TRANSITION-METAL DERIVATIVES OF THE CYCLOPENTADIENYLPHOSPHINE LIGANDS .8. PREPARATIVE APPROACHES AND CHARACTERIZATION OF THE NEW DINUCLEAR COMPLEX [(MU-C5H4P(C6H5)2)MO(CO)2]2 - X-RAY CRYSTAL-STRUCTURE OF THE TETRAMETALLIC COMPLEX [(CO)3MO(MU-C5H4P(C6H5)2)AG]2.2C6H5CH3

With the monometallic anionic complex [(eta5-C5H4P(C6H5)2)Mo(CO)3]- (1), prepared in good yield froM [(eta6-C7H8)Mo(CO)3], as starting material, three synthetic approaches toward the preparation of the homobimetallic doubly bridged derivatives [(mu-C5H4P-(C6H5)2)Mo(CO)2]2 (3) have been investigated, namely an electro- and photochemical procedure, chemical oxidation by silver salt, and photodegradation of the hydride [(eta5-C5H4P(C6H5)2)MO(CO)3H]. An intermediate in the second process, the tetrametallic complex [(CO)3Mo(mu-C5H4P(C6H5)2Ag]2(4), has been isolated; its ring-shaped structure is characterized by normal Mo-Ag bonds and the absence of interaction between the two molybdenum atoms.