Conformational flexibility of palladium BINAP complexes explored by X-ray analyses and DFT studies

Abstract

Several crystal structures and a theoretical DFT structure of the important catalyst (BI-NAP)PdCl2 (BINAP: 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl) have been determined. The conformational flexibilities of the BINAP backbone and of the phenyl rings do not seem to be coupled. Two novel parameter have been introduced that define the Pi-Pi stacking between the phenyl and biaryl rings in systems similar to the BINAP ligand, as well as the delta angle that is sensitive to the important interaction of the exchangeable ligands of the palladium with the equatorial phenyl rings of the BINAP. Furthermore, the calculated bite angle is 3 degrees larger than the experimentally determined bite angles. (C)

Double [3 + 2]-dimerisation cascade synthesis of bis(triazolyl)bisphosphanes, a new scaffold for bidentate bisphosphanes

“…3); it is similar to that of other [IrCl(COD)L 2 ] complexes. 20 As expected the Pd II -complex 12.1 showed a narrower dihedral angle of 48.4°compared to the BINAP-PdCl 2 complex (71.5°), 21 Synphos (73.6°) or difluorphos (73.0°) 9 and was a direct consequence of the 5-membered ring backbone rather than the 6-one.…”

“…3); it is similar to that of other [IrCl(COD)L 2 ] complexes. 20 As expected the Pd II -complex 12.1 showed a narrower dihedral angle of 48.4° compared to the BINAP-PdCl 2 complex (71.5°) 21 , Synphos (73.6°) or difluorphos (73.0°) 9 and was a direct consequence of the 5membered ring backbone rather than the 6-one. The iridium complex 16 was tested as a precatalyst in the hydrogenation of N-(1-phenylethylidene)-aniline 11 into secondary amine 18 (see table 3).…”

Force-Modulated Selectivity of the Rhodium-Catalyzed Hydroformylation of 1-Alkenes

“…For the reasons stated above, we found it surprising that complexes (P–P)­Rh­(CO) 2 H containing the extended macrocyclic ligands E­(3,3) and E­(2,3) adopted an eq-ap chelate structure exclusively, in preference to the seemingly more geometrically suitable eq-eq arrangement. We believe these seemingly contradictory observations can be traced to the rigidity and steric crowding of the binding pocket of the bound macrocyclic bisphosphine ligand, which contrasts the considerable flexibility of the free ligand . For example, structural analysis of square planar rhodium MeOBiphep and Synphos complexes show that the P-bound phenyl groups adopt pseudoaxial and pseudoequatorial orientations, with the pseudoaxial phenyl groups engaging in π–π stacking with the biaryl backbone. , A P–M–P angle of ∼90° appears to maximize the π–π stacking interactions with Ar centroid –Ar centroid distances of ∼3.5 Å; , Pregosin has estimated that these interactions contribute ≥3.6 kcal/mol to the stabilization of the metal complex .…”

Bis(azido)palladium(II) Complexes Bearing an (R or S)‐(BINAP) Ligand: Synthesis, Structures, and Catalytic Application to Suzuki–Miyaura C─C Coupling Reactions

“…The (CH 3 CN) 2 PdCl 2 was prepared by a modified literature method . Complexes [( R )‐(BINAP)PdCl 2 ] ( 1 ), [( S )‐(BINAP)PdCl 2 ] ( 2 ), and [( R )‐(Tol‐BINAP)PdCl 2 ] ( 3 ) were analogously prepared from the general ligand substitution using [Pd(CH 3 CN) 2 Cl 2 ] with an equivalent of the corresponding BINAP ligands …”