Synthesis and Structures of ansa‐Titanocene Complexes with Diatomic Bridging Units for Overall Water Splitting

Abstract

The synthesis of a series of ansa-titanocene dichlorides [Cp'2TiCl2] (Cp' = bridged η(5)-tetramethylcyclopentadienyl) and the corresponding titanocene bis(trimethylsilyl)acetylene complexes [Cp'2Ti(η(2)-Me3SiC2SiMe3)] is described. The ethanediyl-bridged complexes [C2H4(C5Me4)2TiCl2] (2-Cl2) and [C2H4(C5Me4)2Ti(η(2)-Me3SiC2SiMe3)] (2-btmsa; btmsa = η(2)-Me3SiC2SiMe3) can be obtained from the hitherto unknown calcocenophane complex [C2H4(C5Me4)2Ca(THF)2] (1). Furthermore, a heterodiatomic bridging unit containing both, a dimethylsilyl and a methylene group was introduced to yield the ansa-titanocene dichloride [Me2SiCH2(C5Me4)2TiCl2] (3-Cl2) and the bis(trimethylsilyl)acetylene complex [Me2SiCH2(C5Me4)2Ti(η(2)-Me3SiC2SiMe3)] (3-btmsa). Besides, tetramethyldisilyl- and dimethylsilyl-bridged metallocene complexes (structural motif 4 and 5, respectively) were prepared. All ansa-titanocene alkyne complexes were reacted with stoichiometric amounts of water; the hydrolysis products were isolated as model complexes for the investigation of the elemental steps of overall water splitting. Compounds 1, 2-btmsa, 2-(OH)2, 3-Cl2, 3-btmsa, 4-(OH)2, 3-alkenyl and 5-alkenyl were characterised by X-ray diffraction analysis.

Molecular structures of a series of substituted bis(η5-cyclopentadienyl)titanium dihalides Cp R 2TiX 2 [X = F, Cl, Br and I; R = CHPh2, CH(p-Tol)2 and adamantyl]

“…The Ti-Cl bond lengths in 7 and 9 of 2.3331 (3)-2.3804 (4) Å are also in the range of typical Ti-Cl bond lengths, e.g. Cp 2 TiCl 2 [2.367 (2) and 2.361 (1) Å ; Clearfield et al, 1975], Cp*TiCl 2 (thf) [thf is tetrahydrofuran; 2.3426 (2) and 2.3251 (6) Å ; Oswald et al, 2016], TiCl 3 py 3 -(NCy 2 ) [Cy is cyclohexyl; 2.3653 (5), 2.3393 (5) and 2.3023 (5) Å ; Adler et al, 2014] or other complexes (Kessler et al, 2013;Sassmannshausen & Baumgartner, 2008;Edwards et al, 1995); the bond lengths are also in accordance with the already published structure of 8 (Diekmann et al, 2006). As The molecular structure of complex 9.…”

Crystal structure of 1,1,2,2-tetramethyl-1,2-bis(2,3,4,5-tetramethylcyclopenta-2,4-dien-1-yl)disilane

“…For synthesis of the title compound, see: Kessler et al (2013). For group 4 complexes with this ligand, see: Godemann et al (2014Godemann et al ( , 2015; Pinkas et al (2011); Xu et al (1997) Table 1 Hydrogen-bond geometry (Å , ).…”

“…The synthesis of the title compound has been described previously (Kessler et al, 2013). A saturated solution of the title compound in n-hexane was very slowly cooled from 60 °C to room temperature resulting in precipitation of colourless crystals.…”

Hydrolysis of Scandium Alkyl Derivatives Supported by a Pentadentate Diborate Ligand: Interconversion of Hydroxo and Oxo Complexes

“…For the early transition metals, this has mostly relied on controlled hydrolysis of metal alkyls, hydrides, or amides (Scheme 1). [4][5][6][7][8] However, the aforementioned acidity of the desired L n M-OH complex often renders the rate of the second step competitive with the first, and the µ-oxo complex is often favoured both kinetically and thermodynamically.…”