Crystal structure of the 2-hydroxy-3,3,4-trimethyl-2-oxo-5-cyanimino-1, 4,2-diazaphospholidine diethylammonium salt

Crystal structure of the 2-hydroxy-3,3,4-trimethyl-2-oxo-5-cyanimino-1,4,2-diazaphospholidine diethylammonium salt (I) was studied by X-ray diffraction analysis: space group P2₁/c, a=9.773(1), b=12.7617(8), c=12.064(2) Å, β=95.02(1)°, Z=4; R=0.041 (CAD-4 automatic diffractometer, λCuK_α, 2518 independent reflections with I≥3δ). In anion I, the P atom (forming two Pō sesquibonds) has a considerably distorted tetrahedral coordination. In the extended flattened molecular fragment of anion I involving 7 atoms [P?N?C(?N)=N?C≡N], the π-electron densities of the atoms are conjugated. The five-membered heterocycle of anion I has a distorted P,C₃-half-chair conformation. The crystal structure of compound I has interionic hydrogen bonds linking anions I into centrosymmetric H-dimers and also linking anions I and Et₂NH ₂ ⁺ into centrosymmetric H-tetramers.