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Anion‐Directed Copper(II) Metallocages, Coordination Chain, and Complex Double Salt: Structures, Magnetic Properties, EPR Spectra, and Density Functional Study
Author(s) -
Wu JingYun,
Zhong MingShiou,
Chiang MingHsi,
Bhattacharya Dibyendu,
Lee YenWei,
Lai LongLi
Publication year - 2016
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.201505215
Subject(s) - electron paramagnetic resonance , chemistry , crystallography , magnetism , magnetic moment , paramagnetism , magnetization , copper , ion , ligand (biochemistry) , density functional theory , hydrogen bond , population , nuclear magnetic resonance , molecule , computational chemistry , condensed matter physics , magnetic field , physics , biochemistry , receptor , demography , organic chemistry , quantum mechanics , sociology
A series of Cu II metallo‐assemblies showing anion‐directed structural variations, including five metallocages [(G n − )⊂{Cu 2 (Hdpma) 4 }] (8− n )+ (A − ) 8− n (G n − =NO 3 − , ClO 4 − , SiF 6 2− , BF 4 − , SO 4 2− ; A − =NO 3 − , ClO 4 − , BF 4 − , CH 3 SO 4 − ; Hdpma=bis(3‐pyridylmethyl)ammonium cation), a complex double salt, namely, (H 3 dpma) 4 (CuCl 4 ) 5 Cl 2 , and a coordination chain, namely, [Cu 2 (dpma)(OAc) 4 ], are reported. The influence of the anion can be explained by its coordinating ability, the affinity of which for the Cu II center interferes significantly with metallocage formation, and its shape, which offers host–guest recognition ability to engage in weak metal–anion coordination and hydrogen bonding to the organic ligand, which are responsible for metallocage templation. EPR studies of these metallocages in the powder phase at room temperature and 77 K showed a trend of the g values ( g || >2.10 >g ⊥ >2.00) indicating a dx 2- y 2‐based ground state with square‐pyramidal geometry for the Cu II centers. The magnetism of these metallocages can be interpreted as the result of a combination of relatively small magnetic coupling integrals and a substantial contribution of temperature‐independent paramagnetism (TIP). The weak magnetic interaction is corroborated by the results of DFT calculations and the EPR spectra. Availability of the low‐lying state for spin population was confirmed by a magnetization study, which revealed a magnetic moment approaching 2 Nβ , which would explain the presence of the larger TIP term.