Cyclometallation of 2-phenylaniline and ( R)- α-methylbenzylamine by palladium(II) acetate. X-ray molecular structure of [P [formula omitted]H 2C 6H 4)C 6H 4}Br(PPh 3)

Abstract

The action of palladium(II) acetate on the primary amines 2-phenylaniline and ( R)- α-methylbenzylamine and subsequent treatment with LiBr allows the preparation of the corresponding cyclopalladated dimers [P d(CN )Br] 2 ( 1a and 1b respectively). Mononuclear compounds [P d(CN )Br(L)], 3 ( L = py−d 5) and 2 ( L = PPh 3) , have ben obtained by reaction of 1 with py- d 5 and PPh 3. Addition of PPh 3 to chloroform solutions of 2 produces a rapid exchange between coordinated and free PPh 3. 31P{ 1H} NMR at variable temperature suggests that this exchange proceeds for 2a through the fast equilibrium [Pd(CN)Br(PPh 3) 2]⇔[P (CN )Br(PPh 3)], while the usual mechanism in substitution reactions in d 8 planar square complexes is involved in the case of 2b. The X-ray crystal structure of 2a has been determined. 2a crystallizes in the triclinic space group P 1 with a = 12.182(3), b = 10.502(2), c = 9.998(2) A ̊ , α = 99.24(2), β = 94.69(2) and γ = 99.13(2)° .