Reactivity of cycloplatinated amine complexes : intramolecular C–C bond formation, C–H activation, and PPh2 migration in coordinated alkynylphosphines

• Main Authors: Tan, Kien-Wee, Yang, Xiang-Yuan, Li, Yongxin, Huang, Yinhua, Leung, Pak-Hing, Pullarkat, Sumod A.
• Other Authors: School of Physical and Mathematical Sciences
• Format: Article
• Language: English
• Published: 2013
• Online Access: https://hdl.handle.net/10356/101108; http://hdl.handle.net/10220/13696
• Institution: Nanyang Technological University

The monomeric ortho-platinated complexes [Pt{R1CH(1-C6H4)NMe2-C,N}{Ph2PC≡CR2}Cl] (R1 = Me, Et; R2 = Me, Ph) with trans-N,P geometries were obtained regiospecifically from the reaction between the dimeric [Pt2(μ-Cl)2{R1CH(1-C6H4)NMe2-C,N}2] and the corresponding alkynylphosphines in high yields. The phosphine complexes are highly stable in the solid state and in solution. However, in the presence of additional Pt(II) ions, an intramolecular coupling reaction occurred in which a new carbon–carbon bond was formed between the aromatic γ-carbon of the ortho-platinated chiral phenylamine and the α-carbon of the (Ph2P)–Cα≡Cβ–(R2) ligand. The (Ph2P) moiety migrated to the neighboring β-carbon during the coupling reaction. By the judicious selection of the substituents on the alkynylphoshine along with deliberate introduction of selected chirality on the ortho-platinated phenylamine, the coupling reaction and the (Ph2P) migration were found to proceed via an associative intramolecular mechanism that involves a Pt-vinylidene intermediate.