Novel Cofacial Bioctahedral Complexes of Ruthenium: Syntheses and Properties of the Mixed-Valence Species (LRu2.5(μ-X)3Ru2.5L)2+ (X: Cl, Br, I, OH). Crystal Structures of (LRu2.5(μ-OH)3Ru2.5L)(PF6)2·H2O and (LRuIV(μ-O)3RuIVL)(PF6)2·H2