A Theoretical Study on Synthesis Mechanism of fac-[Ir(ppy)(3)] from [Ir(acac)(3)] in the Presence of Bronsted Acids and Water Molecules

作者：Yoshimura Kazuaki; Miyazaki Hiroshi; Matsuo Shinji; Hashimoto Hiromi; Hori Takumi; Yamaguchi Yoshihiro; Sumimoto Michinori; Hori Kenji^*

来源：Bulletin of the Chemical Society of Japan, 2012, 85(2): 209-216.

DOI：10.1246/bcsj.20110122

We recently found new reaction conditions with which [Ir(acac)(3)] reacts with ppyH (2-phenylpyridine) to produce fac-[Ir(ppy)(3)] in high yield. It is desirable that Bronsted acids and water molecules exist in the reaction mixture to achieve both the high yield and the selectivity of fac-[Ir(ppy)(3)]. In this study, the reaction mechanism was investigated theoretically to find reasons of the observed effect of the acid and the water molecule at the B3LYP/SDD level of theory. Although a transition state was located without taking a hydron in the mechanism into account, an IRC calculation confirmed that the TS leads to form a by-product, in which acac makes a bond with ppyH. A neighboring ppyH molecule is involved in the removal of the hydron. A hydron of ppyH was extracted by acac when acac leaves the complex and the orthometalation reaction proceeds. Theoretical calculations showed that the trans effect of the Ir-C bond is key to understanding the selectivity of our reaction.