C−H versus C−N Bond Cleavage Promoted by Niobium(II) Amide

Abstract

Despite their close structural similarity, the potassium and lithium salts of dipyridylamine and diphenylamine[(C 5 H 5 N) 2 N -,Ph 2 N -]reactwith(TMEDA) 2 -Nb 2 Cl 5 Li(TMEDA) in THF to afford two different compounds arising from the cooperative oxidative addition of the two metal centers on either the C-H or C-N bond of the amide ligand.

Double CH Activation of a Masked Cationic Bismuth Amide

“…The ortho metalation of an (NPh 2 ) − group has previously been reported for the niobium cluster [LiNb 2 Cl 5 (tmeda) 3 ] upon reaction with KNPh 2 under mild conditions (room temperature, ca. 24 h), but proceeded with only moderate selectivity (33 % yield; tmeda= N , N , N ′, N ′‐tetramethylethylenediamine) . In main‐group chemistry, the reaction of HNPh 2 with n BuLi in a 3:7 stoichiometry afforded the more complicated cluster [(Ph 2 NLi)[Ph(C 6 H 4 Li)NLi] 2 ( n BuLi) 2 (Et 2 O) 4 ], containing two ortho ‐metalated diphenylamide groups, after a few days .…”

“…24 h), but proceeded with only moderate selectivity (33 % yield;t meda = N,N,N',N'-tetramethylethylenediamine). [11] In main-group chemistry,t he reaction of HNPh 2 with nBuLi in a3 :7 stoichiometry afforded the more complicated cluster [(Ph 2 NLi)[Ph(C 6 H 4 Li)NLi] 2 (nBuLi) 2 (Et 2 O) 4 ], containing two ortho-metalated diphenylamide groups,a fter af ew days. [12] Moreover,r eactions of AlMe 3 or GaMe 3 with HNPh 2 led to one ortho metalation per two metal centers in 84 %o r1 2% yield, respectively,b ut forcing reaction conditions were necessary to promote this transformation (reflux in toluene, 18 hor3d).…”

Bis(μ-diphenylamido-κ2N:N)bis[tris(tetrahydrofuran-κO)potassium(I)]

“…Synthesis of various transition metal diphenylamides: Seidel & Reichardt (1974); Villanueva et al (1994); Barnhart et al (1995); Tayebani et al (1998); Gamer et al (2001); Hitchcock et al (2002); Hevia et al (2002). Potassium diphenylamide as a catalyst in polymerization reactions: Longi et al (1965); Kucera & Jelinek (1959); Grogler & Windemuth (1966).…”

“…One the one hand, potassium diphenylamide has been used for the synthesis of various transition metal diphenylamides, for example those of Cr (Seidel & Reichardt, 1974), Pd (Villanueva et al, 1994), Th (Barnhart et al, 1995), Nb (Tayebani et al, 1998), Y and Sm (Gamer et al, 2001), Yb (Hitchcock et al, 2002), and Re (Hevia et al, 2002). On the other hand, lactones and α,β-unsaturated cycloketones (Longi et al, 1965), octamethylcyclotetrasiloxane (Kucera & Jelinek, 1959), and isocyanates (Grogler & Windemuth, 1966) could be polymerized with potassium diphenylamide as a catalyst.…”

Doppelte CH‐Aktivierung eines maskierten Bismutamid‐Kations

“…Die ortho-Metallierung von (NPh 2 ) À -Einheiten wurde zuvor bei der Reaktion des Niob-Clusters [LiNb 2 Cl 5 (tmeda) 3 ] mit KNPh 2 beobachtet (tmeda = N,N,N',N'-Tetramethylethylendiamin);u nter milden Bedingungen (RT, % 24 h) wurde allerdings nur eine moderate Selektiväte rzielt (33 %A usbeute). [11] Als ein Beispiel aus der Hauptgruppenchemie reagiert HNPh 2 mit nBuLi in einer 3:7-Stçchiometrie innerhalb einiger Tage zu dem komplizierteren Cluster [(Ph 2 NLi)-[Ph(C 6 H 4 Li)NLi] 2 (nBuLi) 2 (Et 2 O) 4 ], der zwei ortho-metallierte Diphenylamidgruppene nthält. [12] Darüber hinaus führen die Reaktionen von AlMe 3 oder GaMe 3 mit HNPh 2 jeweils zu einer ortho-Metallierung pro zwei Metallzentren in 84 %bzw.…”