A computational investigation of J couplings involving ²⁷Al, ¹⁷O, and ³¹P.

Indirect nuclear spin-spin (J) couplings between (31)P, (27)Al, and (17)O are computed for Cl(3)POAlCl(3), Ph(3)PO, Ph(3)PAlCl(3), Al(H(2)O)(6)(3+), an aluminophosphate model system, and grossite model systems, using the B3LYP hybrid functional and the pcJ-n and aug-pcJ-n basis sets. The results provide computational corroboration of the existence of J coupling constants between (31)P, (17)O, and (27)Al of suitable magnitude for INEPT-style experiments in which connectivity is established as a result of magnetization transfer using these couplings. Potentially useful correlations between structure (bond lengths, angles, dihedrals) and the coupling constants (1)J((27)Al, (17)O), (1)J((31)P, (17)O), and (2)J((31)P, (27)Al) are presented. Calculated values of near zero for both (1)J((27)Al, (17)O) and (2)J((31)P, (27)Al), depending on the molecule and the geometry, suggest that some structurally important correlations could be absent in NMR spectra which rely on magnetization transfers solely based on these isotropic coupling constants.