Ziółkowska A, Szynkiewicz N, Ponikiewski Ł. Experimental and theoretical investigation of the reactivity of [(BDI*)Ti(Cl){η
2-P(SiMe
3)-P
iPr
2}] towards selected ketones.
Dalton Trans 2021;
50:1390-1401. [PMID:
33433538 DOI:
10.1039/d0dt04014b]
[Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
In this work, we report a new type of reactivity of [(BDI*)Ti(Cl){η2-P(SiMe3)-PiPr2}] (1) towards ketones (BDI* = 2,6-diisopropylphenyl-β-methyldiketiminate ligand). In the reaction of 1 with acetone, cyclopentanone or cyclohexanone, a ketone moiety is inserted into Ti-Pphosphanyl or Ti-Pphosphido bonds to form complexes with a new C-P-P moiety, providing [(BDI*)Ti(Cl){η2-P(SiMe3)-PiPr2-C(Me)2O}] (2a), [(BDI*)Ti(Cl){η2-OC(Me)2P(SiMe3)-PiPr2}] (2b), [(BDI*)Ti(Cl){η2-P(SiMe3)-P(iPr)2-{C(CH2)4}O}] (3a), and [(BDI*)Ti(Cl){η2-P(SiMe3)-P(iPr)2-{C(CH2)5}O}] (4a). Starting complex 1 reacts with cyclohexanone, yielding a monocrystalline complex [{(ArN[double bond, length as m-dash]C(Me)CHC(Me)[double bond, length as m-dash]NAr)C(CH2)5O}Ti(Cl){PiPr2-P(SiMe3)C(CH2)5O}] (4d) with the insertion of two ketone molecules. Interestingly, we found that monoinserted complexes 2a and 3a may be oxidized via a reaction with AgCl, leading to elimination of the -SiMe3 group and oxidation of the titanium atom. This reaction led us to isolate the Ti(iv) complex [(BDI*)Ti(Cl){η2-P-P(iPr)2-{C(CH2)5}O}] (5) in crystalline form. To identify the kinds of products that may be formed and determine which products are the most energetically favoured ones, we conducted a thermodynamic DFT study of 1 towards acetone, cyclopentanone and cyclohexanone. Structures 2a, 2b, 3a, 3e, 4a, 4d, and 5 were characterized by X-ray crystallography, and complex 5 was also identified by NMR spectroscopy.
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