The P-31 and H-1 nuclear magnetic resonance (NMR) longitudinal relaxation behavior of the hypophosphite ion (H2PO2)(theta) is investigated in D2O solution at various temperatures and two magnetic field strengths. Among a number of different well known methods of preparing the magnetization, a new simple procedure is described. This technique allows the excitation of exclusive longitudinal two- or three-spin order by taking advantage of amplitude modulated pulses. By using the semiclassical Redfield approach and transformation into a normal mode basis, the experimental data are interpreted in terms of an axially symmetric phosphorus chemical shift anisotropy (CSA) tenser and anisotropic rotational diffusion.