Synthesis and substitution reactions of a heterodimetallic molybdenum-manganese complex, [MoMn(μ-H)(μ-PPh₂) (η⁵-C₅H₅)(CO)₆]; X-ray crystal structure of [MoMn(μ-H)(μ-PPh₂)(η⁵-C ₅H₅)(CO)₄(dppm-PP′)]

The photolytic reaction of [MoMn(η⁵-C₅H ₅)(CO)₈] with PPh₂H gives [MoMn(μ-H)(μ- PPh₂)(η⁵-C₅H₅)(CO)₆] (1) and [Mo₂(μ-H)(μ-PPh₂)(η⁵-C ₅H₅)(CO)₄] as the major products. Complex (1) reacts photolytically with two-electron donor ligands, L, to give the substituted complexes [MoMn(μ-H)(μ-PPh₂)(η⁵- C₅H₅)(CO)₅L] [L = P(OMe)₃ (2a), PPh₃ (2b), or CNCH₂Ph (2c)], [MoMn(μ-H)(μ-PPh ₂)(η⁵-C₅H₅)(CO) ₄L₂] [L = P(OMe)₃ (3a), L₂ = dppm-PP′ (3b) (dppm = Ph₂PCH₂PPh₂), or L = CNCH₂Ph (3c)], and [MoMn(μ-H)(μ-PPh₂)(μ-L) (η⁵-C₅H₅)(CO)₄] [L = dppm-PP′ (4)]. An n.m.r. study reveals that the ligands L in complexes (2) and (3) have replaced respectively one or two carbonyl groups on the manganese atom. This has been confirmed for (3b) by X-ray analysis. Complex (4), an isomer of (3b) in which the dppm ligand adopts a bridging rather than a chelating bonding mode, is formed irreversibly from (3b) on photolysis.