Single-molecule magnetism properties of the first strontium-manganese cluster [SrMn14O11(OMe)3(O2CPh)18(MeCN)2].
The preparation and properties of the first strontium-manganese molecular complex are described. The reaction of (NBu(n)4)[Mn4O2(O2CPh)9(H 2O)] (4Mn(III)) with Sr(ClO4)2 in MeCN/MeOH led to the isolation of [SrMn14O11(OMe)3(O2CPh)18(MeCN)2] ( 1; 13Mn(III), Mn(II)). The structure of 1 consists of two [Mn4O3(OMe)] cubane units attached to a central, near-planar, trinuclear [Mn3O4] unit, to which are also attached a Mn and a Sr above the plane and a [Mn2O(OMe)] rhomb below the plane. Peripheral ligation is provided by 18 bridging benzoate and two terminal MeCN groups. Variable-temperature and -field dc magnetization (M) data were collected in the 1.8-10 K and 0.1-4.0 T ranges and fit by matrix diagonalization methods to give S = 9/2, D = -0.50(5) cm(-1), and g = 1.88(10), where S is the ground-state spin and D is the axial zero-field splitting parameter. Magnetization versus dc field sweeps at various temperatures and scan rates exhibited hysteresis loops, confirming 1 to be a new single-molecule magnet. Because complex 1 is the initial molecular example of intimately associated Mn and Sr atoms, Sr EXAFS studies have been performed for the first time on a synthetic Sr-containing molecule. This has also allowed comparisons with the EXAFS data on the Sr-substituted water oxidizing complex (WOC) of Photosystem II (PS II), which contains a SrMn4 complex.
Mishra
Abhudaya
A
Department of Chemistry, University of Florida, Gainesville, Florida 32611, USA.
Pushkar
Yulia
Y
Yano
Junko
J
Yachandra
Vittal K
VK
Wernsdorfer
Wolfgang
W
Abboud
Khalil A
KA
Christou
George
G
D002151:Calorimetry; D008280:Magnetics; D017895:Manganese Compounds / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D010087:Oxides / Q000737:chemistry; D013324:Strontium / Q000737:chemistry*; D013816:Thermodynamics
D017895:Manganese Compounds; D010087:Oxides; C027424:manganese oxide; D013324:Strontium