The variable temperature 1 H NMR spectra of Cp*ReH(CO)(p-N 2 C 6 H 4 OMe) (1) and Cp*Re-(CH 3 )(CO)(p-N 2 C 6 H 4 OMe) (3) and the variable temperature 31 P{ 1 H} NMR spectra of Cp*ReCl-(PR 3 )(p-N 2 C 6 H 4 OMe) [R ) Me (4), OMe (5), Ph (7)] are presented and discussed. The spectra of 1 and 3-5 show that at low temperature two isomers are present in each case and that these isomers interconvert on the NMR time scale. The isomers are interpreted to occur because the p-N 2 C 6 H 4 OMe ligand adopts two different orientations where the aryl group is oriented syn to either the X or Y ligand in these chiral complexes of general formula Cp*ReXY(p-N 2 C 6 H 4 OMe). The bulky PPh 3 ligand in 7 results in an overwhelming preference for orientation only syn to the Cl group and thus only one observable isomer. The activation parameters for the conformational isomerization of the aryldiazenido ligand in these neutral complexes have been obtained from NMR line shape analyses and are compared with data obtained previously for related cationic rhenium aryldiazenido complexes.