Azolium Cyclophanes

Palladium, rhodium and platinum complexes of ortho-xylyl-linked bis-N-heterocyclic carbenes: Synthesis, structure and catalytic activity

“…1 5, 26.9, 28.9, 30.6, 30.8, 30.9, 31.6 (CH 2 from heptyl chain + cod), 51.0, 51.5 (NCH 2 CH 2 + benzylic CH 2 ), 88.4 (d, 1 J Rh,C = 7.7 Hz, cod CH), 88.4 (d, 1 J Rh,C = 8.5 Hz, cod CH), 120. 8,121.4 (Im C4 and Im C5),129.8,131.8 (Ar CH), 134.8 (Ar C), 179.9 (d, 1 J Rh,C = 53.5 Hz, NCN). Anal.…”

“…Me 2 CO"C 39 H 36 Br 2 N 4 OPd, M = 843.0. Triclinic, space group P 1, a = 10.9860 (8), b = 11.9500 (9), c = 13.6870(10) Å , a = 87.081(1), b = 81.304 (2), c = 81.392(2)°, V = 1756 Å 3 . D c (Z = 2) = 1.595 g cm À3 .…”

“…We have been interested in bidentate NHC ligands based on azolium-linked cyclophane systems [7,8], in particular ligands with two imidazol-2-ylidenes linked by two orthoxylyl groups. The imidazolium salts that are precursors to these NHC ligands are readily synthesised and the subsequent formation of mononuclear complexes of Pd(II), Ni(II), Rh(I) and Ir(I), or dinuclear complexes of Ag(I) and Au(I) has proved facile [9][10][11].…”

Calixarene/azolium cyclophane hybrids: synthesis, structure and conformations

“…Azolium-linked cyclophanes have interested chemists for several decades [1], particularly in respect of their synthesis [2][3][4][5][6][7][8][9], interesting structural properties and conformational behaviours [3,8,[10][11][12][13][14], anion-binding properties [15][16][17], interesting mass spectrometry [18], and their ability to act as precursors of N-heterocyclic carbenes (NHCs) and NHC-metal complexes [19][20][21][22][23][24][25]. Much of the conformational behaviour of azolium-linked cyclophanes is reminiscent of the behaviour of calixarenes [26].…”

Palladium complexes of o-xylylene-linked alkoxybenzimidazolin-2-ylidenes containing aryl N-substituents: examples of C–H activation and the formation of a tri-nuclear palladium complex

“…These bis(NHC) ligands generally bind to the metal centre in a rigid fashion [19][20][21][22]. The butoxy groups serve to increase the solubility of the complexes, and also to increase the electron density at the palladium centre, which has been shown to enhance the activity of the catalysts relative to non-butoxy functionalised analogues in the Mizoroki-Heck and Suzuki-Miyaura reactions [15,23].…”