Group Transfer from Nickel Imido, Phosphinidene, and Carbene Complexes to Ethylene with Formation of Aziridine, Phosphirane, and Cyclopropane Products
作者:Rory Waterman、Gregory L. Hillhouse
DOI:10.1021/ja0381914
日期:2003.11.1
carbene ligands with ethylene are reported. In all three cases, corresponding three-membered rings, aziridine, phosphirane, and cyclopropane, were produced in moderate to excellent yields. NMR spectra of the phosphinidene (dtbpe)Ni=P(dmp) reaction with ethylene show a [2+2] cycloaddition adduct before phosphirane formation. A labeling study with trans-ethylene-d2 shows formation of aziridine and phosphirane
Group-Transfer Reactions of Nickel−Carbene and −Nitrene Complexes with Organoazides and Nitrous Oxide that Form New C═N, C═O, and N═N Bonds
作者:Nicole D. Harrold、Rory Waterman、Gregory L. Hillhouse、Thomas R. Cundari
DOI:10.1021/ja904370h
日期:2009.9.16
1-Adamantyl- and mesitylazide react with (dtbpe)Ni=CPh2 (1; dtbpe = 1,2-bis(di-tert-butylphosphino)ethane) at ambient temperature to give the ketimines RN=CPh2 (2a, R = Mes; 2b, R = Ad) in high yield. Kinetic studies for the reaction of 1 with N(3)Ad yield activation parameters of Delta H double dagger = +8(+/- 1) kcal/mol and Delta S double dagger = -44(+/- 3) cat/(mol.K). Treatment of 1 with N2O at low temperature results in clean conversion to the benzophenone complex (dtbpe)Ni(eta(2)-OCPh2) (5) upon elimination of N-2. The nickel-imido complexes (dtbpe)Ni=NR (4a, R = Mes; 4b, R = Ad) react with N(3)Mes and N3Ad at ambient temperature to give the diazenes RN=NR (6a, R = Mes; 6b, R = Ad) in good yield. B3LYP/6-311+G(d) calculations support a mechanism for all three reactions that features 1,3-dipolar cycloaddition to give five-membered ring (Huisgen) intermediates, followed by NZ elimination to give the products. Calculated activation parameters for the reaction of (dhpe)Ni=CH2 (dhpe = 1,2-bis(dihydridophosphino)ethane) with N3Me compare well with the experimental values.
Synthesis, Structure, and Reactions of a Three-Coordinate Nickel-Carbene Complex, {1,2-Bis(di-<i>tert</i>-butylphosphino)ethane}NiCPh<sub>2</sub>
作者:Daniel J. Mindiola、Gregory L. Hillhouse
DOI:10.1021/ja0269183
日期:2002.8.1
(dtbpe)NiCPh2 (3) was prepared from the thermolysis of the diphenyldiazoalkane complex (dtbpe)Ni(N,N‘:η2-N2CPh2) (2) (dtbpe = 1,2-bis(di-tert-butylphosphino)ethane). Complex 3 was structurally characterized by single-crystal X-ray diffraction methods (Ni−C = 1.836(2) A). Complex 3 reacts with 2 equiv of CO2 to afford (dtbpe)NiOC(O)CPh2C(O)O} (4), with diphenylketene to give (dtbpe)NiOC(CPh2)CPh2}