Einfacher Zugang zu modifizierbarem Schwartz‐Reagens – Oxidative Addition von amidischen N‐H‐Bindungen an reduzierte Zirconocenkomplexe

Abstract

Auf den Spuren des Schwartz‐Reagens: Zwei Zirconocen‐Hydridoamidatkomplexe wurden durch formale oxidative Addition von amidischen N‐H‐Bindungen an reduzierten Zirconocenfragmenten hergestellt. Insertionsreaktionen mit Alkenen zeigen ein zu dem klassischen Schwartz‐Reagens unterschiedliches Verhalten und bilden verzweigte Insertionsprodukte. Zusätzlich wurden sowohl das Insertionsprodukt als auch der Hydridokomplex durch Röntgenstrukturanalyse charakterisiert.

Four‐Membered Heterometallacyclic d0 and d1 Complexes of Group 4 Metallocenes with Amidato Ligands

“…The molecular structure of complex 7 a is depicted in Figure 5 (for related molecular structures of 7 b and 8 , see the Supporting Information. These results are in contrast to employing this strategy with [Cp 2 Zr(py)(η 2 ‐Me 3 SiC 2 SiMe 3 )] (py=pyridine) and amides, which did not result in Zr III , complexes but instead gave the formal oxidative addition of the amide NH bond to give the Zr hydride cleanly (Scheme , II ) 6…”

“…These results are in contrast to employing this strategy with [Cp 2 Zr(py)(h 2 -Me 3 SiC 2 SiMe 3 )] (py = pyridine) and amides, which did not result in Zr III , complexes but instead gave the formal oxidative addition of the amide NÀH bond to give the Zr hydride cleanly (Scheme 2, II). [6] In complex 7 a, the Ti center is surrounded by two Cp units and the chelating amidato ligand in a distorted tetrahedral geometry. The central metallacyclic unit is almost flat (torsion angle O1-Ti1-N1-C1 1.678), as has been seen in previously reported Ti-amidate complexes.…”

“…Performing the salt metathesis reaction with the same ligand [(Dipp)NC(Ph)O] but with Schwartz reagent resulted in the formation of the known four‐membered heterometallacycle 3 according to Scheme 6…”

“…Yield: 502 mg (70 %). 1 6 ]benzene (1 mL) and sealed. Already after sealing, gas evolution was observed.…”

Reactions of Group 4 Metallocenes with N,N′‐Diphenylformamidine – Hydrogen Generation versus Oxidative Addition

“…[3] Recently, we reported the synthesis of zirconocene hydrido amidato complexes as a result of formal oxidative addition of an amidic N-H bond at reduced central zirconium atoms, offering a facile synthetic pathway to an alternative and tunable Schwartz's reagent. [4] Also the reaction behavior of various differently substituted titanocene precursor complexes CpЈ 2 of titanocene(III) amidato complexes (Scheme 1) upon oxidation of the central titanium atom. [5] Scheme 1.…”