Transition metal derivatives of arenediazonium ions XVI. The synthesis, structural characterisation and chemical behaviour of (η-cyclopentadienyl)bis(arenediazo)- (triphenylphosphine)molybdenum(0) cations: Versatile reagents for the synthesis of complexes containing the [Mo(N 2C 6H 4R 1)(N 2C 6H 4R 2)] 2+ fragment

Abstract

Procedures are described for the preparation of a series of cationic bis(arenediazo) complexes of general formula [(η-C 5H 4R)Mo(N 2C 6H 4R 1)(N 2C 6H 4R 2) (PPh 3)] + (VII). Although salts of VII are indefinitely stable in the solid state, they are highly labile in solution and either the phosphine ligand alone or both phosphine and cyclopentadienyl ligands can be displaced by a variety of donor species to yield new kinds of neutral, anionic or cationic bis(arenediazo) complexes. The complex [(η-C 5H 5)Mo(N 2C 6H 4CH 3- p)(N 2C 6H 4F- p)(PPh 3)]PF 6, [VIIf]PF 6 and its neutral precursor (η-C 5H 5)Mo(CO)(N 2C 6H 4CH 3- p)(PPh 3) (VIII)_have been characterised by X-ray crystallographic methods. Crystals of [VIIf]PF 6 are triclinic, space group P 1 with two molecules in a unit cell of dimensions a = 13.031(4), b = 14.413(4), c = 11.140(5) Å and α = 93.17(3), β = 104.73(3), and γ = 115.77(3)°. Crystals of VIII are monoclinic, space group P2 1/ c with four molecules in a unit cell of dimensions a = 11.549(2), b = 8.881(4), c = 26.197(11) Å and β = 91.27(2)°. Both structures were determined by the heavy-atom method and refined to final R values of 0.0421 (for 4090 observed reflections, [VIIf]PF 6) and 0.0323 (for 3081 observed reflections, VIII). The arenediazo ligands in both complexes are bonded to Mo in the “singly-bent” coordination mode with MoN 1.838(4), 1.840(4) Å and NN 1.211(6), 1.196 Å in [VIIf]PF 6 and MoN 1.820(3) and NN 1.244(4) Å in VIII.