Issue 34, 2018

Order in disorder: solution and solid-state studies of [M III2M II5] wheels (MIII = Cr, Al; MII = Ni, Zn)

Abstract

A family of heterometallic Anderson-type ‘wheels’ of general formula [MIII2MII5(hmp)12](ClO4)4 (where MIII = Cr or Al and MII = Ni or Zn giving [Cr2Ni5] (1), [Cr2Zn5] (2), [Al2Ni5] (3) and [Al2Zn5] (4); hmpH = 2-pyridinemethanol) have been synthesised solvothermally. The metallic skeleton common to all structures describes a centred hexagon with the MIII sites disordered around the outer wheel. The structural disorder has been characterised via single crystal X-ray crystallography, 1–3D 1H and 13C solution-state NMR spectroscopy of the diamagnetic analogue (4), and solid-state 27Al MAS NMR spectroscopy of compounds (3) and (4). Alongside ESI mass spectrometry, these techniques show that structure is retained in solution, and that the disorder is present in both the solution and solid-state. Solid-state dc susceptibility and magnetisation measurements on (2) and (3) reveal the Cr–Cr and Ni–Ni exchange interactions to be JCr–Cr = −1 cm−1 and JNi–Ni,r = −5 cm−1, JNi–Ni,c = 10 cm−1. Fixing these values allows us to extract JCr–Ni,r = −1.2 cm−1, JCr–Ni,c = 2.6 cm−1 for (1), the exchange between adjacent Ni and Cr ions on the ring is antiferromagnetic and between Cr ions on the ring and the central Ni ion is ferromagnetic.

Graphical abstract: Order in disorder: solution and solid-state studies of [MIII2MII5] wheels (MIII = Cr, Al; MII = Ni, Zn)

Supplementary files

Article information

Article type
Paper
Submitted
20 2 2018
Accepted
09 3 2018
First published
15 3 2018
This article is Open Access
Creative Commons BY license

Dalton Trans., 2018,47, 11834-11842

Order in disorder: solution and solid-state studies of [MIII2MII5] wheels (MIII = Cr, Al; MII = Ni, Zn)

H. W. L. Fraser, G. S. Nichol, D. Uhrín, U. G. Nielsen, M. Evangelisti, J. Schnack and E. K. Brechin, Dalton Trans., 2018, 47, 11834 DOI: 10.1039/C8DT00685G

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