Synthesis of phenyldiazenido, phenylhydrazido and diorganohydrazido complexes of molybdenum and tungsten and their reactions with acids: A comparison with analogous unsubstituted hydrazido (NNH 2) complexes. The crystal structure of [WCl 2(NN(H)Ph)(PMe 2Ph) 3

Abstract

The phenyldiazenido complexes [MCl(NNPh)(PMe 2Ph) 4] (M = Mo,W) and phenyl- and diorganohydrazido(2-) complexes [WCl 2(NN(H)Ph)(PMe 2Ph) 3], [MCl 2 (NNRR′)(PMe 2Ph) 3]] (M = Mo, W ; R = R′ = Me, R = R′ = Ph ; M = W, R = Me, R′ = Ph), [MCl 2(NNPh 2)(dppe)(PMe 2Ph)] (M = Mo,W; dppe = Ph 2PCH 2CH 2PPh 2), [MCl(NNPh 2)(dppe) 2]Cl (M = Mo,W), and [WCl(NN(Me)Ph)(dppe) 2]Cl were synthesized, characterized and their reactions with acids studied. These complexes were prepared in a series of reactions starting with WCl 6 or (MoCl 5) 2 involving (i) introduction of the organohydrazido(2 -) group (NNRR′) using the corresponding hydrazine (R = R′ = Me) or hydrazine hydrochloride (R = R′ = Ph; R = Ph,R′ = H or Me), and (ii) incorporation of phosphine ligands under reducing conditions. The particular product formed in the last step depended upon the reduction time. In almost all cases reaction of the complexes with acid (1 M HCl in Et 2O or H 2SO 4 in MeOH) resulted in the formation of some amine and a correspondingly smaller amount of ammonia. For example, the yields of aniline and ammonia when [MCl(NNPh)(PMe 2Ph) 4]Cl reacted with H 2SO 4 in MeOH were ca 0.2 mol and ca 0.1 mol per mol of W, and 0.70 mol and 0.65 mol per mol of Mo, respectively. A comparison of acid reactions of organodiazenido and organohydrazido(2- ) is made with those of unsubstituted hydrazido(2 -) complexes prepared from coordinated dinitrogen. The crystal structure of reddish-brown [WCl 2(NN(H)Ph)(PMe 2Ph) 3] revealed a distorted octahedral complex in which the hydrazido(2 -) moiety is trans to a chlorine atom and the hydrazido(2 -) phenyl group is coplanar with the plane containing W, N, N and C(Ph) atoms. The second chlorine atom, cis to the hydrazido(2 -) ligand, has a close intermolecular contact (2.62 Å) with the hydrazido(2 -) hydrogen atom of a neighbouring molecule and close intramolecular contact (2.76 Å) with the endo o-phenyl hydrogen atom of the hydrazido(2 -) ligand. Comparison of structural data with those for [WCl 2(NNR 2)(PMe 2Ph) 3] (R 2 = Me 2 or Ph 2) indicates significant differences in W-N(1) and W-Cl( trans) distances between the dimethyl-, and the phenyl- and diphenyl-hydrazido(2 -) complexes, respectively.