We report now the first single molecule magnet (SMM) consisting of d-f elements. The present study demonstrates that the synthesis of the d-f polynuclear molecule is a very promising approach to SMMs. (1) The d-f polynuclear molecule can be easily synthesized by the assembly reaction of the d-component and the f-component, (2) the high-spin ground state can be generated by a smaller number of metal ions than the d complex, and (3) the molecular magnetic anisotropy is easily derived from the f-component.

A series of ruthenium(II)-arene (RAPTA) compounds were evaluated for their ability to inhibit thioredoxin reductase (either cytosolic or mitochondrial) and cathepsin B, two possible targets for anticancer metallodrugs. In general, inhibition of the thioredoxin reductases was lower than that of cathepsin B, although selected compounds were excellent inhibitors of both classes of enzymes in comparison to other metal-based drugs. Some initial structure-activity relationships could be established. On the basis of the obtained data, different mechanisms of binding/inhibition appear to be operative; remarkably the selectivity of the ruthenium compounds toward solid metastatic tumors also correlates to the observed trends. Notably, docking studies of the interactions of representative RAPTA compounds with cathepsin B were performed that provided realistic structures for the resulting protein-metallodrug adducts. Good agreement was generally found between the inhibiting potency of the RAPTA compounds and the computed stability of the corresponding cat B/RAPTA adducts.

The reaction between the [Mn(BS)(H2O)]+ monomeric and [Mn2(μ-BS)2(H2O)2]2+ dimeric cations and [Fe(CN)6]3- gave rise to cation−anion interaction via the formation of [FeC⋮NMn] bridges. Depending on the nature of the Schiff base and regardless of the stoichiometry used, either the trimeric anion [{Mn(BS)}2{Fe(CN)6}]- (BS = 3-MeOsalen, 6; 5-Clsalen, 7; 5-Brsalen, 8; salcy, 10) or the pentameric cation [{Mn(BS)}4{Fe(CN)6}]+ (BS = saltmen, 9) is formed, which has been assembled by the K+ cation or the ClO4 - anion, respectively. The X-ray analysis of 6 revealed a two-dimensional network layer structure. The magnetic measurements showed its metamagnetic behavior, where the ferromagnetic interaction operates within each layer and the antiferromagnetic interaction operates between the layers. The Neel temperature, T N, is 9.2 K, and the critical field at 2 K is 300 Oe. The temperature dependent magnetic susceptibilities of 7 and 8 are in agreement with a discrete, symmetrical, trinuclear structure Mn(III)Fe(III)Mn(III) (S Mn = 2, S Fe = 1/2, S Mn = 2) with a ferromagnetic spin coupling between the Mn(III) and Fe(III) ions, a small antiferromagnetic intertrimer interaction, and a large zero-field splitting of the Mn(III) ion. The structure of 9 consists of a two-dimensional layer containing as the repeating unit a cyclic dodecamer. The layers stack along the c axis, and ClO4 - anions are positioned between the layers. The magnetic measurements showed this compound's ferromagnetic behavior. There are, in fact, two kinds of intralayer magnetic interactions, the interaction between the Fe(III) and Mn(III) ions bridged by CN groups and the interaction between two Mn(III) ions in the dimer [Mn2(saltmen)2], both being ferromagnetic. The interlayer magnetic interaction is ferromagnetic. All of the interactions render to 9 an overall ferromagnetic behavior.

Four-electron reduction of dinitrogen has been achieved in the reaction of N2 with [{p-But-calix[4]-(O)4}2Nb2(μ-M)2] (M = Li, 3; M = Na, 4; M = K, 5), which contain a very reactive NbNb unit [NbNb = 2.659(1) Å; 4], in THF. The reaction leads to the dinuclear complexes [{p-But-calix[4]-(O)4}2(Nb⋮N−N⋮Nb)]2- M+ 2 (M = Li, 6; M = Na, 7; M = K, 8) [Nb⋮N = 1.747(12) Å, N−N = 1.390(17) Å; 7], containing the hydrazido [N2]4- anion. Two-electron reduction of the hydrazido tetraanion in 7 using sodium metal leads to the nitrido species 11, [{p-But-calix[4]-(O)4}2Nb2(μ-N)2(μ-Na)2Na2], which in solution is in equilibrium with the monomeric form 18, [{p-But-calix[4]-(O)4}Nb⋮N−NaS n ]. Two distinct pathways have been identified as a function of the solvent used (THF or DME). In the case of DME, the key intermediate 12 has been intercepted as green crystals. The formation of 12, [{p-But-calix[4]-(O)4}2Nb2(μ-η2:η2-N2)(μ-Na)3Na], results from the reduction of Nb(V) to Nb(IV), which temporarily stores the two electrons in an Nb−Nb bond [N−N = 1.403(8) Å, Nb−Nb, 2.635(1) Å]. Complex 12 contains a μ-η2:η2 side-on N2 group, bonded between two niobiums and preorganized to be transformed into two nitrido anions. Heating in pyridine (90 °C) converts 12 to 11, with simultaneous cleavage of the Nb−Nb and N−N bonds, the heating causing two-electron transfer from the Nb−Nb to the N−N bond. The reaction of 4 with N2, carried out in toluene instead of THF or DME, gives a nitrido complex, [{p-But-calix[4]-(O)4}3Nb3(μ-N)2Na3(THF)2], 15, which can be formed equally well from the reaction of 4a with 7a carried out in a 1:2 molar ratio in toluene. Complex 15 breaks up in CHCl3 or toluene, upon addition of TMEDA, into [{p-But-calix[4]-(O)4}2Nb2(μ-N)2{μ-Na2(TMEDA)2}Na2], 16, and [{p-But-calix[4]-(O)4}2Nb2(μ-N)][Na(TMEDA)2], 17.