Photochemistry of [Ru-3(CO)(12)] with nitrogen heterocycles

The photochemistry of [M-3(CO)(12)] (M = Ru la or Os Ih) with nitrogen heterocycles has been studied. In all cases photolysis leads to photosubstitution products, the heterocycles inhibiting the photofragmentation pathway. With pyridine (py) la formed the orthometallated complex [Ru3H(CO)(10)(C5H4N)] 2a. With osmium, the simple substitution product [Os-3(CO)(11)(py)] 3b can be isolated. With 2-methylpyridine (mpy) [Ru3H(CO)(10)(2-MeC5H3N)] 5a and [Os-3(CO)(11)(mpy)] 6b were formed from la and Ib respectively. With 2,6-dimethylpyridine no net photoreaction was observed. Photolysis of la and Ib with 2,2'-bipyridine led to the formation of [M-3(CO)(10)(bipy)] (M = Ru 7a and Os 7b). The molecular structure of 7b has been obtained by single-crystal X-ray diffraction studies. Photolysis of la and Ib with pyridazine (pydz) led to the substituted products [M-5(CO)(10)(pydz)l (M = Ru 8a or Os 8b).