Eine empfindliche Sonde für Veränderungen in der Koordinationssphäre von Titan: Achtgliedrige Dioxatitanacyclen und ihre metallorganischen Derivate

Abstract

Angesichts der enormen Bedeutung von Titanverbindungen in der Organischen Synthese sind Modellstudien nützlich. TiCl4 setzt sich mit MBPH2 unter HCl‐Entwicklung zu [(mbp)TiCl2] um, einem achtgliedrigen Heterocyclus mit einer O‐Ti‐O‐Einheit und einer gegenüberliegenden CH2‐Gruppe. Deren 1H‐NMR‐Signale reagieren empfindlich auf Veränderungen am Ti‐Atom, die z.B. duch Alkylierungen und Arylierungen sowie durch Erhöhung der Koordinationszahl hervorgerufen werden.

Titanium Complexes Stabilized by a Sulfur‐Bridged Chelating Bis(aryloxo) Ligand as Active Catalysts for Olefin Polymerization

“…The presence of the Ti−C bonds was confirmed by the 1 H NMR spectra at room temperature as a singlet (δ = 2.22 ppm for 2a ; δ = 2.23 ppm for 2b ). For comparison, two singlets (δ = 1.38 and 1.36 ppm) of Ti−CH 3 for [Ti(κ 2 ‐mbp)(CH 3 ) 2 ] [mbp = 2,2′‐methylenebis(6‐ tert ‐butyl‐4‐methylphenolato)]4a and one singlet (δ = 1.22 ppm) for [Ti(CH 3 ) 4 ]·Et 2 O were detected 19. Additional evidence for the formation of the Ti−C bond was achieved during controlled hydrolysis of 2b .…”

Bis(amido)titanium complexes having chelating diaryloxo ligands bridged by sulfur or methylene and their catalytic behaviors for ring-opening polymerization of cyclic esters

“…The Ti-O distances in 2 are comparable to the diisopropoxo complex 6 (1.892 A) [17], and longer than those in the corresponding chloride complex 5 (1.846 A) [17], aryl complex 7 (1.855 A) [9a] and Cp complex (1.827 A) 8 in the titanium complex with the tbp ligand. The Ti-O distances in the methylene-bridged complex 4 are longer than that of the a series of titanium complexes with methylene-bridged bis(aryloxo) ligand (1.751-1.788 A) [19][20][21] and the other titanium complex with monodentate aryloxo or alkoxo ligands [22][23][24][25][26][27], due to the p-donation from the nitrogen atoms to the metal center [28]. The axial Ti-N bond distance in the sulfur-bridged complex 2 is 0.03 A longer than the equatorial one in 2.…”

Resorcin[4]arene‐Derived Mono‐ and Diphosphines in Suzuki Cross‐Coupling

“…[2,3] While ligands of this class have found numerous applications in separation science and sensing technology, [4][5][6][7][8] catalytic properties, surprisingly, have been little studied. [9,10] This is in stark contrast with podands obtained from the related calix [4]arene cavities, [11] in particular their phosphane derivatives, [11][12][13][14][15][16][17][18][19][20] which have already led to a rich transition metal chemistry. [2,21] We have recently described the synthesis of the first mono-and diphosphines built on a resorcinarene cavitand (1-3, Scheme 1) and shown that these are suitable for complexation of transition metals, altering neither the cavity shape nor its receptor properties.…”