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  • Author: Berthold Kersting x
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The syntheses of N-alkylated derivatives of the arenethiol 4-tert-butyl-2,6-(diaminomethyl)- thiophenol and their coordination properties are reported. Compounds 4-tert-butyl-2,6-di(N-isopropyl- aminomethyl)thiophenol (3) and 4-tert-butyl-2-(N-isopropyl-aminomethyl)-6-hydroxymethylthiophenol (6 ) react with Ni(II) salts to give compounds of composition [Ni(3)2]·2HCl (7) and [Ni(6)2] (8). The solid- and solution-state structures of both complexes consist of mononuclear complexes with four-coordinate nickel(II) ions in approximately planar trans- N2S2 coordination environments. In contrast to the parent arenethiol 4a, the sterically more encumbered ligands do not form dinuclear complexes.

Abstract

Metalation of 2,6-Dimethyl-4-tert-butyl-thiophenol (6) with n-BuLi/TMEDA in THF occurs regioselectively at the benzylic positions to produce lithium 2,6-di(lithiomethyl)-4-tert-butyl-benzenethiolate (7). Treatment of compound 7 with elem ental sulfur followed by iodine-oxidation affords an oxidation product 9a of bis(sulfanylmethyl)- 4-tert-butyl-thiophenol (5).

Abstract

The crystal structures of 2-isopropyl-benzisothiazol-3-one-7-carboxylicacid isopropyl amide and of the corresponding selenium and tellurium derivatives have been determined. In contrast to the sulfur and selenium compounds, the tellurium derivative has an unprecedented three-dimensional network structure held together via π-π stacking and hydrogen bonding interactions. The cavities in the 3D molecular network are filled with guestwater molecules that are hydrogen bonded to carbonyl oxygen atoms.

Abstract

The heterocyclic selenium(IV) oxide LSeO is reduced by [Pd(COD)Cl2] in MeCN solution to produce trans- [Pd(LSe)2Cl2] (2) (LSe = 2,3-dihydro-2-isopropyl-7-(Nisopropylcarbamoyl)- 1,2-benzisoselenazole-3-oxide). Complex 2 crystallizes in the triclinic space group P1̅ with a = 10.700(1), b = 10.871(1), c = 15.656(2) Å , α = 104.51(1), β = 94.59(1), γ = 95.25(1), V = 1745.5(3) Å3, and Z = 2. The COD is oxidized to 5,6-epoxycyclooctene.

Abstract

A short and efficient multi-gram synthesis of the title compound has been designed which al­lows its preparation from commercially available material in only three steps in overall yields of 60-70 % .

Abstract

The syntheses and characterization of tetranuclear Ni complexes [(L2)Ni4][ClO4]4 (3) and [(L2)Ni4(NCS)4] (4) of a 40-membered macrocyclic octaamine-tetrathiophenolate ligand (L2)4- are described. Single-crystal X-ray structure analysis of 4 reveals well-separated molecules of the tetranuclear isothiocyanate complex [(L2) NiII 4(NCS)4]. The four NiII centers are arranged in binuclear [N2Ni(μ2-SR)2NiN2(NCS)2] subunits containing distorted square-planar NiN2S2 and distorted octahedral NiN2S2(NCS)2 sites. The fact that the two isothiocyanate groups at the octahedral Ni site are in trans positions can be ascribed to the large ring size of the macrocycle

A short route for the preparation of tetradentate amine-thioether and amine-thiolate ligands derived from thiosalen is reported. The ligating properties of several of the synthesized ligands towards Ni(II) has been examined. The diamine-dithiophenolate ligands (L6)2− [H2L6 = N,N′-dimethyl-N,N;-di(2- mercaptobenzyl)-ethane-1,2-diamine] and (L7)2− [H2L7 = N,N′-di(2-mercaptobenzyl)-piperazine] support the formation of four-coordinate NiIIN2S2 complexes [NiII(L6)] (10) and [NiII(L7)] (11). By contrast, the amine-thioethers 2 [N′,N″-bis(2-(tert-butylthio)benzyl)ethane-1,2-diamine], L2 [8,11- diaza-5,13-dibenzo-1,4-dithia-cyclotetradecane] and its N-methylated derivative L2,Me were found to produce the six-coordinate Ni(II) complexes [NiIICl2(2)2] (9), [NiII 2(μ-Cl)2(L2)2][ClO4]2 (12), [NiII(NCS)2(L2)] (13), and [NiIICl2(L2,Me)] (14). The results of IR, NMR and UV/vis spectroscopy and the crystal structures of complexes 9 - 13 are reported.

Abstract

The preparation, characterization and the molecular structure of a dinuclear uranyl complex [(UO2)2L(OCMe2)2] supported by the bis-salophen ligand N,N′,N″,N′″-tetra-(3,5-di-tert-butylsalicylidene)-1,2,4,5-phenylenetetraamine (L4–) is described. [(UO2)2L(OCMe2)2] was prepared by reaction of uranyl nitrate with the neutral, protonated form of the ligand (H4L) in acetone. From a saturated acetone solution [(UO2)2L(OCMe2)2]·1.5(OCMe2) crystallizes triclinically, space group P1̅ with a = 1522.7(2), b = 1751.4(2), c = 1815.4(2) Å, α = 109.16(1), β = 99.29(1), γ = 105.29(1)° and Z = 2. Each uranium atom is surrounded in a distorted pentagonal bipyramidal fashion by two O and two N atoms of the salicylidene units, one O atom of an acetone ligand, and the two oxo groups. The cyclic voltammogram of [(UO2)2L(OCMe2)2] shows two quasi-reversible redox processes centered at +0.57 V and +0.82 V vs. Fc+/Fc attributed to the sequential oxidation of the coordinating phenolates to phenoxyl radicals. The crystal structure of an ethanol solvate of H4L was also determined by X-ray crystallography. H4L·5EtOH: triclinic, space group P1̅, a = 1003.4(3), b = 1187.7(3), c = 1905.1(5) Å, α = 75.75(2), β = 78.74(2), γ = 66.66(2)°, Z = 1.

The dinuclear nickel(II) complex [Ni2LCl]+ (1), where (L)2− represents a 24-membered macrocyclic hexamine-dithiophenolate ligand, reacts readily with 5-R-tetrazolate ligands to give the complexes [Ni2L(RCN4)]+, where R = H (2), Me (3), Ph (4). The new complexes were either isolated as perchlorate or tetraphenylborate salts and fully characterized by elemental analysis, UV/Vis, and IR spectroscopy. The structures of 2[BPh4] · MeCN, 3[BPh4] · 2MeCN, and 4[BPh4] ·MeCN were determined by X-ray crystallography, showing that all tetrazolate units are in a 2,3-bridging mode to generate dioctahedral N3Ni(μ-S)2(μ-N4CR)NiN3 core structures. The RCN4 groups interact less strongly with the [Ni2L]2+ fragment than pyrazolate ligands (CH)3N2 as reflected in the longer Ni-N distances.

Abstract

The ability of the aromatic tetraaldehyde l,2-bis(4-tert-butyl-2,6-diformylphenylsulfanyl)-ethane (1) to function as a precursor in the preparation of binucleating hexaamine-dithiolate ligands has been investigated. Reductive amination of compound 1 with bis(aminoethyl)amine under medium-dilution conditions affords the macrobicyclic hexaamine-dithioether compound L1. Deprotection of the [1+2] condensation product gives the corresponding 24-membered hexa-amine-dithiophenol ligand H2L2. The formulation of L1 as a macrobicyclic amine-thioether was confirmed by an X-ray crystal structure determination of the tetranuclear nickel(II) complex of L1, [{(L1)Ni2Cl2}2(μ-Cl)3](BPh4) (2b). The formulation of the doubly deprotonated form (L2)2- of H2L2 as a 24-membered amine-thiophenolate ligand was confirmed by an X-ray crystal structure determination of the dinuclear cobalt(III) complex, [(L2)CoIII(μ-OH)](ClO4)2 · Cl (3). The preparation and the crystal structures of the new compounds are described.