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Single‐Strand Molecular Wheels and Coordination Polymers in Copper(II) Benzoate Chemistry by the Employment of α‐Benzoin Oxime and Azides: Synthesis, Structures, and Magnetic Characterization
Author(s) -
Stamatatos Theocharis C.,
Vlahopoulou Gina,
Raptopoulou Catherine P.,
Psycharis Vassilis,
Escuer Albert,
Christou George,
Perlepes Spyros P.
Publication year - 2012
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.201101292
Subject(s) - chemistry , benzoin , crystallography , supramolecular chemistry , oxime , azide , isostructural , ligand (biochemistry) , coordination complex , deprotonation , copper , stereochemistry , dimethylformamide , polymer chemistry , solvent , medicinal chemistry , organic chemistry , crystal structure , ion , metal , biochemistry , receptor
The use of α‐benzoin oxime (bzoxH 2 ) in copper(II) benzoate chemistry, in the absence or presence of ancillary azido ligands, is reported. The reaction of Cu(O 2 CPh) 2 · 2H 2 O with one equivalent of bzoxH 2 in N , N ‐dimethylformamide (DMF) affords the decanuclear complex [Cu 10 (bzox) 10 (DMF) 4 ] ( 1 ) in good yield. Dissolution of 1 in CH 2 Cl 2 leads to the subsequent isolation of the solvent‐free complex [Cu 10 (bzox) 10 ] ( 2 ) in moderate yields. Complexes 1 and 2 are isostructural and possess a loop or single‐strand molecular wheel topology. The bzox 2– dianions behave as η 1 :η 1 :η 2 :μ 3 ligands, which give rise to an overall [Cu 10 (μ‐ONR) 10 (μ‐OR′) 10 ] core. Both 1 and 2 stack to form nanotubular columns with beautiful supramolecular architectures. The reaction of Cu(O 2 CPh) 2 · 2H 2 O with bzoxH 2 and NaN 3 in a 1:1:1 molar ratio in MeOH gives the bzoxH 2 ‐free complex [Cu(N 3 )(O 2 CPh)(MeOH)] n ( 3 ), which is a 1D chain. The Cu II atoms in 3 are linked by a single, end‐on N 3 – group, a syn , syn ‐η 1 :η 1 :μ PhCO 2 – ion, and an oxygen atom from the bridging MeOH ligand. The 1D chains are hydrogen bonded into 2D sheets through N azide ··· H(O MeOH ) interactions. Variable‐temperature, solid‐state direct‐current magnetic studies were carried out on 1 – 3 . The data for 1 and 2 indicate very strong antiferromagnetic exchange interactions and a S = 0 ground state, which is expected for even‐membered loop arrays of Cu II atoms. In contrast, 3 exhibits ferromagnetic exchange interactions; the data were fitted to the appropriate equation derived from the Hamiltonian H = – J Σ( S i · S i +1 ), which includes a zJ′ interchain interaction term. The best‐fit parameters were J = +49.6(4) cm –1 , g = 2.067(3), and zJ′ = 2.3(1) K. The combined results demonstrate the ligating flexibility of both the bzoxH 2 and azido groups and their usefulness in the synthesis of polynuclear Cu II clusters and coordination polymers.