Mixed-valent Mn supertetrahedra and planar discs as enhanced magnetic coolers.
The syntheses and structures of two decametallic mixed-valent Mn supertetrahedra using 2-amino-2-methyl-1,3-propanediol (ampH2), two decametallic mixed-valent Mn planar discs using 2-amino-2-methyl-1,3-propanediol (ampH2) and 2-amino-2-ethyl-1,3-propanediol (aepH2), and a tetradecametallic mixed-valent Mn planar disc using pentaerythritol (H4peol) are reported. The decametallic complexes display dominant ferromagnetic exchange and spin ground states of S = 22, and the tetradecametallic complex displays dominant antiferromagnetic exchange and a spin ground state of S = 7 +/- 1. All display large (the former) and enormous (the latter) magnetocaloric effect--the former as a result of negligible zero-field splitting of the ground state, and the latter as a result of possessing a high spin-degeneracy at finite low temperatures--making them the very best cooling refrigerants for low-temperature applications.
Manoli
Maria
M
School of Chemistry, The University of Edinburgh, West Mains Road, Edinburgh, EH9 3JJ UK.
Collins
Anna
A
Parsons
Simon
S
Candini
Andrea
A
Evangelisti
Marco
M
Brechin
Euan K
EK
D018360:Crystallography, X-Ray; D008280:Magnetics; D008345:Manganese / Q000737:chemistry*; D008958:Models, Molecular; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D011412:Propanolamines / Q000737:chemistry*; D011409:Propylene Glycols / Q000737:chemistry*; D012034:Refrigeration; D012996:Solutions / Q000737:chemistry; D013696:Temperature
D009942:Organometallic Compounds; D011412:Propanolamines; D011409:Propylene Glycols; D012996:Solutions; D008345:Manganese; C019250:2-amino-2-methyl-1,3-propandiol; C008783:pentaerythritol