New cationic, [(Fp)Ph(2)PC=CPPh(2)(F-p)](2+) (1) and [(Fp)Ph(2)PC=CPPh
(2)](+) (2), and anionic, [Fe-3(CO)(9)(mu 3-CCH3)(Ph(2)PC= CPPh(2))](-
) (3) and [{Fe-3(CO)9(mu(3)-CCH3)}2(Ph(2)PC=CPPh(2))](2-) (4), P-coord
inate complexes with bis(diphenylphosphino)acetylene have been prepare
d. The zwitterionic P-coordinated iron complex [{Fe-3(CO)(9)(mu 3-CCH3
)}Ph(2)PC=CPPh(2)(Fp)] (5) has been synthesized in two different ways
and characterized by X-ray crystallography.