RESUMO
Reaction of the lithium triamidostannate [MeSi[SiMe(2)N(p-Tol)](3)SnLi(OEt(2))] (1) with 0.5 molar equivalents of MCl(2) (M=Zn, Cd, Hg) in toluene afforded the corresponding heterodimetallic complexes [MeSi[SiMe(2)N(p-Tol)](3)Sn](2)M [M=Hg (2), Cd (3), and Zn (4)]. The molecular structures of the mercury and cadmium complexes were determined by X-ray diffraction and found to adopt a linear Sn-M-Sn metal-metal bonded array (d(Sn-Hg) 2.6495(2), d(Sn-Cd) 2.6758(1) A), these being the first Hg-Sn and Cd-Sn bonds to be characterized by X-ray diffraction. That the Hg-Sn bonds are shorter than the Cd-Sn bonds in the isomorphous complexes is attributed to relativistic effects in the mercury system. In contrast, the structure of the Zn analogue is unsymmetrical with one stannate unit being Sn-Zn bonded (d(Sn(1)-Zn) 2.5782(4) A), while the Zn(II) atom bridges two amido functions of the second stannate cage, thus representing a second isomeric form of these complexes. The different degree of metal-metal bond polarity is reflected in the (119)Sn NMR chemical shifts of the three complexes. Variable-temperature NMR studies and a series of (1)H ROESY experiments of the cadmium complex 3 in solution revealed a dynamic exchange between the two isomers.
RESUMO
The reaction of [MeSi{Me(2)SiN(Li)(p-tol)}(3)(Et(2)O)(2)] with SnCl(2) in a 1:1 molar ratio leads the tris(amido)stannate [MeSi{Me(2)SiN(p-tol)}(3)SnLi(Et(2)O)] (1), which further reacts with neutral [AuCl(PPh(3))] and anionic [PPN][AuCl(2)], PPN[AuRCl] (R = C(6)F(5), mes), and chlorogold(I) complexes yielding [Au(MeSi{Me(2)SiN(p-tol)}(3)Sn)(PPh(3))] (2) and [PPN][Au(MeSi{Me(2)SiN(p-tol)}(3)Sn)(2)] (3) and [Au(MeSi{Me(2)SiN(p-tol)}(3)Sn)(R)] (R = C(6)F(5), 4; R = mes, 5), respectively. The reaction of 1 with the dinuclear gold(II) derivative [Au(2)(CH(2)PPh(2)CH(2))(2)Cl(2)] in a 1:2 ratio affords [Au(2)(CH(2)PPh(2)CH(2))(2)(MeSi{Me(2)SiN(p-tol)}(3)Sn)(2)] (6). In a similar way but starting from PPN[Au(C(6)F(5))(3)Cl] and reacting with 1 in a 1:1 ratio, the Au(III) complex [PPN][Au(MeSi{Me(2)SiN(p-tol)}(3)Sn)(C(6)F(5))(3)] (7) has been obtained. X-ray crystal structure analyses were performed for compounds 2 and 6, establishing the Sn-Au bonds [d(Au-Sn) = 2.5651(13) and 2.6804(13) Å, respectively). Compound 6 has a nearly linear Sn-Au-Au-Sn array and features the first examples of tin-gold(II) bonds.
