Copper Chloride Catalysis: Do μ4-Oxido Copper Clusters Play a Significant Role?

Copper chloride catalysis is a well-established field in organic and inorganic chemistry. However, in most cases a detailed mechanistic understanding of the individual reaction steps and identification of reactive intermediates are still missing. The present study reports the results of spectroscopic and spectrometric measurements that support formation of copper agglomerates during catalytic processes.

Hexacoordinate Ru-based olefin metathesis catalysts with pH-responsive N-heterocyclic carbene (NHC) and N-donor ligands for ROMP reactions in non-aqueous, aqueous and emulsion conditions.

Three new ruthenium alkylidene complexes (PCy3)Cl2(H2ITap)Ru=CHSPh (9), (DMAP)2Cl2(H2ITap)Ru=CHPh (11) and (DMAP)2Cl2(H2ITap)Ru=CHSPh (12) have been synthesized bearing the pH-responsive H2ITap ligand (H2ITap = 1,3-bis(2',6'-dimethyl-4'-dimethylaminophenyl)-4,5-dihydroimidazol-2-ylidene). Catalysts 11 and 12 are additionally ligated by two pH-responsive DMAP ligands. The crystal structure was solved for complex 12 by X-ray diffraction.

Synthesis of 1,4,7,10-tetra-azacyclododecan-1,4,7,10-tetra-azidoethylacetic acid (DOTAZA) and related "clickable" DOTA derivatives.

Herein, we report the synthesis of two enantiomeric DOTAZA esters and a related DOT3AZA ester. These compounds are tunable analogues of the well-known chelator DOTA and can be easily functionalized through click chemistry of the side-chain azide groups. Like DOTA, DOTAZA forms complexes with various di- and trivalent metals, as demonstrated in the synthesis and structural analysis of CuDOTAZA and the preparation of GdDOTAZA.

Reactions of copper(II) chloride in solution: facile formation of tetranuclear copper clusters and other complexes that are relevant in catalytic redox processes.

Mixing CuCl2⋅2 H2O with benzylamine in alcoholic solutions led to an extremely colorful chemistry caused by the formation of a large number of different complexes. Many of these different species could be structurally characterized. These include relatively simple compounds such as [Cu(L(1))4Cl2] (L(1) = benzylamine) and (HL(1))2[CuCl4].

Salicylamide and salicylglycine oxidovanadium complexes with insulin-mimetic properties.

Reaction of N-(2-hydroxybenzyl)-N-(2-picolyl) glycine (H(2)papy) with VOSO(4) in water gives the oxidovanadium(V) oxido-bridged dimer [{(papy)(VO)}(2) μ-O)] (1). Similarly, reaction of N-(2-hydroxybenzyl) glycine (H(2)glysal) with VOSO(4) gives [(glysal)VO(H(2)O)] (2) and reaction of salicylamide (Hsalam) with VOSO(4) in methanol gives [(salam)(2)VO] (3). The crystal structure of the oxido-bridged complex 1 is reported.

Hexakis(tetra-aqua-sodium) deca-vanadate(V) dihydrate.

The title compound, {[Na(H(2)O)(4)](6)[V(10)O(28)]·2H(2)O}(n), crystallized from a H(2)O/THF/CH(3)CN solution (pH ca 6) containing equimolar amounts of NaVO(3) and N-(2-hydroxy-benz-yl)-N-(2-picol-yl)glycine. In the crystal structure, the deca-vanadate [V(10)O(28)](6-) anion ( symmetry) is coordinated, via four terminal oxide ligands of V centres, to two dinuclear [{Na(H(2)O)(3)}(2)(μ-H(2)O)(2)](2+) units. Inter-connection of these aquasodium-ion-sandwiched deca-vanadates to chains parallel to [001] is effected by μ-[{Na(H(2)O)(3)}(2)(μ-H(2)O)(2)](2+) units, bridging adjacent deca-vanadates via O=V.

Tris(dimethylamino)oxosulfonium difluorotrimethylsilicate, (Me(2)N)(3)SO(+)Me(3)SiF(2)(-) (TAOS Fluoride).

In the OSF(4)/Me(2)NSiMe(3) system besides the long known Me(2)NS(O)F(3) only the trisubstituted derivative is isolated as (Me(2)N)(3)SO(+)Me(3)SiF(2)(-) (3). Similar to (Me(2)N)(3)S(+)Me(3)SiF(2)(-) compound 3 is an excellent fluoride ion donor. With AsF(5) and HF the corresponding hexafluoroarsenate (Me(2)N)(3)SO(+)AsF(6)(-) (4) and the hydrogen bifluoride (Me(2)N)(3)SO(+)HF(2)(-) (5) are formed in almost quantitative yield.

Syntheses and Structures of Bis(azole)difluorosulfuranes.

Bis(imidazole)sulfur difluoride (4), bis(pyrazole)sulfur difluoride (6), and bis(1,2,4-triazole)sulfur difluoride (8) are formed in the reactions of N-(trimethylsilyl)imidazole, N-(trimethylsilyl)pyrazole, and 1-(trimethylsilyl)-1,2,4-triazole with SF(4), in high yield. The ring systems in these three molecules occupy equatorial positions in the pseudo-trigonal-bipyramidal coordination sphere of the central sulfur atoms. The angles between the planes of the ring substituents and the FSF axis for 4 and 6 are in the range 23.