ELECTRON-TRANSFER AND LIGAND-TRANSFER REACTIONS INVOLVING N,N-DIALKYLCARBAMATES - SYNTHESIS AND MOLECULAR-STRUCTURE OF V2[ETA-5-(C5H5)]2[O2CN(C2H5)2]4

Electron- and ligand-transfer reactions of low-valent organometallic compounds of titanium and vanadium with N,N-dialkylcarbamates of titanium(IV) are reported. The reaction of VCp2 (Cp = eta(5)-cyclopentadienyl) with Ti(O2CNEt2)4 affords, inter alia, the dimeric vanadium(III) N,N-diethylcarbamato derivative V2Cp2(O2CNEt2)4 which has been studied by X-ray diffraction methods. Crystal data: triclinic, space group P1BAR; a = 10.802(2), b = 11.004(1), c = 8.960(1) angstrom; alpha = 112.879(9), beta = 102.66(1), gamma = 102.42(1)-degrees; V = 902.3(6) angstrom 3; Z = 1; F(000) = 368, rho(calc) = 1.282 g cm-3; mu = 5.47 cm-1. It consists of a centrosymmetric dimer, the two vanadium atoms being surrounded by four oxygen atoms of the bridging N,N-diethylcarbamato groups and by the cyclopentadienyl ligand. The metal atom exhibits a distorted square-pyramidal coordination geometry with the oxygen atoms occupying the basal plane. The reaction of TiCp2(CO)2 or Vmes2 (mes = eta(6)-1,3,5-Me3C6H3) with Ti(O2CNEt2)4 affords Ti(III) and V(III) N,N-diethylcarbamato derivatives by a simultaneous ligand- and electron-transfer reaction. Magnesium N,N-diisopropylcarbamate, Mg(O2CNPr2i)2, has been obtained by a ligand-transfer reaction between MgCp2 and Ti(O2CNPr2i)3

SYNTHESIS OF N,N-DIALKYLCARBAMATO COMPLEXES OF GROUP-4 METALS (TI, ZR, HF) BY THE METAL CHLORIDE-NHR2-CO2 SYSTEM (R = ET OR PRI) - CRYSTAL AND MOLECULAR-STRUCTURE OF [HF(O2CNPRI2)4]

The compounds [M(O2CNR2)4] (M = Ti, Zr or Hf; R = Et or Pr) have been prepared by treating the corresponding metal tetrachloride with CO2-NHR2 in toluene. The structure of [Hf(O2CNPr2i)4] has been solved by X-ray diffraction methods. Crystal data: monoclinic, space group P2(1)/c, a = 12.756(3), b = 22.131(9), c = 14.548(5) angstrom, beta = 113.03(2)-degrees and Z = 4. It consists of monomeric units, the hafnium atom being surrounded by the eight oxygen atoms of the four N,N-diisopropylcarbamato groups in a slightly distorted dodecahedral arrangement. By reaction with anhydrous hydrogen halides HX (X = Cl, Br or l) the hexahalogenometalate(iv) anions, [MX6]2-, as the diethylammonium derivatives, have been obtained in high yields. The redox reaction between [Ti(O2CNEt2)4] and [V(eta-C5Me5)2] gives the titanium(III) and vanadium(III) complexes [{Ti(O2CNEt2)3}n] and [V(eta-C5Me5)2(O2CNEt2)], respectively

Speculative execution of similarity queries: Real-time parameter optimization through visual exploration

The parameters of complex analytical models often have an unpredictable influence on the models' results, rendering parameter tuning a non-intuitive task. By concurrently visualizing both the model and its results, visual analytics tackles this issue, supporting the user in understanding the connection between abstract model parameters and model results. We present a visual analytics system enabling result understanding and model refinement on a ranking-based similarity search algorithm. Our system (1) visualizes the results in a projection view, mapping their pair-wise similarity to screen distance, (2) indicates the influence of model parameters on the results, and (3) implements speculative execution to enable real-time iterative refinement on the time-intensive offline similarity search algorithm

A Survey of Human-Centered Evaluations in Human-Centered Machine Learning

Visual analytics systems integrate interactive visualizations and machine learning to enable expert users to solve complex analysis tasks. Applications combine techniques from various fields of research and are consequently not trivial to evaluate. The result is a lack of structure and comparability between evaluations. In this survey, we provide a comprehensive overview of evaluations in the field of human-centered machine learning. We particularly focus on human-related factors that influence trust, interpretability, and explainability. We analyze the evaluations presented in papers from top conferences and journals in information visualization and human-computer interaction to provide a systematic review of their setup and findings. From this survey, we distill design dimensions for structured evaluations, identify evaluation gaps, and derive future research opportunities.publishe