Reactions of Pentafulvene Complexes of Titanium with Carbonyl Compounds − Diastereoselective Synthesis of σ,π-Chelate Complexes with Cp~O Ligands

Stroot, Jörg; Beckhaus, Rüdiger; Saak, Wolfgang; Haase, Detlev; Lützen, Arne

doi:10.1002/1099-0682(200207)2002:7<1729::aid-ejic1729>3.0.co;2-k

Cited by 27 publications

(25 citation statements)

References 48 publications

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“…Die Bindungslängen liegen im typischen Bereich dieser Verbindungsklasse [17], so daß auf die Diskussion einzelner Abstände verzichtet werden kann. Auffallend groß ist jedoch der C16ϪC31-Abstand (1.657(2) Å ), der gegenüber C sp3 ϪC sp3 -Einfachbindungen deutlich aufgeweitet ist.…”

Section: Schemaunclassified

Pentafulvenkomplexe des Titans — Synthese, Struktur und Fluktuierendes Verhalten von Cp′Ti{η6-C5H4=C(p-Tol)2}Cl (Cp′ = Cp*, Cp)

Stroot

Lützen

Friedemann

et al. 2002

Z. anorg. allg. Chem.

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Section: Schemaunclassified

Pentafulvenkomplexe des Titans — Synthese, Struktur und Fluktuierendes Verhalten von Cp′Ti{η6-C5H4=C(p-Tol)2}Cl (Cp′ = Cp*, Cp)

Stroot

Lützen

Friedemann

et al. 2002

Z. anorg. allg. Chem.

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“…Whereas the newly formed bond Ti1–O1 with a bond length of 1.854(2) Å constitutes a typical single bond,, the second newly formed bond C16–C26 with a bond length of 1.630(4) Å is significantly elongated compared to typical C(sp 3 )–C(sp 3 ) single bonds . This elongation of the Cp,O σ,π‐chelating ligand framework is comparable to sterically crowded alkanes, and also characteristic for complexes derived from insertion reactions of carbonyl compounds into the polarized M –C q,exo bond of monopentafulvene complexes , , , . The former carbonyl carbon atom C26 is sp 3 ‐hybridizied as shown by the sum of angles around C26 (e.g.…”

Section: Resultsmentioning

confidence: 79%

To Coordinate or not to Coordinate: The Special Role of Chalcogen Ether Functionalities in the Design of Twofold Functionalized Cyclopentadienyl Ligands [Cp,O,Ch (Ch = S, Se)]

Fischer

Schmidtmann

Beckhaus

2019

Zeitschrift anorg allge chemie

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The solvent-and catalyst free synthesis of two β-thio ketones L1a and L1b is reported. L1a, L1b, and a β-seleno ketone L1c were successfully employed as ligand precursors in the synthesis of a novel series of cationic titanium complexes 4a-4c via a wellestablished reaction sequence: insertion of the carbonyl functional group into the polarized Ti-C q,exo bond of the monopentafulvene com-595 ionic titanium complexes 4a-4c bear twofold functionalized cyclopentadienyl [Cp,O,Ch (Ch = S, Se)] ligand frameworks built directly in the coordination sphere of the metal, in which the chalcogen ether functionalities do not coordinate to the central metal atoms as demonstrated by NMR experiments. Consequently, Cp,O σ,π chelating ligand systems are formed with free coordination sites at the central titanium atoms and pendant chalcogen ether moieties. Journal of Inorganic and General Chemistry Zeitschrift für anorganische und allgemeine Chemie ARTICLE Scheme 1. Overview of tridentate Cp,X,Y ligands built directly in the coordination sphere of the metal; synthesis, tuning potential, previous examples, and attempted synthesis of Cp,O,Ch ligands (Ch = S, Se). gands [Cp,O,Ch (Ch = S, Se)]. These complexes are bearing bidentate π,σ Cp,O chelating ligands with unoccupied chalcogen ether functionalities, showing no interaction to the central titanium atom in the final cationic complexes. Results and Discussion Synthesis of the O,Ch-Ligand Precursor Compounds L1a-c (Ch = S, Se)Inspired by pioneering work concerning the solvent-and catalyst free synthesis of various β-substituted diphenylphosphino ketones [10,13] and β-amino ketones, [12] which are accessible without any further purification steps starting from methyl vinyl ketone and appropriate secondary amines and phosphines, the analogous synthesis of β-thio ketones was targeted. The reactions of methyl vinyl ketone with propane-2-thiol and benzylthiol resulted in clean conversions (shown by 1 H NMR analysis) to the corresponding 1,4-addition products L1a and L1b within 16 h of vigorous stirring at room temperature (Scheme 2). 596Scheme 2. Solvent-and catalyst-free synthesis of the β-thio ketones L1a,b, and synthesis of the β-seleno ketone L1c. [14] Journal of Inorganic and General Chemistry Zeitschrift für anorganische und allgemeine Chemie ARTICLE Scheme 3. Three-/two-step synthesis of cationic titanium complexes 4a-4c with twofold functionalized cyclopentadienyl ligands.Compounds 2a-2c and 3a-3c were fully characterized by NMR analyses, and, in the case of 2a, 2c, and 3c crystals for single-crystal X-ray diffraction were obtained either from saturated solution in n-hexane at -26°C (2a, 3c) or by recrystallization in n-hexane at room temperature (2c). The molecular structures of 2a, 2c, and 3c are shown in Figure 1, Figure 2, and Figure 3.

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“…This opens the way to a lot of other synthetically very interesting reactions. [53][54][55][56][57][58][59][60][61][62][63][64][65][66][67][68][69][70][71] The most spectacular example for unexpected results was the reaction of η 5 : η 1 -pentafulvene titanium complexes with the allylidenephosphorylide Ph 3 P=C(H)À C(H)=CH 2 , giving a titanabutatriene complex by a spontaneous double CÀ H bond activation via an intermediate Ph 3 P=C=C=CH 2 . After dimerization the titanabutatriene complex formed a binuclear zig-zag hexapentaene titanium complex (Scheme 9).…”

Section: Beckhaus' Bis(η 5 : η 1 -Pentafulvene) Complexesmentioning

confidence: 99%

“…[39] Beckhaus described the weak MÀ C exo interaction in these complexes as the first examples of heteroatom free organometallic frustrated Lewis pairs in comparison to classical heteroatom containing Lewis pairs. [39,[45][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61] Advantages of η 5 : η 1 -pentafulvene complexes in reactions with selected substrates are the high yields of products, formed at room temperature (Scheme 5-10) with a very high selectivity. This means that for selected substrates in a two step process the selective reaction of two or even more substrates is possible.…”

Section: Beckhaus' Bis(η 5 : η 1 -Pentafulvene) Complexesmentioning

confidence: 99%

Advantages of Group 4 Metallocene Bis(trimethylsilyl)acetylene Complexes as Metallocene Sources Towards Other Synthetically used Systems

Rosenthal

2019

ChemistryOpen

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Active species for synthetic and catalytic applications are formed from well defined complexes or mixtures of compounds. For group 4 metallocenes, three pathways for the formation of the reactive complex fragment [Cp′ 2 M] are known: (i) reductive mixtures and well defined complexes which are able to form the metallocene fragments either by (ii) addition or (iii) substitution reactions. In this account for each of theses systems (i)–(iii) a prominent example will be discussed in detail, (i) the Negishi reagent Cp 2 ZrCl 2 /n‐BuLi, (ii) bis(η 5 : η 1 ‐pentafulvene) complexes and (iii) metallocene bis(trimethylsilyl)acetylene complexes, to show the advantages and the disadvantages for each of these methods for synthetic applications. This account summarizes some main advantages of group 4 metallocene bis(trimethylsilyl)acetylene complexes as metallocene generating agents over other synthetically used systems. For each of the special purposes, all described systems have advantages as well as disadvantages. The aim of this overview is to help synthetic chemists in selecting the most effective system on the basis of [Cp′ 2 M] (M=Ti, Zr) for synthetic or catalytic puposes.

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Reactions of Pentafulvene Complexes of Titanium with Carbonyl Compounds − Diastereoselective Synthesis of σ,π-Chelate Complexes with Cp~O Ligands

Cited by 27 publications

References 48 publications

Pentafulvenkomplexe des Titans — Synthese, Struktur und Fluktuierendes Verhalten von Cp′Ti{η6-C5H4=C(p-Tol)2}Cl (Cp′ = Cp*, Cp)

Pentafulvenkomplexe des Titans — Synthese, Struktur und Fluktuierendes Verhalten von Cp′Ti{η6-C5H4=C(p-Tol)2}Cl (Cp′ = Cp*, Cp)

To Coordinate or not to Coordinate: The Special Role of Chalcogen Ether Functionalities in the Design of Twofold Functionalized Cyclopentadienyl Ligands [Cp,O,Ch (Ch = S, Se)]

Advantages of Group 4 Metallocene Bis(trimethylsilyl)acetylene Complexes as Metallocene Sources Towards Other Synthetically used Systems

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