Solid-state structure, quantum calculations and spectroscopic characterization of the hydrogen-bonded complex [Os(bpy)(2)(CO)(EtO center dot center dot center dot H-DMAP)][PF6](2)

The new H-bonded complex [Os(bpY)(2)(CO)((EtOH)-H-...-DMAP)][PF6](2), where DMAP = 4-(dimethylamino)pyridine and bpy = 2,2'-bipyridine, has been synthesized and characterized by X-ray diffraction, IR, solution and solid-state NMR spectroscopy. The complex shows a strong hydrogen bond between the protonated DMAP moiety and the deprotonated ethanolic group directly bonded to the Os atom. High-speed (28 KHz) solid-state H-1 MAS NMR spectroscopy and quantum-mechanical calculations were used to assess the location of the hydrogen atom involved in the H-bond. Both confirmed a proton characteristic of an N-(HO)-O-...-Y hydrogen bond. A molecular orbital analysis was performed to elucidate the IR CO stretching frequency red shift of the H-bonded complex with respect to [Os(bpy)(2)(CO)O(H)Et]-[OTf](2). Absorption spectra indicate that the H-bond is present both in water and dichloromethane solutions. However, no direct evidence of the H-bond interaction in solution is observed from the H-1 NMR spectrum (CD2Cl2) between 298 and 193 K. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)