OPTICALLY ACTIVE EXOCYCLIC CYCLOPALLADATED DERIVATIVES OF BENZYLIDENE-(R)-(1-PHENYLETHYL)AMINES - SYNTHESES AND X-RAY MOLECULAR STRUCTURES OF [PD(2-((E)-(R)-CHMEN=CH-2',6'-CL(2)C(6)H(3))C6H4)CL(PPH(3))] AND [PD(2-((Z)-(R)-CHMEN=CH-2',6'-F2C6H3)C6H4)I

摘要

The action of Pd(AcO)(2) on benzylidene-(R)-(1-phenylethyl)amines, RCH=NCHMePh (R = 2,6-Cl2C6H3 (la), 2,6-F2C6H3 (Ib), 2,4,6-(MeO)(3)C6H2 (Ic)), and subsequent treatment with LiCl, LiBr, or KI gives the corresponding halogen-bridged exocyclic cyclopalladated dimers [Pd(C-N)X](2) (X = Cl, Br, I) in which the C=N bond is not included in the metallacycle (compounds 2-4, respectively). In relation to the Z or E form adopted by the imines in these cyclopalladated dimers, 2a,b-4a,b consist of a mixture of (Z,Z), (Z,E), and (E,E) isomers, whereas 2c-4c consist of only the (E,E) isomer. The equilibrium (Z,Z) + (E,E) reversible arrow 2(Z,E) is observed in chloroform solutions of 2a,b-4a,b. According to this equilibrium, when 2a,b and 3a,b are eluted through a column of SiO2 with CHCl3, the initial band which contains a mixture of(Z,Z), (Z,E), and (E,E) isomers splits into two bands: the first contains the (Z,Z) isomer and the second the (E,E) isomer. The action of PPh(3) on 2a,b-4a,b yields the corresponding cyclopalladated monomers [Pd(C-N)X(PPh(3))]. When this reaction is carried out with dimers 2c-4c, demethylation of one of the ortho methoxy groups is also observed, giving the tridentate species [Pd(C-N-O)(PPh(3))]. The X-ray crystal structure of two monomers with PPh(3) has been determined. [Pd(2-{(E)-(R)-CHMeN=CH-2',6'-Cl2C6H3}C6H4)Cl(PPh(3))] crystallizes in the monoclinic space group P2(1) with a = 16.996(4) Angstrom, b = 9.006(2) Angstrom, c = 9.655(2) Angstrom, beta = 91.63(3)degrees, and Z = 2. [Pd(2-{(Z)-(R)-CHMeN=CH-2',6'Cl2C6H3}C6H4)I(PPh(3))] crystallizes in the orthorhombic space group P2(1)2(1)2(1) with a = 18.017(3) Angstrom b = 14.204(2) Angstrom, c = 11.978(2) Angstrom, and Z = 4. [References: 72]