Synthesis and Characterization of Sulfur-Bridged Binuclear β-Diketonatoruthenium Complexes and a Monomeric Ruthenium Complex. Crystal and Molecular Structures of Racemic and Meso Isomers of [Ru(acac)₂(μ-topd-O,S,O‘)Ru(acac)₂] (acac = Acetylacetonato and topd = 3-Thioxo-2,4-pentanedione)