Three types of unusual cagelike copper(II) methylsilsesquioxanes, namely, nona- [(MeSiO)(CuO)] 1, hexa- [(MeSiO)(HO)(CuO)(CHN)(MeSiO)(HO)(CHCOO)(CuO)(CHN)] 2, [(MeSiO)(CuO)(MeO)(CHN)] 3, and trinuclear [(MeSiO)(CuO)(CHN)] 4, were obtained in 44%, 27%, 20%, and 16% yields, respectively. Nuclearity and structural fashion of products was controlled by the choice of solvent system and ligand, specifically assisting the assembling of cage. Structures of 1-4 were determined by single-crystal X-ray diffraction analysis. Compounds 1 and 4 are the first cage metallasilsesquioxanes, containing nine and three Cu ions, respectively. Product 1 is the first observation of nonanuclear metallasilsesquioxane ever. Unique architecture of 4 represents early unknown type of molecular geometry, based on two condensed pentamembered siloxane cycles. Topological analysis of metal clusters in products 1-4 is provided. Complex 1 efficiently catalyzes oxidation of alcohols with tert-butylhydroperoxide TBHP to ketones or alkanes with HO to alkyl hydroperoxides in acetonitrile.

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TYREE, M. T., M. E. MACGRECOR, A. PETROV, itnd M. I. UPENIEKS. 1978. A comparison of systematic errors between the Richards and Hammel methods of measuring tissue -water relations parameters. Can. J . Bot. 56: 2153-2161. The pressure bomb is being used to a much greater extent to measure some tissue -water relations parameters such as osmotic pressure, turgol-pressure. and cell wall elasticity. Recently, Richards has developed a faster pressure-bomb method of obtaining these and other parameters than the method used by Hammel and modified by 11s. In this paper. we compare the two methods and conclude that Richards' method should not be used when accu~xcy is deemed important. The Richards method usually overestimatesosmotic pressure by 0.2 MPa(= 2 bars)and sometimes by 0.8 MPa (= 8 bars). TYREE. M. T., M. E. MACGRECOR, A. PETROV et M. I. UPENIEKS. 1978. A comparison of systematic errors between the Richards and Hammel methods of measuring tissue -water relations parameters. Can. J. Bot. 56: 2153-2161. La bombe $ pression est utilisee de plus en plus pour rnesurer certains parametres ayant trait aux relations plante-eau, telles que la pression osmotique, la pression de turgescence et I'elasticite de la pzuoi cellulaire. Pour mesurer ces dernieres ainsi que d'autres pammetres. Richards a ricemment dkveloppe une methode de bombe i~ pression plus lapide que In methode utilisee par Hammel et modifiee par les auteurs. Dnns cet article. les auteurs comparent lesdeux methodes et concluent que celle de Richards ne doit pas itre utilisee lorsque la precision des mesures est importante. La methode de Richards surestime ktbituellement la pression osmotique de 0.2 MPa (= 2 bars) et parfois de0.8 MPa (= 8 bars).[~r a d u i t par le journal]

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In the present work, the thermochemistry of solution, solvation, and hydrogen bonding of cyclic amides in proton acceptor (B) and proton donor (RXH) solvents were studied. The infinite dilution solution enthalpies of δ-valerolactam, N-methylvalerolactam, ε-caprolactam, and N-methylcaprolactam were measured at 298.15 K. The solvation enthalpies of cyclic amides were calculated based on the measured solution enthalpies and sublimation/vaporization enthalpies from literature. The enthalpies of hydrogen bonding between cyclic amides and proton acceptor and donor solvents were then calculated as a difference between the total solvation enthalpy and the non-specific contribution. The latter was estimated via two different approaches in proton donor and proton accepting solvents. The effect of the cycle size on the strength of hydrogen bonding of the cyclic amides in solution is discussed.