Reactivity of [Fe₂(CO)₆(μ-S₂)] toward a Base-Containing Diphosphine (Ph₂PCH₂)₂NCH₃: Formation of Diiron Carbonyl Compounds Having Polydentate Heterofunctionalized Phosphine (PNS = Ph₂PCH₂N(CH₃)CH₂S) and Bidentate Thiophosphinito (Ph₂PS = PS) Bridges

Reaction of the base-containing diphosphine (Ph2PCH2)(2)NCH3 with [Fe-2(CO)(6)(mu-S-2)] (1) yielded at room temperature the novel compound [Fe-2(CO)(4)(mu-kappa(1):kappa(1)-SPPh2){mu-kappa(2):kappa(2)-SCH2N(Me)CH2-PPh2}] (2) resulting from S-S and P-C bond cleavage concomitant with P-S and C-S bond formation. Experiments at low temperature allowed the isolation of an intermediate species, [Fe-2(CO)(5)-(mu-kappa(1):kappa(1)-SPPh2){mu-kappa(2):kappa(2)-SCH2N(Me)CH2-PPh2}] (3), differing from 2 by the coordination mode of the PNS ligand and the presence of one additional carbonyl group. When the reaction was performed in the presence of an excess of tBuNC, an analogous compound of 3 was obtained. The X-ray analysis of this species, 4, revealed that an isocyanide replaced a carbonyl ligand in the axial position at one iron center.