Phosphinohydrazines and phosphinohydrazides M(–N(R)–N(R)–PPh 2) n of some transition and main group metals: synthesis and characterization : Rearrangement of Ph 2P–NR–NR– ligands into aminoiminophosphorane, RN [dbnd]PPh 2–NR–, and related chemistry

Abstract

The reactions of phosphinohydrazines ArNH–N(Ar)–PPh 2 {Ar = Ph ( 2a), p-Bu t –C 6H 4– ( 2b)} with metal silylamides M[N(SiMe 3) 2] n , {M = Fe(II), Fe(III), Co(II), Ni(I), Cu(I)} or the reactions of lithium salts ArN(Li)–N(Ar)–PPh 2 with metal halides (GeCl 2, ZnCl 2, FeBr 2, CoCl 2, NiBr 2, CrCl 3, MnCl 2) are strongly dependent on nature of a metal and its ligand environment.Early transition metals or non-transition metals form stable phosphinohydrazides M[N(Ar)N(Ar)PPh 2] n {M = Li, Zn, Ge(II), Mn(II), Cr(III), Fe(II)}.Starting ligand 2a and germylene Ge(NPhNPhPPh 2) 2 ( 7) were characterized by X-ray analysis.Germanium is coordinated additionally with a phosphorus atom of one of the diphenylphosphine groups.The distance Ge⋯P was found to be 2.563(1) Å.This coordination leads to an appreciable increase in a pyramidal geometry of nitrogen atoms relatively to a non-coordinated fragment.Late transition metals (Co, Ni, Cu) and metals with enhanced oxidation state (Fe 3+) cause transformation of a phosphinohydrazide ligand.For Co(II), Ni(II), Fe(III) this leads quantitatively to aminoiminophosphoranates M(NAr–PPh 2 NAr) n .Complex Co[N(C 6H 4Bu t )–PPh 2 N–C 6H 4Bu t ] 2 ( 11) was characterized by X-ray analysis.Nickel(I) silylamide, (Ph 3P) 2NiN(SiMe 3) 2, being reacted with 2a yields azobenzene complex, (Ph 3P) 2Ni(PhN NPh), while copper(I) silylamide originally forms (PhNH–NPh–PPh 2) 2CuN(SiMe 3) 2 ( 18).Heating of the latter in toluene solution yields insoluble copper(I) diphenylphosphide, azobenzene, 2a and hexamethyldisilazane.The reaction of hydrazobenzene with Ph 2PCl (1:1) in methylene chloride for three days gives aminoiminophosphorane dihydrochloride[PhNH–PPh 2 NPh] · 2HCl ( 3) in quantitative yield.