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Metal–Halogen Secondary Bonding in a 2,5‐Dichlorohydroquinonate Cobalt(II) Complex: Insight into Substrate Coordination in the Chlorohydroquinone Dioxygenase PcpA
Author(s) -
Schofield Jeremy A.,
Brennessel William W.,
Urnezius Eugenijus,
Rokhsana Dalia,
Boshart Monica D.,
Juers Douglas H.,
Holland Patrick L.,
Machonkin Timothy E.
Publication year - 2015
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201500845
Subject(s) - chemistry , halogen , cobalt , hydroquinone , substrate (aquarium) , metal , halogen bond , dioxygenase , transition metal , selectivity , coordination complex , stereochemistry , inorganic chemistry , organic chemistry , catalysis , oceanography , alkyl , enzyme , geology
Despite the unprecedented selectivity of the hydroquinone ring‐cleaving dioxygenase PcpA for ortho ‐chlorohydroquinones, there are no examples of an ortho ‐chlorohydroquinone bound to a transition‐metal complex. Herein, the synthesis and characterization of (Tp Ph2 Co) 2 (μ‐2,5‐dichlorohydroquinonate), for which Tp Ph2 is tris(3,5‐diphenylpyrazolyl)borate, were explored. The dianionic 2,5‐dichlorohydroquinonate bridges two (Tp Ph2 Co) moieties and coordinates each cobalt(II) center through the oxygen and chlorine atoms of the chlorohydroquinone. The Co–Cl distance of 2.778 Å shows the characteristics of a metal–halogen secondary bond, as we previously showed in ortho ‐halophenolate complexes. This compound represents the first example of metal–halogen secondary bonding with a halohydroquinone and, thus, provides a potential structural model for selective substrate binding to the metal center in PcpA.