Syntheses, Structures, and Electrochemical Properties of Platinum(II) Complexes Containing Di-<i>tert</i>-butylbipyridine and Crown Ether Annelated Dithiolate Ligands

A series of new platinum(II) complexes containing both 4,4‘-di-tert-butyl-2,2‘-bipyridine (dbbpy) and the extended tetrathiafulvalenedithiolate ligands have been prepared and characterized. These complexes include [Pt(dbbpy)(C8H4S8)] (1; C8H4S82- = 2-{(4,5-ethylenedithio)-1,3-dithiol-2-ylidene}-1,3-dithiol-4,5-dithiolate), [Pt(dbbpy)(ptdt)] (2; ptdt = 2-{(4,5-cyclopentodithio)-1,3-dithiol-2-ylidene}-1,3-dithiol-4,5-dithiolate), [Pt(dbbpy)(mtdt)] (3; mtdt = 2-{(4,5-methylethylenedithio)-1,3-dithiol-2-ylidene}-1,3-dithiol-4,5-dithiolate), [Pt(dbbpy)(btdt)] (4; btdt = benzotetrathiafulvalenedithiolate), [Pt(dbbpy)(C8H6S8)] (5; C8H6S82- = 2-{4,5-bis(methylthio)-1,3-dithiol-2-ylidene}-1,3-dithiol-4,5-dithiolate), [Pt(dbbpy)(3O-C6S8)] (6; 3O-C6S82- = 2-{4,5-dithia-(3‘,6‘,9‘-trioxaundecyl)-1,3-dithiol-2-ylidene}-1,3-dithiol-4,5-dithiolate), and [Pt(dbbpy)(4O-C6S8)] (7; 4O-C6S82- = 2-{4,5-dithia-(3‘,6‘,9‘,12‘-tetraoxatetradecyl)-1,3-dithiol-2-ylidene}-1,3-dithiol-4,5-dithiolate). The crystal structures of a new ligand precursor (2-[4,5-dithia-(3‘,6‘,9‘,12‘-tetraoxatetradecyl)-1,3-dithiol-2-ylidene]-4,5-bis(2-cyanoethylsulfanyl)-1,3-dithiole, IIIc) and complexes 5−7 have been determined by X-ray crystallography. Complexes 1−7 show intense electronic absorption bands in the UV−vis region due to the intramolecular mixed metal/ligand-to-ligand charge-transfer transition, and they display significant solvatochromic behavior. Redox properties of these compounds have been investigated by cyclic voltammetry, and complex 7 shows a significant response for Na+ ions with a large positive shift of ca. 45 mV.一类同时含有4,4'-二叔丁基-2,2'-联吡啶（4,4'-di-tert-butyl-2,2'-bipyridine，dbbpy）与扩展型四硫富瓦烯二硫醇盐配体的新型铂(II)配合物已被合成并表征。此类配合物包括[Pt(dbbpy)(C₈H₄S₈)]（1号配合物；C₈H₄S₈²⁻ 为2-{(4,5-乙二硫基)-1,3-二硫醇-2-亚基}-1,3-二硫醇-4,5-二硫醇盐）、[Pt(dbbpy)(ptdt)]（2号配合物；ptdt 为2-{(4,5-环戊二硫基)-1,3-二硫醇-2-亚基}-1,3-二硫醇-4,5-二硫醇盐）、[Pt(dbbpy)(mtdt)]（3号配合物；mtdt 为2-{(4,5-甲基乙二硫基)-1,3-二硫醇-2-亚基}-1,3-二硫醇-4,5-二硫醇盐）、[Pt(dbbpy)(btdt)]（4号配合物；btdt 为苯并四硫富瓦烯二硫醇盐（benzotetrathiafulvalenedithiolate））、[Pt(dbbpy)(C₈H₆S₈)]（5号配合物；C₈H₆S₈²⁻ 为2-{4,5-双(甲硫基)-1,3-二硫醇-2-亚基}-1,3-二硫醇-4,5-二硫醇盐）、[Pt(dbbpy)(3O-C₆S₈)]（6号配合物；3O-C₆S₈²⁻ 为2-{4,5-二硫杂-(3',6',9'-三氧杂十一烷基)-1,3-二硫醇-2-亚基}-1,3-二硫醇-4,5-二硫醇盐）以及[Pt(dbbpy)(4O-C₆S₈)]（7号配合物；4O-C₆S₈²⁻ 为2-{4,5-二硫杂-(3',6',9',12'-四氧杂十四烷基)-1,3-二硫醇-2-亚基}-1,3-二硫醇-4,5-二硫醇盐）。本研究通过X射线晶体学解析了一种新型配体前驱体（2-[4,5-二硫杂-(3',6',9',12'-四氧杂十四烷基)-1,3-二硫醇-2-亚基]-4,5-双(2-氰乙基硫基)-1,3-二硫杂环戊烯，IIIc）以及配合物5至7的晶体结构。配合物1至7在紫外-可见光区域展现出强电子吸收带，该吸收带源于分子内混合金属/配体到配体电荷转移跃迁，且此类配合物均表现出显著的溶剂致变色行为。本研究通过循环伏安法探究了此类化合物的氧化还原性质，其中7号配合物对钠离子（Na+）具有显著响应，其氧化还原电位正向偏移约45 mV。