QUADRUPOLE-DIPOLE EFFECTS IN SOLID-STATE P-31, CP-MAS NMR-SPECTRA OF TERTIARY PHOSPHINE SUBSTITUTED ALKYLTETRACARBONYLMANGANESE(I) AND ACYLTETRACARBONYLMANGANESE(I) COMPLEXES

A series of tertiary phosphine substituted alkyl- and acyltetracarbony lmanganese(I) complexes has been studied by cross-polarization and mag ic-angle-spinning (CP-MAS), P-31 solid-state NMR spectroscopy. All the spectra show an asymmetric sextet due to one-bond P-31-Mn-55 spin-spi n coupling and second-order quadrupolar effects, transmitted by dipola r coupling between the Mn-55 and P-31 nuclei, which are not suppressed by magic-angle spinning. The chemical shift tensors, spin-spin coupli ng constants, dipolar coupling constants, quadrupolar coupling constan ts, and anisotropies in the spin-spin coupling have been determined. T he shielding anisotropies of the alkyl complexes are larger than are t hose for the acyl complexes. The solid-state (1)J(Mn-P) spin-spin coup ling constants range from 196 to 204 Hz for the alkyl compounds and fr om 216 to 233 Kz for the acyl complexes. The (1)J(Mn-P) values obtaine d from the solution Mn-55 NMR spectra for the alkyl complexes are simi lar to 50 Hz larger than are those obtained from the P-31 solid-state NMR studies. The nuclear quadrupole coupling constants range from 23 t o 25 MHz.