Syntheses and 1H-, 13C- and 15N-NMR spectra of ethynyl isocyanide, H-C triple bond C-N triple bond C, D-C triple bond C-N triple bond C and prop-1-ynyl isocyanide, H3C-C triple bond C-N triple bond C, D3C-C triple bond C-N triple bond C: high resolution infrared specturm of prop-1-ynyl isocyanide

Ethynyl isocyanide, H-C triple bond C-N triple bond C (1a), deuteroethynyl isocyanide, D-C triple bond C-N triple bond C (1b), prop-1-ynyl isocyanide, H3C-C triple bond C-N triple bond C (1c), and trideuteroprop-1-ynyl isocyanide, D3C-C triple bond C-N triple bond C (1d) are synthesized by flash vacuum pyrolysis of suitable organometallic precursor molecules (CO)5Cr(CN-CCl triple bond CClH) (5a), (CO)5Cr(CN-CCI=CClD) (5b), (CO)5Cr(CN-CCl=CCl-CH3) (5c) and (CO)5Cr(CN-CCI=CCl-CD3) (5d), respectively. Compounds 5a-d are formed in two steps by radical alkylation of tetraethyl-ammonium pentacarbonyl(cyano)chromate, NEt4Cr(CO)5(CN)] (2) by 1,1,2,2,-tetrachloroethane (3a), 1,1,2,2-tetrachloro-1,2-dideuteroethane (3b), 1,1,2,2,-tetrachloropropane (3c), and 1,1,2,2-tetrachloro- 1,3,3,3-tetradeutero-propane (3d) yielding (CO)5Cr(CN-CCl2-CCl2-H)] (4a), (CO)5Cr(CN-CCl2-CCl2D)] (4b), (CO)5Cr(CN-CCl2-CCl2-CH3)] (4c), and (CO)5Cr(CN-CCl2-CCl2-CD3)] (4d). Dehalogenation of 4a-d using zinc in diethylether/acetic acid gives 5a-d, respectively. A multinuclear NMR study revealed the 1H-, 13C- and 15N-NMR data of 1a and 1c. Molecular spectroscopic data of 1c were determined by high resolution infrared spectroscopy. The by-products of the pyrolysis are the E and Z isomers of the halogenated ethenyl isocyanides H(Cl)C=CCl-NC (6a) and H3C(Cl)C=CCl-NC (6c) which have been characterized by IR, MS and NMR spectroscopy.