Tracy L. Lohr

Monomeric Platinum(II) Hydroxides Supported by Sterically Dominant α-Diimine Ligands

The use of two new highly sterically bulky α-diimine ligands for the stabilization of neutral, monomeric platinum(II) hydroxo complexes is described. Halide abstraction from LPtCl(2) complexes of these ligands in the presence of water, followed by deprotonation of the cationic aquo complex, leads to LPt(OH)Cl and LPt(OH)(2). The latter can be reprotonated with HNTf(2) to yield a highly fluxional hydroxoaquoplatinum(II) cation.

Reversible insertion of carbon dioxide into Pt(II)–hydroxo bonds

The reactivity of three monomeric diimine Pt(II) hydroxo complexes, (NN)Pt(OH)R (NN = bulky diimine ligand; R = OH, ; R = C6H5, ; R = CH3, ) towards carbon dioxide has been investigated. Insertion into the Pt-OH bonds was found to be facile and reversible at low temperature for all compounds; the reaction with bis-hydroxide gives an isolable κ(2)-carbonato compound , with elimination of water.

Arene C–H bond activation across Pt(II)–OH bonds: catalyzed vs. uncatalyzed pathways

The monomeric (NN)Pt(OH)2 complex 1 (where NN = a bulky diimine ligand) undergoes sequential C–H bond addition across the Pt oxygen bonds at elevated temperatures in benzene to produce (NN)PtOH(C6H5), 2, and (NN)Pt(C6H5)2, 3, along with two equivalents of water. Several lines of evidence suggest that a slow homogeneous process is superseded by a faster catalysed pathway mediated by in situ produced elemental Pt(0) particles.

Low-Temperature Atomic Layer Deposition of MoS2 Films

Wet chemical screening reveals the very high reactivity of Mo(NMe2 )4 with H2 S for the low-temperature synthesis of MoS2 . This observation motivated an investigation of Mo(NMe2 )4 as a volatile precursor for the atomic layer deposition (ALD) of MoS2 thin films. Herein we report that Mo(NMe2 )4 enables MoS2 film growth at record low temperatures-as low as 60 °C. The as-deposited films are amorphous but can be readily crystallized by annealing. Importantly, the low ALD growth temperature is compatible with photolithographic and lift-off patterning for the straightforward fabrication of diverse device structures.

Efficient catalytic greenhouse gas-free hydrogen and aldehyde formation from aqueous alcohol solutions

Hydrogen is an ideal fuel candidate due to its clean combustion characteristics. Here we report an inexpensive and sustainable Mo-based, carbon-supported catalyst that generates H2 and the corresponding aldehyde from aqueous methanol or ethanol at high rates with negligible greenhouse gas co-production. The aldehyde coproducts lend value to this process without producing CO2.

Scandium-Catalyzed Self-Assisted Polar Co-monomer Enchainment in Ethylene Polymerization

Direct coordinative copolymerization of ethylene with functionalized co-monomers is a long-sought-after approach to introducing polyolefin functionality. However, functional-group Lewis basicity typically depresses catalytic activity and co-monomer incorporation. Finding alternatives to intensively studied group 4 d0 and late-transition-metal catalysts is crucial to addressing this long-standing challenge. Shown herein is that mono- and binuclear organoscandium complexes with a borate cocatalyst are active for ethylene + amino olefin [AO; H2 C=CH(CH2 )n NR2 ] copolymerizations in the absence of a Lewis-acidic masking reagent. Both activity (up to 4.2×102  kg mol-1 ⋅h-1>  atm-1> ) and AO incorporation (up to 12 % at 0.2 m [AO]) are appreciable. Linker-length-dependent (n) AO incorporation and mechanistic probes support an unusual functional-group-assisted enchainment mechanism. Furthermore, the binuclear catalysts exhibit enhanced AO tolerance and enhanced long chain AO incorporation.

N,N′-Bis[3,5-bis­(2,6-diisopropyl­phen­yl)phen­yl]butane-2,3-diimine

The title molecule, C64H80N2, lies on an inversion center wherein the central butanediimine fragment [N=C(Me)—C(Me)=N] is essentially planar [maximum deviation = 0.002 (2) Å] and its mean plane forms a dihedral of 70.88 (10)° with the attached benzene ring. In the symmetry-unique part of the molecule, the dihedral angles between the benzene ring bonded to the N atom and the other two benzene rings are 89.61 (6) and 82.77 (6)°.

1,2-Bis{[3,5-bis-(2,6-diisopropyl-phen-yl)phen-yl]imino}-acenaphthene toluene monosolvate.

In the title compound, C72H80N2·C7H8, the acenaphthene ring system is essentially planar, with a maximum deviation of 0.041 (3) Å. The benzene rings bonded to the the N atoms are essentially parallel, forming a dihedral angle of 0.80 (11)°, and these rings form dihedral angles of 87.49 (9) and 88.25 (10)° with the mean plane of the acenaphthene ring system. The methyl C atoms of three of the isopropyl groups are disordered of two sets of sites of equal occupancy.

Correction: Mono- and tri-ester hydrogenolysis using tandem catalysis. Scope and mechanism

Correction for ‘Mono- and tri-ester hydrogenolysis using tandem catalysis. Scope and mechanism’ by Tracy L. Lohr et al., Energy Environ. Sci., 2016, 9, 550–564.

Efficient carbon-supported heterogeneous molybdenum-dioxo catalyst for chemoselective reductive carbonyl coupling

Reductive coupling of various carbonyl compounds to the corresponding symmetric ethers with dimethylphenylsilane is reported using a carbon-supported dioxo-molybdenum catalyst. The catalyst is air- and moisture-stable and can be easily separated from the reaction mixture for recycling. In addition, the catalyst is chemoselective, thus enabling the synthesis of functionalized ethers without requiring sacrificial ligands or protecting groups.