Preparation, characterization, and reactivities of thienyl nickel complexes bearing indenyl ligands

The complexes (1-R, 2-R′-indenyl)NiPPh3(thienyl) (R′=H, R=Me (1); Et (2); i-Pr (3); CH2Ph (4); R′=Ph, R=Me (5)) have been prepared and characterized by spectroscopic techniques and, in the case of 1, 2 and 5, by X-ray crystallographic studies. When combined with MAO, these compounds catalyze the polymerization of phenylacetylene to cis-transoidal poly(phenylacetylene) with Mw in the range of 5–7.5×104 Da. NMR studies have revealed that MAO methylates these complexes without ionizing the Nithienyl bond; this implies that the polymerization reactions likely follow a non-cationic mechanism similar to that catalyzed by the corresponding NiCCPh complexes studied previously. Complexes 1–5 reacted with CF3SO3H to produce the corresponding NiOSO2CF3 compounds by protonation at the α-C of the thienyl moiety. The compound (1-Bzindenyl)Ni(PPh3)(OSO2CF3) (9) has been isolated and fully characterized.