The synthesis, X-ray and solid state NMR studies of 2-N,N-diisopropylamino-1,3,2λ5- oxaselenaphospholane-2-selone

Abstract

³¹ P and ⁷⁷Se high resolution solid state NMR spectroscopy was employed to study structural properties of 2-N,N-diisopropylamino-1,3,2λ⁵- oxaselenaphospholane-2-selone 5 the compound made in the course of developing reagents for stereocontrolled synthesis of nucleoside–phosphorothioates. Both ³¹P CP/MAS and ⁷⁷Se CP/MAS experiments revealed that the asymmetric unit consists of two independent molecules with different geometry around phosphorus and selenium centres. The principal elements δ_ii of the ³¹P chemical shift tensor were calculated from spinning sideband intensities employing the WIN-MAS program. The established values of anisotropy and asymmetry parameters reflect the distortion of the phosphorus environment and correspond well with X-ray diffraction data. Crystals of 2-N,N-diisopropylamino-1,3,2λ⁵- oxaselenaphospholane-2-selone grown from diethyl ether are triclinic, space group P with a = 7.586(2), b = 13.003(1), c = 13.649(1) Å, α = 89.683(8)°, β = 75.42(1)°, γ = 8.74(1)°, V = 1285(6) ų, D_c = 1.722(2) g cm^-3 and Z = 4. Refinement using 5243 reflections for 235 variables gives R = 0.047.