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 synthesize d and characterized by spectroscopic and X-ray crystallographic method s. In the structure of the complex Mn(C5H4NCO2H)(C5H4NCO2)Cl!2 each m anganese(II) atom is coordinated by two nitrogen atoms at Mn-N distanc es of 2.268(6) angstrom and two carboxylic oxygen atoms O(1) at Mn-O b ond lengths of 2.191(4) angstrom, belonging to two picolinato groups. The Cl- anions act as bridging ligands to build edge-sharing dimeric M n2Cl2 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 fo ur-membered dimeric Mn2Cl2 rings are planar and oriented along the c-a xis of the unit cell. The O(2)...O(2) separation between non-coordinat ed carboxylate oxygen atoms of adjacent dimeric coordination polyhedra is 2.423(7) angstrom. The IR and Raman spectral results confirm the e xistence of neutral picolinic acid as well as the picolinate anion. Th e vibrational bands of diagnostic value are compared with the values o f the carboxylic acid and the free anion.