Structure and Spectroscopy of Furan:H2O Complexes

An analysis of the 1:1 complex of furan and water is presented. In this study, computation and matrix isolation FTIR were used to determine stable complexes of furan:water. Density functional theory and Moller-Plesset second-order, perturbation theory calculations found four, unique geometries for the complex. Two complexes were characterized by C-H center dot center dot center dot O interactions, one complex was characterized by O-H center dot center dot center dot O, and the fourth complex was characterized by O-H center dot center dot center dot pi. Optimizations completed using B3LYP, B3LYP-GD3BJ, M05-2X, and MP2 showed the most stable species to be bound by O-H center dot center dot center dot O interactions. Matrix isolation experiments of mixtures of furan and water held in nitrogen at 15 K showed evidence of stable complexes when probed by FTIR. These signatures grew in intensity when matrices were annealed at 30 K. These vibrational predominately associated with perturbation of the water monomer. Additionally, the spectra of complexes containing water isotopologues were recorded. Analysis of spectral features pointed to the presence of a single geometry formed in the matrix, which is best described as a 1:1 complex stabilized by a O-H center dot center dot center dot O interaction.