“…In these cyclometallated complexes, the metal-oxygen bond cleaves more easily than the metal-sulfur bond. Aroyl-or acylhydrazones of aromatic aldehydes which are similar to semicarbazones can also act as tridentate C,N,O-donor ligands via cyclometallation at the benzylidene ring [5,6]. Structurally characterized cyclometallated complexes of such ligands are very rare [6].…”
“…In these cyclometallated complexes, the metal-oxygen bond cleaves more easily than the metal-sulfur bond. Aroyl-or acylhydrazones of aromatic aldehydes which are similar to semicarbazones can also act as tridentate C,N,O-donor ligands via cyclometallation at the benzylidene ring [5,6]. Structurally characterized cyclometallated complexes of such ligands are very rare [6].…”
“…Within this class of terdentate ligands, the [C,N,N] structural arrangement has been extensively studied. In contrast, relatively few [C,N,O]-cyclometalated ligands have been reported. − …”
Section: Introductionmentioning
confidence: 99%
“…With this idea in mind we decided to undertake a comparative study of the chemical behavior of the four- and five-membered [C,N] metallacycles when fit in potentially terdentate [C,N,O] ligands in which the O-donor is the carbonyl of an amido group (Scheme ). It should be noted that although the coordination ability of the carbonyl of the acetamido group and its potential to direct the orthopalladation reaction were recognized a long time ago, the use of the amido framework in terdentate [C,N,O] ligands has scarcely been explored and is in fact limited to a few acylhydrazones. 3a-e, 1 …”
The reaction of iodo anilines 2-IC6H4−N(Me)−CH2−CO−N(R)2 (R = Me, 1a; R = Et, 1b) with
Pd2(dba)3 afforded binuclear Pd(II) complexes
(R =
Me, 2a; R = Et, 2b), which by reaction with PPh3 and Tl(TfO) were transformed into the cationic binuclear
Pd(II) complexes
(R = Me, 3a; R = Et,
3b). On the contrary, the reaction of aniline 2-I-4-MeC6H3−N(Me)−CH2CH2−CO−N(Me)2 (4) with
Pd2(dba)3 and PPh3 afforded four-membered azapalladacycle [Pd{κ
2
C,N-4-MeC6H3{N(Me)CH2CH2C(O)N(Me)2}-2}I(PPh3)] (5), which on treatment with Tl(TfO) did not yield a complex with the ligand in
a C,N,O-terdentate fashion, the unstable Pd(II) complex [Pd{κ
2
C,N-4-MeC6H3{N(Me)CH2CH2C(O)N(Me)2}-2}OTf(PPh3)] (6) being obtained instead. On the other hand, 2-IC6H4−CH2−N(Bn)−CH2−CO−N(Me)2 (7) reacted with Pd2(dba)3 to give the C,N,O-terdentate complex [Pd{κ
3
C,N,O-C6H4{CH2N(Bn)CH2C(O)N(Me)2}-2}I] (8), which by reaction with PPh3 and Tl(TfO) was transformed into the cationic
C,N,O-terdentate complex [Pd{κ
3
C,N,O-C6H4{CH2N(Bn)CH2C(O)N(Me)2}-2}(PPh3)]TfO (9). Similarly,
treatment of iodo benzylamines 2-IC6H4−CH2−N(R)−CH2CH2−CO−N(Me)2 (R = Bn, 10a; R = Me,
10b) with Pd2(dba)3 and then with PPh3 and Tl(TfO) afforded cationic C,N,O-terdentate complexes [Pd{κ
3
C,N,O-C6H4{CH2N(R)CH2CH2C(O)N(Me)2}-2}(PPh3)]TfO (R = Bn, 12a; R = Me, 12b). Solid-state
structures of palladium complexes 2a, 2b, 3a·C6H6·3THF, and 8 have been determined by X-ray analysis.
Die durch Kondensation von Acetylhydrazin und den Titelketonen gebildeten Acetylhydrazone (Ausb. 42‐78%) reagieren mit aus Li‐ und Pd(II)‐halogenid dargestelltem Li‐tetrahalogenopalladat(II) in situ zu den Cyclopallada‐Verbindungen (I)‐(III).
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