Spectroscopic and theoretical studies of the H-bonded complex of quinuclidine with 2,6-dichloro-4-nitrophenol.

The molecular structure and spectroscopic properties of the 1:1 complex of quinuclidine (Q) with 2,6-dichloro-4-nitrophenol (DCNP) have been characterized by X-ray diffraction, B3LYP/6–311++G(d,p) calculations, UV–vis, FTIR and NMR spectroscopies. In the crystals the proton from DCNP is transferred to Q, and the ionic pair is linked by the N + H⋯O − hydrogen bond of 2.620(2) Å, while in the theoretically optimized structure a molecular complex is present. The band at 405 nm in the UV–vis spectra in ethanol provides the evidence of proton transfer. The calculated natural atomic charges (NBO) show the differences between neutral components Q and DCNP, and the corresponding cation Q + H or anion DCNP − . The potential energy distribution (PED) has been used to assign the vibrational spectra. [ABSTRACT FROM AUTHOR]