A closed-shell monomeric rhenium(1-) anion provided by m-terphenyl isocyanide ligation.

The mixed isocyanide/carbonyl complexes cis- and trans-[Re(CO)3Br(CNArDipp2)2] (ArDipp2 = 2,6-(2,6-(i-Pr)2C6H3)2C6H3)) can be synthesized from reactions of [Re(CO)5Br] and CNArDipp2 depending on the conditions applied. Reduction of the neutral Re(I) species gives the monoanionic complex [Re(CO)3(CNArDipp2)2]- or the neutral [Re(CO)3(CNArDipp2)2], which contain rhenium in the formal oxidation states “-1” and “0”, respectively.