RESUMEN
The chemisorption of magnetically bistable transition metal complexes on planar surfaces has recently attracted increased scientific interest due to its potential application in various fields, including molecular spintronics. In this work, the synthesis of mixed-ligand complexes of the type [NiII2L(L')](ClO4), where L represents a 24-membered macrocyclic hexaazadithiophenolate ligand and L' is a ω-mercapto-carboxylato ligand (L' = HS(CH2)5CO2- (6), HS(CH2)10CO2- (7), or HS(C6H4)2CO2- (8)), and their ability to adsorb on gold surfaces is reported. Besides elemental analysis, IR spectroscopy, electrospray ionization mass spectrometry (ESIMS), UV-vis spectroscopy, and X-ray crystallography (for 6 and 7), the compounds were also studied by temperature-dependent magnetic susceptibility measurements (for 7 and 8) and (broken symmetry) density functional theory (DFT) calculations. An S = 2 ground state is demonstrated by temperature-dependent susceptibility and magnetization measurements, achieved by ferromagnetic coupling between the spins of the Ni(II) ions in 7 (J = +22.3 cm-1) and 8 (J = +20.8 cm-1; H = -2JS1S2). The reactivity of complexes 6-8 is reminiscent of that of pure thiolato ligands, which readily chemisorb on Au surfaces as verified by contact angle, atomic force microscopy (AFM) and spectroscopic ellipsometry measurements. The large [Ni2L] tail groups, however, prevent the packing and self-assembly of the hydrocarbon chains. The smaller film thickness of 7 is attributed to the specific coordination mode of the coligand. Results of preliminary transport measurements utilizing rolled-up devices are also reported.
RESUMEN
Four types of trialkylphosphine-stabilized copper dialkylaluminum ethanedithiolate complexes with the compositions [(i)Pr3PCuSC2H4SAlR2]2 (R = Me, Et, (i)Pr, (t)Bu, vinyl), [((i)Pr3PCu)3(SC2H4S)2AlR2] (R = Et), [(Me3P)3CuSC2H4SAlR2] (R = Me, Et), and [(Me3P)4Cu][SC2H4SAlR2] (R = Me, Et, (i)Pr) have been synthesized and structurally characterized by X-ray diffraction. The first series features an eight-membered (CuSAlS)2 ring as the core structure. The trimethylphosphine complexes can be distinguished as nonionic and ionic compounds, depending on the amount of trimethylphosphine. In systematic thermogravimetric studies, the complexes were converted into the ternary semiconductor CuAlS2. In this process, a novel wurtzite-type CuAlS2 phase was identified. Binary copper sulfide is observed as a minor side product in thermolysis reactions when volatile trialkylaluminum is released. The thermolysis reactions are completed at temperatures between 330 and 470 °C, depending on the aluminum alkyls. The Cu/Al ratio and phase purity of the thermolysis products were determined by Rietveld analysis of the powder X-ray diffraction patterns and by inductively coupled plasma optical emission spectroscopy measurements. To our knowledge, this is the first study of molecular single-source precursors for CuAlS2.
RESUMEN
The synthesis and characterization of a series of homologous tetranuclear complexes [((i)Pr3PCu)2(MR2)2(SCH2CH2S)2] (MR2 = GaMe2 (2), GaEt2 (3), Ga(i)Pr2 (4), Ga(n)Bu2 (5) and InMe2 (6), InEt2 (7), In(i)Pr2 (8), In(n)Bu2 (9)) and of related compounds [((i)Pr3PCu)3(MR2)(SCH2CH2S)2] (MR2 = GaMe2 (10), GaEt2 (11), Ga(i)Pr2 (12), Ga(n)Bu2 (13) and InMe2 (14), InEt2 (15), In(i)Pr2 (16), In(n)Bu2 (17)) are presented. The molecular structures of these were determined by single crystal X-ray diffraction. Thermolysis processes of all the representatives of 2-9 were investigated by simultaneous thermal analysis and thermal decomposition in a nitrogen atmosphere in a quartz glass tube. According to powder X-ray diffraction studies these thermolysis residues predominantly consist of CuMS2 (M = Ga, In), which mainly occurred in the well known tetragonal chalcopyrite-type structure and partially in the hexagonal wurtzite-type structure. As expected from their composition, representatives of 10-17 form mixtures of CuMS2 and large amounts of Cu(2-x)S upon thermolysis.
