Synthesis, Structure, and Magnetic Behavior of Two New 1D Polymeric Manganese Azido Complexes

Syntheses, structural characterization, and thermal behaviour of metal complexes with 3-aminopyridine as co-ligands

Abstract

Six mixed metal complexes with 3-aminopyridine (3-ampy) as a co-ligand have been synthesized: catena-{[M(μ2-3-ampy)(H2O)4]SO4·H2O} (M=Ni (1) and Co (2)), [Co(3-ampy)4(NCS)2] (3), [Co(3-ampy)2(NCS)2] (4), [Co(3-ampy)4(N3)2] (5) and mer-[Co(3-ampy)3(N3)3] (6), (NCS−=isothiocyanate ion, N3− azide ion), and characterized by physio-chemical and spectroscopic methods as well as single crystal X-ray and powder diffraction. In the isostructural complexes 1 and 2 single μ2-3-ampy links the Ni(II) and Co(II) centers into polymeric chains. The mononuclear Co(II) and Co(III) pseudohalide complexes 3–6 reveal only terminal 3-ampy ligands. The 3-ampy ligands form supramolecular hydrogen bonded systems via their NH2-groups and non-covalent π-π ring-ring interactions via their pyridine moieties. Thermoanalytical properties were investigated for 1–3.

Graphic abstract

New Twists and Turns for Actinide Chemistry: Organometallic Infinite Coordination Polymers of Thorium Diazide

Two organometallic 1D infinite coordination polymers and two organometallic monometallic complexes of thorium diazide have been synthesized and characterized. Steric control of these self-assembled arrays, which are dense in thorium and nitrogen, has also been demonstrated: infinite chains can be circumvented by using steric bulk either at the metallocene or with a donor ligand in the wedge.

Different topologies in three manganese-μ-azido 1D compounds: magnetic behavior and DFT-quantum Monte Carlo calculations

The syntheses and structural characterization of three new monodimensional azido-bridged manganese(ii) complexes with empirical formulae [Mn(N3)2(aminopyz)2]n (1), [Mn(N3)2(4-azpy)2]n (2) and [Mn(N3)2(4-Bzpy)2]n (3) (pyz = pyrazine (1,4-diazine)), 4-azpy = 4-azidopyridine and 4-Bzpy = 4-benzoylpyridine) are reported. 1 is a monodimensional compound with double EO azido bridges, 2 is an alternating monodimensional compound with double end-on and double end-to-end azido bridges in the sequence di-EO-di-EE and 3 is a monodimensional compound with double end-on and double end-to-end azido bridges in the sequence di-EO-di-EO-diEO-di-EO-di-EE. The magnetic properties of 1-3 are reported. Periodic DFT calculations were performed to estimate the J values and quantum Monte Carlo simulations were carried out using the calculated J values to check their accuracy in comparison with the experimental magnetic measurements. From this theoretical analysis, two appealing features of the di-EO Mn(ii) compounds can be extracted: first, the exchange coupling becomes more ferromagnetic when the Mn-N-Mn bridging angle becomes larger and the spin density of the bridging nitrogen atoms has an opposite sign to that of the Mn(II) centers.

catena-Poly[[tetra-aqua-copper(II)]-μ-pyrazine-2-carboxamide-κ(3)N(4):N(1),O-[bis-(sulfato-κO)copper(II)]-μ-pyrazine-2-carboxamide-κ(3)N(1),O:N(4)]

In the crystal of the title polymeric compound, [Cu(2)(SO(4))(2)(C(5)H(5)N(3)O)(2)(H(2)O)(4)](n), two independent Cu(II) atoms are located on individual inversion centers. One Cu(II) atom is coordinated by four water mol-ecules and two pyrazine-2-carboxamide ligands in a distorted O(4)N(2) octa-hedral geometry; the other is N,O-chelated by two pyrazine-2-carboxamide ligands and further coordinated by two sulfate anions in a distorted O(4)N(2) octa-hedral geometry. The pyrazine-2-carboxamide ligands bridge the Cu(II) atoms to form a polymeric chain running along [110]. The crystal structure features N-H⋯O, O-H⋯O and weak C-H⋯O hydrogen bonds.

Dichloridobis(pyrazine-2-carboxamide-κN(4))zinc(II)

In the crystal of the title compound, [ZnCl(2)(C(5)H(5)N(3)O)(2)], the mol-ecule has m symmetry, with the Zn(II) cation and Cl(-) anions located on the mirror plane. The Zn(II) cation is coordinated by two Cl(-) anions and two pyrazine-2-carboxamide ligands in a distorted ZnCl(2)N(2) tetra-hedral geometry. The two pyrazine rings are nearly perpendicular to each other [dihedral angle = 86.61 (10)°]. Inter-molecular N-H⋯O and N-H⋯N hydrogen bonds and weak C-H⋯O inter-actions stabilize the crystal packing.

catena-Poly[[[aqua-(pyrazine-2-carboxamide-κ(2)N(1),O)zinc]-μ-pyrazine-2-carboxamide-κ(3)N(1),O:N(4)] dinitrate]

In the crystal of the title compound, {[Zn(C(5)H(5)N(3)O)(2)(H(2)O)](NO(3))(2)}(n), the Zn(II) cation is N,O-chelated by two pyrazine-2-carboxamide (PCA) ligands and is further coordinated by one water mol-ecule and by one pyrazine-N atom from an adjacent PCA ligand in a distorted ZnN(3)O(3) octa-hedral geometry. One of the two independent PCA ligands bridges two Zn(II) cations, forming a zigzag polymeric chain running along the c axis. In the crystal, the NO(3) (-) anions link to the chain via O-H⋯O and N-H⋯O hydrogen bonding. Weak inter-molecular C-H⋯O inter-actions also occur.

Dibromidobis(pyrazine-2-carboxamide-κN(4))zinc

The title complex, [ZnBr₂(C₅H₅N₃O)₂], shows crystallographic mirror symmetry with the Zn atom and the two bromine ligands located on the mirror plane. The Zn atom is four-coordinated in a distorted tetra­hedral fashion by two N atoms from two pyrazine-2-carboxamide ligands and two Br atoms. Only one of the amino H atoms is involved in an N—H⋯O hydrogen bond. The crystal packing is further stabilized by weak N—H⋯N and C—H⋯O inter­actions.

1D and 2D End-to-End Azide-Bridged Cobalt(II) Complexes: Syntheses, Crystal Structures, and Magnetic Properties

Two new polynuclear azido-bridged Co(II) compounds with formulas catena-[Co(mu1,3-N3)(N3)(py)2(H2O)]n (1) and [Co(mu1,3-N3)2(4-acpy)2]n (2) (py=pyridine, 4-acpy=4-acetylpyridine) have been structurally and magnetically characterized. Compound 1 crystallizes in the orthorhombic system Fddd space group and consists of a single end-to-end azido-bridged chain with the Co(II) atoms in a CoN5O slightly distorted octahedron. Compound 2 crystallizes in the monoclinic system P21/a space group and shows 2D sheets built up through end-to-end azido bridges with the Co(II) atoms in a CoN6 environment. The magnetic properties of 1 and 2 are reported. In the high-temperature region, the plots of chiM or chiMT vs T for 1 and 2 compounds can be fitted by using the Curie-Weiss law, and the best-fit values are -69.1 and -22.6 K, respectively. For 2 magnetic ordering and spontaneous magnetization is achieved below Tc=25 K.