The reaction of nicotinic acid (nic), chromic perchlorate hexahydrate, and sodium perchlorate in aqueous solution affords a Cr(III)-vitamin complex whose composition has been established to be Na[Cr3O(nicH)6(H2O)3][ClO4]8·nicH·6H2O, based on analytical data and a single-crystal X-ray analysis. In the [Cr3O(nicH)6(H2O)3]+7 ion a central oxygen atom is bonded to three chromium atoms. The nicotinic and zwitterions bridge these chromium centers through the carboxylate oxygen atoms. On each chromium atom a water oxygen, trans to the central oxygen atom, complexes the octahedral coordination. The ion has crystallographically imposed symmetry 6. The binding of nicotinic acid in this Cr(III)-nicotinic acid complex is significantly different from that currently proposed for the glucose tolerance factor.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry
- Materials Chemistry