Diene–iridium–tin complexes. Comparison of conjugated versus non-conjugated dienes and trimethyltin versus trichlorotin as ligands. Ring opening metathesis polymerization of norbornene by Ir(1,5-cycloocta-diene)2SnCl3

A number of bis(diene)iridium(I)tin complexes have been synthesized to assess the influence of various dienes on the steric and electronic properties of Ir(diene)2Sn(CH3)3, where the diene is DMB = 2,3-dimethyl-1,3-butadiene (1), NBD = 2,5-norbornadiene (2), or COD = cycloocta-1,5-diene (3). Comparisons are also made to a similar series, Ir(diene)2SnCl3, where the diene is DMB = 2,3-dimethyl-1,3-butadiene (4), NBD = 2,5-norbornadiene (5), or COD = cycloocta-1,5-diene (6). The syntheses of 1–5 are reported herein; the syntheses of 5 and 6 have been previously reported. The crystal structures of 1–5 have been determined by single crystal X-ray diffraction. Compounds 1–6 have been characterized by mass spectroscopy and 1H NMR spectroscopy. The olefinic protons of compounds 1–6 exhibit vicinal proton coupling to the tin center. A clear film was isolated after the exposure of norbornene to compound 6 in toluene.