The reactions of [Ru₃(CO)₁₂] with nitrogen-containing heterocycles. Crystal structures of [Ru₃(µ-H)(µ₃-ppy)(CO)₉] and [Ru₃(µ-napy)(µ-CO)₃(CO)₇]

Abstract

The reactions of [Ru3(CO)12] with several nitrogen-containing heterocycles under thermal conditions have been studied. 1H-Pyrrolo[2,3,-b]pyridine (Hppy) and benzimidazole (Hbzim) give the trinuclear clusters [Ru3(µ-H)(µ3-ppy)(CO)9](1a) and [Ru3(µ-H)(µ-bzim)(CO)10](2a), respectively. However, benzotriazole (Hbztz) affords the dinuclear complex [Ru2(µ-bztz)2(CO)6](3a). 1,8-Naphthyridine(napy) produces the carbonyl-bridged cluster [Ru3(µ-napy)(µ-CO)3(CO)7](4). Complex (4) reacts with HBF4 to give the cationic complex [Ru3(µ-H)(µ-napy)(CO)10][BF4](5) which has all terminal carbonyls. Complex (5) regenerates complex (4) on reaction with NEt3, 1,10-Phenanthroline(phen),2,2′-biquinoline(biquin) or 2,2′-bipyrimidine (bipym) react with [Ru3(CO)12] to give [Ru3(L–L)(µ-CO)2(CO)8][L–L = phen (6a), biquin (6b), or bipym (6c)], in which the L–L ligand chelates one ruthenium, and two carbonyl groups bridge the same edge of the tringle. The structures of compounds (1a) and (4) have been established by X-ray diffraction studies. Complex (1a) crystallizes in the monoclinic space group P21/a with a= 14.688(5), b= 16.251(7), c= 8.594(5)Å, β= 97.64(2)°, and Z= 4. Crystals of (4) are monoclinic, space group P21/c with a= 15.374(7), b= 17.336(6), c= 16.167(7)Å, β= 98.02(3)°, and Z= 8. Both structures were solved from diffractometer data by direct and Fouier methods and refined by full-matrix [(1a)] and block-matrix [(4)] least-squares to R= 0.0349 for 3 211 observed reflections for (1a) and to R= 0.0405 for 4 205 observed reflections for (4). In (1a) the pyrrolopyridinate ligand is co-ordinated to three Ru atoms, through the pyridinic N atom to one metal and through the pyrrolic N atom symmetrically bridging the other two, which are involved also in a hydridic bridge. In (4) there are two independent, but very similar, complexes in which three carbonyls bridge the three edges of a triangular metal array; the 1,8-naphthyridine ligand bridges two metal atoms through the two N atoms.