Diverse structures and magnetism of cobalt(II) and manganese(II) compounds with mixed azido and carboxylato bridges induced by methylpyridinium carboxylates.

Herein we present a systematic study of the structures and magnetic properties of six coordination compounds with mixed azide and zwitterionic carboxylate ligands, [M(N(3) )(2) (2-mpc)] (2-mpc=N-methylpyridinium-2-carboxylate; M=Co for 1 and Mn for 2), [M(N(3) )(2) (4-mpc)] (4-mpc=N-methylpyridinium-4-carboxylate; M=Co for 3 and Mn for 4), [Co(3) (N(3) )(6) (3-mpc)(2) (CH(3) OH)(2) ] (5), and [Mn(3) (N(3) )(6) (3-mpc)(2) ] (6; 3-mpc=N-methylpyridinium-3-carboxylate). Compounds 1-3 consist of one-dimensional uniform chains with (µ-EO-N(3) )(2) (µ-COO) triple bridges (EO=end-on); 5 is also a chain compound but with alternating [(µ-EO-N(3) )(2) (µ-COO)] triple and [(EO-N(3) )(2) ] double bridges; Compound 4 contains two-dimensional layers with alternating [(µ-EO-N(3) )(2) (µ-COO)] triple, [(µ-EO-N(3) )(µ-COO)] double, and (EE-N(3) ) single bridges (EE=end-to-end); 6 is a layer compound in which chains similar to those in 5 are cross-linked by a µ(3) -1,1,3-N(3) azido group. Magnetically, the three Co(II) compounds (1, 3, and 5) all exhibit intrachain ferromagnetic interactions but show distinct bulk properties: 1 displays relaxation dynamics at very low temperature, 3 is an antiferromagnet with field-induced metamagnetism due to weak antiferromagnetic interchain interactions, and 5 behaves as a noninnocent single-chain magnet influenced by weak antiferromagnetic interchain interactions. The magnetic differences can be related to the interchain interactions through π-π stacking influenced by different substitution positions in the ligands and/or different magnitudes of intrachain coupling. All of the Mn(II) compounds show overall intrachain/intralayer antiferromagnetic interactions. Compound 2 shows the usual one-dimensional antiferromagnetism, whereas 4 and 6 exhibit different weak ferromagnetism due to spin canting below 13.8 and 4.6 K, respectively.

Diverse manganese(II) coordination polymers with mixed azide and zwitterionic dicarboxylate ligands: structure and magnetic properties.

The reactions of manganese(II) acetate or perchlorate, sodium azide, and the inner-salt-type dicarboxylate ligand 1,3-bis(4-carboxylato-1-pyridinium)propane (L) under different conditions yielded four different Mn(II) coordination polymers with mixed azide and carboxylate bridges: {[Mn(L)(N(3))]ClO(4).0.5H(2)O}(n) (1), {[Mn(2)(L)(2)(N(3))(2)][Mn(N(3))(4)(H(2)O)(2)].2H(2)O}(n) (2), {[Mn(2)(L)(2)(N(3))(2)(H(2)O)(2)]Br(N(3)).2H(2)O}(n) (3), and [Mn(4) (L)(2)(N(3))(8)](n) (4). The compounds exhibit great diversity in their structures and magnetic properties. Both 1 and 2 contain anionic chains featuring a mixed (OCO)(2)(EO-N(3)) triple bridge (EO = end-on) between adjacent Mn(II) ions. In 1, two independent sets of triple bridges with apparently different structural parameters alternate in the AABB sequence, and the resulting alternating chains are cross-linked into a cationic 3D framework by the cationic dipyridinium spacers. Differently, the chains in 2 have uniform bridges and are interlinked into a 2D coordination layer. An expression of the magnetic susceptibility for 1D systems with alternating J(1)J(1)J(2)J(2) interactions has been deduced and applied to 1. Magnetic studies on 1 and 2 reveal that the (OCO)(2)(EO-N(3)) triple bridges induce antiferromagnetic coupling between Mn(II) ions, and magnetostructural analyses suggest that the magnitude of the coupling can be correlated to the Mn-N and Mn-N-Mn parameters. Compound 3 contains 2D coordination layers in which the chains with alternating double EO-azide and double carboxylate bridges are interlinked by the dipyridinium spacers, and magnetic studies suggest alternating ferro- and antiferromagnetic interactions through the alternating bridges. The 3D framework of compound 4 is formed by the organic ligands interlinking the unique manganese-azide-carboxylate layers in which the [Mn(4)(mu(3)-N(3))(2)(mu(2)-N(3))(2)(mu(2)-COO)(4)] clusters are interlinked through EE-azide bridges (EE = end-to-end). The structure represents a novel type of self-catenated 8-connected 3D net. Magnetostructural analyses suggest that all of the short bridging moieties in 4, including (mu(3)-EO-N(3))(2), (OCO)(EO-N(3)), (OCO)(EO-N(3))(2), and single EE-N(3), propagate antiferromagnetic coupling.

Novel three-dimensional metal-azide network induced by a bipyridine-based zwitterionic monocarboxylate ligand: structures and magnetism.

The 4,4'-bipyridine-based zwitterionic monocarboxylate ligand, 4,4'-dipyridinio-1-acetate (L), is used as coligand to construct novel magnetic coordination polymers with mixed azide and carboxylate bridges. Two compounds, [Co(2)(L)(2)(N(3))(4)(H(2)O)] x 4 H(2)O (1) and [Mn(6)(L)(4)(N(3))(12)(H(2)O)] x 5 H(2)O (2), have been structurally and magnetically characterized. Compound 1 consists of one-dimensional (1D) coordination chains in which the unprecedented binuclear motifs with mixed (mu-EO-N(3))(mu-COO)(2) (EO = end-on) triple bridges are cross-linked by the 4,4'-dipyridinium-N-methylene spacers. In compound 2, the azide anions link the metal ions into a very complicated three-dimensional (3D) network with unprecedented topology, and the zwitterionic coligand is embedded in and serves as additional supports for the 3D network. Magnetic studies reveal that the mixed (mu-EO-N(3))(mu-COO)(2) triple bridges transmit ferromagnetic coupling in the Co(II) compound, and the overall antiferromagnetic interactions exist in the Mn(II) compound.

Unprecedented self-catenated eight-connected network based on novel azide-bridged tetramanganese(II) clusters.

The combination of the azide bridge and a neutral inner-salt-type dicarboxylate ligand leads to a three-dimensional coordination framework that contains unprecedented azide-bridged tetramanganese(II) clusters and defines a novel self-catenated, eight-connected net of 4(16) x 6(12) topology.

Isomorphous CoII and MnII materials of tetrazolate-5-carboxylate with an unprecedented self-penetrating net and distinct magnetic behaviours.

Two isomorphous Co(II) and Mn(II) three-dimensional coordination polymers with tetrazolate-5-carboxylate as magnetic mediator exhibit an unprecedented 3,4-connected self-penetrating net topology; a combination of canted antiferromagnetism and metamagnetism was observed in the Co(II) compound, whereas the Mn(II) compound shows typical antiferromagnetic behaviors.

Composition dependence of magnetic relaxation for CoNi chain-based compounds with mixed double azide-tetrazolate bridges.

Seven isomorphous 2D CoNi (0 ≤ x ≤ 1) compounds based on ferromagnetic chains with mixed double [(µ-EO-N3)(µ-N-N-tetrazolate)] (EO = end-on) were synthesized and then structurally and magnetically characterized. They are formulated as [CoNi(L)(N3)(H2O)]·H2O (), (x = 1 (), 0.86 (), 0.74 (), 0.39 (), 0.14 (), 0.10 (), 0 (); L = 3-(5-tetrazole)-N-oxide-pyridine). Magnetic studies revealed that the homo-metallic compounds ( and ) behave as metamagnets, while the hetero-metallic compounds () show interesting composition-dependent slow relaxation due to the synergy effect of Co(II) and Ni(II) ions.

Solvent-modulated slow magnetic relaxation in a two-dimensional compound composed of cobalt(II) single-chain magnets.

A single-chain magnet consisting of Co(II) chains with (EO-N(3))(2) and (µ-COO)(2)(µ-EO-N(3)) bridges reversibly transforms into an antiferromagnetic phase with metamagnetic character and modified slow magnetic relaxation upon dehydration.

Long-range ordering or not: magnetic properties modulated by second ligands in flexible three-dimensional metal-organic frameworks.

The flexibility of the 3D framework derived from Ni(II) and an aromatic dicarboxylate allows for the incorporation of different second bridges, and the resulting materials can be a metamagnet or a paramagnet depending upon the length of the second bridge.

A novel manganese(II) coordination polymer with azide and neutral dicarboxylate ligands: helical structure and magnetic properties.

By using a neutral inner-salt-type dicarboxylate as coligand, a novel two-dimensional (2D) manganese(II) coordination polymer, [Mn(L)(N(3))]ClO(4) x 1/2 H(2)O (L = 1,3-bis(3-carboxylatopyridinium)propane), was synthesized, and characterized by X-ray crystallography and magnetic measurements. The compound contains uniform Mn(II) chains with simultaneous azide and carboxylate bridges between adjacent Mn(II) ions. The formally negative chains are interlinked by the positively-charged 1,3-bis(pyridinium)propane spacer, and the spiral conformation of the spacer imports intriguing helical features to the resulting 2D network, in which [MnL] helices are connected by sharing metal centers with alternating centro- and C(2)-symmetry. The triple (azide)bis(carboxylate) bridge mediates overall antiferromagnetic coupling with J = -3.0 cm(-1), as a result of the competition between the antiferromagnetic (carboxylate) and ferromagnetic (azide) pathways.

Coordination chemistry of tetrazolate-5-carboxylate with manganese(II): synthesis, structure and magnetism.

Six Mn(II) coordination compounds with tetrazolate-5-carboxylate (tzc), have been synthesized and characterized. They are of the formula [Mn2(tzc)2(H2O)2].4H2O (), Mn(tzc)(H2O)2 (), [Mn2(tzc)2(phen)2(H2O)2] (), [Mn(tzc)(2,2'-bpy)(H2O)2] (), [Mn(tzc)(4,4'-bpy)] () and [Mn2(tzc)2(H2O)2].(bpp) (), where phen=1,10-phenanthroline, 2,2'-bpy=2,2'-bipyridyl, 4,4'-bpy=4,4'-bipyridyl, and bpp=1,3-di(4-pyridyl)propane. Versatile coordination modes of the tzc ligand have been recognized in these compounds. In the absence of auxiliary ligands, a dinuclear compound () with the Mn2(N-N)2 moiety and a 1D coordination polymer () consisting of two types of disordered Mn(tzc) chains have been obtained at different temperatures. The incorporation of chelating auxiliary ligands (2,2'-bpy and phen) leads to a mononuclear () and a dinuclear () compounds, the structure of the latter resembling that of . The use of the ditopic auxiliary ligand 4,4'-bpy gives a 2D coordination polymer () in which disordered Mn(tzc) chains are cross-linked by 4,4'-bpy. However, the potentially ditopic ligand bpp is not involved in coordination but serves as hydrogen-bonded bridge between the Mn(tzc) chains to give compound . Magnetic investigations suggest that the double N-N bridges in the dinuclear compounds ( and ) mediate weak ferromagnetic coupling. However, in compounds and , which consist of 1D disordered Mn(tzc) chains with different bridging moieties, the intra-chain interactions are dominated by antiferromagnetic coupling.

Metal-coordination-directed assembly of binuclear trigonal prisms and three-dimensional hydrogen-bonded networks.

The coordination of pyridazine-3,6-dicarboxylate by manganese(II) leads to unusual anionic binuclear trigonal prisms, which coassemble with the hexaaquamanganese(II) antiprisms to generate a hydrogen-bonded CsCl-type three-dimensional network.