Reactions of transition metal σ-acetylide complexes X. Cycloaddition of tetracyanoethene to manganese, iron and nickel complexes, and hydration of a related tungsten complex. X-Ray structures of Fe{C[C(CN) 2]CPhC(CN) 2}(CO) 2(η- C 5H 5) and Ni{C[C(CN) 2]CPhC(CN) 2} (PPh 3)(η-C 5H 5)

Abstract

Tetracyanoethene adds to phenylethynyl-metal complexes of manganese, iron or nickel to give the butadienyl derivatives ML n {C[C(CN) 2]CPhC(CN) 2} (ML n = Mn(CO) 3(dppe), Fe(CO) 2(η-C 5H 5) or Ni(PPh 3)(η-C 5H 5)). In non-polar solvents, intermediate manganese and iron cyclobutenyl complexes L n M{CCPhC(CN) 2C(CN) 2} can be isolated, but rapidly isomerise to the butadienyl complexes. Structural assignments of the isomers can be made on the basis of IR ν(CN), ν(CC) absorptions and FAB MS fragmentation pathways. Crystals of Fe{C[(CN) 2]CPhC(CN) 2}(CO) 2(η-C 5H 5) are triclinic, space group P 1 with unit cell dimensions a 9.378(2), b 13.874(3), c 7.935(4) Å, α 92.92(3), β 101.57(2), γ 108.78(1)° and Z = 2. Crystals of Ni{C[C(CN) 2]CPhC(CN) 2}(PPh 3)(η-C 5H 5) are monoclinic, space group P2 1/c, with unit cell parameters a 13.765(6), b 10.89(2), c 20.753(8) Å, β 95.55(2)° and Z = 4. Both structures were refined by a full-matrix least-squares procedure to final R 0.038, R w 0.044 for 2825 reflections with I ≥ 2.5σ(I) (Fe) and R 0.048, R w 0.054 for 1702 reflections with I ≥ 2.5σ( I) (Ni).