Unique trapping of paddlewheel copper(ii) carboxylate by ligand-bound {Cu2} fragments for [Cu6] assembly. Issue 16 (16th March 2016)

• Record Type: Journal Article
• Authors: Chattopadhyay, Krishna; Shaw, Bikash Kumar; Saha, Shyamal Kumar; Ray, Debashis
• Is Part Of: Dalton transactions. Volume 45:Issue 16(2016)
• Page Start: 6928
• Page End: 6938
• Publication Date: 2016-03-16
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/c6dt00103c
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : Trapping of paddlewheel {Cu2 (carboxylate)4 } by ligand-bound {Cu2 (μ-H2 L)} 3+ units resulted in dumbbell-shaped [Cu6 ] complexes modulating the tetracarboxylate bridged Cu⋯Cu separations. Abstract : The bridging nature of in situ generated hydroxide ions and carboxylates (RCOO − ; R = CH3, C2 H5, CH2 Ph) has been utilized to design a new family of [Cu6 ] coordination complexes: [Cu6 (μ3 -OH)2 (μ-H2 L)2 (μ1, 1, 3 -O2 CCH3 )2 (μ1, 3 -O2 CCH3 )2 (μ-ClO4 )2 ](ClO4 )2 ·H2 O (1 ), [Cu6 (μ3 -OH)2 (μ-H2 L)2 (μ1, 1, 3 -O2 CC2 H5 )4 (μ-ClO4 )2 ](ClO4 )2 ·2H2 O (2 ) and [Cu6 (μ3 -OH)2 (μ-H2 L)2 (μ1, 3 -O2 CCH2 Ph)4 (ClO4 )2 ](ClO4 )2 ·2H2 O (3 ). Tetracarboxylate bridged {Cu2 } core units are trapped between two ligand-bound {Cu2 (μ-H2 L)(μ-OH)} 2+ subunits forming the [Cu6 ] complexes. The hexanuclear {Cu6 (μ3 -OH)2 (H2 L)2 (μ-O2 CR)4 } 4+ cores having six interconnected Cu II ions assume a hitherto unknown dumbbell-shaped topology. Detailed characterizations have been done using X-ray crystallography and variable temperature magnetic measurements. For complexes1–3, the dominant coupling constant ( J ′) values between carboxylate bridged copper centers are −36.2 to −45.2 cm −1 for short Cu⋯Cu separations of 2.540–2.578 Å. In MeCN solutions all three complexes showed catalytic oxidation of 3, 5-di- tert -butyl catechol (3, 5-DTBCH2 ) in air.