SYNTHESIS, STRUCTURE AND POLARIZED OPTICAL SPECTROSCOPY OF 2 NEW FLUOROMANGANESE(III) COMPLEXES

The syntheses and crystal structures of two new fluoromanganese(III) c omplexes are reported; [MnF3(H2O)(2, 2'-bipy)] 1 and 4, 4'-bipyH(2)[Mn F4(H2O)(2)].2H(2)O 2, where 2, 2'-bipy and 4, 4'-bipy are 2, 2'-bipyri dyl and 4, 4'-bipyridyl, respectively. Compound 1: monoclinic, space g roup P2(1)/n, a = 1973.7(4), b = 749.0(2), c = 903.1(3) pm, beta = 95. 22(3)degrees, Z = 4, R1 = 0.051. Compound 2: monoclinic, space group P 2(1), a = 516.4(2), b = 1851.9(4), c = 986.3(3) pm, beta = 99.07(2)deg rees, Z = 2, R1 = 0.028. The manganese co-ordination environment was f ound to be octahedral in both compounds, but strongly distorted by the Jahn-Teller effect as a result of the high-spin d(4) configuration of Mn3+. A very extensive intermolecular hydrogen-bond framework is pres ent in both compounds. For compound 1 the octahedra are linked through hydrogen bridges resulting in octahedral manganese chains. For compou nd 2, the octahedra [MnF4(H2O)(2)](-) are associated via hydrogen bond s into chains, which in turn are connected by interchain hydrogen brid ges. The polarized optical spectra of single crystals are presented an d explained in terms of intraconfigurational d(4) transitions split by ligand fields of nearly C-s and D-4h symmetries for compounds 1 and 2 , respectively. The results are compared with those available for othe r Mn-III fluorides.