Methyleneimidazoline complexes of iridium, rhodium, and palladium from selective C(sp3)-H bond activation.
Palladium, iridium, and rhodium complexes of 2-methyleneimidazolines have been synthesized by selective phosphine-assisted activation of the 2-methyl C-H bonds in 2-methylimidazolium compounds. Metallacycles of various sizes were obtained in the reaction of phosphine-tethered 2-methylimidazolium compounds and [{M(cod)X}(2)] (M = Rh or Ir; cod = 1,5-cyclooctadiene; X = alkoxyl or Cl). Representative complexes were characterized by X-ray crystallography. The selectivity for aliphatic C(sp(3))H versus aromatic C(sp(2))H activation could be adjusted by means of the steric bulk of the OR ligand, whereby a bulky OR group favors activation of the 2-methyl C(sp(3))-H bond. Experimental results confirmed that a methyl C-H activation product (a seven-membered iridacycle) is the kinetic product, while the aryl C-H activation product (a six-membered iridacycle) is the thermodynamic product.
Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore.
Guoyong
G
Song
Xingwei
X
Li
Zhongcheng
Z
Song
Jing
J
Zhao
Hongjie
H
Zhang
D018360:Crystallography, X-Ray; D007093:Imidazoles / Q000138:chemical synthesis* / Q000737:chemistry; D007495:Iridium / Q000737:chemistry*; D008697:Methane / Q000031:analogs & derivatives / Q000737:chemistry; D008968:Molecular Conformation; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D010165:Palladium / Q000737:chemistry*; D012238:Rhodium / Q000737:chemistry*; D013816:Thermodynamics
D007093:Imidazoles; D009942:Organometallic Compounds; C030011:carbene; D007495:Iridium; D010165:Palladium; D012238:Rhodium; D008697:Methane