31P-NMR. Measurements on Palladium-Phosphine Complexes. Nuclear overhauser effects and spin-lattice relaxation times

The ³¹P{¹H} nuclear Overhauser effects (NOE's) and ³¹P-spin-lattice relaxation times (T₁) for a series of trans-PdCl₂P₂], P ? PEt₃, PPr₃ⁿ, PBu₃ⁿ, PMe₂Ph, PMePh₂, P(p-Tol)₃, P(cyclohexyl)₃ complexes are reported. Both the NOE and T₁ values depend upon the choice of solvent. The dipole-dipole mechanism dominates the spin-lattice relaxation of the coordinated phosphorus atom with the T₁ values for the PEt₃, PPr₃ⁿ, and P (cyclohexyl)₃ complexes decreasing with increasing molecular weight of the phosphine.