Transition-metal silyl complexes. XXVIII. Preparation and stereochemistry of phosphite-substituted hydrido silyl complexes of iron and derived anionic complexes

Article abstract of DOI:10.1016/0022-328X(89)87175-X

Fe(CO)3(H)SiR3 (R'=Et,Ph) (1) and Fe(CO)22(H)SiR3 (2) are obtained by photochemical reaction of Fe(CO)4 or Fe(CO)32 with a number of different silanes.To avoid side reactions, triphenylphosphite derivatives Fe(CO)22(H)SiR3 (5) are better prepared by thermal reaction of the known ortho-metallated complex Fe(CO)22 with silanes.Monophosphite substituted complexes 1 have a mer arrangement of the CO ligands and a trans disposition of the SiR3 and P(OR')3 ligands.In the bis-phosphite derivatives 2 and 5 the CO ligands are mutually trans and the phosphite ligands cis.For Fe(CO)22(H)SiMeCl2 (5a) a second isomer, with cis-CO ligands and trans-P(OPh)3 ligands, is observed at low temperature.The hydrido silyl complexes 1, 2 and 5 are fluxional at room temperature.Deprotonation of 2 or 5 with KH gives anionic silyl complexes K2SiR3> (7).The reactivity of 7 is exemplified by reactions of the Si(OEt)3 derivative 7b with Me3SnCl, Me2SnCl2 or Ph3PAuCl (L_nMCl), which gives the corresponding substitution products Fe(CO)22ML_n (9).The latter compounds have the same geometry as 2 and 5.While the Ph3PAu derivative 9c is fluxional at room temperature, the stannyl derivatives 9a, 9b adopt static structures.