A solid-state study of a novel ³¹P spin pair using magic-angle-spinning nuclear magnetic resonance spectroscopy

The present investigation concerns the solid-state nuclear magnetic resonance spectroscopy of the ³¹P spin pair in the novel three-membered heterocyclic compound 3-(dichloromethylene)-trans-1,2-bis(2,4,6-tri-tert-butylphenyl)- 1,2-diphosphirane using the magic-angle-spinning (MAS) technique. The homogeneous ³¹P lineshapes are analyzed to extract the principal components of the shielding tensors using the Maricq and Waugh description of homonuclear spin-pair systems by average-Hamiltonian theory, modified to encompass the n = 0 rotational resonance situation. The experimental values of the shielding-tensor components are compared with those obtained from ab initio calculations performed on the model molecule P₂C₂H₄ to aid further the interpretation of the ³¹P MAS NMR spectrum of the chloromethylene-diphosphirane. The magnitudes and orientations of calculated shielding-tensor components of the model compound methylene-diphosphirane P₂C₂H₄ are compared with those for the phosphorus spin pair in the molecular environments of P₂, P₂H₂, and P₂H₄. The electronic structures and bonding in all of those molecular species are discussed.