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首页> 外文期刊>Dalton transactions: An international journal of inorganic chemistry >Steric effects caused by N-alkylation of the tripodal chelator N,N',N'-tris(2-pyridylmethyl)-cis,cis-1,3,5-triaininocyclohexane (tachpyr):structural and electronic properties of the Mn(II),Co(II),Ni(II),Cu(II) and Zn(II) complexes
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Steric effects caused by N-alkylation of the tripodal chelator N,N',N'-tris(2-pyridylmethyl)-cis,cis-1,3,5-triaininocyclohexane (tachpyr):structural and electronic properties of the Mn(II),Co(II),Ni(II),Cu(II) and Zn(II) complexes

机译：三脚架螯合剂N，N'，N“-三（2-吡啶基甲基）-顺，顺-1,3,5-三氨基ino环己烷（tachpyr）的N-烷基化引起的立体效应：Mn（II）的结构和电子性质），Co（II），Ni（II），Cu（II）和Zn（II）配合物

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The effects of steric hindrance on the complexation of Mn(II),Co(II),Ni(II),Cu(II) and Zn(II) by chelators based on m,cw-l,3,5-triaminocyclohexane (tach) have been studied.The chelators studied are the 2-mefhylpyridyl pendant-arm derivatives of tach,'tachpyr' (N,N',N"-tris(2-pyridylmethyl)-cis,cis-1,3,5-triaminocyclohexane),and the JV-alkylated analogs '(N-Me)_3tachpyr' (N,N',N"-trimethyl- N,N',N"-tris(2-pyridyhnethyl)-cw,cw-1,3,5-triaminocyclohexane) and '(N-Et)3tachpyr' (N,N',N"-triethyl- N,N',N"-tris(2-pyridylmethyl)-cM,cM-1,3,5-triaminocyclohexane).Hexacoordinate complexes,[M"L]X2 resulted from reaction of the appropriate metal ion salts with L in alcoholic medium (M = Mn,Co,Ni,Cu,Zn;L = tachpyr,(N-Me)3tachpyr,(N~Et)3 tachpyr;X = C1O_4~,NO_3~,Cl~).The Mn(li) and Co(n) complexes have high-spin electron configurations,based on solution magnetic susceptibility,electronic spectral and/or X-ray crystallographic studies.However,solution visible-near IR electronic spectra and single-crystal X-ray crystallography demonstrate weakened bonding in the complexes of (N-R)3tachpyr relative to tachpyr,due to steric effects of methyl or ethyl groups on coordinated tach amines.Structures of [Zn(tachpyr)]2+ and [Ni(tachpyr)]2 + indicate a clear preference of tachpyr and derivatives for octahedral geometry,while [Cu((N-Me)3tachpyr)]2* exhibits a classic Jahn-Teller tetragonal distortion.The complex [Mn(tachpyr)](C10,,)2 demonstrates a striking influence of the metal ion on the coordination geometry,with a trigonal-prismatic coordination of Mn(n) and considerable distortion of the tach-amino donor groups.The.coordination geometry and distortions are attributed to the large size of high-spin ds Mn(n) and the absence of ligand-field stabilization energy,coupled with the observed preference of tachpyr derivatives for octahedral geometry.The [M"(tachpyr)]2+ complexes (M = Co,Ni,Cu and Zn) are inert in aqueous pH 5.5 media.However,all metal complexes of JV-alkylated tachpyr,as well as [Mn(tachpyr)](ClO_4)2,dissociate metal ion in aqueous pH 5.5 medium,consistent with their steric hindrance and distortions respectively.
机译：位阻对基于m，cw-1,3,5-三氨基环己烷（tach）的螯合剂对Mn（II），Co（II），Ni（II），Cu（II）和Zn（II）络合的影响所研究的螯合剂是tach，'tachpyr'（N，N'，N“-三（2-吡啶基甲基）-顺式，cis-1,3,5-三氨基环己烷的2-甲基吡啶基侧链衍生物）和JV烷基化类似物'（N-Me）_3tachpyr'（N，N'，N“-三甲基-N，N'，N” -tris（2-pyridyhnethyl）-cw，cw-1,3， 5-三氨基环己烷）和'（N-Et）3tachpyr'（N，N'，N“-三乙基-N，N'，N”-三（2-吡啶基甲基）-cM，cM-1,3,5-三氨基环己烷）。六配位配合物，[M“ L] X2是由适当的金属离子盐与L在酒精介质中反应生成的（M = Mn，Co，Ni，Cu，Zn; L = tachpyr，（N-Me）3tachpyr，（ N〜Et）3 tachpyr; X = C1O_4〜，NO_3〜，Cl〜）.Mn（li）和Co（n）配合物具有高自旋电子构型，基于溶液的磁化率，电子光谱和/或X-射线晶体学研究。但是，溶液可见近红外电子光谱和单晶X射线晶体学分析表明，由于甲基或乙基对配位的tach胺的空间影响，（NR）3tachpyr的配合物相对于tachpyr的键合减弱。[Zn（tachpyr）] 2+和[Ni（tachpyr） ] 2 +表示明显倾向于tachpyr及其衍生物为八面体几何，而[Cu（（N-Me）3tachpyr）] 2 *具有经典的Jahn-Teller四边形畸变。[Mn（tachpyr）]（C10 ,, ）2证明了金属离子对配位几何形状的显着影响，Mn（n）的三角棱柱配位和tach-氨基供体基团的明显变形。配位几何形状和变形归因于高旋转ds Mn（n）和不存在配体场稳定能，再加上观察到的tachpyr衍生物偏爱八面体几何形状。[M“（tachpyr）] 2+配合物（M = Co，Ni，Cu和Zn）在pH 5.5的水性介质中呈惰性。但是，所有JV-烷基化tachpyr的金属配合物，以及[ Mn（tachpyr）]（ClO_4）2，在水性pH 5.5介质中离解金属离子，分别与它们的空间位阻和畸变一致。

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