Low-Valent Titanocene Products from Attempted Syntheses of Titanocene Bearing Dimethyl(3,3,3-trifluoropropyl)silyl Groups

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Title:Low-Valent Titanocene Products from Attempted Syntheses of Titanocene Bearing Dimethyl(3,3,3-trifluoropropyl)silyl Groups
Creators:
Lukešová, Lenka
Horáček, Michal
Gyepes, Róbert
Císařová, Ivana
Štěpnička, Petr
Kubišta, Jiří
Mach, Karel
Journal or Publication Title:
Collection of Czechoslovak Chemical Communications, 70, 1, pp. 11-33
Uncontrolled Keywords:Titanocenes, Titanium, X-Ray diffraction, Hydrides, Magnesium, Silyl derivatives, Sandwich complexes, Metallocenes, (3,3,3-Trifluoropropyl)silyl group, Crystal structure, ESR spectroscopy

Abstract

Reduction of silyl-substituted titanocene dichloride [TiCl<sub>2</sub>{η<sup>5</sup>-C<sub>5</sub>Me<sub>4</sub>(SiMe<sub>2</sub>CH<sub>2</sub>CH<sub>2</sub>CF<sub>3</sub>)}<sub>2</sub>] (<strong>1</strong>) with one molar equivalent of magnesium afforded a mixture of products, thus precluding the isolation of the possibly formed titanocene [Ti{(η<sup>5</sup>-C<sub>5</sub>Me<sub>4</sub>(SiMe<sub>2</sub>CH<sub>2</sub>CH<sub>2</sub>CF<sub>3</sub>)}<sub>2</sub>]. The presence of isolable monochloride [TiCl{η<sup>5</sup>-C<sub>5</sub>Me<sub>4</sub>(SiMe<sub>2</sub>CH<sub>2</sub>CH<sub>2</sub>CF<sub>3</sub>)}<sub>2</sub>] (<strong>2</strong>) in the mixture indicates that the mangnesium is consumed in concurrent reactions, that produce various titanocene compounds of which some were obtained by the reduction of <strong>1</strong> with excess magnesium. Those include the trinuclear Ti<sup>III</sup>-Mg<sup>II</sup>-Ti<sup>III</sup> hydride-bridged complex [Ti{η<sup>5</sup>-C<sub>5</sub>Me<sub>4</sub>- (SiMe<sub>2</sub>CH<sub>2</sub>CH<sub>2</sub>CF<sub>3</sub>)}<sub>2</sub>(μ-H)<sub>2</sub>]<sub>2</sub>Mg (<strong>3</strong>) and a dimeric dinuclear Ti-Mg complex <strong>4</strong> containing the&nbsp;[Ti<sup>III</sup>(μ-H)<sub>2</sub>Mg(μ-X)]<sub>2</sub> core where, however, the nature of the bridging moiety X remains unknown. The reduction of <strong>1</strong> with excess magnesium in the presence of bis(trimethylsilyl)ethyne afforded the product of C-H activation [Ti{η<sup>5</sup>-C<sub>5</sub>Me<sub>4</sub>(SiMe<sub>2</sub>CH<sub>2</sub>CH<sub>2</sub>CF<sub>3</sub>)}- {η<sup>5</sup>:η<sup>1</sup>-C<sub>5</sub>Me<sub>3</sub>(CH<sub>2</sub>)(SiMe<sub>2</sub>CH<sub>2</sub>CH<sub>2</sub>CF<sub>3</sub>)}] (<strong>5</strong>) in 47% yield. This compound reacted rapidly with <i>tert</i>-butylethyne to give the Ti<sup>III</sup>-acetylide complex [Ti(η<sup>1</sup>-C≡CCMe<sub>3</sub>){η<sup>5</sup>-C<sub>5</sub>Me<sub>4</sub>- (SiMe<sub>2</sub>CH<sub>2</sub>CH<sub>2</sub>CF<sub>3</sub>)}<sub>2</sub>] (<strong>6</strong>). All the reductions of <strong>1</strong> at molar ratios Mg:Ti ≥ 1 gave mixtures, where a good deal of the reduction products remained in the mother liquors unidentified. The structures of <strong>1</strong>, <strong>2</strong>, <strong>3</strong>, <strong>5</strong>, and <strong>6</strong> were determined by X-ray diffraction analysis and, for <strong>2</strong>, <strong>3</strong>, <strong>4</strong>, <strong>5</strong>, and <strong>6</strong>, further corroborated by ESR spectra. <p>

Title:Low-Valent Titanocene Products from Attempted Syntheses of Titanocene Bearing Dimethyl(3,3,3-trifluoropropyl)silyl Groups
Creators:
Lukešová, Lenka
Horáček, Michal
Gyepes, Róbert
Císařová, Ivana
Štěpnička, Petr
Kubišta, Jiří
Mach, Karel
Uncontrolled Keywords:Titanocenes, Titanium, X-Ray diffraction, Hydrides, Magnesium, Silyl derivatives, Sandwich complexes, Metallocenes, (3,3,3-Trifluoropropyl)silyl group, Crystal structure, ESR spectroscopy
Divisions:Life and Chemical Sciences > Institute of Organic Chemistry and Biochemistry > Collection of Czechoslovak Chemical Communications
Journal or Publication Title:Collection of Czechoslovak Chemical Communications
Volume:70
Number:1
Page Range:pp. 11-33
ISSN:0010-0765
E-ISSN:1212-6950
Publisher:Institute of Organic Chemistry and Biochemistry
Related URLs:
URLURL Type
http://dx.doi.org/10.1135/cccc20050011UNSPECIFIED
ID Code:2339
Item Type:Article
Deposited On:06 Feb 2009 17:17
Last Modified:06 Feb 2009 16:17

Citation

Lukešová, Lenka; Horáček, Michal; Gyepes, Róbert; Císařová, Ivana; Štěpnička, Petr; Kubišta, Jiří; Mach, Karel (2005) Low-Valent Titanocene Products from Attempted Syntheses of Titanocene Bearing Dimethyl(3,3,3-trifluoropropyl)silyl Groups. Collection of Czechoslovak Chemical Communications, 70 (1). pp. 11-33. ISSN 0010-0765

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