Some transition metal complexes of the diacetylenic diphosphine Ph2PC2C2PPh2: synthesis and crystal structures

Abstract

Several complexes of the acetylenic ditertiary phosphine, Ph₂PC₂C₂PPh₂, containing Mo, W, Fe, Ru or Au have been prepared; one CC triple bond in the Mo, W or Fe derivatives has been co-ordinated to Co₂(CO)₆ or Pt(PPh₃)₂ groups. Crystal structure determinations of [{Fe(CO)₄}₂(µ-PPh₂C₂C₂PPh₂)]3 and [Co₂{µ-η²-[(OC)₅W(PPh₂)]CC [C₂(PPh₂)W(CO)₅]}(CO)₆]7 show that the P-bonded M(CO)_n groups take up transoid positions; in 3, the PCCCCP chain, which is situated about a centre of inversion, is nearly linear [P–C–C, 173.2(5); C–C–C 179.7(6) for molecule a and 174.7(5) and 177.6(6)°, respectively, for molecule b] with CC distances of 1.192(7)Å[1.201(6)Å, molecule b]. In 7, co-ordination of the Co₂(CO)₆ group to one CC bond lengthens that bond by 0.13 Å, compared with the unco-ordinated CC bond, and induces bend-back of the substituents of 141–143(1)°(PPh₂) and 145–146(1)°(C₂PPh₂). Crystals of 3 are triclinic, space group P, a= 11.261(1), b= 12.456(2), c= 13.061(2)Å, α= 79.23(2), β= 75.73(1), γ= 78.75(2)°, Z= 2; 2870 data were refined to R= 0.042, R′= 0.046. Crystals of 7 are triclinic, space group P, a= 17.940(4), b= 19.695(4), c= 16.449(2)Å, α= 111.92(1), β= 108.83(1), γ= 100.29(2)°, Z= 4; 5942 data were refined to R= 0.055, R′= 0.056.