Three trinuclear Mn2Mo molecules based on the orbitally degenerate [Mo(CN)7](4-) anion were prepared, one of which is the first single-molecule magnet (SMM) based on heptacyanomolybdate. The blocking temperature and the energy barrier (U = 40.5 cm(-1)) are records for a cyanide-based SMM. Wide hysteresis loops and sharp quantum tunneling steps were observed from single-crystal measurements.

A series of end-to-end azido-bridged perovskite-type compounds [(CH3)nNH4-n][Mn(N3)3] (n = 1-4) were synthesized and characterized. Structural phase transitions indicating the general lattice flexibility were observed and confirmed by the crystal structures of different phases. These materials show cation-dependent magnetic ordering at up to 92 K and magnetic bistability near room temperature.

Field-induced slow magnetic relaxation was observed for air-stable mononuclear cobalt(II) compounds with pentagonal bipyramid geometry. These are the first examples of such behavior observed in the seven-coordinated mononuclear 3d metal compounds.

The electronic and magnetic properties of double-layered Roddlesdon-Popper compounds, La 1ϩ2x Sr 2Ϫ2x Mn 2 O 7 with different doping x from 0.0 to 0.2 have been calculated using the full-potential linear muffin-tin orbital method. The total energies, band structures, densities of states, and Fermi surfaces were investigated by means of the virtual crystal approximation. The band structure of La 1ϩ2x Sr 2Ϫ2x Mn 2 O 7 is found to be that of a half-metallic ferromagnet, in agreement with experiment. The density of states shows that La and Sr act solely as electron donors and have almost no states at or below the Fermi level, and therefore a rigid band approximation can be considered as a good approximation to describe the effects of doping. The calculated Mn magnetic moments increase from 3.09 B to 3.24 B when the doping increases from 0.0 to 0.2, which is in qualitative agreement with experiment. The calculated Fermi surface shows pronounced nesting features along the ⌫-X directions in the undoped case, which implies a possible charge-or spin-density wave instability in this material.There is considerable research interest in the double-layered Roddlesdon-Popper compounds La 1ϩ2x Sr 2Ϫ2x Mn 2 O 7 , where x is the electron doping in the Mn-O planes. 1,2 This material is comprised of perovskite double layers of corner-linked MnO 6 octahedra forming infinite sheets, and double layers of (La,Sr)MnO 3 that are separated along the c axis by insulating ͑La,Sr͒O layers. With proper doping, this kind of manganite exhibits intrinsic colossal magnetoresistance ͑CMR͒ associated with a phase transition from a high-temperature paramagnetic and insulating phase to a low-temperature ferromagnetic and metallic phase. Such anomalous magnetotransport behavior in perovskite materials is usually explained on the basis of Zener's double-exchange concept, 3-5 which has been recently modified to take into account lattice Jahn-Teller distortions 6 characterstic for these materials. [7][8][9] In contrast, the doublelayered manganites show very small lattice distortions. 10,11 The existence of insulating ͑La,Sr͒O layers in this layered system makes its physical properties strongly anisotropic. This material is also important and interesting due to its pronounced CMR in low field. 2

Dye-based rhodamine derivatives have been utilized for the isolation of mononuclear lanthanide compounds characteristic of field-induced single molecule magnets.