การศึกษาเชิงทฤษฎีฟอสฟีนอสมมาตร สำหรับเมทานอลคาร์บอนิลเลชัน (ตอน 1)

Abstract

Quantum Mechanics (QM) calculations bascd on Hiutree-Fock (HF) and the Density Functional Thcory (DFT) havc been caried our fbr an asymmetric phosphine ligand pF, pCH2 CH2 pMe2 1.r. This ligand was employed as a promoter of the rhodium catalyzed mcthanol carbonylation. A rhodium cation 1.2 are calculated. Contplexcs 1.3 and 1,4 arc also invcstigated on electronic propcrties 10 specity the most stable structure. A comparison between lhe various methods indicatcd that DFT with LANL2DZ basis set is the appropriate method fbr such structures.
       By the consideration of rhe B3LYP/LANL2DZ calculated energies, complex 1.3 is more stablc than complex 1.4. It can notices rhat the stereochemistry at rhodium in which the p(Me), rrans to the co and the PF2 lrars to the Me group arc preferred. The results indicate that thc presence of strong electroncgativity fluorine aloms in PF, makcs them weik o-donors but much stronger 7[ acccptors and the presence of Me groups in P(Mc), makes them stronger o-donors but much weakcr l[ acceptors, with conlirming by 2.356 and z.aso A o1 a Rh-P(F, ) and rhe Rh p(Me r) bond lengths in conlplex 1.3.
        The molccular orbital confirmed that thc dz? orbital is lowcr energy than the d*2_r2 orbital as expectcd for a low spin d8orbital Rh (l) conligurarion. The difl'crences of cnergy (AE) values were used to calculate thc cquilibrium constant and confinncd the possibiliry to make this model 1.3.