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首页> 外文期刊>Dalton transactions: An international journal of inorganic chemistry >Imidazol-2-ylidene-N '-phenylureate ligands in alkali and alkaline earth metal coordination spheres - heterocubane core to polymeric structural motif formation
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Imidazol-2-ylidene-N '-phenylureate ligands in alkali and alkaline earth metal coordination spheres - heterocubane core to polymeric structural motif formation

机译：碱金属和碱土金属配位领域中的咪唑-2-亚甲基-N'-苯脲酸酯配体-杂多核核心形成聚合物结构基序

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摘要

The synthesis and isolation of two potassium, one lithium and two calcium complexes of imidazol-2-ylidene-N'-phenylureate ligands [Im(R)NCON(H)Ph] [(R = tBu (1a); Mes (1b) and Dipp (1c); Mes = mesityl, Dipp = 2,6-diisopropylphenyl] are described. Potassium complexes, [{kappa(2)-(Im(Mes)NCONPh)K}(4)](2b) and[{kappa(3)-(Im(Dipp)NCONPh)K}(2){KN(SiMe3)(2)}(2)](n) (2c), were prepared in good yields by the reactions of 1b and 1c, respectively, with potassium bis(trimethyl) silyl amide at ambient temperature in toluene. Lithium complex [{(2,6-tBu(2)-4-Me-C6H2O) Li(Im(tBu)NCON(H)Ph)}(2){Im(tBu)NCON(H)Ph}] (3a) was isolated by a one-pot reaction between 1a and LiCH2SiMe3, followed by the addition of 2,6-tBu(2)-4-Me-C6H2OH in toluene. Calcium complex [{kappa(2)-(Im(tBu)NCONPh)Ca{N(SiMe3)(2)}-{KN(SiMe3)(2)}] n (4a) was isolated by the one-pot reaction of 1a with [KN(SiMe3)(2)] and calcium diiodide in THF at ambient temperature. The solid-state structures of ligand 1a and complexes 2b, 2c, 3a and 4a were confirmed by single-crystal X-ray diffraction analysis. It was observed that potassium was coordinated to the oxygen atom of urea group and to the nitrogen atom of the imidazolin-2-imine group, in the solid-state structure of 2b. In complex 4a, the calcium ion was ligated to the monoanionic imidazol-2-ylidene-N'-phenylureate ligand in a bi-dentate (kappa(2)) fashion through the oxygen and nitrogen atoms of the isocyanate building block leaving the imidazolin-2-imine fragment uncoordinated. In the solid state of the potassium complex 2c, tri-dentate (kappa(3)) coordination from the imidazol-2-ylidene-N'-phenylureate ligand was observed through the oxygen and nitrogen atoms of the isocyanate building block and of the imidazolin-2-imine fragment. In contrast, in the dimeric lithium complex 3a, the neutral imidazol-2-ylidene-N'-phenylureate ligand was bound to the lithium centre in a mono-dentate fashion (kappa(1)) through an oxygen atom of the isocyanate moiety. It is to be noted that in each complex thus observed, the elongated carbon-nitrogen bond distances indicate substantial electron delocalisation from the imidazole ring to the ureate group present in ligand 1.
机译：咪唑-2-亚甲基-N'-苯脲酸酯配体[Im（R）NCON（H）Ph] [（R = tBu（1a）; Mes（1b））的两个钾，一个锂和两个钙络合物的合成和分离和Dipp（1c）; Mes = mesityl，Dipp = 2,6-diisopropylphenyl]描述了钾络合物[{kappa（2）-（Im（Mes）NCONPh）K}（4）]（2b）和[{通过1b和1c的反应以高收率制备了kappa（3）-（Im（Dipp）NCONPh）K}（2）{KN（SiMe3）（2）}（2）]（n）（2c），锂络合物[{（（2,6-tBu（2）-4-Me-C6H2O）Li（Im（tBu）NCON（H）Ph）}（）分别在室温下与双（三甲基）甲硅烷基钾酰胺在甲苯中2）{Im（tBu）NCON（H）Ph}]（3a）通过1a和LiCH2SiMe3之间的一锅反应分离，然后在其中加入2,6-tBu（2）-4-Me-C6H2OH一锅法分离钙络合物[{kappa（2）-（Im（tBu）NCONPh）Ca {N（SiMe3）（2）}-{KN（SiMe3）（2）}] n（4a）在室温下1a与[KN（SiMe3）（2）]和二碘化钙在THF中的反应。配体1a和配合物2b，2c，3a和通过单晶X射线衍射分析确认了图4a。观察到在2b的固态结构中，钾与脲基的氧原子和咪唑啉-2-亚胺基的氮原子配位。在配合物4a中，钙离子通过异氰酸酯结构单元中的氧和氮原子以双齿（kappa（2））的方式与单阴离子咪唑-2-亚甲基-N'-苯脲酸酯配体连接，从而使咪唑啉- 2-亚胺片段不协调。在钾络合物2c的固态下，通过异氰酸酯结构单元和咪唑啉的氧原子和氮原子观察到咪唑-2-亚甲基-N'-苯脲酸酯配体的三齿（kappa（3））配位-2-亚胺片段。相反，在二聚体锂络合物3a中，中性咪唑-2-亚烷基-N′-苯脲酸酯配体通过异氰酸酯部分的氧原子以单齿形式（kappa（1））结合到锂中心。要注意的是，在由此观察到的每个络合物中，拉长的碳-氮键距离表示从咪唑环到配体1中存在的脲酸酯基团的大量电子离域。

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