Ring-Expanded N-Heterocyclic Carbene Complexes of Rhodium with Bifluoride, Fluoride, and Fluoroaryl Ligands
摘要:
Thermolysis of Rh(PPh3)(4)H in the presence of the six-membered N-heterocyclic carbene 1,3-bis(2-propyl)-3,4,5,6-tetrahydropyrimidin-2-ylidine (6-Pr-i) gave the monocarbene complex Rh(6-Pr-i)(PPh3)(2)H as a 1:2 mixture of the cis- and trans-phosphine isomers la and 1b. This same isomeric mixture was formed as the ultimate product from treating Rh(PPh3)(3)(CO)H with 6-Pr-i at room temperature, although pathways involving both CO and PPh3 loss were observed at initial times. Treatment of 1a/1b with Et3N center dot 3HF generated the bifluoride complex cis-Rh(6-Pr-i)(PPh3)(2)(FHF) (2a), which upon stirring with anhydrous Me4NF was converted to the rhodium fluoride complex cis-Rh(6-Pr-i)(PPh3)(2)F (3a). Thermolysis of 1a/1b with C6F6 resulted in C-F bond activation to afford a mixture of 3a and the pentafluorophenyl complex trans-Rh(6-Pr-i)(PPh3)(2)(C6F5) (5b). Complexes 1b, 2a, 3a, and 5b were structurally characterized.
Structural investigations of metalcarbonyl complexes with acyclic diamino carbenes
作者:Guido D. Frey、Eberhardt Herdtweck、Wolfgang A. Herrmann
DOI:10.1016/j.jorganchem.2006.01.033
日期:2006.5
and cyclic aminocarbene substituted carbonyl complexes of group 6 metals. The reaction of bis(diisopropyl)aminocarbene with photolytically produced (ether)M(CO)5 leads to unstable η1-carbene complexes, which convert to η2-carbene complexes; crystallographic data are presented for the tungsten complex, where one amino group of the carbene coordinates to the metal. The Mo and W η2-complexes can be converted
在这里,我们报告第6组金属的无环和环状氨基卡宾取代的羰基配合物的合成。双(二异丙基)aminocarbene与光解产生(醚)M(CO)的反应5所导致不稳定的η 1种-carbene复合物,其转换为η 2个-carbene络合物; 给出了钨配合物的晶体学数据,其中卡宾的一个氨基与金属配位。的Mo和Wη 2-可以在消除丙烯的情况下将复合物转化为亚胺复合物;具有化学,光谱和晶体学数据的特征。进行了新的双(二烷基)氨基卡宾和相应的亚甲基盐的DFT计算,并与后者的相应晶体学数据进行了比较。在(乙醚)Cr(CO)5与游离的六元环卡宾的反应过程中的副反应中,形成了三核的阴离子金属羰基羰基Nido络合物(C 14 H 10 Cr 3 O 12)2-,可以通过光谱学和晶体学数据来表征。
Active catalysts for the Suzuki coupling: Palladium complexes of tetrahydropyrimid-2-ylidenes
作者:Sabine K. Schneider、Wolfgang A. Herrmann、Eberhardt Herdtweck
DOI:10.1016/j.molcata.2005.08.046
日期:2006.2
An alternative way to synthesize a mixed N-heterocyclic carbenes (NHC) phosphine palladium(II) complex is described in this work. A free carbene, generated by deprotonation of a tetrahydro-pyrimidinium salt, was reacted with Pd(PPh3)(2)Cl-2 to yield the desired mixed NHC phosphine palladium(II) complex.In this work, we have combined the superior activity of mixed NHC phosphine palladium complexes in Suzuki-coupling reactions with the additional advantage of a stronger or-donating ligand. The combination of these two effects results in an increased catalytic activity in Suzuki reactions than found for corresponding mixed imidazole-ylidene phosphine complexes.Using this new class of catalysts, TONs of approximately 1 Mio. after a reaction time of 14 h can be achieved. Desactivated bromoarenes could also be coupled efficiently, using quite a low amount of catalyst (0.005 mol%). Even aryl chlorides can be coupled: TONs of approximately 6000 can be reached after only 14 It without any detectable catalyst deterioration using only 0.01 mol% of catalyst. (c) 2005 Elsevier B.V. All rights reserved.
Ring-Expanded N-Heterocyclic Carbene Complexes of Rhodium with Bifluoride, Fluoride, and Fluoroaryl Ligands
作者:Candela Segarra、Elena Mas-Marzá、John P. Lowe、Mary F. Mahon、Rebecca C. Poulten、Michael K. Whittlesey
DOI:10.1021/om300984v
日期:2012.12.24
Thermolysis of Rh(PPh3)(4)H in the presence of the six-membered N-heterocyclic carbene 1,3-bis(2-propyl)-3,4,5,6-tetrahydropyrimidin-2-ylidine (6-Pr-i) gave the monocarbene complex Rh(6-Pr-i)(PPh3)(2)H as a 1:2 mixture of the cis- and trans-phosphine isomers la and 1b. This same isomeric mixture was formed as the ultimate product from treating Rh(PPh3)(3)(CO)H with 6-Pr-i at room temperature, although pathways involving both CO and PPh3 loss were observed at initial times. Treatment of 1a/1b with Et3N center dot 3HF generated the bifluoride complex cis-Rh(6-Pr-i)(PPh3)(2)(FHF) (2a), which upon stirring with anhydrous Me4NF was converted to the rhodium fluoride complex cis-Rh(6-Pr-i)(PPh3)(2)F (3a). Thermolysis of 1a/1b with C6F6 resulted in C-F bond activation to afford a mixture of 3a and the pentafluorophenyl complex trans-Rh(6-Pr-i)(PPh3)(2)(C6F5) (5b). Complexes 1b, 2a, 3a, and 5b were structurally characterized.
Complexation of stable carbenes with alkali metals
作者:Roger W. Alder、Michael E. Blake、Christel Bortolotti、Simone Bufali、Craig P. Butts、Emma Linehan、Josep M. Oliva、A. Guy Orpen、Michael J. Quayle
DOI:10.1039/a808951e
日期:——
Stable diaminocarbenes, including imidazol-2-ylidenes, undergo complexation with lithium, sodium and potassium species; the crystal structure of a complex of 1,3-diisopropyl-3,4,5,6-tetrahydropyrimid-2-ylidene 1 with KN(SiMe3)2 is reported.