Crystal structure of NaCd(H2PO3)3·H2O and spectroscopic study of NaM(H2PO3)3·H2O, M = Mn, Co, Ni, Zn, Mg and Cd

Abstract NaCd(H 2 PO 3 ) 3 ·H 2 O was synthesized in solution and its structure was studied by single-crystal X-ray diffraction. It crystallizes in the orthorhombic system ( Pbca , Z  = 8) with the cell parameters: a  = 9.2895(14) A, b  = 15.124(2) A, c  = 15.0592(12) A. Final residual factors R / R w are 0.0297/0.0790. Both Na + and Cd 2+ are octahedrally coordinated, [NaO 6 ] and [CdO 6 ] share edges to form zigzag chains along [1 0 0]. The 3D framework is build upon these chains which are interconnected by H 2 PO 3 pseudo-pyramids and an intricate network of weak hydrogen bonds. NaCd(H 2 PO 3 ) 3 ·H 2 O belongs the series of isostructural phosphites NaM(H 2 PO 3 ) 3 ·H 2 O (M = Mn, Co, Ni, Zn and Mg). IR spectroscopic studies show the bands confirming the presence of the phosphite H 2 PO 3 2− anion in the whole series NaM(H 2 PO 3 ) 3 ·H 2 O, M = Mn, Co, Ni, Zn, Mg and Cd. The UV–Vis spectroscopy was used for characterizing the d–d transitions in the Mn, Co and Ni phosphites.