Porous and Nonporous Coordination Polymers Induced by Pseudohalide Ions for Luminescence and Gas Sorption.

The three-dimensional (3D) coordination polymers [Cd(tpmd)(NCX)2]n [X = O (1), S (2), and BH3 (3); tpmd = N,N,N',N'-tetrakis(pyridin-4-yl)methanediamine] have been determined to display their network structures through coordinated anionic ligands. Polymers 1 and 2 show nonporous structures, whereas polymer 3 shows a porous coordination framework. On the basis of the Cd(II) network structures, the 3D coordination polymer [Zn(tpmd)(NCBH3)2]n·nMeOH (4) was self-assembled. In the cases of polymers 1 and 2, pseudohalide ions acted to form nonporous network structures; however, in polymers 3 and 4, NCBH3- helps to construct porous network structures. Polymers 1-4 show strong ultraviolet luminescence emissions, depending on the pseudohalide ions present, compared to the tpmd ligands. Interestingly, coordination polymers 3 and 4 that possess NCBH3- ions exhibit high porosities and gas sorption properties. The polymers appeared to absorb N2, H2, CO2, and CH4. In the case of polymer 4, the structure is almost identical with that of polymer 3, except for the Cd(II) ion. However, polymer 4 has a larger void volume and higher gas absorption ability for N2 gas than polymer 3. For the sorption of gases, polymers 3 and 4 showed similar behaviors.

Dinuclear Iron(III) and Nickel(II) Complexes Containing N-(2-Pyridylmethyl)-N'-(2-hydroxyethyl)ethylenediamine: Catalytic Oxidation and Magnetic Properties.

Dinuclear FeIII and NiII complexes, [(phenO)Fe(N3 )]2 (NO3 )2 (1) and [(phenOH)Ni(N3 )2 ]2 (2), were prepared by treating Fe(NO3 )3 ⋅9 H2 O and Ni(NO3 )2 ⋅6 H2 O in methanol, respectively, with phenOH (=N-(2-pyridylmethyl)-N'-(2-hydroxyethyl)ethylenediamine) and NaN3 ; both 1 and 2 were characterized by elemental analysis, IR spectroscopy, X-ray diffraction, and magnetic susceptibility measurements. Two ethoxo-bridged FeIII and two azido-bridged NiII were observed in 1 and 2, respectively; corresponding antiferromagnetic interaction via the bridged ethoxo groups and strong ferromagnetic coupling via the bridged end-on azido ligands within the dimeric unit were observed. Complex 1 did not exhibit any catalytic activity, while 2 exhibited excellent catalytic activities for the epoxidation of aliphatic, aromatic, and terminal olefins.

Mononuclear Fe(III) complexes with 2,4-dichloro-6-((quinoline-8-ylimino)methyl)phenolate: synthesis, structure, and magnetic behavior.

Three Fe(III)-based coordination complexes [Fe(dqmp)2](NO3)·H2O (1), [Fe(dqmp)2](BF4)·2CH3COCH3 (2), and [Fe(dqmp)2](ClO4) (3) were synthesized from Fe(NO3)3·9H2O/Fe(ClO4)3·xH2O, NaBF4, and 2,4-dichloro-6-((quinoline-8-ylimino)methyl)phenol (Hdqmp) in methanol/acetone and characterized. The structures of complexes 1-3 were determined via single-crystal X-ray crystallography at 100 K and room temperature, and their magnetic properties in the solid and solution forms were investigated. All complexes showed meridional structures with two tridentate dqmp- ligands coordinated with Fe(III) cations. In the solid state, complex 1 showed an abrupt and complete spin crossover at 225 K, whereas complexes 2 and 3 exhibited an incomplete spin crossover at 135 and 150 K, respectively. In a dimethylformamide solution, the complexes showed counterion-dependent spin transitions. In contrast to the solid state, in solution, complex 1 did not exhibit complete spin crossover. However, complexes 2 and 3 showed more complete spin transitions in solutions than in the solid state. The relaxation times, T1 and T2, for 1 and 2 were determined and both increased with temperature from 220 to 380 K. The T1 of 1 was larger than that of 2 at 380 K, and the T1 values were larger than the T2 values.

Weak ferromagnetic ordering of the Li(+)[TCNE](•-) (TCNE = tetracyanoethylene) organic magnet with an interpenetrating diamondoid structure.

Li[TCNE] (TCNE = tetracyanoethylene) magnetically orders as a weak ferromagnet (canted antiferromagnet) below 21.0 ± 0.1 K, as observed from the bifurcation of the field-cooled and zero-field-cooled magnetizations, as well as remnant magnetization. The structure, determined ab initio from synchrotron X-ray powder diffraction data, consists of a planar µ4-[TCNE](•-) bound to four tetrahedral Li(+) ions. The structure consists of two interpenetrating diamondoid sublattices, with closest interlattice distances of 3.43 and 3.48 Å. At 5 K this magnetic state is characterized by a coercivity of ~30 Oe, a remnant magnetization of 10 emu·Oe/mol, and a canting angle of 0.5°.

Three-dimensional Zinc(II) and cadmium(II) coordination frameworks with N,N,N',N'-tetrakis(pyridin-4-yl)methanediamine: structure, photoluminescence, and catalysis.

Coordination polymer networks, i.e., [Zn(tpmd)(H2O)](NO3)2·7H2O (1) and [Cd(tpmd)(H2O)2](NO3)2·4H2O·4CH3OH (2), were assembled from M(II)(NO3)2 hydrates (M = Zn, Cd) and N,N,N',N'-tetrakis(pyridin-4-yl)methanediamine (tpmd) in CH3OH and characterized. 1 and 2 feature three-dimensional networks formed by coordination of the metal ions to the tpmd ligands. 1 exhibits a strong blue emission at ∼397 nm, while 2 shows strong emission at ∼361 nm. 1 is a more efficient catalyst for the transesterification of various esters than 2.

Synthesis and chiral recognition of nickel(II) macrocyclic complex with (R)-naphthylethyleneamine pendant groups and its self-assembled framework.

A novel nickel(II) hexaaza macrocyclic complex, [Ni(L(R,R))](ClO(4))(2) (1), containing chiral pendant groups was synthesized by an efficient one-pot template condensation and characterized (L(R,R) ═1,8-di((R)-α-methylnaphthyl)-1,3,6,8,10,13-hexaazacyclotetradecane). The crystal structure of compound 1 was determined by single-crystal X-ray analysis. The complex was found to have a square-planar coordination environment for the nickel(II) ion. Open framework [Ni(L(R,R))](3) [C(6)H(3)(COO)(3)](2) (2) was constructed from the self-assembly of compound 1 with deprotonated 1,3,5-benzenetricarboxylic acid, BTC(3-). Chiral discrimination of rac-1,1'-bi-2-naphthol and rac-2,2,2-trifluoro-1-(9-anthryl)ethanol was performed to determine the chiral recognition ability of the chiral complex (1) and its self-assembled framework (2). Binaphthol showed a good chiral discrimination on the framework (2). The optimum experimental conditions for the chiral discrimination were examined by changing the weight ratio between the macrocyclic complex 1 or self-assembled framework 2 and racemates. The detailed synthetic procedures, spectroscopic data including single-crystal X-ray analysis, and the results of the chiral recognition for the compounds are described.

Supramolecular interactions of terpyridine-derived cores of metallomesogen precursors.

Use of Hirshfeld surfaces calculated from crystal structure determinations on various transition metal ion complexes of three terpyridine ligands carrying trimethoxyphenyl substituents has enabled an assessment of the contribution made by the ligand components to the interactions determining the lattice structures, interactions expected also to be present in metallomesogens derived from similar ligands. The form of the link joining the trimethoxyphenyl substituent to the 4' position of 2,2';6',2''-terpyridine is of some importance. In the case of the Co(II) complexes of two of the ligands, their spin-crossover characteristics can be rationalised in terms of the different interactions seen in their lattices.

N,N,N',N'-Tetra-kis(pyridin-4-yl)methane-diamine monohydrate.

In the title compound, C(21)H(18)N(6)·H(2)O, two 4,4'-dipyridyl-amine groups are linked by a methyl-ene C atom, which sits on a twofold axis. The lattice water mol-ecule is located slightly off a twofold axis, and is therefore disordered over two positions. In the crystal, the organic mol-ecules and the water mol-ecule are linked by O-H⋯N hydrogen bonds. The organic mol-ecules exhibit extensive offset face-to-face π-π inter-actions to symmetry equivalents [centroid-centroid distances = 3.725 (3) and 4.059 (3) Å].

Air oxidation-induced single-crystal-to-single-crystal transformation of mixed-valence tetranuclear Fe(II)-Fe(III) complexes.

A mixed valence tetranuclear iron complex [(Hpmide)FeII(NCSe)2FeIII(pmide)]2·5CH3OH (1) underwent oxidation and ligand exchange in the solid state (H2pmide = N-(2-pyridylmethyl)iminodiethanol). Upon air oxidation, 1 was converted into [(pmide)FeIII(NCSe)FeIII(pmide)]2(NCSe)2·2H2O (2), which was accompanied by deprotonation and ligand exchange through a single crystal-to-single-crystal transformation.

Acetonitrile-{3-[bis-(2-pyridyl-methyl-κN)amino-κN]propanol-κO}(perchlorato-κO)copper(II) perchlorate.

In the title compound, [Cu(ClO(4))(C(2)H(3)N)(C(15)H(19)N(3)O)]ClO(4), the Cu(II) ion is coordinated by three N atoms and a hydroxyl-O atom of the tetra-dentate ligand, an O atom of a perchlorate ion and an N atom of an acetonitrile ligand giving a tetra-gonally distorted octa-hedral environment around the copper(II) atom. There is an offset inter-complex face-to-face π-π inter-action [centroid-centroid distance = 3.718 (2) Å] involving one of the pyridine rings of the ligand as well as an intra-complex O-H⋯O hydrogen-bonding inter-action between the coordinated hydroxyl group of the ligand and the perchlorate counter-ion.

Diazido-{(S)-1-phenyl-N,N-bis-[(2-pyrid-yl)meth-yl]ethanamine}-copper(II).

In the title compound, [Cu(N(3))(2)(C(20)H(21)N(3))], the Cu(II) ion is coordinated by the three N atoms of the (S)-1-phenyl-N,N-bis-[(2-pyrid-yl)meth-yl]ethanamine ligand and two N atoms from two azide anions, resulting in a distorted square-pyramidal environment. A weak inter-molecular C-H⋯N hydrogen-bonding inter-action between one pyridine group of the ligand and an azide N atom of an adjacent complex unit gives a one-dimensional chain structure parallel to the c axis.

Magnetism in a helicate complexes arising with the tetradentate ligand.

The synthesis of [M(dimphen)(NCS)2] (1; M = FeII), (2; M = CoII), (3; M = MnII) and [Fe(dimphen)(NCSe)2] (4), where dimphen = [1,2-bis(9-methyl-1,10-phenanthrolin-2-yl)ethane], are reported. The crystal packing structures of 1-3, show intermolecular π-π stacking and NCSSCN interactions. The complex 1 shows ferromagnetic interaction, and the complex 2 displays single-molecular magnet behaviour.

Self-assembly and chiral recognition of a two-dimensional coordination polymer from a chiral nickel(II) macrocyclic complex and trimesic acid.

A two-dimensional chiral open framework, [Ni(L(R,R))](3)[C(6)H(3)(COO)(3)](2).12H(2)O.CH(3)CN (3), is prepared from a nickel(II) macrocyclic complex with chiral pendants and benzenetricarboxylate in MeCN/H(2)O and characterized [L(R,R) = 1,8-bis[(R)-alpha-methylbenzyl]-1,3,6,8,10,13-hexaazacyclotetradecane]. The open framework shows selective chiral recognition by interactions between the solid 3 and rac-1,1'-bi-2-naphthol.

Anomalous non-Prussian blue structures and magnetic ordering of K(2)Mn(II)[Mn(II)(CN)(6)] and Rb(2)Mn(II)[Mn(II)(CN)(6)].

The reaction of Mn(II) and KCN in aqueous and non-aqueous media leads to the isolation of three-dimensional (3-D) Prussian blue analogues, K(2)Mn[Mn(CN)(6)] (1a-d, 1e, respectively). Use of RbCN forms Rb(2)Mn[Mn(CN)(6)] (2). 1 and 2 are isomorphic {monoclinic, P2(1)/n: 1 [a = 10.1786(1) A, b = 7.4124(1) A, c = 6.9758(1) A, beta = 90.206(1)(o)]; 2 [a = 10.4101(1) A, b = 7.4492(1) A, c = 7.2132(1) A, beta = 90.072(1)(o)]}, with a small monoclinic distortion from the face centered cubic (fcc) structure that is typical of Prussian blue structured materials that was previously reported for K(2)Mn[Mn(CN)(6)]. Most notably the average Mn-N-C angles are 148.8 degrees and 153.3 degrees for 1 and 2, respectively, which are significantly reduced from linearity. This is attributed to the ionic nature of high spin Mn(II) accommodating a reduced M-CN-M' angle and minimizing void space. Compounds 1a,b have a sharp, strong nu(OH) band at 3628 cm(-1), while 1e lacks a nu(OH) absorption. The nu(OH) absorption in 1a,b is attributed to surface water, as use of D(2)O shifts the nu(OH) absorption to 2677 cm(-1), and that 1a-e are isostructural. Also, fcc Prussian blue-structured Cs(2)Mn[Mn(CN)(6)] (3) has been structurally [Fm3m: a = 10.6061(1) A] and magnetically characterized. The magnetic ordering temperature, T(c), increases as K(+) (41 K) > Rb(+) (34.6 K) > Cs(+) (21 K) for A(2)Mn[Mn(CN)(6)] in accord with the increasing deviation for linearity of the Mn-N-C linkages [148.8 (K(+)) > 153.3 (Rb(+)) > 180 degrees (Cs(+))], decreasing Mn(II)...Mn(II) separations [5.09 (K(+)) < 5.19 (Rb(+)) < 5.30 A (Cs(+))], and decreasing size of the cation (increasing electrostatic interactions). Hence, the bent cyanide bridges play a crucial role in the superexchange mechanism by increasing the coupling via shorter Mn(II)...Mn(II) separations, and perhaps enhanced overlap. In addition, the temperature dependent magnetic behavior of K(4)[Mn(II)(CN)(6)].3H(2)O is reported.

{3-[Bis(2-pyridyl-methyl-κN)amino-κN]propanol}bis-(nitrato-κO)copper(II).

In the title compound, [Cu(NO(3))(2)(C(15)H(19)N(3)O)], the Cu(II) ion is coordinated by the N atoms of the tetra-dentate 3-[bis-(2-pyridyl-meth-yl)amino]-propanol ligand and two O atoms from two monodentate nitrate anions, resulting in a distorted square-pyramidal environment. An inter-molecular O-H⋯O hydrogen-bonding inter-action between the free hy-droxy group of the ligand and a nitrate O atom of an adjacent complex unit, gives a chain structure which extends across the (101) planes.

trans-{1,8-Bis[(S)-1-phenyl-eth-yl]-1,3,6,8,10,13-hexa-aza-cyclo-tetra-deca-ne}bis(thio-cyanato--κN)copper(II).

In the title thio-cyanate-coordinated aza-macrocyclic copper(II) complex, [Cu(NCS)(2)(C(24)H(38)N(6))], the Cu(II) atom is coordinated by the four secondary N atoms of the aza-macrocyclic ligand and by the two N atoms of the thio-cyanate ions in a tetra-gonally distorted octa-hedral geometry. The average equatorial Cu-N bond length is shorter than the average axial Cu-N bond length [2.010 (2) and 2.528 (4) Å, respectively]. An N-H⋯N hydrogen-bonding inter-action between the secondary amine N atom and the adjacent thio-cyanate ion leads to a polymeric chain along the a axis.

Two-dimensional square-grid iron(ii) coordination polymers showing anion-dependent spin crossover behavior.

Two Fe(ii)-based coordination polymers [Fe(tpmd)2(NCS)2]·5.5H2O (1) and [Fe(tpmd)2(NCSe)2]·7H2O (2) with the framework of square-grid type have been assembled from FeSO4·7H2O, N,N,N',N'-tetrakis(pyridin-4-yl)methanediamine (tpmd), and KNCS/KNCSe in methanol and characterized. By utilizing two pyridine groups of a tpmd ligand, 1 and 2 are formed in two-dimensional layered structures through coordination of octahedral iron(ii) ions with the tpmd to NCS-/NCSe- ligands in which they have a supramolecular isomorphous conformation. 1 shows a paramagnetic behavior between 2 and 300 K, while 2 exhibits two-step spin crossover (ca. 145 and 50 K) in the temperature range due to the coordination of NCSe- ligands. At 300 K 2 is fully high-spin state. However, at 100 K 2 becomes ca. 50% high spin and 50% low spin iron(ii) ions, which is verified by magnetic moments. In the structural analysis of 2 at 100 K, two different layers are observed with different bond distances around iron(ii) ions in which the layers are stacked alternately.

Observation of redox-induced electron transfer and spin crossover for dinuclear cobalt and iron complexes with the 2,5-di-tert-butyl-3,6-dihydroxy-1,4-benzoquinonate bridging ligand.

Dinuclear [(TPyA)M(II)(DBQ(2-))M(II)(TPyA)](BF(4))(2) [TPyA = tris(2-pyridylmethyl)amine; DBQ(2-) = 2,5-di-tert-butyl-3,6-dihydroxy-1,4-benzoquinonate; M = Co (1(2+)), Fe (2(2+)), Ni (3(2+))] complexes have been prepared by the reaction of M(2+), TPyA, H(2)DBQ, and triethylamine in MeOH solution. Their monooxidized form [(TPyA)M(III)(DBQ(*3-))M(III)(TPyA)](3+) [Co = (1(3+)), Fe (2(3+))] has been synthesized by using ferrocenium tetrafluoroborate, and the dioxidized form of 1(2+), [(TPyA)Co(III)(DBQ(2-))Co(III)(TPyA)](4+) (1(4+)), has been obtained by using thianthrinium tetrafluoroborate. These dinuclear compounds were characterized by X-ray crystallography, electrochemistry, magnetism, and EPR spectroscopy. Valence ambiguous 1(3+) forms via redox-induced electron transfer, whereby the one-electron oxidation of the [Co(II)(DBQ(2-))Co(II)](2+) core forms [Co(III)(DBQ(*3-))Co(III)](3+), and it also exhibits spin crossover behavior to the core [Co(III)(DBQ(2-))Co(II)](3+) above room temperature. The M ions in 1 and 2 have a distorted octahedral geometry by coordination with four nitrogens of a TPyA, two oxygens of a DBQ(2-/*3-). Due to the interdimer offset face-to-face pi-pi and/or herringbone interactions, 1(2+), 1(3+), and 2(2+) show extended 1-D and/or 2-D supramolecular structures. The existence of DBQ(*3-) in 1(3+) is confirmed from both solid-state magnetic and solution EPR data. Co- and Ni-based 1(2+) and 3(2+) show weak antiferromagnetic interactions [1(2+): g = 2.44, J/k(B) = -3.20 K (-2.22 cm(-1)); 3(2+): g = 2.13, J/k(B) = -3.22 K (-2.24 cm(-1)), H = -2JS(1)*S(2) for 1(2+) and 3(2+)], while Fe-based 2(2+) exhibits strong spin crossover behavior above room temperature. 1(2+) has three reversible one-electron transfer waves at E(1/2) (vs SCE in MeCN) = -1.121, 0.007, and 0.329 V, and a fourth wave at -1.741 V that exhibits a slight chemical irreversibility. The first three correspond to [Co(II)DBQ(2-)Co(II)](2+) reduction to [Co(II)DBQ(*3-)Co(II)](+), and oxidation to [Co(III)DBQ(*3-)Co(III)](3+) and [Co(III)DBQ(2-)Co(III)](4+), respectively. The mechanism of the multielectron transfer oxidation from [Co(II)DBQ(2-)Co(II)](2+) to [Co(III)DBQ(*3-)Co(III)](3+) is unknown; the energy of stabilization for oxidizing the Co(II) centers in the presence of DBQ(*3-), relative to oxidizing the Co(II) centers in the presence of DBQ(2-) is computed to be 1.45 eV. 2(2+) also has three reversible one-electron transfer waves at 0.802, 0.281, and -1.007 V that correspond to two successive one-electron oxidations (2(2+)/2(3+) and 2(3+)/2(4+)), and a one-electron reduction (2(2+)/2(+)). 2(2+) has the [Fe(hs)(II)(DBQ(2-))Fe(hs)(II)](2+) electronic structure that becomes [Fe(hs)(III)(DBQ(*3-))Fe(hs)(III)](3+) upon oxidation. The latter undergoes spin crossover above room temperature to populate the [Fe(hs)(III)(DBQ(2-))Fe(hs)(II)](3+) excited state.

Tristability arising from singlet-triplet and quartet spin states for dimeric Co(II)salen.

The magnetic behavior of N,N'-ethylenebis(salicylideniminato)cobalt(II) (Co(II)Salen, 1) has been reinvestigated and reveals spin-crossover behavior above 295 K. It has a singlet ground state and a triplet excited state at 30 K (21 cm(-1); 60 cal/mol) above the ground state, and at a higher temperature spin crossover to the quartet, a second excited state occurs.

trans-{1,8-Bis[(R)-α-methyl-benz-yl]-1,3,6,8,10,13-hexa-azacyclo-tetra-deca-ne}dithio-cyanato-nickel(II).

The title compound, [Ni(NCS)(2)(C(24)H(38)N(6))], is a thio-cyanate-coordinated aza-macrocyclic nickel(II) complex. There are two independent mol-ecules in the asymmetric unit and their bond lengths and angles are similar. Both Ni atoms have a tetra-gonally distorted octa-hedral geometry, in which the Ni(II) ion is coordinated by the four secondary N atoms of the aza-macrocyclic ligand and by two N atoms of the thio-cyanate ions. The average equatorial Ni-N bond lengths are shorter than the average axial Ni-N bond lengths [2.071 (1) and 2.115 (2) Å, respectively]. N-H⋯S hydrogen-bonding inter-actions between a secondary amine N atom and the adjacent thio-cyanate ion leads to a polymeric chain along [100].