NEW INVESTIGATIONS IN SILANEDIYL COMPLEX CHEMISTRY - SYNTHESIS, STRUCTURE, AND BONDING OF 1-METALLA-2-SILA-1,3-DIENES

The synthesis and chemical behavior of the intra- and intermolecular d onor-stabilized silanediyl complexes (C6H4CH2NMe2-2)(Cl)Si=MLn (4, MLn = Cr(CO)(5) 5, MLn = Fe(CO)(4)), (C6H5HC=CH)(Cl)Si=MLn. OP(NMe2)(3) ( 21, MLn = Cr(CO)(5); 22, MLn = Fe(CO)(4)), and (C6H5HC=CH)(C6H5)Si=Fe( CO)(4). OP(NMe2)(3) (23) is discussed. Nucleophilic substitution of th e chloro atom in compounds 4 and 5 by different nucleophiles leads to a great variety of further functionalized silanediyl complexes of the type (C6H4CH2NMe2-2)(R)Si=MLn (MLn = Cr(CO)(5): 7, R = CH3; 9, R = C6H 5; 11, R = P(C6H5)(2); 13, R = CH=CH2 MLn = Fe(CO)(4): 14, R = CH=CH2; 15, R = CH3)(.) Moreover, the 1-metalla-2-sila-1,3-dienes (C6H4CH2NMe 2-2)(H2C=CH)Si=MLn (13, MLn = Cr(CO)(5); 14, MLn = Fe(CO)(4)) can be p repared by treatment of the hypervalent dichlorosilane (C6H4CH2NMe2-2) (H2C=CH)SiCl2 (19) with the carbonylate dianions MLn2- (2, MLn = Cr(CO )(5); 3, MLn = Fe(CO)(4)). Additionally, compounds of the latter type are accessible by photochemical coupling reactions of the pentavalent silane (C6H4CH2NMe2-2)(CH3)SiH2 (16) with the transition-metal carbony ls Cr(CO)(6) (17a), Fe(CO)(5) (17b), and (eta 5-C5H5)Mn(CO)(3) (17c), respectively. The intermolecular donor-stabilized 1-metalla-2-sila-1,3 -dienes 21-23 can be prepared by the reaction of tetravalent dichloros ilanes [(R)-(H)C=CH](R')SiCl2 (20a, R = H, R' = Cl; 20b, R = R' = C6H5 ) with the carbonylmetalates 2 and 3 and in the presence of OP(NMe2)3.