The co-ordination of small molecules by manganese(II) phosphine complexes. Part 14. Some novel mixed tertiary phosphine–t-butyl isocyanide complexes of manganese(II): [MnBr2(CNBut)(PPhMe2)] and [Mn(CNBut)4(PR3)2]2+(PR3= PPhMe2, PPh2Me, PPhEt2, or PPrn3), and the X-ray crystal structure of bis(dimethylphenylphosphine)tetrakis(t-butyl isocyanide)manganese(II) bis[tribromo(dimethylphenylphosphine oxide)manganate(II)], [Mn(CNBut)4(PPhMe2)2][MnBr3(OPPhMe2)]2

Abstract

The complex [MnBr₂(CNBu^t)(PPhMe₂)] has been prepared by reaction of [MnBr₂(PPhMe₂)] with CNBu^t. In ethanol solution rearrangement occurs to give the complex [Mn(CNBu^t)₄(PPhMe₂)₂][MnBr₄] and this reacts with other phosphines to yield [Mn(CNBu^t)₄(PR₃)₂]²⁺(PR₃= PPrⁿ₃, PPhEt₂, or PPh₂Me). Air oxidation of an ethanol solution of [Mn(CNBu^t)₄(PPhMe₂)₂]²⁺ produces red crystals of [Mn(CNBu^t)₄(PPhMe₂)₂][MnBr₃(OPPhMe₂)]₂ the structure of which is reported. In the cation Mn^II is octahedrally co-ordinated and lies on a crystallographic inversion centre. The latter also relates each pair of anions which have Mn^II in tetrahedral co-ordination. The Mn–P bonds of the cation are rather short at 2.344(3)Å whereas all other cation and anion dimensions are unremarkable.