Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA.
Acta Crystallogr C Struct Chem. 2021 Sep 1;77(Pt 9):544-550. doi: 10.1107/S2053229621008500. Epub 2021 Aug 23.
The phenyltris[(tert-butylthio)methyl]borate ligand, [PhTt], has been studied extensively as a platform for coordination, organometallic, and bioinorganic chemistry, especially with 3d metals. While [PhTt]Co(3,5-DBCatH) (3,5-DBCatH is 3,5-di-tert-butylcatecholate), a Co-monoanionic catecholate complex, was successfully isolated to model the active site of cobalt(II)-substituted homoprotocatechuate 2,3-dioxygenase (Co-HPCD) [Wang et al. (2019). Inorg. Chim. Acta, 488, 49-55], its iron(II) counterpart, [PhTt]Fe(3,5-DBCatH), was not accessible via similar synthetic routes. Switching the nucleophile from catecholate to alkoxide or aryloxide, however, led to the successful isolation of three highly air-sensitive Fe-alkoxide and -aryloxide complexes, namely, (triphenylmethoxo){tris[(tert-butylsulfanyl)methyl]phenylborato-κS,S',S''}iron(II), [Fe(CHBS)(CHO)], (2), (2,6-dimethylphenolato){tris[(tert-butylsulfanyl)methyl]phenylborato-κS,S',S''}iron(II), [Fe(CHBS)(CHO)], (3), and bis{μ-tris[(tert-butylsulfanyl)methyl]phenylborato-κS,S':S''}bis[(phenolato-κO)iron(II)] toluene disolvate, [Fe(CHBS)(CHO)]·2CH, (4). In the solid state, compounds (2) and (3) are monomeric, with [PhTt] acting as a tridentate ligand. In contrast, compound (4) crystallizes as a dimeric complex, wherein each [PhTt] ligand binds to an iron centre with two thioethers and binds to the other iron centre with the third thioether. The molecular structures of (2)-(4) demonstrate a diversity in the binding modes of [PhTt] and highlight its potential use for assembling multinuclear complexes. In addition, the successful isolation of (2)-(4), as well as the structural information of a [PhTt] modification product, namely, bis{μ-tris(tert-butylsulfanyl)methylborato-κO,O',S,S':O'}dicobalt(II), [Co(CHBOS)], (5), obtained from the reaction of [PhTt]CoCl with potassium monoanionic catecholate, shed light on the origin of the instability of [PhTt]Fe(3,5-DBCatH).
苯基三[(叔丁基硫基)甲基]硼酸盐配体[PhTt]已被广泛研究用于配位、有机金属和生物无机化学，特别是与 3d 金属。虽然[PhTt]Co(3,5-DBCatH)(3,5-DBCatH 是 3,5-二叔丁基儿茶酸盐)，一个 Co-单阴离子儿茶酸盐配合物，成功地被分离出来以模拟钴(II)取代的高丙二酸盐 2,3-加双氧酶(Co-HPCD)的活性位点[Wang 等人。(2019).无机化学学报, 488, 49-55]，但其铁(II)对应物[PhTt]Fe(3,5-DBCatH)，无法通过类似的合成途径获得。然而，将亲核试剂从儿茶酸盐切换为烷氧基或芳氧基，导致三种高度敏感的 Fe-烷氧基和芳氧基配合物的成功分离，即(三苯甲氧基){三[(叔丁基硫基)甲基]苯基硼酸酯-κS，S'，S''}铁(II)，[Fe(CHBS)(CHO)]，(2)，(2,6-二甲基苯酚基){三[(叔丁基硫基)甲基]苯基硼酸酯-κS，S'，S''}铁(II)，[Fe(CHBS)(CHO)]，(3)，和双{μ-三[(叔丁基硫基)甲基]苯基硼酸酯-κS，S':S''}双[(苯酚基-κO)铁(II)]甲苯二合物，[Fe(CHBS)(CHO)]·2CH，(4)。在固态下，化合物(2)和(3)是单体的，[PhTt]作为三齿配体。相比之下，化合物(4)结晶为二聚体配合物，其中每个[PhTt]配体与一个铁中心结合两个硫醚，并与另一个铁中心结合第三个硫醚。(2)-(4)的分子结构展示了[PhTt]的多种结合模式，并突出了其用于组装多核配合物的潜力。此外，(2)-(4)的成功分离以及[PhTt]修饰产物，即双{μ-三(叔丁基硫基)甲基硼酸酯-κO，O'，S，S':O'}二钴(II)，[Co(CHBOS)]，(5)，从[PhTt]CoCl 与钾单阴离子儿茶酸盐反应获得的结构信息，阐明了[PhTt]Fe(3,5-DBCatH)不稳定的原因。
