111-78-4Relevant articles and documents
CATALYTIC REACTIONS INVOLVING BUTADIENE. III. OLIGOMERIZATION WITH CATIONIC BIS(TRIPHENYLPHOSPHINE)(η3-ALLYL) COMPLEXES
Grenouillet, P.,Neibecker, D.,Tkatchenko, I.
, p. 213 - 222 (1983)
The bis(triphenylphosphine)(η3-crotyl)nickel cation is a catalyst precursor for the oligomerisation of butadiene to cyclic or linear dimers.Polymers and oligomers are also produced in variable amounts.The product distributions depend strongly on the type of solvent used and on the nature of co-catalysts.In the aprotic polar solvent DMF, the starting complex undergoes disproportionation, leading finally to a zerovalent nickel-phosphine catalyst.In protic solvents (alcohols) a cationic hydridonickel-phosphine catalyst is produced, but addition of sodium methoxide induces the formation of the zerovalent nickel-phospnine, therefore accounting for the changes in product selectivities.
Tada et al.
, p. 2871 (1969)
Bosmajian et al.
, (1964)
Corey,Wat
, p. 2757 (1967)
Day et al.
, p. 8289,8291 (1976)
Chapman et al.
, p. 2660,2663 (1964)
Martin,Eisenmann
, p. 661 (1975)
16-Electron Nickel(0)-Olefin Complexes in Low-Temperature C(sp2)-C(sp3) Kumada Cross-Couplings
Lutz, Sigrid,Nattmann, Lukas,N?thling, Nils,Cornella, Josep
supporting information, p. 2220 - 2230 (2021/05/07)
Investigations into the mechanism of the low-temperature C(sp2)-C(sp3) Kumada cross-coupling catalyzed by highly reduced nickel-olefin-lithium complexes revealed that 16-electron tris(olefin)nickel(0) complexes are competent catalysts for this transformation. A survey of various nickel(0)-olefin complexes identified Ni(nor)3as an active catalyst, with performance comparable to that of the previously described Ni-olefin-lithium precatalyst. We demonstrate that Ni(nor)3, however, is unable to undergo oxidative addition to the corresponding C(sp2)-Br bond at low temperatures (a nickel(0)-alkylmagnesium complex. We demonstrate that this unique heterobimetallic complex is now primed for reactivity, thus cleaving the C(sp2)-Br bond and ultimately delivering the C(sp2)-C(sp3) bond in high yields.
Isolation of a Bimetallic Cobalt(III) Nitride and Examination of Its Hydrogen Atom Abstraction Chemistry and Reactivity toward H2
Sengupta, Debabrata,Sandoval-Pauker, Christian,Schueller, Emily,Encerrado-Manriquez, Angela M.,Metta-Maga?a, Alejandro,Lee, Wen-Yee,Seshadri, Ram,Pinter, Balazs,Fortier, Skye
supporting information, p. 8233 - 8242 (2020/05/08)
Room temperature photolysis of the bis(azide)cobaltate(II) complex [Na(THF)x][(ketguan)Co(N3)2] (ketguan = [(tBu2CN)C(NDipp)2]-, Dipp = 2,6-diisopropylphenyl) (3a) in THF cleanly forms the binuclear cobalt nitride Na(THF)4{[(ketguan)Co(N3)]2(μ-N)} (1). Compound 1 represents the first example of an isolable, bimetallic cobalt nitride complex, and it has been fully characterized by spectroscopic, magnetic, and computational analyses. Density functional theory supports a CoIII═N═CoIII canonical form with significant π-bonding between the cobalt centers and the nitride atom. Unlike other group 9 bridging nitride complexes, no radical character is detected at the bridging N atom of 1. Indeed, 1 is unreactive toward weak C-H donors and even cocrystallizes with a molecule of cyclohexadiene (CHD) in its crystallographic unit cell to give 1·CHD as a room temperature stable product. Notably, addition of pyridine to 1 or photolyzed solutions of [(ketguan)Co(N3)(py)]2 (4a) leads to destabilization via activation of the nitride unit, resulting in the mixed-valent Co(II)/Co(III) bridged imido species [(ketguan)Co(py)][(ketguan)Co](μ-NH)(μ-N3) (5) formed from intermolecular hydrogen atom abstraction (HAA) of strong C-H bonds (BDE ～100 kcal/mol). Kinetic rate analysis of the formation of 5 in the presence of C6H12 or C6D12 gives a KIE = 2.5 ± 0.1, supportive of a HAA formation pathway. The reactivity of our system was further probed by photolyzing benzene/pyridine solutions of 4a under H2 and D2 atmospheres (150 psi), which leads to the exclusive formation of the bis(imido) complexes [(ketguan)Co(μ-NH)]2 (6) and [(ketguan)Co(μ-ND)]2 (6-D), respectively, as a result of dihydrogen activation. These results provide unique insights into the chemistry and electronic structure of late 3d metal nitrides while providing entryway into C-H activation pathways.
