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Activation of an Au−Cl Bond by a Pendent Sb III Lewis Acid: Impact on Structure and Catalytic Activity
Author(s) -
Jones J. Stuart,
Gabbai François P.
Publication year - 2017
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201604521
Subject(s) - antimony , chemistry , lewis acids and bases , cycloisomerization , ligand (biochemistry) , medicinal chemistry , electrophile , denticity , intramolecular force , natural bond orbital , stereochemistry , catalysis , crystallography , crystal structure , inorganic chemistry , organic chemistry , molecule , biochemistry , receptor
Abstract With the objective of identifying new coordination modes of ambiphilic ligands, we have investigated the bidentate Sb/P ligands ( o ‐(Ph 2 P)C 6 H 4 )SbCl 2 ( L Cl ) and ( o ‐(Ph 2 P)C 6 H 4 )SbPh 2 ( L Ph ). Reaction of these ligands with (tht)AuCl affords the monoligated species L Cl AuCl ( 1 ) and L Ph AuCl ( 2 ), respectively, in which the antimony centers are only weakly engaged with the coordinated gold atom. Treatment of 1 with PPh 3 induces an intramolecular transfer of a chloride ligand from gold to antimony to form the zwitterionic species o ‐(Cl 3 Sb)C 6 H 4 (Ph 2 P)Au(PPh 3 ) ( 3 ). Natural bond orbital (NBO) calculations show that the antimony and gold centers are involved in weak Sb→Au and Au→Sb interactions, the latter reflecting the Lewis acidity of the pendent antimony group. Finally, we demonstrate that the ability of the antimony center in 1 to abstract a gold‐bound chloride in the presence of a Lewis basic substrate may be utilized to activate the gold center for the electrophilic cycloisomerization of propargylic amides.