四核铑配合物中桥联苯并咪唑 -2-硫醇盐配体配位模式产生的氢键和异构现象

Hydrogen Bonding and Isomerism Arising from the Coordination Modes of Bridging Benzimidazole-2-thiolate Ligands in Tetranuclear Rhodium Complexes.

作者信息

Tejel Cristina, Villarroya B. Eva, Ciriano Miguel A., Edwards Andrew J., Lahoz Fernando J., Oro Luis A., Lanfranchi Maurizio, Tiripicchio Antonio, Tiripicchio-Camellini Marisa

机构信息

Departamento de Química Inorgánica, ICMA, Universidad de Zaragoza-CSIC, E-50009 Zaragoza, Spain, and Dipartimento di Chimica Generale ed Inorganica, Chimica Analitica, Chimica Fisica, Centro di Studio per la Strutturistica Diffrattometrica del CNR, Università di Parma, Viale delle Scienze 78, I-43100 Parma, Italy.

出版信息

Inorg Chem. 1998 Aug 10;37(16):3954-3963. doi: 10.1021/ic971376p.

DOI:10.1021/ic971376p

PMID:11670509

Abstract

Reaction of the dinuclear complex [Rh(2)(&mgr;-HBzimt)(2)(cod)(2)] with [Rh(2)(&mgr;-Cl)(2)(cod)(2)] (cod = 1,5-cyclooctadiene) gives the neutral tetranuclear complex [Rh(4)(&mgr;-HBzimt)(2)Cl(2)(cod)(4)] (2) in dichloromethane and the trinuclear cationic complex [Rh(3)(&mgr;-HBzimt)(2)(cod)(3)]Cl (3) in methanol, respectively. The ionization ability of the solvent seems to be the driving force to give 3, while the ability to coordinate a further RhCl(cod) fragment leads to 2 in poorer ionizing media. The complexes [M(4)(&mgr;-HBzimt)(2)Cl(2)(diolefin)(4)] (M = Rh, diolefin = tetrafluorobenzobarrelene (tfbb) (5); M = Ir, diolefin = cod (6)), formally analogous to 2, were isolated from the reactions of the appropriate complexes [MCl(H(2)Bzimt)(diolefin)] and [M(acac)(diolefin)] in acetone. A X-ray diffraction study on 2 shows the HBzimt(-) ligands to bridge two rhodium atoms through the sulfurs, forming a basic four-membered Rh(2)(&mgr;-(1:2kappaS)-HBzimt)(2) ring along with two RhCl(cod) moieties bonded to the nitrogen atoms. Two intramolecular hydrogen bonds between the chloro ligands and the acidic NH protons should stabilize the syn-endo disposition of the thiolate type bridging ligands. Replacement of the olefin in 2 by carbon monoxide gives [Rh(4)(&mgr;-HBzimt)(2)Cl(2)(cod)(CO)(6)] and [Rh(4)(&mgr;-HBzimt)(2)Cl(2)(CO)(8)] (7) depending on the reaction conditions. The X-ray structure of 7 shows the HBzimt(-) ligands in a HT-Rh(2)(&mgr;-(1kappaN,2kappaS)-HBzimt)(2) disposition with two RhCl(CO)(2) fragments coordinated to the sulfur atoms. In addition, two tetranuclear units 7 are associated in a dimer through four intermolecular hydrogen bonds. This association occurs even in solution, where the two species are observed. The equilibrium constant for the dissociation fits a linear plot of ln K(eq) versus 1/T, which gives DeltaH = 43.3 kJ mol(-)(1) and DeltaS = 114.7 J K(-)(1) mol(-)(1). Deprotonation of 7 with [Rh(2)(&mgr;-OMe)(2)(cod)(2)] gives the hexanuclear complex [Rh(6)(&mgr;-Bzimt)(2)(&mgr;-Cl)(2)(cod)(2)(CO)(8)] (10). Complexes 7 and 10 show identical conformations of the eight-membered HT-Rh(2)(&mgr;-(1kappaN,2kappaS)-Bzimt)(2) metallacycle and identical configurations of the sulfur atoms.

摘要

双核配合物[Rh₂(μ - HBzimt)₂(cod)₂]与[Rh₂(μ - Cl)₂(cod)₂]（cod = 1,5 - 环辛二烯）反应，分别在二氯甲烷中生成中性四核配合物[Rh₄(μ - HBzimt)₂Cl₂(cod)₄] (2)，在甲醇中生成三核阳离子配合物[Rh₃(μ - HBzimt)₂(cod)₃]Cl (3)。溶剂的电离能力似乎是生成3的驱动力，而在电离能力较差的介质中，进一步配位一个RhCl(cod)片段的能力则导致生成2。配合物[M₄(μ - HBzimt)₂Cl₂(diolefin)₄]（M = Rh，二烯烃 = 四氟苯并桶烯 (tfbb) (5)；M = Ir，二烯烃 = cod (6)），与2形式上类似，是由相应的配合物[MCl(H₂Bzimt)(diolefin)]和[M(acac)(diolefin)]在丙酮中的反应分离得到的。对2的X射线衍射研究表明，HBzimt⁻配体通过硫原子桥连两个铑原子，与两个键合到氮原子上的RhCl(cod)部分一起形成一个基本的四元Rh₂(μ - (1:2κS) - HBzimt)₂环。氯配体与酸性NH质子之间的两个分子内氢键应能稳定硫醇盐型桥连配体的顺式 - 内型排列。用一氧化碳取代2中的烯烃，根据反应条件可得到[Rh₄(μ - HBzimt)₂Cl₂(cod)(CO)₆]和[Rh₄(μ - HBzimt)₂Cl₂(CO)₈] (7)。7的X射线结构表明，HBzimt⁻配体呈HT - Rh₂(μ - (1κN,2κS) - HBzimt)₂排列，两个RhCl(CO)₂片段配位到硫原子上。此外，两个四核单元7通过四个分子间氢键形成二聚体。这种缔合即使在溶液中也会发生，在溶液中可以观察到这两种物种。解离的平衡常数符合ln K(eq)对1/T的线性图，得到ΔH = 43.3 kJ mol⁻¹和ΔS = 114.7 J K⁻¹ mol⁻¹。用[Rh₂(μ - OMe)₂(cod)₂]使7去质子化得到六核配合物[Rh₆(μ - Bzimt)₂(μ - Cl)₂(cod)₂(CO)₈] (10)。配合物7和10显示出八元HT - Rh₂(μ - (1κN,2κS) - Bzimt)₂金属环的相同构象以及硫原子的相同构型。