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Three ureido-pyrimidone derivatives (N-L H ) were used to generate in combination with four dinuclear arene ruthenium clips, ( p -cymene) 2 Ru 2 (OO∩OO)Cl 2 (OO∩OO = oxalato, 2,5-dioxido-1,4-benzoquinonato, 2,5-dichloro-1,4-benzoquinonato, 5,8-dioxido-1,4-naphtoquinonato), twelve cationic arene ruthenium metalla-cycles of the general formula [( p -cymene) 2 Ru 2 (OO∩OO)(N-L H ) 2 ] 2 (CF 3 SO 3 ) 4 . The ureido-pyrimidone moieties are able to form strong hydrogen-bonds by self-pairing, thus giving rise to dimeric structures in solution. In addition, to better understand the behavior of the tetranuclear metalla-cycles in solution, the neutral dinuclear arene ruthenium ureido-pyrimidone complexes of the general formula {( p -cymene)RuCl 2 (N-L H )} 2 were also prepared and characterized. All metalla-assemblies were studied in solution by NMR spectroscopy, confirming the high stability of the metalla-cycles and the usefulness of hydrogen-bonds in constructing supramolecular assemblies. [ABSTRACT FROM AUTHOR]

The hydrogen-bonded arene ruthenium metalla-rectangle, [(p-cymene)2Ru2(OO⌒OO)(UPy)2]24+, obtained from 1-(4-oxo-6-undecyl-1,4-dihydropyrimidin-2-yl)-3-(pyridin-4-ylmethyl)urea (UPy) and the dinuclear arene ruthenium clip (p-cymene)2Ru2(OO⌒OO)Cl2 (OO⌒OO = 2,5-dioxido-1,4-benzoquinonato), is investigated by means of solution-phase NMR spectroscopy. Rotating frame nuclear Overhauser effect measurements are used to probe the H-bond network that drives the UPy self-assembly as well as the full rectangular supramolecular system. An effective distance that takes into account both intra- and intermolecular polarization-transfer pathways is utilised for data analysis. The experimental findings are corroborated by DFT calculations of NMR parameters and internuclear distances, thus confirming the formation of a very stable tetranuclear metalla-assembly. [ABSTRACT FROM AUTHOR]

A high-yield, solvent-free approach to the synthesis of 1,3,5-trisubstituted pyrazoles is reported. Four compounds, (3,5-di-tert-butyl-1H-pyrazole, (2-(3,5-dimethyl-1H-pyrazol-1-yl)ethanol, 2-(3,5-di-tert-butyl-1H-pyrazol-1-yl)ethanol, 2-(3,5-diphenyl-1H-pyrazol-1-yl)ethanol were readily prepared by solvent-free condensation of the appropriate diketone and the respective hydrazine. The crystal structures of the three pyrazolyl-ethanols are typical of N-substituted pyrazoles. All three pyrazolyl compounds show interesting inter-molecular hydrogen bonding. For the 3,5-dimethyl compound the molecules form discrete hydrogen bonded dimers within a unit cell, while for the others the hydrogen bonding is in a head-to-tail arrangement resulting in the formation of chains. [ABSTRACT FROM AUTHOR]