Some Mixed Transition Metal Compounds of 1,3-Diyne with Metallacycles Derived by Cross-Coupling of Alkynyl Ligands and Sequential C−C Bond Coupling between 1,3-Diyne and Carbon Monoxide

By treating cis-Pt(C⋮CPh)2(dppe) (1) with Mn2(CO)9(CH3CN) in refluxing toluene, cross-coupling of alkynyl ligands occurs to afford mixed transition metal compound of 3,4-diphenyl-1,3-butadiyne, [Mn2Pt(μ3-η1:η1:η2:η4-PhCCCCPh)(CO)6(dppe)] (2) in 19−38% isolated yield.
2 has a structure formed by an unprecedented heterometal complexation of 1-manganacyclo-2,3,4-pentatriene. The Pt(II) acetylide, by treating with Ru3(CO)9(PPh3)3, directly converts
into a π-complex of 1,3-diyne, Pt(η2-PhCCCCPh)(dppe) (4), in 38% yield. By reacting π-alkyne
compound Pt(η2-PhCC−C⋮CPh)(PPh3)2 with Fe(CO)5 and Ru3(CO)12, bimetallic [FePt(μ3-η1:η1:η2-COC4Ph2)(CO)3(PPh3)2] (5a) and triangular cluster [MPt2(μ3-η1:η1:η2-PhCC−C⋮CPh)(CO)5(PPh3)2] (6a) have successionally been isolated in considerable yields. A dimetallic
analogue of alkyne [FePt{μ2-η1:η1:η2-C(O)C2H2}(CO)3(PPh3)2] (5b) and trimetallic [MPt2(μ3-η1:η1:η2-R1CCR2)(CO)7-n(PPh3)n] (6b−f) {R1 = Ph, R2 = C⋮CPh, n = 3, M = Fe, 6b; R1 = R2
= H, n = 3, M = Fe, 6c; R1 = R2 = Ph, n = 2, M = Fe, 6d and iso-6d; R1 = R2 = OCOCH3,
n = 2, M = Fe, 6e; M = Ru, 6f} have consecutively been prepared. Crystal structures of five
of the compounds have been determined.