pubs.acs.org/Organometallics Published on Web 11/01/2010 r 2010 American Chemical Society 6172 Organometallics 2010, 29, 6172–6185 DOI: 10.1021/om100257x Hydroquinoid Chromium Complexes Bearing an Acyclic Conjugated Bridge: Chromium-Templated Synthesis, Molecular Structure, and Haptotropic Metal Migration Peter Hegele, † Bindu Santhamma, †,4 Gregor Schnakenburg, § Roland Fr€ ohlich, ) Olga Kataeva, ) Martin Nieger, §,^ Konstantinos Kotsis, ‡ Frank Neese,* ,‡ and Karl Heinz D€ otz* ,† † Kekul  e-Institut f € ur Organische Chemie und Biochemie, Rheinische Friedrich-Wilhelms-Universit € at Bonn, Gerhard-Domagk-Strasse 1, D-53121 Bonn, Germany, ‡ Institut f€ ur Physikalische und Theoretische Chemie, Rheinische Friedrich-Wilhelms-Universit € at Bonn, Wegelerstrasse 12, D-53115 Bonn, Germany, § Institut f€ ur Anorganische Chemie, Rheinische Friedrich-Wilhelms-Universit € at Bonn, Gerhard-Domagk-Strasse 1, D-53121 Bonn, Germany, ^ Laboratory of Inorganic Chemistry, Department of Chemistry, University of Helsinki, P.O. Box 55 (A.I. Virtasen aukio 1), FIN-00014, Finland, ) Organisch-Chemisches Institut, Westf€ alische Wilhelms-Universit€ at M€ unster, Corrensstrasse 40, D-48149 M€ unster, Germany, and 4 Cellular and Structural Biology, UT Health Science Center, San Antonio, Texas 78229, United States Received April 1, 2010 The naphthohydroquinoid tricarbonyl chromium complexes 3 and 6, bearing a styryl or phenylazo moiety, have been synthesized and studied for the haptotropic metal migration along the extended π-system. Quantum chemical calculations suggested a feasible stepwise rearrangement of the Cr(CO) 3 fragment from the hydroquinoid to the other terminal phenyl ring for the azo- rather than for the ethene- bridged system. An experimental and kinetic study of the ethene-bridged complex 3 revealed a haptotropic metal shift onto the adjacent naphthalene ring to give isomer 7 and suggested a competing intermolecular decomplexation-recomplexation pathway for the coordination of the terminal phenyl ring, affording bismetalated complexes 8 and 9. Attempts of a controlled metal migration in the azo complex analogue 6 under similar conditions were unsuccessful and resulted in partial decomposition. Introduction Metal complexes bearing a ligand that offers more than a single coordination mode may undergo an intramolecular metal shift along the ligand platform. 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