Chromium Complexes Containing Polycyclic Condensed Aromatic Ligands: Mono- and Bidirectional Synthesis from Chromium-Carbenes, Molecular Structures, and Rearrangement Reactions

• Published in: European journal of inorganic chemistry Vol. 2014; no. 9; pp. 1462 - 1469
• Main Authors: Hegele, Peter, Schnakenburg, Gregor, Daniels, Jörg, Dötz, Karl Heinz
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 01.03.2014; WILEY‐VCH Verlag; Wiley Subscription Services, Inc
• Subjects: Accessibility; Arene ligands; Benzannulation; Bidirectional; Carbenes; Chromium; Complexation; Ligands; Metal migration; Migration; Precursors; Reaction kinetics; Transformations
• ISSN: 1434-1948; 1099-0682
• DOI: 10.1002/ejic.201301409

Chromium–pyrenylcarbenes accessible from halopyrene precursors undergo benzannulation upon gentle warming with 3‐hexyne to give hydroquinoid benzopyrene–Cr(CO)3 complexes. Kinetic benzannulation product 3 rearranges into thermodynamic haptotropomer 4 at 70 °C in octafluorotoluene under first‐order kinetics. Further complexation of 3 by Cr(NH3)3(CO)3 affords syn and anti dinuclear chromium–benzopyrene complexes. Bidirectional extension of the benzannulation protocol results in the formation of syn and anti dibenzopyrene–dichromium complexes, which are structurally characterized by X‐ray analysis. A benzannulation/metal migration sequence allows the thermocontrolled regioselective transformation of pyrenylcarbene–chromium into hydroquinoid benzopyrene–chromium complexes. Bidirectional extension of the protocol to a 1,8‐pyrenediylbis(carbene) complex affords syn‐ and anti‐dinuclear dibenzopyrene–Cr(CO)3 complexes. TBDMS = tert‐butyldimethylsilyl, Tf = trifluoromethylsulfonyl.