Synthesis and characterization of ruthenium quinolin-8-olate complexes. Unexpected formation of a κ1-hydrotris(pyrazolyl)borate complex

The complex [Ru(η6-p-MeC6H4Pri)Cl2]2 reacted with K[quin] (quin = quinolin-8-olate) to yield the half-sandwich complex Ru(η6-p-MeC6H4Pri)(quin)Cl 1. Chloride abstraction from 1 with AgCF3SO3 affords the neutral complex Ru(η6-p-MeC6H4Pri)(quin)(κ1O-CF3SO3). The lability of the CF3SO3− ligand in 2 is apparent by the reaction with CH3CN giving [Ru(η6-p-MeC6H4Pri)(quin)(CH3CN)]CF3SO33. Refluxing RuTp(COD)Cl in the presence of K[quin] resulted in the formation of Ru(COD)(quin)24 containing no Tp ligand; 4 has also been obtained in good yield by treating [Ru(COD)Cl2]n with K[quin] in boiling methanol. Treatment of either 1 or 3 with 1 equivalent of KTp resulted in the formation of the unusual complex Ru(η6-p-MeC6H4Pri)(quin)(κ1N-Tp) (5) featuring a κ1-co-ordinated Tp ligand. However, if 1 is treated with KTp in the presence of AgCF3SO3 the cationic complex [Ru(η6-p-MeC6H4Pri)(quin)(κ1-Hpz)]CF3SO36 is obtained containing a pyrazole ligand as a result of B–N bond cleavage. Complexes 1, 4, 5, and 6 have been characterized by X-ray crystallography.