Solvents and Ligands Matter: Structurally Variable Palladium and Nickel Clusters Assembled by Tridentate Selenium- and Tellurium-Containing Schiff Bases.

Structurally variable organochalcogen clusters containing palladium(II) and nickel(II) ions were assembled starting from the salicylidene-substituted dichalcogenides (Y-C6H4-N═CH-C6H4-OH)2 ({HLY}2, where Y = Se or Te), and palladium or nickel acetate. The tetrameric palladium clusters contain reduced chalcogenolato ligands {Y-C6H4-N═CH-C6H4-O)}2- ({L'Y}2-, where Y = Se or Te), while the initially formed trimeric nickel clusters contain the intact, coordinated dichalcogenides. The palladium clusters have a general formula of [Pd4(L'Y)4] and represent the first examples of palladium complexes where both a gyrobifastigial and a pseudocubane arrangement of the central Pd4Y4 unit could be established with the same ligand, only depending on the solvents used for crystallization. Reduced density gradient (RDG) considerations based on density functional theory calculations suggest that the commonly referred to stabilizing chalcogen-palladium or palladium-palladium interactions for the two geometric arrangements are weak van der Waals contacts resulting from the contact of two nonbinding lone pairs. In the case of the pseudocubane arrangement, a repulsive steric effect, which is indicated by RDG analysis, is clearly supported by the cuplike distortions detected in the solid-state structure of the compound. In contrast to the reactions with palladium acetate, where the dichalcogenides were cleaved, during similar reactions with nickel acetate, the dichalcogenides remained intact and trimeric clusters of the composition [Ni-µ2-κ2-(Ni{κ5-LY}2)2-µ2-(OAc)2] (Y = Se, Te) were formed. Air oxidation and hydrolysis of [Ni-µ2-κ2-(Ni{κ5-LTe}2)2-µ2-(OAc)2] gave a rare example of a hexanuclear nickel cluster of the composition [Ni2-κ5-(Ni4-κ6-µ6-{(L'Te2O3)(L'TeO2)2}2)-µ2-(H2O)2], which is composed of a well-defined framework consisting of tellurinic anhydride and tellurinate units, which proves the comparably higher oxidation sensitivity of the trinickel dichalcogenide complexes. Electron spray ionization mass spectrometry spectra of both the palladium and nickel clusters indicate that they show fluctional behavior with varying nuclearity in solution and can adopt multiple charge states especially because of the noninnocence of the chalcogen-based ligands. The complexes were fully characterized by spectroscopic methods, elemental analyses, and X-ray diffraction.

Large Telluroxane Bowls Connected by a Layer of Iodine Ions.

Phenyltelluroxane clusters of the composition [{(PhTe)19 O24 }2 I18 (solv)] (1) are formed during the hydrolysis of [PhTeI3 ]2 or the oxidation of various phenyltellurium(II) compounds with iodine under hydrolytic conditions. The compounds consist of two half-spheres with a {(PhTe)19 O24 }9+ network, which are connected by 18 iodine atoms. The spherical clusters can accommodate solvent molecules such as pyridine or methanol in the center of two rings formed by iodine atoms. The presence of other metal ions during the cluster formation results in a selective replacement of the central {PhTe}3+ units of each half-sphere as has been demonstrated with the isolation of [{(PhTe)18 ({Ca(H2 O)2 }O24 }2 I16 ] (2) and [{(PhTe)18 ({Y(NO3 )(H2 O)}O24 }2 I16 ] (3). A crownether-like coordination by six oxygen atoms of the telluroxane network is found for the {Ca(H2 O}2 }2+ and {Y(NO3 )(H2 O)}2+ building blocks. Mass spectrometric studies show that considerable amounts of the intact clusters are transferred to the gas phase without dissociation.

Crystal structure of cis-1-phenyl-8-(pyridin-2-ylmeth-yl)dibenzo[1,2-c:2,1-h]-2,14-dioxa-8-aza-1-borabi-cyclo-[4.4.0]deca-3,8-diene.

The title compound, C26H23BN2O2, was obtained as by product during synthetic attempts of a complexation reaction between the tripodal ligand H2L [N,N-bis-(2-hy-droxy-benz-yl)(pyridin-2-yl)methyl-amine] and manganese(III) acetate in the presence of NaBPh4. The isolated B-phenyl dioxaza-borocine contains an N→B dative bond with a cis conformation. In the crystal, C-H⋯O hydrogen bonds define chains parallel to the b-axis direction. A comparative analysis with other structurally related derivatives is also included, together with a rationalization of the unexpected production of this zwitterionic heterocycle.

Intermolecular Pb...N interactions in lead(II) dimers producing a supramolecular two-dimensional metal-organic compound: bis[µ2-N'-(2-oxidobenzylidene)benzohydrazidato-κ(4)O:O,N',O']dilead(II).

Aroylhydrazones of ortho-hydroxy aldehydes are Schiff base ligands that typically coordinate as a chelate in an O,N,O'-manner. Dinuclear complexes are normally observed, with the phenolate O atom acting as the bridging atom. The switchable protonation state of the tridentate N'-(2-hydroxybenzylidene)benzohydrazide (H2sabhz) ligand can lead to variations in the resulting supramolecular structure. The title compound, [Pb2(C14H10N2O2)2], was prepared by the reaction of [Pb(OAc)2]·3H2O (OAc is acetate) with the benzoylhydrazone derivative of salicylaldehyde, i.e. H2sabhz, in the presence of triethylamine in methanol. In the crystal structure, each Pb(II) atom of the dimer has an NO3 coordination environment, with one sabhz ligand coordinating in an O,N,O'-manner and with the second sabhz ligand coordinating via the bridging phenolate O atom, since the dimers are located on a centre of inversion. It has been found that the dimers are connected by Pb...N interactions, resulting in a two-dimensional supramolecular network which shows the [3(2).5(2),3.5(3)] net topology. The s(2) electron pair of the Pb(II) ion clearly influences the observed intermolecular interactions.

[4-amino-N-(pyrimidin-2-yl)benzenesulfonamido-kappaN](triphenylphosphine-kappaP)gold(I).

The title compound, [Au(C(10)H(9)N(4)O(2)S)(C(18)H(15)P)], is nearly linear at Au(I), with Au-N = 2.0707 (18) A, Au-P = 2.2310 (8) A and N-Au-P 171.93 (5) degrees. The molecules are linked by intermolecular N-H...O bonds.