TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preparation (Disclosed): Preparation of (I) comprises reaction of the monocationic carbene precursors with ruthenium compounds of formula (Ru(LL)Cl3) in ethyleneglycol at 150 degrees C in the presence of triethylamine; and replacement of the chloro ligand in water assisted by added silver triflate or triflic acid to give ruthenium complex of formula (trans-(Ru(LL)(NC)(OH2))2+).LL = 2,6-bis(1-methylbenzimldazol-2-yl)pyridine, 2,6-bis((dimethylamino)methyl)pyridine or 2, 2':6',2"-terpyridine; andNC = 3-methyl-1-pyridylimidazol-2-ylidene, 3-methyl-1-pyridylbenzimidazol-2-ylidene or 3-methyl-1-pyrazylbenzimidazol-2-ylidene.Preferred Components: The supporting substrate comprises fluorine-doped tin oxide or tin(IV)-doped indium oxide. The device further comprises a proton acceptor base, which is dihydrogen phosphate, acetate or monohydrogen phosphate. Preferred Method: The method-1 further comprises exposing the electrolytic media which contains the catalyst to light radiation to generate hydrogen and/or oxygen gases. The method-2 further comprises exposing the reaction media which contains the catalyst to light radiation to generate methanol, hydrocarbons and/or oxygen. Preferred Definitions:    L1 = 2,2'-bipyridine, 2,2'-bipyrimidine, 2,2'-bipyrazine, acetylacetonate, 6-methyl-pyridine-2-carboxylate, 2,6-bis(1-methylbenzimidazol-2-yl)pyridine, 2,6-bis(1-methylbenzimidazol-2-yl)pyrazine, 2-(3-methyl-2,3-dihydro-imidazol-1-yl)-pyrazine or 4,4'-diphosphonomethyl-(2,2')bipyridine;    L2 = 2,6-bis(1-methylbenzimldazol-2-yl)pyridine, 2,6-bis((dimethylamino)methyl)pyridine or 2, 2':6',2"-terpyridine; and    L3 = water.    SPECIFIC COMPOUNDS - 16 Compounds (I) are specifically claimed e.g. 2':6',2"-terpyridine-2,2'-bipyridine-aqua-ruthenium(II) of formula (Ia), 2':6',2"-terpyridine-2,2'-bipyrimidine-aqua-ruthenium(II), 2':6',2"-terpyridine-2,2'-bipyrazine-aqua-ruthenium(II), 2,6-bis((dimethylamino)methyl)pyridine-2,2'-bipyridine-aqua-ruthenium(II) and 2':6',2"-terpyridine-2,2'-bipyridine-aqua-osmium(II).    EXAMPLE - (2,6-Bis(1-methylbenzimidazol-2-yl)pyridine)-ruthenium trichloride was allowed to react with 2,2'-bipyridine in 2:1 ethanol-water mixture in the presence of triethylamine to form (2,6-bis(1-methylbenzimidazol-2-yl)pyridine)-2,2'-bipyridine-chloro-ruthenium (II) complex. The chloride ligand was subsequently displaced by the more labile triflate anion in neat triflic acid. Upon addition of water, rapid aquation occurred and the resulting aqua complex ((2,6-bis(1-methylbenzimidazol-2-yl)pyridine)-2,2'-bipyridine-aqua ruthenium (II)) was isolated as the triflate salt by addition of excess lithium triflate.