Aqueous transformation of a metal diformate to a metal dihydride carbonyl complex accompanied by H-2 evolution from the formato ligands

作者：Ogo S^*; Nishida H; Hayashi H; Murata Y; Fukuzumi S

来源：Organometallics, 2005, 24(20): 4816-4823.

DOI：10.1021/om0504147

The rhodium diformate complex [Rh-III(tacn)(HCOO)(2)](OTf) (2, tacn = 1,4,7-triazacyclononane, OTf- = CF3SO3-) reacts with HCOONa at pH 6-7 at 80 degrees C in water to form a rhodium dihydride CO complex, [Rh-III(tacn)(H)(2)(CO)](OTf) (5), with H-2 evolution from the formato ligands of 2. This is the first example of H-2 evolution from hydrogen atoms of formato ligands of a metal diformate complex. Complex 2 was synthesized from the reaction of a rhodium aqua complex, [Rh-III(tacn)(H2O)(3)](OTf)(3) (1), with HCOONa in water. Recrystallization of 2 with HCOONa in water gave crystals of a rhodium triformate complex, [Rh-III(tacn)(HCOO)(3)] (3), whose structure was unequivocally determined by X-ray analysis. The key intermediate in the transformation from 2 to 5 is a rhodium hydride formate complex, [Rh-III(tacn)H(HCOO)](OTf) (4), which was obtained by heating of an aqueous solution of the rhodium diformate complex 2 with 10 equiv of dimethyl sulfoxide (DMSO) at pH 6-7 in water. Complex 4 was well characterized by isotopic labeling measurements of H-1 NMR, electrospray ionization mass spectrometry (ESI-MS), and GC.

• 出版日期2005-9-26