Bis(cyclopentadienyl)phenylphosphine as ligand precursor for assembling heteropolymetal complexes

The dilithium salt of bis(cyclopentadienyl)phenylphosphine has been used as a multidentate ligand to generate unprecedented heteropolymetal arrays via the bimetal precursors [MI(CO)3]2[(η5-C5H4)P(Ph)(η5- C5H4)] (9, M ) Mo; 10, M ) W). The trimetal complexes MI(CO)3[(η5-C5H4)P(Ph)(η5-C5H4)](CO)3- MPd(PPh3)I (14, M ) Mo; 15, M ) W), obtained by reaction of 9 and 10 with Pd(PPh3)4, respectively, have been found to lose PPh3 converting to the hexametal derivatives {MI(CO)3[(η5-C5H4)P(Ph)(η5- C5H4)](CO)3MPd}(μ-I2){PdM(CO)3[(η5-C5H4)P(Ph)(η5-C5H4)](CO)3MI} (18, M = Mo; 19, M = W). Compound 18 also has been prepared by reaction of 9 with a PPh3-free zerovalent palladium species such as Pd2(dba)3; treatment of 18 with PPh3 regenerated the trimetal complex 14. The pentametal complex {MoI(CO)3[(η5-C5H4)P(Ph)(η5-C5H4)](CO)3Mo}Pd{Mo(CO)3[(η5-C5H4)P(Ph)(η5-C5H4)](CO)3MoI} (22), containing a linear Mo-Pd-Mo array, has been spectroscopically observed by reacting 18 with 1,2- bis(diphenylphosphino)ethane.