| Abstract |
Treatment of gold(III)-isocyanides [AuCl3(CNR1)] (R-1 = Xyl 1, Cy 2, Bu-t 3) with an equimolar amount of 5,5-dimethyl-1-pyrroline-N-oxide (4) in CH2Cl2 at -74 degrees C leads to the generation of the heterocyclic aminocarbene species [AuCl3\C((ONCMe2CH2CH2CH)-C-a-H-b)-NeR1\(N-a-C-b)(C-b-N-e)] 8 (for R-1 = Bu-t) or gold(III) complexes cis-[AuCl2\N-a((CMe2CH2CH2CNR1)-N-b-R-e)C-d= O\(N-a-C-b)(N-e-C-d)] 9 and 10 (for R-1 = Xyl and Cy) in good isolated yields (75-87\%). DFT calculations show that deprotonation of the endocyclic CH group in the carbene ligand leads to spontaneous N-O bond cleavage, and acidity of this group is a factor controlling the different chemical behavior of 1-3 depending on the nature of substituent R-1. The reaction of equimolar amounts of the aldonitrone p-TolCH=N+(Me)O- (5) or the ketonitrones Ph2C=N+(R-2)O- (R-2 = Ph 6, CH2Ph 7) with 1-3 in CD2Cl2 at -70 degrees C in air (or under N-2) revealed the formation of the carbene complexes [AuCl3\C(ONMeCaH-p-Tol)-(NR1)-R-b\(C-a-N-b)] (R-1 = Cy 11, Xyl 12, Bu-t 13), [AuCl3\C(ONPhCaPh2)-(NR1)-R-b\(C-a-N-b)] (R-1 = Cy 14, Bu-t 15), or [AuCl3\C(ON(CH2Ph)CaPh2)-(NR1)-R-b\(C-a-N-b)] (R-1 = Cy 16, Xyl 17), as studied by H-1 NMR. The reaction of 6 with 1 and of 7 with 3 did not furnish carbene products. Compounds 8-10 were characterized by ESI-MS, IR, 1D (H-1, C-13\H\) and 2D (H-1,H-1-COSY, H-1,C-13-HSQC, H-1,C-13-HMBC) NMR spectroscopic techniques, and, only for 8, elemental analyses (C, H, N), while compounds 11-17 were characterized by D-1 (H-1, C-13\H\) and 2D (H-1,C-13-HSQC) NMR. Structures of compounds 8, 9, and 13 were additionally established by single-crystal X-ray diffraction. |
