Influence of Pseudohalide Ions on the Molecular Structure and Magnetic Properties of the Manganese(II)−Bipyrimidine−Pseudohalide System

Abstract

The compounds [Mn2(bpm)3(NCS)4] (1), [Mn(bpm)(NCO)2] (2), and [Mn2(bpm)(N3)4] (3) (where bpm= 2,2‘-bipyrimidine) have been synthesized and characterized. Compound 1 crystallizes in the triclinic P1̄ space group, with a = 9.122(1) Å, b = 9.229(1) Å, c = 11.710(2) Å, α = 74.89(1)°, β = 80.30(1)°, γ = 61.04(1)°, V = 831.7(2) Å3, Z = 2, R(F o) = 0.029, and wR(F o 2) = 0.078. Compound 2 crystallizes in the monoclinic C2/c space group, with a = 7.309(1) Å, b = 14.498(2) Å, c = 10.740(4) Å, β = 99.93(4)°, V = 1121.0(5) Å3, Z = 4, R = 0.025, and wR(F o 2) = 0.060. In the case of compound 3, the crystal parameters of the monoclinic C2/m space group are a = 6.206(2) Å, b = 15.084(2) Å, c = 8.909(1) Å, β = 95.75(2)°, V = 829.8(3) Å3, Z = 4, R = 0.029, and wR(F o 2)= 0.069. The pseudohalide ions have a dramatic influence in the molecular structures of the three compounds. Compound 1 is dinuclear, with the manganese(II) ions bridged by bpm ligands and with terminal bpm and NCS groups; compound 2 is a linear chain of manganese(II) ions bridged by bpm ligands in cis conformation, with terminal cyanate groups; compound 3 shows a two-dimensional honeycomb like structure, where the sheets consist of an infinite hexagonal array of manganese(II) ions bridged by bischelating bpm ligands and double end-on azido bridges. The manganese(II) ions have octahedral environments in all cases. Magnetic susceptibility measurements show antiferromagnetic couplings for compounds 1 and 2, while alternating ferro-antiferromagnetism is observed for compound 3. The obtained exchange parameters are J = −0.72 K and J = −0.78 K for compounds 1 and 2, respectively. No theoretical model is available for compound 3, which represent the first two-dimensional honeycomb-like compound showing alternating signs in the magnetic interactions.

Azido, Cyanato, and Thiocyanato Coordination Induced Distortions in Pentacoordinated [CoIIA(bip)]2 (A = NCS–, N3–, or NCO–) Complexes

“…The ν(C=N) stretching frequency of the free ligand is observed at 1636 cm -1 . Complex 1·dmf records one strong band at 2070 cm -1 for the ν(CN) stretching of the terminally coordinated NCS - [38] ion, but the ν(CS) stretching frequency in the 700-825 cm -1 region could not be identified with certainty in the presence of strong absorptions by the organic ligand in this region. [39] Terminal coordination of azide groups to cobalt(II) ions in 2·CH 3 OH shows a very strong sharp band at 2050 cm -1 and a weak band at 1345 cm -1 for the ν as (N 3 -) and ν s (N 3 -) stretching vibrations, respectively.…”

One-dimensional polymeric chain structure of bis(aniline)dithiocyanatocadmium(II)

“…It has been reported that these networks may have electronic, magnetic, optical or catalytic applications (Batten & Robson, 1998;Dunbar & Heintz, 1997). For designing in®nite inorganic organic frameworks, we and others (Kim et al, 1999;Cortes et al, 1997;Demunno et al, 1997) (Wells, 1984 (Wells, 1984). The bond lengths and angles of the SCN and aniline ligands of (I) are unexceptional and similar to those reported in the literature (ZukermanSchpector et al, 1988).…”

Synthesis, Spectroscopic and Thermal Investigation, and Crystal Structure of Triaqua-trans-bis(3,4-dimethylpyridine)-nitratomanganese(II) Nitrate

“…The complex cation can be described by a distorted octahedral environment around the central manganese(II) ion MnN 2 O 4 . Each manganese(II) ion is trans-coordinated by a pair of 3,4-dimethylpyridine ligands (Mn±N(1) 2.247(5) Mn±N(2) 2.289(5) A Ê ) in analogy to complexes containing N-(3,4-dimethylpyridine) and bipyrimidine [4,17]. The trans-angles deviate from linearity (N(1)±Mn±N(2) 175.7(2) ) as expected due to the geometrical constraints of the nitrate anion.…”