Synthesis and Crystal Structures of A New Series of Intramolecular Bridged Alkylcobaloxime Complexes

A new series of intramolecular bridged alkylcobaloxime complexes were prepared by heating a solution of aqua-(3-bromopropyl)cobaloxime (1) through an intramolecular nucleophilic substitution. They are characterized by EA, ESI-MS, and 1H NMR. Crystal structures of Br(O−C3H6−(dmgH))(dmgH)CoIII (2), [H2O(O−C3H6−(dmg))(dmgH2)CoIII]ClO4 (3), [Py(O−C3H6−(dmg))(dmgH2)CoIII]ClO4 (4), [Bzm(O−C3H6−(dmg))(dmgH2)CoIII]ClO4 (5), and Im(O−C3H6−(dmg))(dmgH)CoIII (6‘) were determined by X-ray diffraction. It is revealed that an intramolecular tri-methylene bridge exists between cobalt and one of the equatorial oxime oxygens forming a six-membered ring in the complexes. Additionally, the axial bases have some influences in their structure parameters, for example, Co−L bond lengths; folding angles in equatorial ligands; hydrogen atom positions in O−H−O bridge; and the orientations of those L planes with respect to the equatorial planes.