Correlation of O-H stretching frequencies and O-H•••O hydrogen bond lengths in minerals

A correlation of O-H stretching frequencies (from infrared spectroscopy) with O ... O and H ... O bond lengths (from structural data) of minerals was established. References on 65 minerals yielded 125 data pairs for the d(O ... O)-v correlation; due to rare or inaccurate data on proton positions, only 47 data pairs were used for the d(H O)-v correlation. The data cover a wide range of wavenumbers from 1000 to 3738 cm(-1) and O ... O distances from 2.44 to 3.5 Angstrom. They originate from silicates, (oxy)hydroxides, carbonates, sulfates, phosphates, and arsenates with OH-, H2O, or even H3O2- units forming very strong to very weak H bonds. The correlation function was established in the form v(cm(-1))= 3592-304.10(9) exp(-d(O ... O)/0.1321), R-2 = 0.96. Because of deviations from ideal straight H bonds, i.e, bent or bifurcated geometry, dynamic proton behavior, but also due to factor group splitting and cationic effects, data scatter considerably around the regression line. The trends of previous correlation curves and of theoretical considerations were confirmed.