Synthesis and characterisation of iron and cobalt complexes with phosphinothiolate ligands

Neutral iron complexes of a series of arenephosphinothiol proligands, PhxP(ArSH)3−x, (x=0–2, Ar=C6H4, C6H3SiMe3) have been synthesised. Compounds [Fe{2-(Ph2PO)C6H4S}3] (1), [Fe{2-(Ph2P)-6(Me3Si)C6H3S}3] (2), [Fe{2-(Ph2PO)-6(Me3Si)C6H3S}3] (3) and [Fe2{PhP(C6H4S-2)2}3] (4) were obtained most conveniently by the electrochemical oxidation of an iron anode in a cell containing an acetonitrile solution of the corresponding proligand. [Fe{2-(Ph2P)C6H4S}2(CO)2] (5) was obtained by the addition of the appropriate proligand to an acetonitrile solution of FeCl2 saturated with CO. The reaction of FeCl2 with PhP(C6H4SH-2)2 in methanol in the presence of CO and bis-diphenylphosphinoethane (dppe) gave [Fe{PhP(C6H4S-2)2}(dppe)(CO)] (6) in good yield. The reaction of FeCl2 with the potentially tetradentate P(C6H4SH-2)3 proligand in presence of PMe2Ph or dppe allows the synthesis of [Fe{P(C6H4S-2)3}(PMe2Ph)2] (7) and [Fe{P(C6H4S-2)3}(dppe)] (8). Corresponding reactions of the phosphinothiolates with CoCl2 in the presence of CO and/or phosphine ligands gave [CoCl{PhP(C6H4S-2)2}(dppe)] (9), [Co{PhP(C6H4S-2)2}(dppe)(CO)]BPh4 (10), [Co{PhP(C6H4S-2)2}(dppe) ] (11), [Co(P(C6H4S-2)3L] (L=dppe, 12, L=PMe2Ph, 13. The X-ray crystal structures of complexes 2, 4, 7 and 8, are discussed.