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

•Preparation and properties of six bimetallic, iridium(diene)–tin complexes.•Significant crystallographic details, particularly those involving Ir–Sn bond length.•Karplus type tin–vinylic proton coupling is exhibited.•The ROMP of norbornene occurs in the presence of Ir(COD)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.

Graphical abstractPreparation, properties, and crystallographic analyses of five bimetallic iridium(diene)–tin complexes. These compounds exhibit Karplus type tin–vinylic proton coupling. The ring-opening metathesis polymerization of norbornene occurs in the presence of Ir(COD)2SnCl3.Figure optionsDownload full-size imageDownload as PowerPoint slide