Solid‐State Structure, Quantum Calculations and Spectroscopic Characterization of the Hydrogen‐Bonded Complex [Os(bpy) 2 (CO)(EtO···H‐DMAP)][PF 6 ] 2

The new H‐bonded complex [Os(bpy) 2 (CO)(EtO ··· H‐DMAP)][PF 6 ] 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 1 H 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−H ··· 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 1 H NMR spectrum (CD 2 Cl 2 ) between 298 and 193 K. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)