In the title compound, [Rh(C6H5N4)Cl2(C12H27P)2], the Rh(III) ion is chelated by the singly deprotonated 2,2'-biimidazolate (Hbim(-)) ligand and coordinated by two chloride ions and two tri-n-butyl-phosphane ligands. The chloride ions and N atoms of the Hbim(-) ligand lie in a plane where the sum of X-Rh-X angles between cis sites is 360°. The phosphane ligands occupy the sites perpendicular to the plane, completing the overall distorted octahedral coordination sphere. The complex forms a self-complementary hydrogen-bonded dimer with the inversion-related complex through N-H⋯N hydrogen bonds.
Keywords: biimidazole; crystal structure; hydrogen bonding; rhodium complex.