BIS(ALKYNYL) AND ALKYNYL-VINYLIDENE IRON(LL) COMPLEXES WITH MONODENTATE PHOSPHITE LIGANDS

The bis(alkynyl) derivatives [Fe(C=CR)(2)L(4)] [R=Ph. p-tolyl or Bu(t) ; L=P(OMe)(3), P(OEt)(3) or PPh(OEt)(2)] were prepared and their proto nation and methylation reactions with HBF4 and CF(3)SO(3)Me afforded a lkynyl-vinylidene cations [Fe(C=CR){=C=C(H)R}L(4)](+) and [Fe(C=CR){=C =C(Me)R}L(4)](+) respectively. The aryldiazovinylidene [Fe(C=CR){=C=C( N=NC(6)H(4)Me-p)Ph}(P(OEt)(3)}(4)] BPh(4) was also prepared. The compl exes were characterized by infrared and(1)H. P-31 and(13)C NMR spectra and the crystal structure of [Fe(C=CPh){=C=C(H)Ph}{P(OEt)(3)}(4)]BF4 has been determined. The reactivity of the new vinylidene complexes wa s studied and showed the rearrangement in solution of the [Fe(C=CR){=C =C(H)R}L(4)](+) cations to enynyl [Fe(eta(3)-RC(3)CHR)L(4)](+) derivat ives only in the case of L=PPh(OEt)(2). Deprotonation with base giving [Fe(C=CR)(2)L(4)] as well as substitution of the vinylidene ligand in [Fe(C=CR){=C=C(H)R)L(4)(+) cations by CO and CNC(6)H(4)Me-p giving [F e(C=CR)-(Co){POEt)(3)}(4)](+) and [Fe(C=CR)(p-MeC(6)H(4)NC){P(OEt)(3)} (4)](+) derivatives are also discussed.