Issue 6, 1997

New heterosiloxanes of bivalent Group 14 elements and their reactions with [Mo(CO)6]: crystal structures of [{M(µ-OBut)(OSiPh3)}2] (M = Ge or Sn) and [{Sn(µ-OBut)(OSiPh3)}2 Mo(CO)5]

Abstract

The protolysis of Ph 3 SiOH with a toluene solution of [{M(OBu t ) 2 } n ] (M = Ge II or Sn II , n = 2; M = Pb II , n = 3) in 1∶1 molar ratio at room temperature via alcohol elimination facilitated the isolation of high yields of heteroleptic alkoxosiloxides of the type [{M(µ-OBu t )(OSiPh 3 )} 2 ] (M = Ge II 1, Sn II 2 or Pb II 3). Crystal structural analyses of compounds 1 and 2 revealed them to be isomorphous and isostructural. Both the dimeric structures feature a perfect planar M 2 O 2 (M = Sn 1 or Ge 2) core with a crystallographically imposed centre of inversion. Each metal atom is bound to two bridging tert-butoxide ligands and one terminal triphenylsiloxide ligand resulting in a trigonal-pyramidal co-ordination geometry around the metal atom. The stereochemical activity of the lone pair of electrons present on the metal atoms of 1 and 2 is demonstrated by their ability to form M–Mo bonds in [{M(µ-OBu t )(OSiPh 3 )} 2 Mo(CO) 5 ] (M = Ge 4 or Sn 5) on their reaction with an equimolar amount of [Mo(CO) 6 ] in refluxing toluene via displacement of CO from the inner co-ordination sphere of [Mo(CO) 6 ]. The asymmetry in compound 5 was revealed by its crystal structure. The structure consists of a four-co-ordinate tin(II) centre, bearing an Mo(CO) 5 unit, linked via two bridging tert-butoxide groups to another Sn II which exhibits (3 + 6) co-ordination with three normal Sn–O bonds and a weak tin(II)–arene (η 6 ) interaction originating from the orientation of a phenyl ring of the OSiPh 3 ligand such that the tin to ring centre distance is 3.58 Å. The identity of all the compounds in solution has been confirmed by multinuclear ( 1 H, 13 C, 29 Si, 119 Sn and 207 Pb) NMR and IR spectra and elemental analyses.

Article information

Article type
Paper

J. Chem. Soc., Dalton Trans., 1997, 995-1000

New heterosiloxanes of bivalent Group 14 elements and their reactions with [Mo(CO)6]: crystal structures of [{M(µ-OBut)(OSiPh3)}2] (M = Ge or Sn) and [{Sn(µ-OBut)(OSiPh3)}2 Mo(CO)5]

M. Veith, C. Mathur and V. Huch, J. Chem. Soc., Dalton Trans., 1997, 995 DOI: 10.1039/A607153H

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