REACTION OF THE OCTACHLORODIRHENATE(III) ION WITH METHYL ISOCYANIDE GIVING THE PENTACHLORO(METHYLISOCYANO)RHENIUM(IV) ION

Methyl isocyanide reacts rapidly with (NBun4)2Re2Cl8 in ethanol at 25 °C give a green product, shown by X-ray crystallographic study to be (NBun4) [ReCl5(CNCH3)]. The [ReCl5(CNCH3)]- ion is essentially octahedral, with all cis Re-Cl distances in the range 2.316(7) Å to 2.336(7) Å and the trans ReCl distance equal to 2.343(6), thus indicating little or no structural trans effect by the isocyanide ligand. The failure to find any simple substitution product, such as Re2Cl6(CNCH3)2, is consistent with other observations where strongly π-acid ligands cause degradation of MM multiple bonds, although we cannot entirely rule out the formation of a small amount of such a product, nor is the identity of the oxidizing agent that converts ReIII to ReIV known. The compounds crystallizes in space group P21/c with a = 11.255(3) Å, b = 14.651(6) Å, c = 16.274(6) Å, β = 93.82(6)°, V = 2677(3) Å3, and Z = 4. The structure was refined to R1 = 0.065 and R2 = 0.076 using 1558 reflections with I > 3σ(I) and corrected for absorption. © 1979.