Synthesis and characterization of N-heterocyclic carbene palladium

Abstract

A mixed-halogen bis(1-(4-tert-butylbenzyl)-3-(2, 4, 6-trimethylbenzyl)-1H-benzo[d]imidazol-2-ylidene) palladium(II) complex, trans-[Pd(Cl0.7Br0.3)2(C28H32N2)2], has been synthesized and characterized by elemental analysis, 1H-NMR, 13C-NMR, and IR spectroscopy, and single crystal X-ray diffraction. The palladium in the mononuclear complex is four-coordinate in a square-planar configuration with two carbenes of two benzo[d]imidazole rings and two halides. The two halides are disordered between Br and Cl, with the Cl: Br ratio approximately 0.7 : 0.3. The angles C1-Pd1-Br1, 88.63(11)degrees and C1i-Pd1-Br1i, 91.37(11)degrees (i: 1-x, 1-y, 1-z) in the coordination sphere are very close to the ideal value of 90 degrees. The Pd-X distance is slightly longer than other carbene derivative Pd-Cl single bond distances and slightly shorter than Pd-Br single bond distances. These results agree with the Cl/Br disorder at the halogen position. The palladium-carbene complex was tested as a catalyst in the direct arylation reaction of benzoxazoles and benzothiazoles with aryl bromides.

C1 [Arslan, Hakan] Mersin Univ, Dept Chem, Fac Pharm, TR-33169 Mersin, Turkey.

[Arslan, Hakan] Fayetteville State Univ, Dept Nat Sci, Fayetteville, NC 28301 USA.

[Ozdemir, Ismail; Demir, Serpl] Inonu Univ, Dept Chem, Fac Sci & Arts, TR-44280 Malatya, Turkey.

[Vanderveer, Don] Clemson Univ, Dept Chem, Clemson, SC 29634 USA.

[Cetinkaya, Bekir] Ege Univ, Dept Chem, Fac Sci, TR-35100 Bornova, Turkey.