Inorganic Chemistry, Vol.34, No.16, 4069-4078, 1995
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 -plumbates 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 as crystallographic 3-fold symmetry and established a short direct Li-Sn contact [d(av)(Sn-Li) = 2.93(5); two independent molecules in the unit 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)Li counterion to two N-functions of the triamido metalate unit in a bridging 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 [{MeN(CH(2)CH(2)NMe(2))(2)Li},Cl][HC{SiMe(2)N(4-CH3C6H4)}Sn-3] (5) is formed, which contains a solvated Li2Cl](+) cation. Crystal data of 5 as established in an X-ray structure analysis : triclinic, P-l (No. 2), alpha = 12.377(2) Angstrom, b = 15.360(2) Angstrom, c = 17.594(3) Angstrom, alpha = 77.41(1)degrees, beta = 74.16(2)degrees, gamma = 70.94(3)degrees, Z = 2, V= 3011.2 Angstrom(3), R = 0.072. While reaction of H3CC{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 data is thought to have a similar structure to 7 and 8, the analogous plumbate could be isolated neither from the reaction with Cp(2)Pb nor with PbCl2. The latter showed marked redox reactivity effecting fragmentation of the ligand. From the reaction mixture of this system a crystalline solid was isolated in ca. 25% yield. This was identified by elemental 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.
Keywords:MAIN-GROUP-METALS;STRUCTURAL CHARACTERIZATION;REGIOSPECIFIC CONVERSION;LITHIUM AMIDES;CRYSTAL;DERIVATIVES;CHEMISTRY;OXIRANES;COMPOUND;LIGANDS