Synthesis, X-ray structures and luminescence properties of three multidimensional metal-organic frameworks incorporating the versatile 5-(pyrimidyl)tetrazolato bridging ligand.

The hydrated sodium salt of the novel and versatile 5-(pyrimidyl)tetrazolato ligand (pmtz(-)), Na(pmtz).H(2)O (1), has been prepared in very mild conditions from 2-cyanopyrimidine and NaN(3). Two coordination polymers [Cd(pmtz)(2)]n (2)and [Cd(pmtz)(micro-Cl)(0.5)(micro-N(3))(0.5)(H(2)O)](n)(3), , have been synthesized from (1)under conventional or hydrothermal conditions, respectively, and fully characterized by single-crystal or powder X-ray diffraction methods. Compounds and consist of mono-dimensional polymeric chains, further stabilized by interchain pi-pi stacking and hydrogen bond interactions. Compound , containing octacoordinated Cd ions of crystallographic D(2) symmetry, exhibits neutral (4, 4) layers formed by square units of the metallacalix[4]arene type in 1,3-alternate conformation. Species , and display intense, room temperature, photoluminescence in the solid state.

Hexacyanocobaltate(III) anions as precursors of Co(II)-Ni(II) cyano-bridged multidimensional assemblies: hydrothermal syntheses, crystal and powder X-ray structures, and magnetic properties.

Three novel cyanide-bridged heterobimetallic coordination polymers have been synthesized by hydrothermal routes, in superheated water solutions, by using K3[Co(CN)6], NiCl2.6H2O, and alpha-diimine ligands: [Ni(CN)4Co(phen)] (1; phen = 1,10-phenanthroline), [Ni(CN)4Co(2,2'-bipy)] (2; 2,2'-bipy = 2,2'-bipyiridine), and [Ni(CN)4Co(2,2'-bipy)2] (3). The isostructural compounds 1 and 2 contain a two-dimensional network with Co(II) centers octahedrally coordinated by one chelating 2,2'-bipy ligand and four cyanide groups of four distinct [Ni(CN)4]2-, through crystallographically equivalent, bridging units. Compound 3 contains one-dimensional zigzag chains in which the Co(II) ion is coordinated by two chelating 2,2'-bipy ligands and two cyanides from two different [Ni(CN)4]2- units cis to each other. These compounds have been fully characterized by single-crystal or unconventional powder X-ray diffraction analyses and variable-temperature magnetic measurements.

Extended polymorphism in copper(II) imidazolate polymers: a spectroscopic and XRPD structural study.

Copper(II) bisimidazolate affords five different polymorphs; of these, one was structurally characterized 40 years ago by standard single-crystal X-ray diffraction (Jarvis, J. A. J.; Wells, A. F. Acta Crystallogr. 1960, 13, 1027), while the remaining four, selectively prepared as pure polycrystalline phases, have been now studied by X-ray powder diffraction (XRPD) methods. Of the four new (blue, green, olive-green, and pink) phases, three were solved by the ab initio XRPD technique and refined by the Rietveld method, and the fourth phase (pink) could not be structurally characterized. Crystal data for [Cu(imidazolate)(2)](n): blue phase, a = 27.559(3) A, c = 5.3870(9) A, trigonal, R3 macro, Z = 54; green phase, a = 21.139(1) A, b = 19.080(1) A, c = 9.2842(8) A, orthorhombic, Ccca, Z = 20; olive-green phase, a = 11.7556(8) A, b = 23.422(2) A, c = 9.0727(9) A, beta = 104.993(5) degrees, monoclinic, C2/c, Z = 12. All polymorphs contain four-coordinate CuN(4) chromophores and (N,N')-exobidentate imidazolate ligands, but show different spectroscopic and structural properties, the latter ranging from 2D to different 3D networks of the PtS, sodalite, and moganite archetypes. The intermediacy of the [Cu(imidazole)(2)CO(3)]-H(2)O species in the synthesis of the blue polymorph has been confirmed by spectroscopic and thermal analyses. FTIR, Raman, and electronic spectra were correlated with the structural features revealed in the present work, and used to gain insight into the coordination geometry of copper(II) ions of the pink polymorph. In addition, the correct Raman spectrum for copper(II) bisimidazolate, common for all polymorphs, has been definitely determined.

Synthesis and X-ray characterization of the phosphido-carbonyl cluster anions.

The [Co(9)P(CO)(21)](2)(-) anion has been isolated from the products of the reaction between Na[Co(CO)(4)] and PCl(5) in tetrahydrofuran at reflux. The structure of the cluster anion [Co(9)P(CO)(21)](2)(-) in its tetraphenylphosphonium salt has been elucidated by X-ray analysis. The crystals are monoclinic, space group P2(1)/n, a = 12.528(3), b = 14.711(5), c = 19.312(6) A, beta = 93.68(2) degrees, Z = 2. Final R = 0.065 for 2300 unique reflections having I > 3sigma(I). The anion, which is disordered about an inversion center, consists of a monocapped square antiprismatic cluster containing an interstitial phosphide and surrounded by 13 terminal and 8 edge-bridging carbonyl ligands. Average values are: Co-Co 2.685 A, and Co-P 2.256 A. The [Co(10)P(CO)(22)](3)(-) anion has been obtained by condensation of the [Co(9)P(CO)(21)](2)(-) anion with [Co(CO)(4)](-) in tetrahydrofuran at reflux. While the [Co(9)P(CO)(21)](2)(-) anion is stable under CO, the [Co(10)P(CO)(22)](3)(-) anion is decomposed to [Co(9)P(CO)(21)](2)(-) and [Co(CO)(4)](-). The benzyltrimethylammonium salt of the [Co(10)P(CO)(22)](3)(-) anion has been studied by X-ray analysis. It gives triclinic crystals, space group P_1, a = 11.452(3), b = 23.510(6), c = 25.606(4) A, alpha = 112.46(1), beta = 95.79(1), gamma = 73.548(2) degrees, Z = 4. Final R = 0.041 for 8600 unique reflections having I > 3sigma(I). There are two independent trianions in the asymmetric unit, both showing similar geometries, consisting of bicapped square antiprismatic clusters with a central P atom, each bearing 10 terminal and 12 edge-bridging carbonyl ligands, 8 of which, bound to the capping metals, are markedly asymmetric. Average values are: Co-Co 2.678 A, and Co-P 2.262 A. Electrochemistry shows that [Co(9)P(CO)(21)](2)(-) and [Co(10)P(CO)(22)](3)(-) in acetonitrile solution undergo either a one-electron oxidation or a two-electron reduction. This latter process appears as a single step in the case of the dianion and as two separated one-electron steps in the case of the trianion. All the processes are accompanied by slow chemical complications, thus testifying that no stable redox congeners exist for these phosphide clusters.

Metal imidazolato complexes: synthesis, characterization, and X-ray powder diffraction studies of group 10 coordination polymers.

Binary metal imidazolates of the group 10 metals have been prepared and typically found amorphous. However, the intermediacy of a number of (poly)crystalline species during their formation has been evidenced; their selective preparation and characterization, by chemical, spectroscopic, and thermal methods and their structure solution by the ab initio X-ray powder diffraction technique lead to the discovery of new interesting structural features, such as those of polymeric Ni(Him)(2)(im)(CH(3)COO) (Him = imidazole) and of the hydrogen-bonded polymers of general Pd(x)Pt(1-x)(Him)(2)(im)(2) formula (x = 0, 0.5, 1). The latter are built upon 2D frameworks of (pseudo)square meshes, which, in the pure Pd derivative, form an entangled structure based upon interpenetrating 2D layers, coupled in pairs. The different structures are discussed in terms of different conformations of the new "im-H-im" ligand, which acts as monoanionic exobidentate fragment, similar to im, pyrazolate (pz), "pz-H-pz", and pyrimidin-2-olate.

[Pt]

The intermediacy of CO/NO substitution in the condensation of [Pt(19)(CO)(22)](4-) into [Pt(38)(CO)(44)](2-) (structure shown) has been demonstrated. Two high-nuclearity carbonyl metal clusters, including one with an unprecedented nitrosyl ligand, have been synthesized and structurally characterized.