Baddour Frederick G, Hyre Ariel S, Guillet Jesse L, Pascual David, Lopez-de-Luzuriaga José Maria, Alam Todd M, Bacon Jeffrey W, Doerrer Linda H
Department of Chemistry, Boston University , Boston, Massachusetts 02215, United States.
Departamento de Química, Centro de Investigación en Síntesis Química, Universidad de La Rioja , Madre de Dios, 51, 26004 Logroño, Spain.
Inorg Chem. 2017 Jan 3;56(1):452-469. doi: 10.1021/acs.inorgchem.6b02372. Epub 2016 Dec 12.
Pt-based heterobimetallic lantern complexes of the form [PtM(SOCR)(L)] have been shown previously to form intermolecular metallophilic interactions and engage in antiferromagnetic coupling between lanterns having M atoms with open shell configurations. In order to understand better the influence of the carboxylate bridge and terminal ligand on the electronic structure, as well as the metal-metal interactions within each lantern unit, a series of diamagnetic lantern complexes, [PtMg(SAc)(OH)] (1), [PtMg(tba)(OH)] (2), [PtCa(tba)(OH)] (3), [PtZn(tba)(OH)] (4), and a mononuclear control (PhP)[Pt(SAc)] (5) have been synthesized. Crystallographic data show close Pt-M contacts enforced by the lantern structure in each dinuclear case. Pt-NMR spectroscopy of 1-4, (PhP)[Pt(SAc)] (5), and several previously reported lanterns revealed a strong chemical shift dependence on the identity of the second metal (M), mild influence by the thiocarboxylate ligand (SOCR; R = CH (thioacetate, SAc), CH (thiobenzoate, tba)), and modest influence from the terminal ligand (L). Fluorescence spectroscopy has provided evidence for a Pt···Zn metallophilic interaction in [PtZn(SAc)(OH)], and computational studies demonstrate significant dative character. In all of 1-4, the short Pt-M distances suggest that metal-only Lewis donor (Pt)-Lewis acceptor (M) interactions could be present. DFT and NBO calculations, however, show that only the Zn examples have appreciable covalent character, whereas the Mg and Ca complexes are much more ionic.
此前已表明，[PtM(SOCR)(L)]形式的铂基异双金属灯笼配合物会形成分子间亲金属相互作用，并在具有开壳层构型的M原子的灯笼之间发生反铁磁耦合。为了更好地理解羧酸盐桥和末端配体对电子结构的影响，以及每个灯笼单元内的金属-金属相互作用，已合成了一系列抗磁性灯笼配合物，[PtMg(SAc)(OH)] (1)、[PtMg(tba)(OH)] (2)、[PtCa(tba)(OH)] (3)、[PtZn(tba)(OH)] (4)，以及一个单核对照物(PhP)[Pt(SAc)] (5)。晶体学数据表明，在每个双核情况下，灯笼结构会强制形成紧密的Pt-M接触。对1-4、(PhP)[Pt(SAc)] (5)以及几个先前报道的灯笼配合物进行的Pt-NMR光谱分析表明，化学位移强烈依赖于第二种金属(M)的身份，硫代羧酸盐配体(SOCR；R = CH₃(硫代乙酸盐，SAc)、CH₅(硫代苯甲酸盐，tba))的影响较小，末端配体(L)的影响适中。荧光光谱为[PtZn(SAc)(OH)]中的Pt···Zn亲金属相互作用提供了证据，计算研究表明存在显著的给体性质。在所有1-4中，较短的Pt-M距离表明可能存在仅涉及金属的Lewis供体(Pt)-Lewis受体(M)相互作用。然而，DFT和NBO计算表明，只有锌的例子具有明显的共价性质，而镁和钙的配合物则更具离子性。
