INOR 125 |
| Diaminocyclopropenylidenes, (R2NC)2C:, are a new class of stable “bottle-able” carbenes [1], although cyclopropenylidene complexes with transition metals and main group elements have been known for many years [2,3]. Previous attempts to isolate these carbenes in the free state have failed [4], and the demonstration of their inherent stability will certainly stimulate interest in cyclopropenylidene chemistry and establish diaminocyclopropenylidenes as viable alternatives to the intensively studied imidazolin-2-ylidenes. It should be noted that these two carbene types represent constitutional isomers with the molecular formula C3N2R4 and that the direct substitution of the carbene carbon atom by nitrogen atoms in imidazolin-2-ylidenes has now been replaced by a remote heteroatom stabilization of the cyclopropenylidene ring by two secondary amine moieties. Bis[bis(R-1-phenylethyl)amino]cyclopropenylidene 2 represents the first chiral diaminocyclopropenylidene, which was isolated in 60% yield by deprotonation of bis[bis(R-1-phenylethyl)amino]cyclopropenylium-tetrafluoroborate (1)BF4 with potassium bis(trimethylsilyl)amide. Studies of these compounds especially for using these novel chiral carbenes in asymmetric homogeneous catalysis will be of interest. [1] Lavall, V.; Canac, Y.; Donnadieu, B.; Schoeller, W. W.; Bertrand, G. Science 2006, 312, 722. [2] Schumann, H.; Glanz, M.; Girgsdies, F.; Hahn, F. E.; Tamm, M.; Grzegorzewski, A. Angew. Chem. Int. Ed. 1997, 36, 2232. [3] (a) Öfele, K. Angew. Chem. Int. Ed. Engl. 1968, 7, 950. (b) Weiss, R.; Priesner, C. ibid. 1978, 17, 457. (c) Tamm, M.; Grzegorzewski, A.; Hahn, F. E. J. Organomet. Chem. 1995, 309. [4] (a) Weiss, R.; Priesner, C.; Wolf, H. Angew. Chem. Int. Ed. 1978, 17, 446. (b) Weiss, R.; Hertel, M.; Wolf, H. Angew. Chem. Int. Ed. 1979, 18, 473. (c) Yoshida, Z. Pure & Appl. Chem. 1982, 54, 1059.
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Organometallic Synthesis
1:30 PM-5:20 PM, Sunday, August 19, 2007 BCEC -- 212, Oral
Division of Inorganic Chemistry |
