Low-frequency pulsed electron spin echo modulation spectroscopy has been successfully applied to the study of the dipolar interaction between a molybdenum(V) center and a phosphorus nucleus in the model six-coordinate oxomolybdenum(V) compounds, LMoO(cat-3-OPO(OPh)(2)) (I) and LMoO(cat-4-OPO(OPh)(2)) (II). L is the facially coordinating tridentate hydrotris(3,5-dimethyl-1-pyrazolyl)borate ligand; cat-3-OPO(OPh)(2) and cat-4-OPO(OPh)(2) are 1,2-catecholate ligands that contain pendant diphenylphosphate ester groups at the 3- and 4-position, respectively. The molybdenum-phosphorus interaction is detectable if the distance between molybdenum and phosphorus nuclei does not exceed 7-8 Angstrom. Experimental data obtained for I, the complex with the smaller molybdenum-to-phosphorus distance, cannot be explained by a single distance parameter, suggesting that the phosphate ester group of I adopts a distribution of rotational conformations in frozen toluene solution. The success of low-frequency pulsed electron spin echo modulation spectroscopy in detecting dipolar molybdenum-phosphorus interaction in II implies that this technique should be applicable to the study of the dipolar interaction between molybdenum(V) and phosphorus in the molybdenum cofactor (Mo-co) of enzymes.