Synthesis and structures of ruthenium(II) mono [1,2-phenylenebis(dimethylarsine)] complexes: precursors to trans metal-to-ligand charge-transfer chromophoric assemblies

The complex fac-[RuCl3(pdma)(NO)] [pdma = 1,2-phenylenebis(dimethylarsine)] reacts with silver(I) salts, AgX, at room temperature in acetonitrile to afford disubstituted derivatives cis[RuClX2(pdma)(NO)] (X− = trifluoroacetate 1, p-toluenesulphonate 2 or nitrate 3). Reflux of fac[RuCl3(pdma)(NO)] in 1 : 4 pyridine/methanol containing an excess of AgO2CCF3 causes conversion into cis[Ru(OMe)(pdma)(py)2(NO)][PF6]24 (py = pyridine). Reaction of fac-[RUCl3(pdma)(NO)] in refluxing 1 : 7 pyridine/acetonitrile containing 2 equivalents of AgO2CCF3 affords cis-[RuCl(pdma)(py)2(NO)][PF6]2 (5). 5 is also prepared by reaction of 1 in refluxing pyridine/acetonitrile. The mixed-chelate salts trans[RuCl(pdma)(L-L)(NO)][PF6]n [n = 2, L-L = 2,2′-bipyridine 6, 1,10-phenanthroline 7, 4,4′-dimethyl-2,2′-bipyridine 8 or 1,2-bis(diphenylphosphino)ethane 9; n = 1, L-L = picolinate 10] are produced by reaction of fac-[RuCl3(pdma)(NO)] with an excess of L-L in refluxing methanol. The yields of the reactions to produce 5–10 vary according to the ligating ability of the incoming ligand(s). Single-crystal structures of fac[RuCl3(pdma)(NO)], 2·Me2CO, 3 and 6 have been determined. 3 is the first ruthenium complex containing monodentate nitrato ligand(s) to be structurally characterized.