Design of 4‐Coordinate Ti Imido Aryloxide on the Surface of Silica for Catalytic Oxo/Imido Heterometathesis. Issue 6 (30th May 2022)

• Record Type: Journal Article
• Authors: Pichugov, Andrey V.; Bushkov, Nikolai S.; Rumyantsev, Andrey V.; Zhizhin, Anton A.; Aleshin, Dmitry Y.; Strelkova, Tatyana V.; Talanova, Valeria N.; Takazova, Rina U.; Mance, Deni; Allouche, Florian; Mougel, Victor; Dolgushin, Fedor M.; Ustynyuk, Nikolai A.; Zhizhko, Pavel A.; Zarubin, Dmitry N.
• Is Part Of: Helvetica chimica acta. Volume 105:Issue 6(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-05-30
• Subjects: grafting -- heterometathesis -- imido compounds -- metathesis -- titanium -- surface chemistry; Chemistry -- Periodicals; Chemistry, Analytical -- periodicals; Chimie -- Périodiques; 540
• DOI: 10.1002/hlca.202200030
• Languages: English
• ISSNs: 0018-019X

Abstract

Abstract: We report here the synthesis of 4‐coordinate Ti imido complexes Ti(=N t Bu)(OAr t Bu )2 (py) (2 ) and Ti(=N t Bu)(OAr t Bu )(Me2 Pyr)(py) (3 ) (Ar t Bu = O ‐2, 6‐ t Bu2 ‐4‐MeC6 H2, Me2 Pyr=2, 5‐dimethylpyrrolyl) and study their grafting onto the surface of partially dehydroxylated silica with the aim to prepare 4‐coordinate Ti imido aryloxide surface species. Study of the resulting materials with IR, solid‐state NMR, elemental and mass balance analyses demonstrates that grafting of bis ‐ aryloxide complex 2 leads to a predominant formation of silica‐supported Ti amide (≡SiO)Ti(NH t Bu)(OAr t Bu )2 (py) resulting from the protonation of the imido ligand with the surface silanols and only a smaller fraction of the desired imido species (≡SiO)Ti(=N t Bu)(OAr t Bu )(py). The use of the tailored complex 3 where one of the aryloxides is replaced with a more reactive pyrrolyl ligand significantly increases the selectivity of grafting leading to the formation of the Ti imido aryloxide (≡SiO)Ti(=N t Bu)(OAr t Bu )(py) as major surface species. The obtained materials show high activity in catalytic oxo/imido heterometathesis supporting the previously proposed hypothesis that electron‐donating environments are favorable for this transformation. Abstract :