Two heads are better than one:improving magnetic relaxation in the dysprosium metallocene DyCp*₂BPh₄ upon dimerization by use of an exceptionally weakly-coordinating anion

Abstract Partial metathesis between two weakly-coordinating anions in the archetypical dysprosium metallocene DyCp*₂BPh₄ results in the first example of [BPh₄]⁻ as a bridging ligand in 4f metals, with a unique η₂,η₂:η₂,η₂-bridge. Magnetic susceptibility and relaxation dynamics studies along with ab initio calculations reveal improved slow relaxation of the magnetization in [Dy₂Cp*₄(μ-BPh₄)][Al(OC(CF₃)₃)₄] over its mononuclear congener, resulting in an energy barrier of 490 K/340 cm⁻¹ and waist-restricted hysteresis up to 6.5 K

Synthesis and Reactivity of Mn–CF3 Complexes

The synthesis, characterization and reactivity of several bi- and tridentate, N-ligated manganese carbonyl trifluoromethyl complexes are presented. These complexes exhibit elongated Mn–CCF3 bonds (versus Mn(CF3)(CO)5), suggesting a lability that could be utilized for the transfer or insertion of the CF3 functional group into organic substrates. Unlike their Mn–X congeners (X = Cl, Br), these Mn–CF3 complexes exhibit a preference for hard donor ancillary ligands, thus enabling the synthesis of 4 N-ligated Mn–CF3 complexes including a mixed-donor tridentate complex using an NNS Schiff base ([2-(methylthio)-N-(1-(pyridin-2-yl)ethylidene)aniline]). Although we have not yet identified efficient CF3 transfer reactions, fluoride abstraction from the Mn–CF3 complexes using trimethylsilyl triflate affords the first stable Mn fluorocarbenes as evidenced by 19F NMR spectroscopy

Oxidative Cleavage of the CN Bond on Al(I)

Reaction of the cyclic guanidine TolNSIMe with the aluminum­(I) compound NacNacAl (<b>1</b>) results in the unprecedented cleavage of the C–N multiple bond to give, after rearrangement, the carbene-ligated Al­(III) amide, NacNac′­Al­(NHTol)­(SIMe) (<b>6</b>). DFT calculations revealed that these reactions proceed via a bimolecular mechanism in which either the basic Al­(I) center or the transient AlNTol species deprotonates the methyl group of the NacNac ligand

Zinc-Catalyzed Hydrosilylation and Hydroboration of N‑Heterocycles

The zinc hydride NacNacZnH (<b>2</b>) (NacNac = [Ar′NC­(Me)­CHC­(Me)­NAr′]⁻, Ar′ = 2,6-Me₂C₆H₃) catalyzes regioselective hydrosilylation and hydroboration of pyridines, including the hydroboration of phenanthroline. Mechanistic studies of hydrosilylation, including labeling, kinetic analysis, and density functional theory calculations, suggest the possibility of a reaction pathway based on hydride transfer from an out-of-sphere activated silane

Zinc-Catalyzed Hydrosilylation and Hydroboration of N‑Heterocycles

The zinc hydride NacNacZnH (<b>2</b>) (NacNac = [Ar′NC­(Me)­CHC­(Me)­NAr′]⁻, Ar′ = 2,6-Me₂C₆H₃) catalyzes regioselective hydrosilylation and hydroboration of pyridines, including the hydroboration of phenanthroline. Mechanistic studies of hydrosilylation, including labeling, kinetic analysis, and density functional theory calculations, suggest the possibility of a reaction pathway based on hydride transfer from an out-of-sphere activated silane

Nickel-Catalyzed Homologation of Vinylidene Difluoride (CH₂CF₂): Selective β‑F <i>vs</i> β‑H Elimination

Hydrofluoroolefins (HFOs) constitute the newest generation of fluorocarbon refrigerants and foam-blowing agents due to their reduced global warming potential vs their saturated analogues. To identify new synthetic routes to HFOs, we show that reactions of bulky Ni(0) phosphine and −NHC complexes with vinylidene difluoride (VF2) afford μ-fluoro-1,1,3-trifluorobut-3-enyl Ni complexes. Moreover, addition of triisopropylsilane allows for reductive elimination of the reduced product2,4,4-trifluoro-1-butenedemonstrating the Ni-catalyzed hydrodefluorodimerization of VF2. Accompanying DFT calculations identify the T-shaped nickelacyclopentane intermediate that spontaneously undergoes selective intramolecular β-F (vs β-H) elimination