Interligand interactions affecting specific metal bonding to nucleic acid bases.: A case of [Rh2(OAc)4], [Rh2(HNOCCF3)4], and [Rh2(OAc)2(HNOCCF3)2] toward purine nucleobases and nucleosides
Interligand interactions affecting specific metal bonding to nucleic acid bases.: A case of [Rh2(OAc)4], [Rh2(HNOCCF3)4], and [Rh2(OAc)2(HNOCCF3)2] toward purine nucleobases and nucleosides
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DOI：
10.1016/s0020-1693(02)01042-3
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发表时间：
2002-11-15
影响因子：
2.8
通讯作者：
Salam, MA
中科院分区：
文献类型：
--
作者：
Aoki, K;Salam, MA
[Rh-2(OAc)(4)]与腺嘌呤、9-甲基腺嘌呤、9-乙基鸟嘌呤、腺苷、鸟苷、脱氧鸟苷或肌苷在甲醇水溶液中在室温下反应，特异性定量地生成腺嘌呤或其衍生物的粉红色络合物( = L)，[Rh-2(OAc)(4)(L)]（二铑核：L比例为1:1）。 [Rh-2(HNOCCF3)(4)] 或 [Rh-2(OAc)(2)(HNOCCF3)(2)] 与这些核碱基或核苷 (= L) 的反应产生非特异性的粉红色或红色复合物，其中二铑核：对于腺嘌呤衍生物，L = 1:1，对于鸟嘌呤衍生物，L = 1:2。 9-甲基腺嘌呤加合物从硝酸溶液中重结晶得到[Rh-2(OAc)(2)(HNOCCF3)(2)(9-甲基腺嘌呤)(2)].(NO3)(2) (1)，其晶体结构通过X射线衍射测定，表明两个N(1)-质子化的9-甲基腺嘌呤分子与a的两个轴向位置配位。 [Rh-2(OAc)(2)(HNOCCF3)(2)]核通过N(7)形成分子内配体N(6)-H...O(乙酰基)氢键。鸟嘌呤衍生物的晶体结构，[Rh-2(OAc)(2)(HNOCCF3)(2)(9-乙基鸟嘌呤)(2)].2MeOH.2H(2)O (2)、[Rh-2(HNOCCF3)(4)(L)(2)].3H(2)O（L = 鸟苷 (3)、脱氧鸟苷 (4) 或肌苷 (5)），和测定了[Rh-2(OAc)(2)(HNOCCF3)(2)(鸟苷)(2)].3H(2)O (6)，表明二铑核心的任一轴侧通过N(7)被两个鸟嘌呤或次黄嘌呤部分占据，形成分子内配体N(酰胺基)-H...O(6)氢键。 3、4和6中的每个鸟苷分子或5中的肌苷分子均采用顺式、高斯-高斯(或对于3中的一个分子为高斯-反式)和C(2')-endo(或对于4中的一个分子为C(2')-endo-C(3')-exo)构象，形成分子内0(5')-H...N(3)氢键。配体间 N(6)-H...O 氢键的形成与与 N(7) 键合的铑原子（如 1 中观察到的）和/或腺嘌呤的 N(1) 的空间约束八面体配位几何相关，可能为 [Rh-2(OOCR)(4)] 的腺嘌呤特异性反应性提供结构基础，其中羧基配体只能充当氢键受体。类似地，2-6 中观察到的配体间 NH...O(6) 氢键的形成表明 [Rh-2(HNHNCR)(4)] 可以充当鸟嘌呤特异性试剂，其中脒基配体只能充当氢键供体。由于八面体配位几何形状而产生的配体间空间限制也可以解释 [Rh-2(OOCR)(4)] 对天然 B-DNA（右手双链结构）没有反应性，但与单链和可能与左手双链结构特异性结合。 (C) 2002 Elsevier Science B.V. 保留所有权利。
The reaction of [Rh-2(OAc)(4)] with adenine, 9-methyladenine, 9-ethylguanine, adenosine, guanosine, deoxyguanosine, or inosine in methanolic aqueous solution at room temperature gave specifically and quantitatively pink complexes of adenine or its derivatives ( = L), [Rh-2(OAc)(4)(L)] (the dirhodium-core:L ratio of 1:1). The reaction of [Rh-2(HNOCCF3)(4)] or [Rh-2(OAc)(2)(HNOCCF3)(2)] with these nucleobases or nucleosides ( = L) gave non-specifically pink or red complexes with dirhodium-core:L = 1: 1 for adenine derivatives while 1:2 for guanine derivatives. Recrystallization of a 9-methyladenine adduct from a nitric acid solution yielded [Rh-2(OAc)(2)(HNOCCF3)(2)(9-methyladeninium)(2)].(NO3)(2) (1), whose crystal structure was determined by X-ray diffraction, showing that two N(1)-protonated 9-methyladeninium molecules coordinate to both the axial-positions of a [Rh-2(OAc)(2)(HNOCCF3)(2)] nucleus through N(7) with the formation of an intramolecular interligand N(6)-H...O(acetato) hydrogen bond. Crystal structures of guanine derivatives, [Rh-2(OAc)(2)(HNOCCF3)(2)(9-ethylguanine)(2)].2MeOH.2H(2)O (2), [Rh-2(HNOCCF3)(4)(L)(2)].3H(2)O (L = guanosine (3), deoxyguanosine (4), or inosine (5)), and [Rh-2(OAc)(2)(HNOCCF3)(2)(guanosine)(2)].3H(2)O (6) were determined, showing that the dirhodium core is occupied at either axial-side by two guanine or hypoxanthine moieties through N(7) with the formation of an intramolecular interligand N(amidato)-H...O(6) hydrogen bond. Each of guanosine molecules in 3, 4, and 6 or inosine molecules in 5 adopts the syn, gauche-gauche (or gauche-trans for one molecule in 3), and C(2')-endo (or C(2')-endo-C(3')-exo for one molecule in 4) conformations to form an intramolecular 0(5')-H...N(3) hydrogen bond. The formation of interligand N(6)-H...O hydrogen-bonding associated with the sterically constrained octahedral coordination geometry about the rhodium atom bonded to N(7), as observed in 1, and/or to N(1) of adenine may give a structural basis for the adenine-specific reactivity of [Rh-2(OOCR)(4)], where the carboxylato ligand could function as hydrogen-bonding acceptor only. Similarly, the formation of interligand NH...O(6) hydrogen-bonding observed in 2-6 suggests that [Rh-2(HNHNCR)(4)] could function as guanine-specific reagents, where the amidinato ligand could function as hydrogen-bonding donor only. The interligand steric constraint due to the octahedral coordination geometry may also explain no reactivity of [Rh-2(OOCR)(4)] toward native B-DNA (right-handed double-stranded structure) but specific bonding to single-stranded and possibly to left-handed double-stranded structures. (C) 2002 Elsevier Science B.V. All rights reserved.