Isotypic one-dimensional coordination polymers: catena-poly[[di-chlorido-cadmium]-μ-5,6-bis-(pyridin-2-yl)pyrazine-2,3-di-carboxyl-ato-κ(2) N (5):N (6)] and catena-poly[[di-chlorido-mercury(II)]-μ-5,6-bis-(pyridin-2-yl)pyrazine-2,3-di-carboxyl-ato-κ(2) N (5):N (6)].

The isotypic title one-dimensional coordination polymers, [CdCl2(C18H14N4O4)] n , (I), and [HgCl2(C18H14N4O4)] n , (II), are, respectively, the cadmium(II) and mercury(II) complexes of the dimethyl ester of 5,6-bis-(pyridin-2-yl)pyrazine-2,3-di-carb-oxy-lic acid. In both compounds, the metal ions are located on a twofold rotation axis and a second such axis bis-ects the Car-Car bonds of the pyrazine ring. The metal ions are bridged by binding to the N atoms of the two pyridine rings and have an MN2Cl2 bisphenoidal coordination geometry.

Dimethyl and diethyl esters of 5,6-bis-(pyridin-2-yl)pyrazine-2,3-di-carb-oxy-lic acid: a comparison.

In dimethyl 5,6-bis-(pyridin-2-yl)pyrazine-2,3-di-carboxyl-ate, C18H14N4O4, (I), and diethyl 5,6-bis-(pyridin-2-yl)pyrazine-2,3-di-carboxyl-ate, C20H18N4O4, (II), the dimethyl and diethyl esters of 5,6-bis-(pyridin-2-yl)pyrazine-2,3-di-carb-oxy-lic acid, the orientation of the two pyridine rings differ. In (I), pyridine ring B is inclined to pyrazine ring A by 44.8 (2)° and the pyridine and pyrazine N atoms are trans to one another, while pyridine ring C is inclined to the pyrazine ring by 50.

A comparative XAS and X-ray diffraction study of new binuclear Mn(III) complexes with catalase activity. indirect effect of the counteranion on magnetic properties.

Four new binuclear Mn(III) complexes with carboxylate bridges have been synthesized: [[Mn(nn)(H(2)O)](2)(mu-ClCH(2)COO)(2)(mu-O)](ClO(4))(2) with nn = bpy (1) or phen (2) and [[Mn(bpy)(H(2)O)](2)(mu-RCOO)(2)(mu-O)](NO(3))(2) with RCOO = ClCH(2)COO (3) or CH(3)COO (4). The characterization by X-ray diffraction (1 and 3) and X-ray absorption spectroscopy (XAS) (1-4) displays the relevance of this spectroscopy to the elucidation of the structural environment of the manganese ions in this kind of compound. Magnetic susceptibility data show an antiferromagnetic coupling for all the compounds: J = -2.

Generation and coupling of [Mn(dmpe)2(C triple bond CR)(C triple bond C)]* radicals producing redox-active C4-bridged rigid-rod complexes.

The symmetric d(5) trans-bis-alkynyl complexes [Mn(dmpe)(2)(C triple bond CSiR(3))(2)] (R = Me, 1 a; Et, 1 b; Ph, 1 c) (dmpe = 1,2-bis(dimethylphosphino)ethane) have been prepared by the reaction of [Mn(dmpe)(2)Br(2)] with two equivalents of the corresponding acetylide LiC triple bond CSiR(3). The reactions of species 1 with [Cp(2)Fe][PF(6)] yield the corresponding d(4) complexes [Mn(dmpe)(2)(C triple bond CSiR(3))(2)][PF(6)] (R = Me, 2 a; Et, 2 b; Ph, 2 c). These complexes react with NBu(4)F (TBAF) at -10 degrees C to give the desilylated parent acetylide compound [Mn(dmpe)(2)(C triple bond CH)(2)][PF(6)] (6), which is stable only in solution at below 0 degrees C.

A facile and novel route to unprecedented manganese C4 cumulenic complexes.

The theoretically characterized (DFT) C4 cumulenic species Mn(C5H4R)(dmpe) [=C=C=C=C(SnPh3)2] was obtained by photolysis of the C(sp2)-Sn bond in the vinylidene complex Mn(C5H4R)(dmpe)[=C=C(SnPh3)-C[triple bond]CSnPh3], which in turn was prepared by a thermal reaction from MnC5H4R(dmpe)(C7H8) and Ph3Sn-C4-SnPh3.