Supramolecular Maleate Adducts of Copper(II) 12‐Metallacrown‐4: Magnetism, EPR, and Alcohol Sorption Properties. Issue 41 (9th November 2017)

• Record Type: Journal Article
• Authors: Pavlishchuk, Anna V.; Kolotilov, Sergey V.; Zeller, Matthias; Lofland, Samuel E.; Kiskin, Mikhail A.; Efimov, Nikolay N.; Ugolkova, Elena A.; Minin, Vadim V.; Novotortsev, Vladimir M.; Addison, Anthony W.
• Is Part Of: European journal of inorganic chemistry. Issue 41(2017)
• Page Start: 4866
• Page End: 4878
• Publication Date: 2017-11-09
• Subjects: Crown compounds -- Magnetic properties -- Copper -- Adsorption -- Mass spectrometry; Chemistry, Inorganic -- Periodicals; Organometallic chemistry -- Periodicals; Bioinorganic chemistry -- Periodicals; Solid state chemistry -- Periodicals; 546
• DOI: 10.1002/ejic.201700976
• Languages: English
• ISSNs: 1434-1948

Abstract

Abstract : With maleate, [Cu5 (ahpha)4 ] 2+ gives two complexes, [Cu5 (ahpha)4 (DMF)2 ](MalH)2 · 2DMF (1 ) and [Cu5 (ahpha)4 (MalH)2 ] (2 ) (ahpha 2– is 3‐amino‐3‐hydroximinopropane hydroxamate; MalH2 is maleic acid). Both1 and2 contain non‐oligomerized [Cu5 (ahpha)4 ] 2+ metallacrown blocks; in1, two MalH – are bound to [Cu5 (ahpha)4 ] 2+ only via H‐bonds, while in2, they coordinate to Cu 2+ . The X‐band EPR of1 was observed at 20 K, 100 K, and 295 K. The EPR at 20 K was of an S = 1/2 ground state, while at room temperature anisotropic |Δ M s | = 1 and |Δ M s | = 2 resonances around 3200 G ( g ≈ 2.19) and 1600 G ( g ≈ 4.25) were observed for the Cu5 system, due to partial occupation of an S = 3/2 state. The room temperature EPR of1 was simulated as the weighted sum of the spectra of its various S = 1/2, 3/2, and 5/2 states. Its magnetic behavior was fitted with a χ M T vs. T model using a spin Hamiltonian accounting for central–peripheral ( J 1 ), peripheral–peripheral ( J 2 ) Cu 2+ –Cu 2+ and intercrown ( zJ′ ) spin interactions, yielding J 1 = –156(4) cm –1, J 2 = –63(1) cm –1, and zJ′ = –4.5(3) cm –1 . For sorption of methanol and ethanol vapors at 293 K by a desolvated polycrystalline sample of1, the shape of the adsorption and desorption isotherms indicated a "gates opening" phenomenon. Abstract : ESI‐mass spectra evidence the dependence of copper 12‐MC‐4 crown aggregation on counter‐anion charge, and an EPR analysis elucidates the populations of the crown's spin states.