Encapsulation of the 4-Mercaptobenzoate Ligand by Macrocyclic Metal Complexes: Conversion of a Metallocavitand to a Metalloligand

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• 作者：Jochen Lach ; Alexander Jeremies ; Daniel Breite ; Bernd Abel ; Benjamin Mahns ; Martin Knupfer ; Vitaly Matulis ; Oleg A. Ivashkevich ; Berthold Kersting
• 刊名：Inorganic Chemistry
• 出版年：2014
• 出版时间：October 20, 2014
• 年：2014
• 卷：53
• 期：20
• 页码：10825-10834
• 全文大小：557K
• ISSN：1520-510X

文摘

Complexation of the ambidentate ligand 4-mercaptobenzoate (4-SH-C₆H₄CO₂H, H₂mba) by the macrocyclic complex [Ni₂L(渭-Cl)]ClO₄ (L^{2鈥?/sup> represents a 24-membered macrocyclic hexaazadithiophenolate ligand) has been examined. The monodeprotonated Hmba鈥?/sup> ligand reacts with the Ni₂ complex in a selective manner by substitution of the bridging chlorido ligand to produce 渭_1,3-carboxylato-bridged complex [Ni₂L(Hmba)]+ (2+), which can be isolated as an air-sensitive perchlorate (2ClO₄) or tetraphenylborate (2BPh₄) salt. The reactivity of the new mercaptobenzoate complex is reminiscent of that of a 鈥渇ree鈥?thiophenolate ligand. In the presence of air, 2ClO₄ dimerizes via a disulfide bond to generate tetranuclear complex [{Ni₂L}₂(O₂CC₆H₄S)₂]2+ (32+). The auration of 2ClO₄ with [AuCl(PPh₃)], on the other hand, leads to monoaurated complex [NiII₂L(mba)AuIPPh₃]+ (4+). The bridging thiolate functions of the N₆S₂ macrocycle are deeply buried and are unaffected/unreactive under these conditions. The complexes were fully characterized by electrospray ionization mass spectrometry, IR and UV/vis spectroscopy, density functional theory, cyclic voltammetry, and X-ray crystallography [for 3(BPh₄)₂ and 4BPh₄]. Temperature-dependent magnetization and susceptibility measurements reveal an S = 2 ground state that is attained by ferromagnetic coupling between the spins of the NiII ions in 2ClO₄ (J = +22.3 cm鈥?) and 4BPh₄ (J = +20.8 cm鈥?; H = 鈭?JS₁S₂). Preliminary contact-angle and X-ray photoelectron spectroscopy measurements indicate that 2ClO₄ interacts with gold surfaces.}