Synthesis and crystal structure of [{Mn(η-C5H4Me)(CO)2}2{µ-(2–3-η:4–5-η)-MeCCCCMe}], a manganese-conjugated diacetylene complex

Abstract

The photochemical reaction of hexa-2,4-diyne and [Mn(η-C₅H₄Me)(CO)₃] gives as the single product the title compound (13), which has been unambiguously identified by X-ray crystallography. The compound crystallizes in the monoclinic space group P2₁/a with a= 10.073(4), b= 13.302(7), c= 8.012(3)Å, β= 105.52(4)°, and Z = 2. The structure has been solved by the heavy-atom method and refined by least squares to final agreement indices of R= 0.034 and R′= 0.042 for 944 reflections. Structural and i.r. data suggest that the alkyne ligand in (13) is a good σ donor but a poor π acceptor. This is the first crystallographic study of a [Mn(η-C₅H₄R)(CO)₂(alkyne)] species, even though many such compounds are known.