TY - JOUR
T1 - A family of manganese rods
T2 - Syntheses, structures, and magnetic properties
AU - Rajaraman, Gopalan
AU - Murugesu, Muralee
AU - Sañudo, E. Carolina
AU - Soler, Monica
AU - Wernsdorfer, Wolfgang
AU - Helliwell, Madeleine
AU - Muryn, Chris
AU - Raftery, Jim
AU - Teat, Simon J.
AU - Christou, George
AU - Brechin, Euan K.
PY - 2004/12/1
Y1 - 2004/12/1
N2 - The reaction of the mixed-valent metal triangles [Mn3O(O 2CR)6(py)3] (R = CH3, Ph, C(CH 3)3) with the tripodal ligands H3thme (1,1,1-tris(hydroxymethyl)ethane) and H3tmp (1,1,1- tris(hydroxymethyl)-propane) in MeCN, produces a family of manganese rodlike complexes whose structures are all derived from a series of edge-sharing triangles. Variable temperature direct current (dc) magnetic susceptibility data were collected for all complexes in the 1.8-300 K temperature range in fields up to 7.0 T. Complex 1, [Mn12O4(OH)2(PhCOO) 12(thme)4(py)2], has an S = 7 ground state with the parameters g = 1.98 and D = -0.13 K. Complex 2, [Mn8O 4((CH3)3CCO2)10(thme) 2(py)2] has a ground state of S = 6, with g = 1.81 and D = -0.36 K. Complex 3, [Mn7O2(PhCO2) 9(thme)2(py)3], has a spin ground states of S = 7 with the parameters g = 1.78 and D = -0.20 K. The best fit for complex 4, [Mn6((CH3)3CCO2)8(tmp) 2(py)2], gave a spin ground state of S = 3 with the parameters g = 1.73 and D = -0.75 K, but was of poorer quality than that normally obtained. The presence of multiple Mn2+ ions in the structure of 4 leads to the presence of low-lying excited states with energy levels very close to the ground state, and in the case of complex 5, [Mn 6(CH3CO2)6(thme)2(H 2tea)2], no satisfactory fit of the data was obtained. DFT calculations on 4 and 5 indicate complexes with spin ground states of S = 4 and S = 0 respectively, despite their topological similarities. Single-crystal hysteresis loop and relaxation measurements show complex 1 to be a SMM.
AB - The reaction of the mixed-valent metal triangles [Mn3O(O 2CR)6(py)3] (R = CH3, Ph, C(CH 3)3) with the tripodal ligands H3thme (1,1,1-tris(hydroxymethyl)ethane) and H3tmp (1,1,1- tris(hydroxymethyl)-propane) in MeCN, produces a family of manganese rodlike complexes whose structures are all derived from a series of edge-sharing triangles. Variable temperature direct current (dc) magnetic susceptibility data were collected for all complexes in the 1.8-300 K temperature range in fields up to 7.0 T. Complex 1, [Mn12O4(OH)2(PhCOO) 12(thme)4(py)2], has an S = 7 ground state with the parameters g = 1.98 and D = -0.13 K. Complex 2, [Mn8O 4((CH3)3CCO2)10(thme) 2(py)2] has a ground state of S = 6, with g = 1.81 and D = -0.36 K. Complex 3, [Mn7O2(PhCO2) 9(thme)2(py)3], has a spin ground states of S = 7 with the parameters g = 1.78 and D = -0.20 K. The best fit for complex 4, [Mn6((CH3)3CCO2)8(tmp) 2(py)2], gave a spin ground state of S = 3 with the parameters g = 1.73 and D = -0.75 K, but was of poorer quality than that normally obtained. The presence of multiple Mn2+ ions in the structure of 4 leads to the presence of low-lying excited states with energy levels very close to the ground state, and in the case of complex 5, [Mn 6(CH3CO2)6(thme)2(H 2tea)2], no satisfactory fit of the data was obtained. DFT calculations on 4 and 5 indicate complexes with spin ground states of S = 4 and S = 0 respectively, despite their topological similarities. Single-crystal hysteresis loop and relaxation measurements show complex 1 to be a SMM.
UR - http://www.scopus.com/inward/record.url?scp=9644281381&partnerID=8YFLogxK
U2 - 10.1021/ja0471929
DO - 10.1021/ja0471929
M3 - Article
AN - SCOPUS:9644281381
SN - 0002-7863
VL - 126
SP - 15445
EP - 15457
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
IS - 47
ER -