TRIPODAL TRIAMIDOSTANNATES AND TRIAMIDOPLUMBATES

Reaction of the tripodal trilithium amides HC{SiMe(2)N(Li)(4-CH3C6H4)} (3)(THF)(2) (1) and CH3Si{SiMe(2)N(Li)-(tBu)(3)(THF)(x) with SnCl2 or Cp(2)Pb gave the corresponding lithium triamidostannates and -plumbate s HC{SiMe(2)N(4-CH3C6H4)}3SnLi(THF)(3) (2), [HC{SiMe(2)N(4-CH3C6H4)}Pb -3][Li(THF)(4)] (4), and CH3Si{SiMe(2)N(tBu)}(3-)MLi(THF) (M = Sn: 7; Pb: 8). The X-ray structure analysis of 2 revealed molecular as well a s crystallographic 3-fold symmetry and established a short direct Li-S n contact [d(av)(Sn-Li) = 2.93(5); two independent molecules in the un it cell]. 2: hexagonal, P6(3) (No. 173), alpha = 15.664(4) Angstrom, c = 22.421(11) Angstrom, Z = 4, V = 4765(3) Angstrom(3), R = 0.038. An X-ray structure analysis of 8 established direct bonding of the (THF)L i counterion to two N-functions of the triamido metalate unit in a bri dging fashion, a situation that, as the NMR spectra show, pertains in solution. 8: orthorhombic, Pbca (No. 61), alpha = 10.8201(2) Angstrom, b = 20.0825(3) Angstrom, c = 31.5806(3) Angstrom, Z= 8, V= 6862.3(3) Angstrom(3), R = 0.076. If two molar equivalents of MeN(CH(2)CH(2)NMe( 2))(2) are added to the in situ generated 2 the ''solvent separated'' ion pair H(2)NMe(2))(2)Li},Cl][HC{SiMe(2)N(4-CH3C6H4)}Sn-3] (5) is for med, which contains a solvated Li2Cl](+) cation. Crystal data of 5 as established in an X-ray structure analysis: triclinic, P-l (No. 2), al pha = 12.377(2) Angstrom, b = 15.360(2) Angstrom, c = 17.594(3) Angstr om, alpha = 77.41(1)degrees, beta = 74.16(2)degrees, gamma = 70.94(3)d egrees, Z = 2, V= 3011.2 Angstrom(3), R = 0.072. While reaction of H3C C{N(Li)SiMe(3)}(3)(THF)(3) With SnCl2 gives the corresponding stannate H3CC(NSiMe(3))(3)SnLi(THF) which on the basis of its spectroscopic da ta is thought to have a similar structure to 7 and 8, the analogous pl umbate could be isolated neither from the reaction with Cp(2)Pb nor wi th PbCl2. The latter showed marked redox reactivity effecting fragment ation of the ligand. From the reaction mixture of this system a crysta lline solid was isolated in ca. 25% yield. This was identified by elem ental analysis and X-ray structure analysis as [H3CC(CH(2)NSiMe(3))(2) (CH2O(Li))Pb](2) (11) which has a fused cage structure. 11: triclinic, Pi (No. 2), alpha = 8.4889(2) Angstrom, b = 11.1832(4) Angstrom, c = 11.7308(3) Angstrom, alpha = 62.010(5)degrees, beta = 71.163(4)degrees , gamma 68.528(5)degrees, Z = 2, V = 899.5(2) Angstrom(3), R = 0.054.