Zhong-Hai Ni

Hydrogen-Bond Directed Cyanide-Bridged Molecular Magnets Derived from Polycyanidemetalates and Schiff Base Manganese(III) Compounds: Synthesis, Structures, and Magnetic Properties

A series of six new cyanide-bridged heterometallic complexes including two tetranuclear T-like Fe(III)Mn(III)(3) compounds, {[Mn(L(1))(H(2)O)](3)[Fe(CN)(5)(1-CH(3)im)]}ClO(4) x 1.5 H(2)O (1) and {[Mn(L(2))(H(2)O)](3)[Fe(CN)(5)(1-CH(3)im)]}ClO(4) x 3 H(2)O (2); two heptanuclear cage-shaped M(III)Mn(III)(6) (M = Fe, Cr) compounds, {[Mn(L(2))(H(2)O)](6)[Fe(CN)(6)]}[Fe(CN)(6)] x 6 CH(3)OH (3) and {[Mn(L(2))(H(2)O)](6)[Cr(CN)(6)]}[Cr(CN)(6)] x 6 CH(3)OH (4); and two two-dimensional M-Mn(III) networks, {[H(3)O][Mn(L(1))](2)[Fe(CN)(6)]} x 2 DMF (5) and {K[Mn(L(1))](2)[Cr(CN)(6)]} x 1.5 CH(3)CN x CH(3)OH (6) (L(1) = N,N-ethylene-bis(3-methoxysalicylideneiminate, L(2) = N,N-ethylene-bis(3-ethoxysalicylideneiminate) have been successfully assembled from three polycyanidemetalates containing five or six cyanide groups and two manganese(III) building blocks containing bicompartmental Schiff base ligands. The cyanide-bridged polynuclear complexes are self-complementary through a coordinated aqua ligand from one complex and the free O(4) compartment from the neighboring complex, giving supramolecular one-dimensional ladders and three-dimensional networks for 1 and 2 and for 3 and 4, respectively. Investigation over magnetic susceptibilities of the six complexes reveals the overall ferromagnetic interactions for complexes 1, 2, 3, and 5 and antiferromagnetic interaction for 4 and 6. Compounds 1-4 show some characteristics of metamagnet behavior at low temperatures due to the relatively strong intermolecular hydrogen-bonding interaction. The two complexes with two-dimensional structure exhibit three-dimensional antiferromagnetic ordering with typical metamagnetic behavior below 8.4 K for 5 and 11.5 K for 6, respectively. The present result appears to add new members to the very few examples of polynuclear clusters exhibiting 3D magnetic ordering relying on intermolecular interactions, to the best of our knowledge, which will be helpful for providing valuable information for the understanding and application of intermolecular hydrogen-bonding interactions in the molecular magnetic materials.

Diverse Ni(II) MOFs constructed from asymmetric semi-rigid V-shaped multicarboxylate ligands: structures and magnetic properties

Novel nickel(II) coordination polymers have been constructed from asymmetric semi-rigid V-shaped multicarboxylate ligands with the help of 4,4′-bipyridine (4,4′-bpy) ligand. The hydrothermal reaction between 3-(4-carboxy-phenoxy)-phthalic acid (H3L1) and Ni(OAc)2·4H2O led to the formation of [Ni3(L1)2(μ-4,4′-bpy)3(H2O)2]n·(4,4′-bpy)n·(H2O)5n (1). In contrast, the same reaction using 3-(2-carboxy-phenoxy)-phthalic acid (H3L2) as a starting material instead of H3L1 resulted in [Ni3(L2)2(H2O)4(μ-4,4′-bpy)3]n·(H2O)2n (2) and [Ni3(L2)2(H2O)4(μ-4,4′-bpy)4]n·(H2O)2n (3) at 120 and 150 °C, respectively, revealing the effect of reaction temperature on the structure of the coordination polymer formed from the semi-rigid V-shaped ligand of L2. Single-crystal X-ray diffraction analysis reveals that complex 1 shows a 3D framework structure assembled from right- and left-handed helices together with isolated tubes. This compound represents the first metal–organic hybrid tube constructed from an asymmetric semi-rigid V-shaped multicarboxylate ligand. Compound 2 also exhibits a 3D network composed of discontiguous trinuclear Ni(II) clusters, while the 3D architecture of 3 consisting of isolated Ni(II) ions separated in a long distance is constructed by two kinds of 2D (6,3) networks. Magnetic studies reveal the overall antiferromagnetic interaction between the neighbouring Ni(II) ions in 1–3.

Heterobimetallic porphyrin-based single-chain magnet constructed from manganese(III)-porphyrin and trans-dicyanobis(acetylacetonato) ruthenate(III) containing co-crystallized bulk anions and cations

Two cyanide-bridged alternated 1 : 1 Ru(III)/Mn(III) complexes structurally characterized as single-chain containing co-crystallized bulk anions and cations have been successfully assembled from [Mn(TPP)(H(2)O)(2)](+) and [Ru(acac)(2)(CN)(2)](-) blocks. Systematic investigation of their magnetic properties reveals typical single-chain magnet (SCM) behaviors for both of them.

Synthesis, crystal structures, and luminescent properties of Cd(II) coordination polymers assembled from asymmetric semi-rigid V-shaped multicarboxylate ligands

A series of seven Cd(II) coordination polymers, namely [Cd3(L1)2(phen)3]n·(H2O)2n (1), [Cd3(L1)2(2,2′-bpy)3(H2O)2]n·(H2O)3n (2), [Cd3(L1)2(4,4′-bpy)2]n·(H2O)4n (3), [Cd3(L2)2(phen)2]n (4), [Cd3(L2)2(2,2′-bpy)2]n (5), [Cd3(L3)2(phen)2(H2O)]n·(H2O)2n (6), and [Cd3(L4)2(phen)2(H2O)2]n·(H2O)3n (7), have been prepared on the basis of four asymmetric semi-rigid V-shaped multicarboxylate ligands including 4-(2-carboxyphenoxy)phthalic acid (H3L1), 3-(2-carboxyphenoxy)phthalic acid (H3L2), 3-(4-carboxyphenoxy)phthalic acid (H3L3), and 4-(4-carboxyphenoxy)phthalic acid (H3L4) with the help of 1,10-phenanthroline (phen), 2,2′-bipyridine (2,2′-bpy), or 4,4′-bipyridine (4,4′-bpy) as secondary ligand. Single-crystal X-ray diffraction analysis reveals that compounds 1, 4, 5, and 6 exhibit one-dimensional (1D) double chain structures constructed from trinuclear Cd(II) clusters, which further forms 2D supramolecular architecture via intermolecular π–π interaction. Complex 2 possesses a 3D supramolecular network assembled from 2D layered architecture composed of dinucelar cadmium subunits and isolated Cd(II) ions via intermolecular π–π interaction. Compound 3 shows a 3D framework structure which is generated from 2D layered motif comprised of trinuclear cadmium subunits pillared by 4,4′-bpy ligands, while the 3D framework of 7 is constructed from two different directional ribbon chains consisting of dinuclear cadmium clusters and isolated Cd(II) ions as node. The different molecular structure for compounds 1–3 formed from the same L1 ligand reveals the spacer effect of secondary ligands on tuning the structure of coordination polymers, while the structural difference among 1, 4, 6, and 7 built from different asymmetric semi-rigid V-shaped multicarboxylate ligand (L1, L2, L3, or L4) but employing the same secondary ligand of phen reveals the important role of the positions of carboxylic substituents at the asymmetric multicarboxylate ligand in the formation of coordination compounds. Photophysical properties over the series of complexes 1–7 have been systematically and comparatively investigated.

Heterometallic trinuclear CuIIMIII2 (M = Fe or Cr) complexes with novel bridges and unusual magnetic properties

Three new trinuclear complexes based on [Cu(Ln)]2+ (L1 = 1,5,8,12-tetramethyl-1,3,6,8,10,13-hexaazacyclotetradecane, L2 = 1,3-propanediamine (tn)) and [M(bpb)(CN)2]− (bpb2− = 1,2-bis(pyridine-2-carboxamido)benzenate, M = Fe or Cr) have been synthesized and characterized structurally and magnetically. The Cu(II) ions adopt an axially-elongated octahedron with four N atoms from the Ln ligands occupying the equatorial plane and another two atoms (cyano nitrogen atoms or amide oxygen atoms) from two [M(bpb)(CN)2]− moieties at the axial positions, resulting in a neutral linear trinuclear complex. Magnetic studies show that the CuFe2 compound bridged by the amido group exhibits ferromagnetic behaviour. The two cyano-bridged CuFe2 or CuCr2 compounds show unusual magnetic properties: weak antiferromagnetic Cu(II)–Fe(III) coupling and negligible Cu(II)–Cr(III) magnetic exchange, proved by the results of the field dependence of magnetization.

Cyanide-bridged 1D Mn(iii)-Fe(iii) bimetallic complexes: synthesis, crystal structure and magnetic properties

Cyanide-bridged Mn(III)–Fe(III) complexes have been synthesized in order to find new molecular materials with interesting magnetic properties. 1D complexes of trans-dicyanoferrite(III), [Mn(5-Cl-salen)Fe(bpClb)(CN)2]·0.67MeCN·0.5H2O (1), [Mn(5-Cl-salen)Fe(bpb)(CN)2]·0.5H2O·MeOH (2), [Mn(5-Br-salen)Fe(bpb)(CN)2]·0.5H2O·MeOH (3), and [Mn(5-Me-salen)Fe(bpb)(CN)2]·0.5H2O·MeOH (4) have been prepared and characterized by X-ray single-crystal structure analysis and magnetic measurements. All complexes possesses 1D chains of alternate [Mn(5-R-salen)]+ and [Fe(bpRb)(CN)2]− units that are linked by two trans-cyanide ligands of [Fe(bpRb)(CN)2]−. Magnetic studies reveal that they exhibit overall intermetallic ferromagnetic coupling, while complex 4 shows a frequency-dependent AC magnetic susceptibility typical of a single-chain magnet.

Rational design of cyanide-bridged heterometallic M(I)–Mn(II) (M = Ag, Au) one-dimensional chain complexes: synthesis, crystal structures and magnetic properties

Two mononuclear seven-coordinated macrocycle Mn(II) compounds and four new cyanide-bridged MI–MnII (M = Ag, Au) one-dimensional chain complexes have been synthesized and crystallographically characterized: [Mn(L1)Cl2] · H2O (1), [Mn(L2)Cl2]·H2O (2), [Ag(CN)2Mn(L1)][Ag(CN)2] (3), [Ag(CN)2Mn(L2)][Ag(CN)2] · 1.5H2O (4), [Au(CN)2Mn(L1)][Au(CN)2] (5) and [Au(CN)2Mn(L2)][Au(CN)2] · 1.5H2O (6). The structure of the one-dimensional complexes consists of alternating units of [Mn(L)]2+ and [M(CN)2]−, generating a cyanide-bridged cationic polymeric chain with [M(CN)2]− as the counteranion. In all complexes, the coordination geometry of manganese ion is a slightly distorted pentagonal-bipyrimidal with the cyanide nitrogen atoms at the trans positions and N5 or N3O2 coordinating mode in the equatorial plane from ligand L1 or L2. Investigation over magnetic properties of these four one-dimensional complexes reveals the whole very weak antiferromagnetic interaction between neighbouring Mn(II) ions bridged by the long NC–M–CN unit. A best-fit to the magnetic susceptibility of these complexes leads to the magnetic coupling constant of J = −0.065(2), −0.23(3), −0.15(6) and −0.13(5) cm−1 for complex 3, 4, 5, and 6, respectively.

4,5-Diamino­benzene-1,2-dicarbonitrile

The molecular skeleton of the title molecule, C8H6N4, is essentially planar [maximum deviation from the mean plane of 0.037 (2) Å]. All N atoms are involved in the formation of intermolecular N—H⋯N hydrogen bonds. The crystal packing exhibits also dipole–dipole interactions between the cyano groups of neighbouring molecules [C⋯C 3.473 (2) Å].

A three-dimensional polymeric mixed-valence copper complex: poly[tri-μ-azido-μ-di-2-pyridyl­diazene-dicopper(I,II)]

The title complex, [Cu2(N3)3(C10H8N4)]n, shows a three-dimensional poylmeric structure. Each Cu atom is surrounded by five N atoms from three bridging azide ligands and one di-2-pyridyldiazene ligand [Cu—N = 2.002 (5), 2.317 (6), 2.020 (4), 1.995 (5) and 1.985 (3) A], forming a CuN5 trigonal bipyramid. One μ1,1-azide bridges two Cu atoms and the other two μ1,1-azides bridge pairs of Cu atoms, forming a —Cu—N—Cu—N2— chain. The di-2-pyridyldiazene bridges two Cu atoms of different —Cu—N—Cu—N2— chains, forming a three-dimensional polymeric structure. On the basis of charge equilibrium, the presence of one CuII and one CuI ion are deduced and the two ions are disordered because of the occurrence of only one unique Cu atom in the structure.

Bis(diethyl­enetriamine-κ3N,N′,N′′)nickel(II) bis­(1,2-dicyanoethene-1,2-dithiolato-κ2S,S′)nickel(II)

The title compound, [Ni(C4H13N3)2][Ni(C4N2S2)2], has been synthesized by the reaction of Ni(ClO4)2·6H2O, diethylenetriamine (deta) and Na2[Ni(mnt)2] [mnt = maleonitriledithiolate(2-)] in methanol. The structure is composed of a [Ni(deta)2]2+ cation and a [Ni(mnt)2]2− anion. The coordination geometry of the NiII ion in the cation is slightly distorted octahedral, defined by six N atoms from two deta ligands, while the NiII ion in the anion is four-coordinated by four S atoms from two mnt ligands in a slightly distorted square-planar geometry. The cations and anions are connected by N—H⋯N hydrogen bonds.