Synthesis and Structural Characterization of [Ir4(CO)8(η1-Ph)(μ4-η3-PhPC(H)CPh)(μ-PPh2)], with a η1-Phenyl Group Arising from Selective Cleavage of a Coordinated Ph2PC(H)CPh Ligand, and of the CO-Inserted Product [Ir4(CO)8(η1-C(O)Ph)(μ4-η3-PhPC(H)CPh)(μ-PPh2)]