The Crystal and Molecular Structures of trans-Bis(trimethylphosphine)-[1,2-bis(methoxycarbonyl)vinyl](phenylethynyl)palladium(II)

The X-ray molecular structure of the addition product of trans-HPd(PEt3)2(C≡CPh) with dimethyl acetylene-dicarboxylate has been determined to be [trans-{(MeO2C)HC=C(CO2Me)}Pd(PEt3)2(C≡CPh)]. The crystal belongs to the monoclinic system, space group P21/c, with eight formula units in a cell with dimensions of a=17.844(3), b=9.476(3), c=36.061(4) A, β=98.18(1)°. Two independent molecules have similar structures except for the conformation of the phenylethynyl groups and one of the triethylphosphine groups. The 1,2-bis(methoxycarbonyl)vinyl and phenylethynyl groups are σ-bonded to the palladium atom. No significant difference is observed between the Pd–C(sp)[2.04(2) and 2.03(2) A] and Pd–C(sp2)[2.05(2) and 2.06(2) A] bond lengths. The environment of the palladium atom is approximately square-planar: Pd–P=2.321(5), 2.312(5), and 2.305(5), 2.311(5) A.