Isolable acetylene complexes of copper and silver.

Copper and silver play important roles in acetylene transformations but isolable molecules with acetylene bonded to Cu(i) and Ag(i) ions are scarce. This report describes the stabilization of π-acetylene complexes of such metal ions supported by fluorinated and non-fluorinated, pyrazole-based chelators. These Cu(i) and Ag(i) complexes were formed readily in solutions under an atmosphere of excess acetylene and the appropriate ligand supported metal precursor, and could be isolated as crystalline solids, enabling complete characterization using multiple tools including X-ray crystallography.

Isolable Copper(I) η-Cyclopropene Complexes.

Treatment of bis(pyrazolyl)borate ligand supported [(CF)Bp]Cu(NCMe) with 1,2,3-trisubstituted cyclopropenes produced thermally stable copper(I) η-cyclopropene complexes amenable to detailed solution and solid-state analysis. The [(CF)Bp]Cu(NCMe) also catalyzed [2 + 1]-cycloaddition chemistry of terminal and internal alkynes with ethyl diazoacetate affording cyclopropenes, including those used as ligands in this work. The tris(pyrazolyl)borate [(CF)Tp]Cu(NCMe) is a competent catalyst for this process as well.

Umpolung -Silylation of Cyclopropyl Acetates via Low-Temperature Catalytic C-C Activation.

We report a redox-neutral, catalytic C-C activation of cyclopropyl acetates to produce silicon-containing five-membered heterocycles in a highly region-and chemoselective fashion. The umpolung -selective silylation leading to dioxasilolanes is opposed to contemporary -selective C-C functionalization protocols of cyclopropanols. Lewis base activation of dioxasilolanes as -silyl carbinol equivalents undergoes the unconventional [1,2]-Brook rearrangement to form tertiary alcohols.

Monoanionic, Bis(pyrazolyl)methylborate [(PhB)CH(3,5-(CH)Pz))] as a Supporting Ligand for Copper(I)-ethylene, cis-2-Butene, and Carbonyl Complexes.

The monoanionic bidentate ligand [(PhB)CH(3,5-(CH)Pz))] has been prepared from lithium bis(pyrazolyl)methanide and triphenylborane. This useful new ligand is closely related to the well-established bis(pyrazolyl)borate and bis(pyrazolyl)methane ligands but has key differences to both analogues as well. The ethylene, cis-2-butene, and carbon monoxide adducts [(PhB)CH(3,5-(CH)Pz)]Cu(L) (where L = CH, cis-CHHC═CHCH, and CO) have been prepared from [(PhB)CH(3,5-(CH)Pz))]Li(THF), copper(I) triflate, and the corresponding coligand.

Fluorinated triazapentadienyl ligand supported ethyl zinc(ii) complexes: reaction with dioxygen and catalytic applications in the Tishchenko reaction.

Ethyl zinc complexes [N{(C3F7)C(Dipp)N}2]ZnEt, [N{(C3F7)C(Cy)N}2]ZnEt, [N{(CF3)C(2,4,6-Br3C6H2)N}2]ZnEt and [N{(C3F7)C(2,6-Cl2C6H3)N}2]ZnEt have been synthesized from the corresponding 1,3,5-triazapentadiene and diethyl zinc. X-ray data show that [N{(C3F7)C(Dipp)N}2]ZnEt has a distorted trigonal planar geometry at the zinc center. The triazapentadienyl ligand binds to zinc in a κ(2)-mode.

Zinc(II)-Mediated Carbene Insertion into C-H Bonds in Alkanes.

The cationic zinc adduct {[HB(3,5-(CF3)2Pz)3]Zn(NCMe)2}ClO4 catalyzes the functionalization of tertiary, secondary, and primary C-H bonds of alkanes via carbene insertion. Ethyl diazoacetate serves as the :CHCO2Et carbene precursor. The counteranion, supporting ligand, and coordinating solvents affect the catalytic activity.

Aggregation kinetics of single-walled carbon nanotubes investigated using mechanically wrapped multinuclear complexes: probing the tube-tube repulsive barrier.

The rational design of supraparticle assemblies requires a detailed understanding of directed assembly processes. The stability of dispersions of nanoscale materials, like single-walled carbon nanotubes (SWCNTs), is still not fully understood, nor are the mechanisms of aggregation and assembly. A detailed balance of attractive van der Waals type interactions with various repulsive barrier mechanisms is needed to control the assembly of industrially viable and functional hybrid-nanoscale supraparticles.