| Abstract |
The reaction between metal-bound isonitriles in cis-[PdCl2(CNRt)(2)] [R-1 = cyclohexyl (Cy) 1, Bu-t 2, C6H4(2,6-Me-2) (Xyl) 3, CMe2CH2CMe3 4] and 1,3-diiminoisoindoline (9) in CHCl3 under reflux for 4 h provides the carbene species [Pd\C(N=C-a(C6H4CNHNb))=N(H)R-1\(2)](a-b) (R-1 = Cy 10, 82\% isolated yield) or cis-[PdCl\C(N=C-a(C6H4CNHNb))=N(H)R-1\(CNRt)](a-b) (R-1 = Bu-t 11, 78\%; Xyl 12, 84\%; CMe2CH2CMe3 13, 79\%), derived from the addition of two or one equivs of 9 to the starting 1-4, respectively. The corresponding integration of cis-[PdCl2(CNRt)(PPh3)] (R-1 = Cy 5, Bu-t 6, CMe2CH2CMe3 8) with 1 equiv of 9 in CHCl3 under reflux for 4 h affords the carbene species cis-[PdCl\C(N=C-a(C6H4CNHNb))=N(H)R-1\(PPh3)](a-b) (R-1 = Cy 14, 84\%; Bu-t 15, 76\%; CMe2CH2CMe3 16, 75\%). Complexes 10-16 were characterized by elemental analyses (C, H, N), ESI+-MS, IR, and 1D (H-1, C-13\H-1\) and 2D (H-1,H-1-COSY, H-1,C-13-HMQC/H-t,C-13-HSQC, H-1,C-13-HMBC) NMR spectroscopies. In addition, the structures of aminocarbene complexes 10 and 12 were elucidated by X-ray diffraction. The catalytic properties of 10-16 in the Suzuki-Miyaura cross-coupling of aryl halides, viz., 4-(RC6H4X)-C-2 (X = I, R-2 = OMe; X = Br, R-2 = Me, OMe, and NO2), with phenylboronic acid (in EtOH as solvent, K2CO3 or Cs2CO3 as base, 80 degrees C) yielding biaryl species 4-(RC6H4Ph)-C-2, were evaluated. Complexes 14-16 exhibit a high catalytic activity (yields up to 98\%, TONs up to 9.8 x 10(4), TOFs up to 3.9 x 10(4)). |
