Two New One-Dimensional Compounds with End-to-End Dicyanamide as a Bridging Ligand:  Syntheses and Structural Characterization of trans-[Mn(4-bzpy)₂(N(CN)₂)₂]_n and cis-[Mn(Bpy)(N(CN)₂)₂]_n, (4-bzpy = 4-benzoylpyridine; bpy = 2,2‘-bipyridyl)

Abstract

Two new one-dimensional compounds, trans-[Mn(4-bzpy)2(N(CN)2)2]n (1) and cis-[Mn(bpy)(N(CN)2)2]n (2), have been synthesized and studied from a magnetic point of view (4-bzpy = 4-benzoylpyridine; bpy = 2,2'-bipyridyl). The crystal structures of 1 and 2 have been solved. Compound 1 crystallizes in the monoclinic system, P2(1)/n group, a = 6.374(2) A, b = 7.584(2) A, c = 26.766(5) A, beta = 91.87 degrees, and Z = 2, whereas compound 2 crystallizes in the monoclinic system, C2/c group, a = 6.707(2) A, b = 17.188(5) A, c = 13.096(5) A, beta = 90.54 degrees, and Z = 4. The two compounds consist of chains with double mu 1,5-dicyanamide bridges between neighboring manganese(II) atoms. The weak antiferromagnetic coupling found for the two compounds (J = -0.3 cm-1 for 1 and -0.4 cm-1 for 2) has been studied by MO analysis, and the superexchange pathway through the mu 1,5-(NCNCN-) bridge has been compared with the shorter mu 1,3-(NNN-).

Synthesis, Crystal Structures, and Magnetic Properties of Ternary M(II)-Dicyanamide-hydroxypyridine Complexes

“…In recent years, much attention has been devoted to dicyanamide-anion-(dca-) bridged coordination polymers [30][31][32][33][34][35][36][37][38][39][40][41][42] for the large variety of magnetic properties, especially the -M(dca) 2 series of compounds, which have isomorphous rutile-like structure, display ferromagnetism (Co, Ni) [43][44][45][46], spin-canted antiferromagnetism (Cr, Mn, Fe) [47,48], and paramagnetism (Cu) [45,46]. Of further importance, from a structural perspective, when auxiliary L ligands are introduced to the ternary M II -dca-L systems, different coordination architectures, such as mononuclear and dinuclear compounds [49], 1D chains [50][51][52][53][54][55][56][57][58], 2D (4,4) or (6,3) [59][60][61][62][63] sheets, and 3D network topologies [64][65][66][67], could be constructed (Scheme 1). Inter...…”

Syntheses, Structure and Magnetic Properties of the First µ1,5‐Dicyanamido‐Bridged Dinuclear Compounds [Ni(µ1,5‐dca)(dca)(dpt)]2 and [Ni(µ1,5‐dca)(dca)(medpt)]2

“…The best fit parameters were J ϭ 0.7(1) cm Ϫ1 and g ϭ 2.17(1) (Figure 4). In a previous work [10] we concluded from extended Hückel MO calculations that the dicyanamide µ 1,5 bridge possesses two superexchange pathways: t 2g -π y -t 2g and e g -σ-e g . The t 2g -π y -t 2g pathway leads always to weak antiferromagnetically coupled systems, but in cases where this pathway is not active (d 8 and d 9 ions) there exists the possibility of accidental orthogonality via the e g -σ-e g pathway for MϪNϪC(dicyanamide) angles around 160°.…”

Two manganese(II) complexes based on anthracene-9-carboxylate: Syntheses, crystal structures, and magnetic properties

“…A more pronounced drop is observed below 50 K, with the v M T product reaching a value of 0.07 cm 3 K mol -1 at 2 K (close to 0 cm 3 K mol -1 ). The susceptibility follows the CurieWeiss law in down to 20 K, with C = 4.79 and a Weiss constant H = -20 K. The magnetism of this kind of 1D Mn II system has been theoretically studied by several authors, such as Wagner et al [43][44][45] and, mainly, Fisher [44]. Fisher's treatment allows one to analyze the magnetic data by means of an analytical expression assuming an infinite number of classical spins (S = 5/2) [44].…”