Synthesis of cis- and trans-[M(CN)2(1-CH3-C6H10-NC)4] (M = Fe, Ru) and crystal structure of trans-[Ru(CN)2(1′-CH3-C6H10-NC)4]

The reaction of the metal carbonyls Fe2(CO)9 or Ru3(CO)12 with 1-isocyano-1-methyl-cyclohexane produces the octahedral metal(II) cyano complexes [M(CN)2(1-CH3-C6H10-NC)4] in good yields. The cis-isomer is not isolated as a pure compound due to rearrangement processes that yield the sterically less crowded trans-isomer. The molecular structure of the trans-isomer of the ruthenium complex shows the expected almost ideal octahedral coordination of the central ruthenium ion with two cyanide and four isocyanide ligands. This reaction again indicates that isocyanides exhibiting quarternary carbon atoms in α-position with respect to the isocyano substituent in general react with di- or trinuclear metal carbonyls to yield cyano complexes with oxidized metal centres and concomitant reductive cleavage of the respective isocyanide.