Copper–Oxygen Complexes Revisited: Structures, Spectroscopy, and Reactivity

Abstract

A longstanding research goal has been to understand the nature and role of copper–oxygen intermediates within copper-containing enzymes and abiological catalysts. Synthetic chemistry has played a pivotal role in highlighting the viability of proposed intermediates and expanding the library of known copper–oxygen cores. In addition to the number of new complexes that have been synthesized since the previous reviews on this topic in this journal (Mirica, L. M.; Ottenwaelder, X.; Stack, T. D. P. Chem. Rev. 2004, 104, 1013–1046 and Lewis, E. A.; Tolman, W. B. Chem. Rev. 2004, 104, 1047–1076), the field has seen significant expansion in the (1) range of cores synthesized and characterized, (2) amount of mechanistic work performed, particularly in the area of organic substrate oxidation, and (3) use of computational methods for both the corroboration and prediction of proposed intermediates. The scope of this review has been limited to well-characterized examples of copper–oxygen species but seeks to provide a thorough picture of the spectroscopic characteristics and reactivity trends of the copper–oxygen cores discussed.

Decoding the Mechanism of Intramolecular Cu-Directed Hydroxylation of sp3 C–H Bonds

“…17,22,29 The proposed mechanistic scenario was mainly based on the stoichiometry of the reaction (yields < 50%) and on the tendency of L 2 Cu I complexes bearing bidentate ligands (e.g., S1–S5) to form L 2 Cu 2 O 2 species [i.e., L 2 Cu II 2 (O 2 2− ) and L 2 Cu III 2 (O 2− ) 2 ]. 26,27,30,31 However, no detailed mechanistic study (e.g., characterization of LCu/O 2 -derived species) was performed to validate the reaction pathways that led to C−H oxidation.…”

Copper-Catalyzed Vinylogous Aerobic Oxidation of Unsaturated Compounds with Air

“…An additional possibility that cannot be ruled out at this time is the role of bimetallic copper complexes, including those with bridging oxygen ligands. 38 …”

Synthesis of Hetero- and Homo-multinuclear Complexes with a Tetracyanonickelate Anion: Structural Characterization [Cu(bcen)Ni(CN)4]2

“…[6][7][8][9][10] Self-assembly is the most efficient approach for the construction of such molecular systems. [11][12][13] Another popular and successful approach for the preparation of multinuclear complexes with unusual and interesting properties is to employ cyano complexes (metalloligand) such as Ag(CN) 2 -, Ni(CN) 4 2-, Cr(CN) 6 3-, Pd(CN) 4 2-, Pt(CN) 4 2-, etc. [14][15][16][17] The cyano anion is able to act either as a terminal or as a bridging ligand.…”