Reactions of metal carbonyl derivatives

The ditertiary phosphines (C6H5)2P(CH2)nP(C6H5)2 (n = 1 and 2), cis(C6H5)2PC2H2P(C6H5)2 and (C6H5)2PN(C2H5)P(C6H52 and the ditertiary arsines (C6H5)2As(CH2)nAs(C6H5)2 (n = 1 and 2) react with [Fe(CO)3SC6H5]2 to give a wide range of products, the nature of which depends on the reaction conditions and the ligand involved. Examples of the different types of comp isolated include, (i) Fe2(CO)5[(C6H5)2PCH2P(C6H5)2](SC6H5)2, in which the ligand acts as a monodentate, (ii) {[Fe(CO)2SC6H5]2[(C6H5)2PC2H4P(C6H5)2]}2, in which two [Fe(CO)2SC6H5]2 moieties are bridged by two diphosphine ligands, (iii) [Fe(CO)2SC6H5]2[(C6H5)2PN(C2H5)P(C6H5)2], in which the ligand bridges the two iron atoms, and (iv) Fe(CO)3(SC6H5)2Fe(CO)[(C6H5)2PC2H2P(C6H5)2], which contains the ligand chelated to a single iron atom. The tertiary phosphines PR3 (R=C2H5 and C6H5), phosphites P(OR′)3(R′ = CH3, C2H5, i-C3H7 and C6H5) and the stibine Sb(C6H5)3 bring about mono-, bis- or tris-substitution in [Fe(CO)3SC6H5]2 depending on the reaction conditions and the ligand involved. Whereas in solution [Fe(CO)2L(SC6H5)]2 [L = PR3 (R = C2H5 and C6H5), P(OC6H5)3 and Sb(C6H5)3] exist as a single isomer, [Fe(CO)2L′(SC6H5)]2 [L′=P(OR′)3 (R'=CH3, C2H5 and i-C3H7)] occur as a mixture of isomers.