Chemistry of Coordinatively Unsaturated Bis(thiolato)ruthenium(II) Complexes (η6-arene)Ru(SAr)2 [SAr = 2,6-Dimethylbenzenethiolate, 2,4,6-Triisopropylbenzenethiolate; (SAr)2 = 1,2-Benzenedithiolate; Arene = Benzene, p-Cymene, Hexamethylbenzene]