Reaction of bromotricarbonylbis(dimethylphenylphosphine)manganese(I) with anhydrous hydrazine to yield isocyanato(dicarbonyl)hydrazinebis(dimethylphenylphosphine)manganese(I)

Abstract

Bromotricarbonylbis(dimethylphenylphosphine)manganese(I)(1), prepared by the photochemical reaction of bromopentacarbonylmanganese(I) with 2·2 molar equivalents of dimethylphenylphosphine, reacts with anhydrous hydrazine at room temperature in tetrahydrofuran to yield the air-sensitive isocyanato(dicarbonyl)hydrazinebis(dimethylphenylphosphine)manganese(I)(2). The hydrazine ligand is readily replaced by CO or PMe₂Ph yielding the new complexes [Mn(NCO)(CO)₃(PMe₂Ph)₂](3) and [Mn(NCO)(CO)₂(PMe₂Ph)₃](4) respectively. The isocyanate ligand in [Mn(NCO)(CO)₂(PMe₂Ph)₃](4) undergoes metathetical replacement with the bromo-ligand. [Mn(NCO)(CO)₂(NH₂·NH₂)(PMe₂Ph)₂] decomposes in chlorinated solvents to yield a bright green solution. [Mn(NCO)(CO)₂(NH₂·NH₂)(PMe₂Ph)₂] reacts with hydrogen chloride to yield a similar solution, from which [MnCl(CO)₃(PMe₂Ph)₂](6) was isolated. The stereochemistries of these new complexes are discussed in terms of their i.r. spectra. The mass spectrum of [Mn(NCO)(CO)₃(PMe₂Ph)₂] is presented. The ¹H n.m.r. spectra of these complexes cannot be used to determine stereochemistry as the ‘J’(P–P) coupling in trans-[MnBr(CO)₃-(PMe₂Ph)₂] is not strong enough to produce a well defined 1:2:1 triplet.