Conformational analysis of a TADDOL-based phosphoramidite P,N ligand in a palladium(II) η3-π-allyl complex

Publication date: Available online 18 July 2018Source: Computational and Theoretical ChemistryAuthor(s): Tülay A. Ateşin, Abdurrahman C. Atesin, Oscar Rodriguez, Diego Rivera, Lohany Y. GarciaAbstractThe most stable conformations of a TADDOL-based phosphoramidite P,N ligand coordinated to a palladium(II) η3-π-allyl fragment have been investigated using molecular mechanical and quantum mechanical calculations. The conformational analysis initially generated 53 unique structures within 5 kcal/mol and subsequent geometry optimization narrowed the number of low-energy conformers down to 13. The two lowest energy conformers differ mainly in the conformation of the allyl group. The conformer with an endo allyl group has a slightly higher relative energy than the conformer with an exo allyl group. Comparison of the main geometric parameters around the Pd(II) metal center in the two lowest energy conformers with the available X-ray single crystal structures of Pd(II)η3-π-allyl complexes of P,N ligands shows a good agreement in both the bond lengths and angles. The lowest energy structure has a “chair” conformation of the seven-membered phospha-dioxa-cycloheptane ring and “edge-on/face-on/face-on/edge-on” arrangement of the phenyl rings. The next lowest energy conformer with an exo allyl group has a “twist” conformation of the seven-membered ring and alternating “edge-on” and “face-on” arrangement of the phenyl rings as anticipated from the Knowles “edge-on...

Source: Computational and Theoretical Chemistry - July 19, 2018 Category: Chemistry Source Type: research