Phosphine induced migratory CO insertion into the Fe-CH2 bond of the organometallic polymer -[(eta(5)-C5H4)Fe(CO)2CH2SiMe2]n- and characterization of model iron complexes.

Thermal and photochemical treatment of 1-sila-3-ferracyclobutane, (eta(5)C(5)H(4))Fe(CO)(2)CH(2)SiMe(2) (1) results in ring-opening polymerization (ROP). Phosphine-induced migratory CO insertion into the Fe-CH(2) bond of the preformed polymer, -[(eta(5)-C(5)H(4))Fe(CO)(2)CH(2)SiMe(2)](n)- (2) results in either linear polymers, -[(eta(5)-C(5)H(4))Fe(CO)(PR(3))C(O)CH(2)SiMe(2)](n)- [R(3) = Me(2)Ph (3), Ph(3) (4)] or diphosphine bridged polymers, -{[(eta(5)-C(5)H(4))Fe(CO)C(O)CH(2)SiMe(2)](2)(P-P)}(n)- [P-P = dppe (5), dppp (6), dppb (7), trans-dppen (8), dmpe (9); dppe = 1,2-bis(diphenylphosphino)ethane, dppp = 1,2-bis(diphenylphosphino)propane, dppb = 1,2-bis(diphenylphosphino)butane, cis-dppen = cis-1,2-bis(diphenylphosphino)ethylene, dmpe = 1,2-bis(dimethylphosphino)ethane]. The analogous model complexes, {[(eta(5)-C(5)H(5))Fe(CO)C(O)CH(3)](2)P-P} [P-P = dppp (10), dppb (11), trans-dppen (12), dmpe (13)] were synthesized and characterized as models of the acylated polymers. The X-ray crystal structure of 11 and 13 were determined to establish the bridging nature of the diphosphines in the model complexes and to get insight of the crystal packing.