| SM ISO690:2012|
DRAGANCEA, Diana; BOUROSH, Paulina; SHOVA, Sergiu; KRAVTSOV, Viktor. Trinuclear manganese(II) cluster based on semicarbazone ligand. In: Materials Science and Condensed Matter Physics. Editia a 7-a, 16-19 septembrie 2014, Chișinău. Chișinău, Republica Moldova: Institutul de Fizică Aplicată, 2014, p. 183.
|Materials Science and Condensed Matter Physics
Editia a 7-a, 2014
Conferința "Materials Science and Condensed Matter Physics" |
Chișinău, Moldova, 16-19 septembrie 2014
In the course of our investigations on the design and preparation of polynuclear metal complexes with special geometries the potentially tetradentate, rigid N,O ligand, o-vanillin semicarbazone (H2L) was used to generate metal clusters. The relative positions of donor atoms in this ligand are predisposed to polynucleating, although the nuclearity of the resulting systems is hard to predict. The reaction of two equivalents of hydrated manganese(In nitrate with one equivalent of H2L in methanol produces a trinuclear complex [Mn3(HL)4](NO3)2·2H2O (1). Compound 1 c1ystallizes in the monoclinic space group C2/c, a=25.454(1), b=l5.8912(5), c=l4.3754(7) A, =118.52(7)0, V=5109 .3( 4) A3. The strncture of 1 comprises a non-linear trinuclear "bent" cluster assembled from Mn(II) ions [Mnl···Mn2 separation is 3.305(2) A and angle Mnl···Mn2···MnlA =138°] and four deprotonated HL- ligands (Fig. 1). Complex resides on two-fold axis passed through central Mn2 ion, and thus having C2 molecular symmetry. The charge of the complex is compensated by two NO3- anions. Two HL- ligands are tetradentate and tris-chelating and coordinate to metals via carbonyl oxygen, imine nitrogen, methoxy, and phenoxide oxygen atoms. Other two ligands are tridentate and do not use methoxy group for coordination. The Mnl ion is hexacoordinated and its 0-2 coordination smTounding may be described as highly distorted trigonal prismatic, while 06 geomet1y around the Mn2 ion is best described as highly distorted octahedron.The metal-donor atom distances are in the ranges Mnl-O 2.112(4) - 2.231(4), Mnl-N 2.236(4) - 2.290(4), and Mn2-O 2.110(4) - 2.374(4) A. This compound exhibits fascinating features of self-assembly of manganese metal centers and overall architecture of cluster results from the fusion of two doublestranded helicates to form a unique trinuclear double-stranded dihelicate (Fig. 2). To the best of our knowledge 1 is a rare example of trinuclear Mn(II) double-stranded dihelicate, and only one similar strncture has been known till now [ 1]. In the crystal ionic components and water molecules are linked by N-H-··O and ON-H···O hydrogen bonds.