A Family of Titanium Complexes with Catechol Ligands: Structural Investigation and Catalytic Application. Issue 33 (24th October 2016)

• Record Type: Journal Article
• Authors: Bazhenova, Tamara A.; Kovaleva, Nadezhda V.; Shilov, Gennady V.; Petrova, Galina N.; Kuznetsov, Denis A.
• Is Part Of: European journal of inorganic chemistry. Issue 33(2016)
• Page Start: 5215
• Page End: 5221
• Publication Date: 2016-10-24
• Subjects: Titanium -- O ligands -- Catechol -- Acetylene -- Reduction; Chemistry, Inorganic -- Periodicals; Organometallic chemistry -- Periodicals; Bioinorganic chemistry -- Periodicals; Solid state chemistry -- Periodicals; 546
• DOI: 10.1002/ejic.201600804
• Languages: English
• ISSNs: 1434-1948

Abstract

Abstract : Four new titanium catecholate complexes – [Ti2 (Cat)2 (CatH)2 (OCH3 )2 (CH3 OH)2 ] (1 ; Cat = C6 H4 O2 2– ), [Ti2 (4 t BuCat)4 (CH3 OH)2 ]· 2CH3 OH (2· 2CH3 OH; 4 t BuCat = [4‐ t ‐C4 H9 ‐C6 H3 O2 ] 2– ), [Ti(Cat)2 (dmf)2 ] (3 ; dmf = N, N ‐dimethylformamide), and [Na(dme)Ti(Cat)3 ]2 [Na(dme)CH3 OH]2 (4 ; dme = 1, 2‐dimethoxyethane) – have been obtained by treatment of Ti(OCH3 )4 with catechols in methanol and structurally characterized. Complex3 is the first example of a neutral mononuclear titanium catecholate containing more than one catechol molecule per titanium atom. Complexes1 and2 are neutral dimers in the solid state, each with a catechol/Ti ratio equal to 2 and featuring one of the catechol ligands bridging two titanium centres in a singly bridging chelate µ2 ‐(O, O′, O′) mode. The other catechol molecule is either a terminal bidentate chelating ligand (complex2 ) or a Ti monodentate ligand (complex1 ). Complex4 is a heterometallic aryloxide complex with a tetrameric [{Na(dme)Ti(Cat)3 )2 ] 2– (Ti2 Na2 ) core as an anionic moiety and Na ions, solvated by methanol and dme ligands – [{Na(dme)(CH3 OH)}2 ] 2+ – as a cationic counterpart. Each Ti centre in4 is octahedrally coordinated by three catechol ligands, demonstrating three distinct types of bridging modality. It was shown that1 –4 effectively catalyze the selective homogeneous hydrogenation of acetylene to ethylene. Various kinetic relationships were determined and analyzed, enabling a reaction pathway for this catalytic reaction to be proposed. Abstract : A series of titanium(+4) catecholate complexes with different architectures has been synthesized and structurally characterized. The investigated compounds demonstrated excellent activity as catalysts for C2 H2 → C2 H4 conversion, representing a rare example of selective hydrogenation of acetylene catalyzed by a non‐precious metal.