Coordination Polymers of Dicyanamide and Methylpyrazine:  Syntheses, Structures, and Magnetic Properties

Abstract

The crystal structures of M(dca) 2 (Mepyz) 2 ·H 2 O, M = Co ( 1 ), Ni ( 2 ), dca = dicyanamide, N(CN) 2 -, and Mepyz = methylpyrazine; [Mn(dca) 2 (Mepyz) 2 ][Mn(dca) 2 (Mepyz)] 2 ·2MeCN ( 3 ); and Mn 2 (dca) 3 (NO 3 )(Mepyz) 2 ( 4 ) are reported. Compounds 1 and 2 are isomorphous and consist of two-dimensional (2D) (4,4) sheets, with bridging μ 1,5 -dca ligands and trans-disposed monodentate Mepyz ligands. Compounds 3 and 4 were obtained as an intimate mixture from the same reaction mixture. Compound 3 contains both one-dimensional (1D) chains, in which Mn atoms are bridged by double μ 1,5 -dca bridges and the Mepyz ligands are trans and monodentate, and 2D (4,4) sheets, in which similar 1D chains are connected by bridging Mepyz ligands. The structure of 4 contains two interpenetrating 4,6-connected three-dimensional networks, with bridging μ 1,5 -dca anions, bridging Mepyz ligands, and chelating NO 3 - anions. Only very weak coupling and no long-range magnetic ordering intrinsic to these materials were observed for 1 or 2, although traces of the ferromagnets α-Co(dca) 2 and α-Ni(dca) 2 were observable in very small applied fields, with ordering temperatures at 9 and 21 K, respectively.