SYNTHESIS, SPECTRAL AND STRUCTURAL CHARACTERIZATION OF A BRIDGING CHLORO COMPLEX OF MANGANESE(II) WITH PICOLINIC-ACID - [MN(C5H4NCO2H)(C5H4NCO2)CI]2

The title compound of manganese(II) with picolinic acid was synthesized and characterized by spectroscopic and X-ray crystallographic methods. In the structure of the complex [Mn(C5H4NCO2H)(C5H4NCO2)Cl]2 each manganese(II) atom is coordinated by two nitrogen atoms at Mn-N distances of 2.268(6) angstrom and two carboxylic oxygen atoms O(1) at Mn-O bond lengths of 2.191(4) angstrom, belonging to two picolinato groups. The Cl- anions act as bridging ligands to build edge-sharing dimeric Mn2Cl2 units [Mn-Cl = 2.500(2) angstrom] with the Mn...Mn separation of 3.608(2) angstrom and Cl...Cl separation of 3.462(1) angstrom. The four-membered dimeric Mn2Cl2 rings are planar and oriented along the c-axis of the unit cell. The O(2)...O(2) separation between non-coordinated carboxylate oxygen atoms of adjacent dimeric coordination polyhedra is 2.423(7) angstrom. The IR and Raman spectral results confirm the existence of neutral picolinic acid as well as the picolinate anion. The vibrational bands of diagnostic value are compared with the values of the carboxylic acid and the free anion.