.51; number of unique reflections ) 1029;
RF ) 0.057, Rw ) 0.070. The Sn and S atoms were found on special
positions. The positions of some of the ligand atoms, which were found
to be disordered over two locations, were modeled by splitting the
occupancy over the two sites.
Complex 4: space group P2/n (monoclinic); a ) 13.0395(2) Å, b
) 13.0263(2) Å, c ) 23.8856(2) Å, â ) 95.719(3)°; Z ) 2; empirical
formula C56H100N8Sn2S2, this structure also contained 1 molecule of
benzene and 4 molecules of THF in the crystal lattice; F(000) )
1637.47; number of unique reflections ) 6936; RF ) 0.055, Rw ) 0.044.
Acknowledgment. This work was supported by the Natural
Sciences and Engineering Research Council of Canada.
Supporting Information Available: A listing providing a
description of the structural solutions, tables of atomic positions,
thermal parameters, crystallographic data, bond distances and
angles, and ORTEP drawings for compounds 2-4 (40 pages).
See any current masthead page for ordering and Internet access
instructions.
[[C6H11NC(Me)NC6H11]2SnS]2 (3). Complex 1 (0.80 g, 1.43 mmol)
was dissolved in 15 mL of hexane followed by the addition of excess
styrene sulfide. The reaction mixture was stirred at room temperature
overnight. The resulting white solid was collected by filtration and
dried under oil pump vacuum (0.79 g, 93%, 1.33 mmol). Crystals were
obtained by cooling a concentrated THF solution of 3 to -30 °C. Mp
JA960350E