Phenoxy-Linked Mesoionic Triazol-5-ylidenes as Platforms for Multinuclear Transition Metal Complexes

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• 作者：Daniel Mendoza-Espinosa ; Rodrigo Gonz谩lez-Olvera ; Guillermo E. Negr贸n-Silva ; Deyanira Angeles-Beltr谩n ; Oscar R. Su谩rez-Castillo ; Alejandro 脕lvarez-Hern谩ndez ; Rosa Santillan
• 刊名：Organometallics
• 出版年：2015
• 出版时间：September 28, 2015
• 年：2015
• 卷：34
• 期：18
• 页码：4529-4542
• 全文大小：637K
• ISSN：1520-6041

文摘

The preparation and full characterization of a variety of mono- ([L1-H]), di- ([L2-H₂], [L2A-H2]), and tri- ([L3-H₃]) 1,2,3-triazolium salts constructed form 鈥渃licked鈥?hydroxybenzene derivatives are reported. Deprotonation with potassium hexamethyldisilazide, followed by in situ metalation, allowed for the synthesis of a series of mono- (L1路[M]), di- (L2路[M]₂, L2路[M]₂), and trinuclear (L3路[M]₃) group 9鈥?1 (M = [Rh(CO)₂Cl], [Pd(allyl)Cl], and [AuCl]) triazol-5-ylidene metal complexes. In solution, all metal complexes feature symmetrical patterns displaying C₂ and C₃ fold axes when supported by di- and tritriazol-5-ylidene ligands. The vibration frequencies of Ln路[Rh(CO)₂Cl]_n (n = 1鈥?) complexes indicate that the electron-donor properties of the new ligands are comparable to those for previously reported MIC complexes and superior to classical NHCs. Prompting coordination of the vicinal phenoxy group to the metal centers proved unsuccessful after treatment of the Ln路[Rh(CO)₂Cl]_n and Ln路[Pd(allyl)Cl]_n (n = 1鈥?) precursors with AgBF₄; the expected chelated cationic complexes were highly unstable, indicating a weak or no coordination availability through the oxygen atom. Crystal structures of the complexes L1路[AuI] and L2A路[Pd(allyl)I]₂ illustrated the metal center geometrical environment and confirmed the lack of coordination through the phenoxy moiety of the ligand. Preliminary catalytic trials established the enhanced performance of di- and trimetallic palladium complexes in cross-coupling reactions and the intramolecular cyclization of enynes catalyzed by gold complexes.