Syntheses and characterization of [Ru(η5-C5H5) (AsPh3)(L)X] and [Ru(η5-C5H5)(AsPh3)(L)(MeCN)]+mY− (L = PPh3 or AsPh3; X = F, Cl, Br, I, CN, H or SnCl3; Y = HgCl3, Zn2Cl6 or BPh4; m = 1 or 2)