35Cl Nqr spectroscopy of the [PO 2Cl 2] − and POCl 3 groups in Me(PO 2Cl 2) 2·2D (Me = Mg, Ca, Mn; D = POCl 3,CH 3COOC 2H 5,CH 3COCH 3)

Abstract

35Cl NQR spectra of dichlorophosphates Me(PO 2Cl 2) 2 · 2D (Me = Mg, Ca, Mn; D = CH 3COOC 2H 5, CH 3COCH 3, POCl 3) are studied in the temperature range 77 ⩽ T (K) ⩽ 305. It is shown that the three compounds with CH 3COOC 2H 5 as donor are isomorphic at 77 K, the crystal structure of Mn(PO 2Cl 2) 2· 2CH 3COOC 2H 5. The structure of Mg(PO 2Cl 2) 2 − · 2CH 3COCH 3 and of Mg(PO 2Cl 2) 2 · 2POCl 3 probably consists of infinite chains as found for Mn(PO 2Cl 2) 2· 2CH 3COOC 2H 5. Mg(PO 2Cl 2) 2· 2CH 3COOC 2H 5 shows phase transformations and a complicated dynamical behaviour leading to strong deviations from a Bayertype NQR function v = f( T). The donor capacity of POCl 3 in Mg(PO 2Cl 2) 2· 2POCl 3 is comparable with the donor strength in AsCl 3 · POCl 3 · A d π-p π overlap of the P-O bond influences the P-Cl bond.