作者:Rajni K. Wilson (née Sanyal)、Sally Brooker
DOI:10.1039/c3dt33057e
日期:——
A metal-free 16-membered N4-donor [1 + 1] Schiff-base macrocycle was isolated as HLPrPrPr·2acid, by 1 : 1 condensation of diphenylamine-2,2′-dicarboxaldehyde (1), dipropylene triamine and an excess of either acetic or formic acid, or as HLPrPrPr·(tosylic acid) when just one equivalent of tosylic acid was employed. Interestingly, the acid-free synthesis employed for the 14-membered analogue HLEtEt failed to generate pure HLPrPrPr macrocycle, but nevertheless the crude product obtained was able to be used in subsequent complexation reactions to form five mononuclear complexes: ZnIILPrPrPr(BF4)·H2O·0.5IPA (where IPA is isopropylalcohol), [CuIILPrPrPr](BF4), [NiIILPrPrPr](BF4), [CoIILPrPrPr](BF4)·0.5H2O, [FeIIILPrPrPr(NCS)2]·1.5H2O. Crystal structure determinations show that, like the HLEtEt analogues, [NiIILPrPrPr](BF4) features a square planar N4 coordinated NiII centre and [FeIIILPrPrPr(NCS)2]·0.15MeOH·0.2H2O features an octahedral N6 coordinated FeIII centre (two NCS anions bound axially). In both cases the N4-donor macrocycle is bound equatorially to the metal ion. Cyclic voltammograms of the BF4 complexes were carried out in MeCN vs. 0.01 mol L−1 AgNO3/Ag and revealed multiple redox processes. The ZnII complex exhibits multiple ligand-centered redox processes. Interestingly, [NiIILPrPrPr](BF4) has two reversible redox processes, at Em = +0.38 (ΔE = 0.06 V) and −1.7 V (ΔE = 0.06 V), whereas the previously reported analogue [NiIILEtEt](BF4) had a process at Epc = +0.59 V with only a weak return wave. Likewise, [CuIILPrPrPr](BF4) has a reversible process, at Em = −1.17 V (ΔE = 0.06 V) plus a process at Epc = +0.45 V, whereas previously reported [CuIILEtEt](BF4) only featured irreversible processes, with the oxidation occurring at Epc = +0.50 V.
通过二苯胺-2,2'-二甲醛 (1)、二亚丙基三胺和过量的 1 : 1 缩合,分离出不含金属的 16 元 N4 供体 [1 + 1] 席夫碱大环化合物 HLPrPrPr·2酸乙酸或甲酸,或者当仅使用一当量的甲苯磺酸时作为HLPrPrPr·(甲苯磺酸)。有趣的是,14元类似物HLEtEt采用的无酸合成未能生成纯HLPrPrPr大环,但所得粗产物能够用于后续络合反应,形成五个单核络合物:ZnIILPrPrPr(BF4)·H2O· 0.5IPA(其中IPA为异丙醇)、[CuIILPrPrPr](BF4)、[NiIIILPrPrPr](BF4)、[CoIILPrPrPr](BF4)·0.5H2O、[FeIIILPrPrPr(NCS)2]·1.5H2O。晶体结构测定表明,与 HLEtEt 类似物一样,[NiIIILPrPrPr](BF4) 具有方形平面 N4 配位 NiII 中心,[FeIIILPrPrPr(NCS)2]·0.15MeOH·0.2H2O 具有八面体 N6 配位 FeIII 中心(两个 NCS 阴离子)轴向约束)。在这两种情况下,N4-供体大环均与金属离子平键结合。 BF4 配合物的循环伏安图在 MeCN 与 0.01 mol L−1 AgNO3/Ag 中进行,揭示了多个氧化还原过程。 ZnII 配合物表现出多种以配体为中心的氧化还原过程。有趣的是,[NiIIILPrPrPr](BF4) 在 Em = +0.38 (ΔE = 0.06 V) 和 -1.7 V (ΔE = 0.06 V) 时有两个可逆氧化还原过程,而之前报道的类似物 [NiIIILEtEt](BF4) 有一个过程Epc = +0.59 V,只有微弱的返回波。同样,[CuIILPrPrPr](BF4) 在 Em = −1.17 V (ΔE = 0.06 V) 时具有可逆过程,加上 Epc = +0.45 V 时的过程,而之前报道的 [CuIILEtEt](BF4) 仅具有不可逆过程,其中氧化发生在 Epc = +0.50 V 处。