Synthesis, structure and substitution reactions of a heterodimetallic tungsten - manganese complex [(η5-C5H5)(OC)2W( μ-H)( μ-PPh2)Mn(CO)4]

Article abstract of DOI:10.1016/S0022-328X(96)06595-3

The room temperature reaction of [(η⁵-C₅H₅)W(CO)₃(PPh₂)] with [Mn(CO)₅] in tetrahydrofuran (THF) followed by protonation with H₃PO₄ gives [(η⁵-C₅H₅)(OC)₂W( μ-H)( μ-PPh₂)Mn(CO)₄] 1 as the major product. Among the identified minor products from this reaction are [Mn₂(CO)₉(PPh₂H)] 2a, [Mn₂(CO)₉(PPh₂PPh₂)] 2b, [Mn₂( μ-H)( μ-PPh₂)(CO)₈] 2c, and [Mn₂( μ-PPh₂)₂(CO)₈] 2d. ¹³CO reacts with complex 1 substituting both the manganese and tungsten carbonyl groups. In contrast, other two-electron donor ligands, L, only substitute the manganese carbonyl groups to give the substituted products [(η⁵-C₅H₅)(OC)₂W( μ-H)( μ-PPh₂)Mn(CO)₃L] (L = P(OMe)₃ 3a, PMe₂Ph 3b, PMePh₂ 3c, PPh₂H 3d), [(η⁵-C₅H₅)(OC)₂W( μ-H)( μ-PPh₂)Mn(CO)₂L₂] (L = P(OMe)₃ 4a or PMe₂Ph 4b). In the case of the photolytic reaction of 1 with the diphosphine, dppm (dppm = Ph₂PCH₂PPh₂), two products are obtained, one in which the ligand is chelated to the manganese centre, [(η⁵-C₅H₅)(OC)₂W( μ-H)( μ-PPh₂)Mn(CO)₂(dppm)] 5, and the other in which the ligand bridges the tungsten manganese centres, [(η⁵-C₅H₅)(OC)W( μ-H)( μ-PPh₂)( μ-dppm)Mn(CO)₃] 6. Conversion of complex 5 to 6 can be achieved by prolonged UV irradiation of 5. A single crystal X-ray diffraction study for [(η⁵-C₅H₅)(OC)₂W( μ-H)( μ-PPh₂)Mn(CO)₄] 1 is presented.