Structural Analysis, Spectroscopic, and Magnetic Properties of the 1D Triple-Bridged Compounds [M(dca)₂(bpa)] (M = Mn, Fe, Co, Zn; dca = dicyanamide; bpa = 1,2-bis(4-pyridyl)ethane) and the 3D [Ni(dca)(bpa)₂]dca·6H₂O

Abstract

The family of compounds [Mn(dca) 2 (bpa)] (1), [Fe(dca) 2 (bpa)] (2), [Co(dca) 2 (bpa)] (3), [Zn(dca) 2 (bpa)] (4), and [Ni(dca)(bpa) 2 ]dca 3 6H 2 O (5), with dca = dicyanamide and bpa = 1,2-bis(4-pyridyl)ethane, has been synthesized. These compounds have been characterized by single crystal (1, 2, 4, and 5) and powder X-ray diffraction (3), by Fourier transform infrared (FTIR), UV-vis, and electron paramagnetic resonance (EPR) spectroscopies, and by magnetic measurements. Compound 1 crystallizes in the monoclinic C2/c space group, Z = 4, with a = 16.757( 6), b = 9.692(3), and c = 13.073(4) A ˚, and β = 123.02(2)°; Compound 2 crystallizes in the monoclinic C2/c space group, Z=4, with a=16.588(5), b = 9.661(3), c = 12.970(5) A ˚, and β = 123.16(3)°; Compound 4 crystallizes in the monoclinic C2/c space group, Z = 4, with a = 16.519(2), b = 9.643(2), c = 12.943(2) A ˚, and β = 123.15(1)°; Compound 5 crystallizes in the monoclinic C2/c space group, Z = 4, with a = 18.504(4), b = 19.802(3), and c = 8.6570(18) A ˚, and β = 99.74( 2)°. The compounds 1-4 are isostructural and show a one dimensional (1D) disposition, with the metal(II) ions bridged by double μ 1,5 dca ligands and unusually by a third bridge consisting of the bpa ligand, which adopts a very low torsion angle to accommodate in the structure. This kind of structure is unusual, even considering the voluminous bpa bridge. The compound 5 shows a 3D structure with layers of Ni-bpa joined by single dca bridges. Magnetic susceptibility measurements show antiferromagnetic couplings, increasing for 1-3. Compound 5 shows very slight antiferromagnetic interactions.

Structure, DFT Calculations, and Magnetic Characterization of Coordination Polymers of Bridged Dicyanamido-Metal(II) Complexes

“…The χ M T values decrease with decreasing the temperature and reaching a value of 1.11 cm 3 mol −1 K at 2 K. The decrease in the χ M T values when the temperature decreases is partially attributed to antiferromagnetic intra-chain interactions, but this can be assumed to display minor exchange interactions, which are mediated by the µ 1,5 -bridging dicyanamido bridges. This result is in agreement with previously published experimental data and MO calculations [63][64][65][66][67][68]. Therefore, in order to obtain an approximate estimate for the coupling constant, J, the magnetic behavior of the Co(II)-ion in axially distorted octahedral coordination may be well described with the effective spin S = 1/2 and strongly anisotropic g factor.…”

Thermal stability and crystallochemical analysis for CoII-based coordination polymers with TPP and TPPS porphyrins

“…33 In addition, we have a large experience with these connectors. [34][35][36][37][38][39] In this context, we have been exploring CoP-bipy combinations where P is either TPP (TPP = meso-tetraphenylporphyrin) or TPPS (TPPS = meso-tetraphenylporphine-tetrasulfonic acid tetrasodium salt), and bipy is 4,49-bipyridine. It is worth mentioning that just four crystalline compounds have been reported for TPPS-based metalloporphyrins, [40][41][42] and none of them has cobalt.…”

One-, Two-, and Three-Dimensional Heterospin Complexes Consisting of 4-(N-tert-Butyloxylamino)pyridine (4NOpy), Dicyanamide Ion (DCA), and 3d Metal Ions: Crystal Structures and Magnetic Properties of [MII(4NOpy)x(DCA)y(CH3CN)z]n (M = Mn, Co, Ni, Cu, Zn)

“…Both 4NOpy and DCA connectors effectively operate as bridging ligands to form polymeric complexes having 1-D to 3-D structures. For the bridging ligand DCA, five coordination modes have been reported to date; μ-1-, μ 2 -1,3-, μ 2 -1,5-, μ 3 -1,3,5-, and μ 4 -1,3,5,5-DCA (Scheme S1), In these complexes, DCA coordinates to the metal ions in a μ 2 -1,5-DCA mode in all cases except 4aα , which has μ 2 -1,5- and μ 3 -1,3,5-DCA modes. All of the complexes have polymeric structures, with a 3-D structure for 1 , 2-D structures for 2 , 3 , 4a , 5 , and 5′ , and a 1-D structure for 4b through ligation with 4NOpy and DCA.…”