화학공학소재연구정보센터
Inorganic Chemistry, Vol.54, No.3, 1136-1144, 2015
M-3(P2O7)(2)(2)-Type Open Frameworks Featuring [M2O8] and [M3O12] Multinuclear Transition-Metal Oxide Units. Serendipitous Synthesis of Six Polymorphic Salt-Inclusion Magnetic Solids: Na2M3(P2O7)(2)-center dot ACl (M = Mn, Fe; A = Rb, Cs) and K2M3(P2O7)(2)center dot CsCl (M = Fe, Mn)
Single crystals of six polymorphic salt-inclusion phosphates of the A(2)M(3)(P2O7)(2)center dot A'Cl type, Na2Mn3(P2O7)(2)center dot CsCl (1), Na2Mn3(P2O7)2 center dot RbCl (2), Na2Fe3(P2O7)(2)center dot CsCl (3), Na2Fe3(P2O7)(2)center dot RbCl (4), K2Mn3(P2O7)(2)center dot CsCl (5), and K2Fe3(P2O7)(2)center dot CsCl (6), were grown in reactive molten chloride flux media. Compounds 1-4 are isostructural and crystallize in the space group C2/c (No. 15), while 5 and 6 crystallize in P2/c (No. 13) and P (1) over bar (No. 2), respectively. The title compounds have demonstrated an unprecedented versatility, where the M-3(P2O7)(2)(2-) covalent open frameworks contain [M3O12] (M = Mn2+, Fe2+) trimeric units in 1-4 and [M2O8] dimers in 5 and 6. These multinuclear, transition-metal oxide units are linked by Cl- ions through the M-Cl bonds to form one-dimensional (1D) chains. The 1D chains and [P2O7] groups share common O atoms to form the extended network. The M-3(P2O7)(2)(2-) open-framework structures exhibit channels where the respective Na+/K+ ions and A'Cl salt (A' = Rb, Cs) reside. Magnetic susceptibility of 2 and 4 suggests bulk antiferromagnetic properties as expected. The local structure and thermal decomposition are examined by IR and differential scanning calorimetry of representative compounds. The factors that determine the reticular chemistry of the M-3(P2O7)(2)(2-) type are illustrated in terms of the inclusion of ionic lattices of different sizes and contents.