Uebergangsmetall-Carben-Komplexe CXXXXI. Untersuchungen zum Reaktionsverhalten der Carben-Komplexe cis-(CO)4(SnPh3)Re (R = iPr, chex) gegenueber Lewis-Saeuren

Article abstract of DOI:10.1016/S0022-328X(00)99046-6

In the reaction of cis-(CO)4(SnPh3)Re (R = ⁱPr (isopropyl), ^chex (cyclohexyl)) with BI3 the Lewis acid attacks the triphenylstannyl ligand.Substitution of a phenyl for a iodine group leads to equilibrium mixtures of rhenium carbene complexes of general formulacis-(CO)4(SnPh_3-xI_x)Re (x = 1-3; R = ⁱPr, ^chex).By changing the solvent and ratio of reactants, the equilibria can be shifted such that only one major product is formed.Thus this reaction pathway can be used for the preparation of cis-(CO)4(SnPhI2)Re (R = ⁱPr, ^chex).Even when a large excess of BI3 is present electrophilic attack by the Lewis acid on the carbene ligand is not observed.Synthesis of cis(CO)4(SnPh_3-xI_x)Re (x = 1-3; R = ⁱPr, ^chex) can be achieved in high yield by reaction of cis-(CO)4(SnPh3)Re (R = ⁱPr, ^chex) with one, two or three equivalents of HI.This reaction, with successive rupture of the tin-carbon bonds in the triphenyl stannyl ligand and the simultaneous formation of benzene, affords the desired substitution product irreversibily.Reaction of cis(CO)4(SnPh3)Re (R = ⁱPr, ^chex) with I2 gives the compounds cis-(CO)4(SnI3)Re (R = ⁱPr, ^chex), in relatively low yields.