Synthesis and structures of the dinuclear tin(II) complexes [R = Ph, X(Z) = CPh; R = SiMe3, X(Z) = PPh2] and of related compounds

Article abstract of DOI:10.1016/j.jorganchem.2009.06.025

Tin(II) compounds containing the ligands [CH(C₆H₃Me₂-2,5)C(Bu^t) NSiMe₃]^- (≡ L¹), [CH(Ph)C(Ph)NSiMe₃]^- (≡L²), [CH(SiMe₃)P(Ph)₂NSiMe₃]^- (≡ L³), {A figure is presented} (≡ L⁴), [C(Ph)C(Ph)NSiMe₃]^2- (≡ L⁵), and [C(SiMe₃)P(Ph)₂NSiMe₃]^2- (≡ L⁶) are reported: the transient SnBr(L¹) (1) and SnBr(L²) (2), Sn(L¹)₂ (3) [P.B. Hitchcock, J. Hu, M.F. Lappert, M. Layh, J.R. Severn, J. Chem. Soc., Chem. Commun. (1997) 1189], the labile Sn(L²)₂ (4), [Sn(L⁵)]₂ (5), SnCl(L³) (6), Sn(L³)₂ (7), [Sn(L⁶)]₂ (8), Sn(L⁴)₂ (9) and Pb(L⁴)₂ (10). They were prepared from (i) SnBr₂ and K(L¹) (1, 3) or K(L²) (2, 4, 5); (ii) SnCl₂ and Li(L³) (6-9); or (iii) PbCl₂ and Li(L⁴) (10). Each of 1, 3 and 5-10 has been characterised by multinuclear NMR spectra; 3, 5, 6, 8, 9 and 10 by EI-mass spectra, but only 3, 5, 8, 9 and 10 were isolated pure and furnished X-ray quality crystals. Of greatest novelty are the title binuclear fused tricyclic ladder-like compounds 5 and 8. Quantum chemical calculations, on alternative pathways to 5 from 2 and to 8 from 7, are reported.