Metal–Metal Bonds between Group 12 Metals and Tin: Structural Characterization of the Complete Series of Sn-M-Sn (M=Zn, Cd, Hg) Heterodimetallic Complexes

✍ Scribed by Matthias Lutz; Bernd Findeis; Matti Haukka; Roland Graff; Tapani A. Pakkanen; Lutz H. Gade

• Publisher: John Wiley and Sons
• Year: 2002
• Tongue: English
• Weight: 188 KB
• Volume: 8
• Category: Article
• ISSN: 0947-6539
• DOI: 10.1002/1521-3765(20020715)8:14<3269::aid-chem3269>3.0.co;2-w

✦ Synopsis

Reaction of the lithium triamidostannate [MeSiSiMe(2)N(p-Tol)SnLi(OEt(2))] (1) with 0.5 molar equivalents of MCl(2) (M=Zn, Cd, Hg) in toluene afforded the corresponding heterodimetallic complexes [MeSiSiMe(2)N(p-Tol)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.