Dehydrocoupling of dimethylamine–borane promoted by manganese(<scp>ii</scp>) <i>m</i>-terphenyl complexes
作者:Helen R. Sharpe、Ana M. Geer、Toby J. Blundell、Fiona R. Hastings、Michael W. Fay、Graham A. Rance、William Lewis、Alexander J. Blake、Deborah L. Kays
DOI:10.1039/c7cy02086d
日期:——
Two- and three-coordinate manganese m-terphenyl complexes are precatalysts for the dehydrogenation of dimethylamine–borane (Me2NH·BH3) affording one equivalent of molecular hydrogen and half an equivalent of [Me2N–BH2]2. Experimental studies into the nature of the catalyst indicate that small changes in the coordination environment give rise to significant differences in the reaction mechanism, occurring
Synthesis and Reactivity of Dimeric Ar‘TlTlAr‘ and Trimeric (Ar‘ ‘Tl)<sub>3</sub> (Ar‘, Ar‘ ‘ = Bulky Terphenyl Group) Thallium(I) Derivatives: Tl(I)−Tl(I) Bonding in Species Ligated by Monodentate Ligands
作者:Robert J. Wright、Andrew D. Phillips、Shirley Hino、Philip P. Power
DOI:10.1021/ja0432259
日期:2005.4.1
The synthesis and characterization of three new organothallium(I) compounds are reported. Reaction of (Ar'Li)(2) (Ar' = C6H3-2,6-(C6H3-2,6-Pr'(2))(2)) and Ar"Li (Ar" = C6H3-2,6-(C6H3-2,6-Me-2)(2)) with TICI in Et2O afforded (Ar'TI)(2) (1) and (Ar"TI)(3) (2). The "dithallene" 1 is the heaviest group 13 dimetallene and features a planar, trails-bent structure with Ar'TI-TI = 119.74(14)degrees and TI-TI = 3.0936(8) angstrom. Compound 2 is the first structurally characterized neutral, three-membered ring species of formula c-(MR)(3) (M = AI-TI; R = organo group). The TI3 ring has TI-TI distances in the range ca. 3.21-3.37 angstrom as well as pyramidal TI geometries. The TI-TI bonds in 1 and 2 are outside the range (2.88-2.97 angstrom) of TI-TI single bonds in R2TITIR2 compounds. The weak TI-TI bonding in 1 and 2 leads to their dissociation into Ar'TI and Ar"TI monomers in hexane. The Ar'TI monomer behaves as a Lewis base and readily forms a 1:1 donor-acceptor complex with B(C6F5)(3) to give Ar'TIB(C6F5)(3), 3. Adduct 3 features an almost linear thallium C(ipso)-TI-B angle of 174.358(7)degrees and a TI-B distance of 2.311(2) angstrom, which indicates strong association. Treatment of 1 with a variety of reagents resulted in no reactions. The lower reactivity of 1 is in accord with the reluctance of TI(I) to undergo oxidation to TI(III) due to the unreactive character of the 6s(2) electrons.