On an unusual shortening of the C(sp3)–C(sp3) bonds in n-propylcobaloximes

The structures of two n-propyl cobaloximes, [(n-Pr)Co(Hdmg)2(L)]·H2O where L=H2O (6) and NH2Ph (7), and Hdmg=monoanion of dimethylglyoxime, are described. The large static disorder undergone by the n-propyl group is attributed to different conformations of n-Pr, differing in the torsional angle around the axial Co–L bond. This result contrasts with those reported for the anhydrous [(n-Pr)Co(Hdmg)2(H2O)] (1) derivative and its inclusion compound with α-cyclodextrin (2), where a significant lengthening of 0.16 Å in the Cα–Cβ bond of n-Pr in 2, with respect to an incredibly short bond in 1, was attributed to the interaction of the cobaloxime with α-cyclodextrin.