简介：TheelectrochemicalbehaviorsandthedetectionofNO2-haveattractedincreasingattentionrecentlybecauseoftheimportantrolesplayedbyNO2-inenvironmentandlifeprocesses.Thus,advancedtechniquesforthedetermination,especiallyon-sitedetermination,ofthenitriteinfoods...

简介：Auranylcompound,K4UO2（CO3）3hasbeencharacterizedbypowderX-raydiffractionmethod.M.W.=606.46,monoclinic,C2/c（No.15）,a=1.0240（7）,b=0.9198（4）,c=1.2222（12）nm,β=95.12（4）°,V=1.1466（5）nm3,Z=4,Dm=3.468g/cm3,Dc=3.513g/cm,λ（CuKα1）=O.1540598nm,T=298K.ThestructurewassolvedbyheavyatommethodandFouriersynthesis,andrefinedbyfull-matrixleast-squaresmethodtoR=0.1185for275reflections.Theuranium（Ⅵ）atomisinaneight-coordinatedistortedhexagonal-bipyramidalenvironmentwithcreasyfanshape.Thelinearuranylgroupapproachestoperpendiculartotheequatorialplaneinwhichthreecarbonategroupsarechelated.U（Ⅵ）hastwolinearoxygenatomsclosertoit（U-O=0.1767（5）nm）thansixotherneighbours（U-Orangingfrom0.2516to0.2568nm）.Thedistancesbetweencarbonatomsanduncoordinatedoxygenatomsare0.122（1）and0.123（1）nm,whicharedistinctlydifferentfromthosebetweencarbonandcoordinatedoxygenatoms（mean0.134（6）nm）.Thisfactrevealsthenon-eq-uivalenceofoneoxygenatomtotheothertwoineachcarbonate.InK4UO2（CO3）3,theO-Odis-tancefortheadjacentcarbonategroupsis0.2794（4）nmapproachingtothesumofVanderWaalsradiioftwooxygenatoms.TheK-Odistancesvarybetween0.2667and0.3131nm,andeachanionisimmediatelysurroundedbysixpotassiumions,onlyfourofwhichcanbeconsideredtobelongtothesamestructuralformulaunit,andtheyaresymmetricallylocatedaboveandbelowtheequatorialplane.