591-26-4Relevant articles and documents
Mechanistic Insight into H/D Exchange by a Pentanuclear Ni-H Cluster and Synthesis and Characterization of Structural Analogues of Potential Intermediates
Shoshani, Manar M.,Liu, Junyang,Johnson, Samuel A.
supporting information, p. 116 - 126 (2018/01/17)
Experiments to gain mechanistic insight into catalytic H/D exchange of unactivated arenes by [(iPr3P)Ni]5H6 (1) are described. The reaction order with respect to 1, arene substrate, and added iPr3P were determined, as well as the temperature dependence of reaction rate. Site-selectivity data were obtained by monitoring the reaction of 1 with fluorobenzene and 2-methoxynaphthalene. H/D exchange competition reactions between arenes reacted with 1 were performed. The addition of an excess of Hg to a solution of 1 provided the new heterometallic cluster [(iPr3P)Ni]5H6(μ4-Hg) (2); this species also undergoes H/D exchange with C6D6, albeit more slowly than 1. Reaction of cluster 1 with TlCp (Cp = C5H5) gave (η5-Cp)Ni[(iPr3P)Ni]4(μ2-H)4(μ4-Tl) (3) with the loss of H2. A similar transfer of cyclopentadienyl to Ni occurred when 1 was reacted with MgCp2, to give (η5-Cp)Ni[(iPr3P)Ni]4H6(μ4-MgCp) (4), but not H2 loss. Reaction of 1 with cyclopentadiene gave the 5-coordinate hydride complex (η5-Cp)Ni[(iPr3P)Ni]4(μ2-H)4(μ5-H) (5). The Cp? analogue, (η5-Cp)Ni[(iPr3P)Ni]4(μ2-H)4(μ5-H) (6) (where Cp? = C5Me5), was synthesized by reacting 1 with LiCp? in THF, or by reaction of 1 with pentamethylcyclopentadiene.
A product analytical study of the thermal and photolytic decomposition of some arenediazonium salts in solution
Canning, Peter S. J.,Maskill, Howard,McCrudden, Katharine,Sexton, Brian
, p. 789 - 800 (2007/10/03)
Products of thermal and photochemical reactions of eleven arenediazonium tetrafluoroborates in various solvents have been analyzed. All compounds in most solvents undergo unimolecular heterolysis to give singlet aryl cations which are captured by solvent. This mechanism is dominant for arenediazonium ions without electron-withdrawing substituents in all solvents, and the only reaction observed in water. Additionally, appreciable yields of fluoroarenes are obtained by fluoride abstraction by the aryl cation from fluorinated solvents and from tetrafluoroborate in fluorinated solvents. Yields from photochemical processes are very similar to those from thermal reactions indicating that the main reactions proceed through common or very similar intermediates. Aryl cations formed from ion-paired diazonium ions may react with the counterion, but fragmentation of dissociated diazonium ions leads only to solvent-derived product. Some arenediazonium ions in some solvents undergo an alternative radical reaction leading principally to hydrodediazoniation. It is proposed that this reaction involves initial rate-limiting electron transfer from ethanol to the arenediazonium ion followed rapidly by homolysis of the resultant aryldiazenyl radical. Within the same solvent cage, the aryl radical then either abstracts an α-hydrogen from the ethanol radical cation generated in the first step to give the reduction product and protonated acetaldehyde, or combines with it at the oxygen to give a protonated aryl ethyl ether.
