Isostructural Crystals of Bis(Guanidinium) Trioxofluoro-Phosphate/Phosphite in the Ratio 1/0, 0.716/0.284, 0.501/0.499, 0.268/0.732, 0/1—Crystal Structures, Vibrational Spectra and Second Harmonic Generation

Abstract

The title structures of bis(guanidinium) trioxofluorophosphate, bis(guanidinium) trioxofluorophosphate-phosphite (0.716/0.284), bis(guanidinium) trioxofluorophosphate-phosphite (0.501/0.499), bis(guanidinium) trioxofluorophosphate-phosphite (0.268/0.732), and bis(guanidinium) phosphite are crystal-chemically isotypic. Their structures correspond to the structure of bis(guanidinium) trioxofluorophosphate which was determined by Prescott, Troyanov, Feist & Kemnitz (Z. Anorg. Allg. Chem. 2002, 628, 1749–1755). The P and O atoms of the substituted trioxofluorophosphate and phosphite anions share the same positions while the P-F and P-Hhydrido are almost parallel and oriented in the same direction. Two symmetry-independent anions and two of three symmetry-independent cations are situated on the crystallographic mirror planes. The ions are interconnected by N-H⋯O hydrogen bonds of moderate strength. The most frequent graph set motif is R22(8), which involves interactions between the primary amine groups and the trioxofluorophosphate or phosphite O atoms. Fluorine, as well as the hydrido hydrogen, avoids inclusion into the hydrogen-bond network. The Hirshfeld surface analysis was also performed for the comparison of intermolecular interactions in the title structures of bis(guanidinium trioxofluorophosphate and bis(guanidinium) phosphite. The title crystals were also characterized by vibrational spectroscopy methods (FTIR and Raman) and the second harmonic generation (SHG). The relative SHG efficiency considerably decreases from bis(guanidinium) trioxofluorophosphate to bis(guanidinium) phosphite for the fundamental 1064 nm laser line.

Keywords

• crystal structure
• vibrational spectroscopy
• second harmonic generation
• hydrogen bonding
• mixed crystals
• trioxofluorophosphate