LINKING METAL CENTERS WITH BIS(DIPHENYLPHOSPHINO)ACETYLENE (DPPA) - SYNTHESES AND MOLECULAR-STRUCTURES OF [(MO(CO)(4)(MU-DPPA))(2)] AND [(MO(CO)(3))(2)(MU-DPPA)(3)]

Addition of bis(diphenylphosphino)acetylene (DPPA) to [Mo(CO)(4)(piper idine)(2)] yielded doubly-bridged cis,cis-[{Mo(CO)(4)(mu-DPPA)}(2)] (1 ), while further addition of DPPA afforded triply-bridged fac,fac-[{Mo (CO)(3)}2(mu-DPPA)(3)] (2). Both have been characterized crystallograp hically, the former showing a twisted arrangement of diphosphine bridg es, while in the latter the three diphosphines are approximately paral lel to one another and the metal-metal vector. (C) 1996 Elsevier Scien ce Ltd.