Hydroxylation of a methyl group: synthesis of [Cu2(btmmO)2I]+ and of [Cu2(btmmO)2]2+ containing the novel ligand {bis(trimethylmethoxy)guanidino}propane (btmmO) by copper-assisted oxygen activation

The reaction of the bisguanidine copper(I) compounds [Cu(btmgp)I] and [Cu2(btmgp)2][PF6]2 with molecular oxygen afforded at low temperatures complexes containing the bis-μ-oxo dicopper(III) core, which is capable to hydroxylate one of the N–CH3-groups of the {bis(tetramethyl)guanidino}propane ligands. The formation of the novel ligand {bis(trimethylmethoxy)guanidino}propane (btmmO) is reported as it represents the first hydroxylation of a N-methyl group. The products of this reaction are novel alkoxo-bridged binuclear copper complexes, namely [Cu2(btmmO)2I]+ containing an iodide ion in a novel bridging situation, as well as [Cu2(btmmO)2]2+ which have been identified in their complex salts View the MathML source[Cu2(btmmO)2I]I·12C2H5OH and [Cu2(btmmO)2][PF6]2 · 2MeCN, respectively. Concomitantly, the hydroxo-bridged binuclear copper compounds [Cu2(btmgp)2(μ-OH)2]I2 and [Cu2(btmgp)2(μ-OH)2][PF6]2 are formed as couple products. The formation of the bis-μ-oxodicopper(III) complexes was monitored by UV/Vis-spectroscopy, and the reaction products were characterised by X-ray diffraction, vibrational spectroscopy and elemental analysis.