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

Abstract Tin(II) compounds containing the ligands [CH(C 6 H 3 Me 2 -2,5)C(Bu t )NSiMe 3 ] − (≡ L 1 ), [CH(Ph)C(Ph)NSiMe 3 ] − (≡ L 2 ), [CH(SiMe 3 )P(Ph) 2 NSiMe 3 ] − (≡ L 3 ), (≡ L 4 ), [C(Ph)C(Ph)NSiMe 3 ] 2− (≡ L 5 ), and [C(SiMe 3 )P(Ph) 2 NSiMe 3 ] 2− (≡ L 6 ) are reported: the transient SnBr( L 1 ) ( 1 ) and SnBr( L 2 ) ( 2 ), Sn( L 1 ) 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( L 2 ) 2 ( 4 ), [Sn( L 5 )] 2 ( 5 ), SnCl( L 3 ) ( 6 ), Sn( L 3 ) 2 ( 7 ), [Sn( L 6 )] 2 ( 8 ), Sn( L 4 ) 2 ( 9 ) and Pb( L 4 ) 2 ( 10 ). They were prepared from (i) SnBr 2 and K( L 1 ) ( 1 , 3 ) or K( L 2 ) ( 2 , 4 , 5 ); (ii) SnCl 2 and Li( L 3 ) ( 6–9 ); or (iii) PbCl 2 and Li( L 4 ) ( 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.