Dinuclear and Trinuclear Ni−, Pd−, and Pt−Halide Complexes of the Easily Accessible Chiral Ligand P,P,P-Tris[(+)-9-phenyldeltacyclan-8-yl]-1,2-bis(phosphanyl)benzene

Abstract

The synthesis of seven dinuclear complexes [(+)δ-LMHal]2 (M = Ni, Pd, Pt; Hal = Cl, Br, I) is described, in which (+)δ-L− represents the deprotonated chiral chelate ligand P,P,P′tris[(+)-9-phenyldeltacyclan-8-yl]-1,2-bis(phosphanyl)benzene, easily accessible in a highly enantioselective homo-Diels−Alder reaction. All the dinuclear complexes are bent at the phosphido bridges which connect the two square-planar halves of the molecules. The phosphorus atoms of the phosphido bridges are stereogenic centers. For [(+)δ-LNiBr]2 and [(+)δ-LPdCl]2 both diastereomers with (SP,SP) and (RP,RP) configuration were observed, whereas for [(+)δ-LPdBr]2, [(+)δ-LPdI]2, and [(+)δ-LPtCl]2 only the (SP,SP) isomers could be obtained. Furthermore, the synthesis of eight trinuclear complexes [(+)δ-L2M3Hal4] (M = Pd, Pt; Hal = Cl, Br) is reported, which contain unusual three-square arrays. In the trinuclear complexes all the halogens are oriented to one side. Halogeno and phosphido bridges connect the three squares leading to chair configurations (opposite scaffold chirality possible) and boat configurations. For [(+)δ-L2Pd3Cl4], [(+)δ-L2Pd3Br4], and [(+)δ-L2Pt3Cl4] the two diastereomers with (SP,SP) and (RP,RP) configuration and for [(+)δ-L2Pt3Br4] the diastereomers with (SP,SP) and (SP,RP) configuration could be isolated. In addition, the dinuclear complex [(+)δ-LPt2Br3(cod)] (cod = 1,5-cyclooctadiene) containing a single phosphido bridge was obtained. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)