Synthesis and characterization of mixed-valent manganese phosphonate cage complexes.
The reaction of phenylphosphonic acid (PhPO(3)H(2)) with the mixed-valent basic oxo-centered manganese triangle [Mn(3)O(O(2)CCMe(3))(6)(py)(3)] (1; where py=pyridine) in the presence of a suitable base gives four different manganese clusters depending on the identity of the base. The syntheses and structural characterization of [Mn(18)(mu(3)-O)(8)(PhPO(3))(14)(O(2)CCMe(3))(12)(py)(6)(H(2)O)(2)] (2), [Mn(7)(mu(3)-O)(3)(O(3)PPh)(3)(O(2)CCMe(3))(8)(py)(3)] (3), [Mn(9)Na(mu(3)-O)(4)(mu(4)-O)(2)(O(3)PPh)(2)(O(2)CCMe(3))(12)(H(2)O)(2)(H(2)O)(0.67)(Py)(0.33)] (4), and [Mn(13)(mu(3)-O)(8)(OMe)(8)(O(3)PPh)(4)(O(2)CCMe(3))(10)] (5) are described. Complexes 4 and 5 are homovalent Mn(III) cages, while 2 and 3 contain divalent, trivalent, and/or tetravalent ions. All the manganese centers are valence-localized, the octahedral Mn(III) sites being recognizable by marked Jahn-Teller distortions. The magnetic properties of compounds 2-5 have been investigated in the polycrystalline state by magnetic susceptibility and high-field magnetization measurements, which reveal that spin ground states vary from 0< or =S > or =8. AC susceptibility measurements performed on 4 and 5, in the 1.6-10.0 K ranges show the presence of out of AC susceptibility signal (chi(M)'') for 4, and an effective energy barrier (U(eff)) for the re-orientation of the magnetization is found to be 17 K, but for 5, the chi(M)'' maximum is found to be below 1.5 K.
Shanmugam
Maheswaran
M
School of Chemistry, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
Chastanet
Guillaume
G
Mallah
Talal
T
Sessoli
Roberta
R
Teat
Simon J
SJ
Timco
Grigore A
GA
Winpenny
Richard E P
RE
D001665:Binding Sites; D008024:Ligands; D008280:Magnetics; D008345:Manganese / Q000737:chemistry*; D017895:Manganese Compounds / Q000138:chemical synthesis*; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000138:chemical synthesis; D063065:Organophosphonates / Q000737:chemistry*; D013696:Temperature
D008024:Ligands; D017895:Manganese Compounds; D009942:Organometallic Compounds; D063065:Organophosphonates; D008345:Manganese