Characterization and Phenylacetylene-Assisted Cyclometalation of an Isolable Hydrido–Selenolato Pt<sup>II</sup> Complex Having Phosphite Ligands, <i>cis</i>-[PtH(SeTrip){P(OPh)<sub>3</sub>}<sub>2</sub>]
作者:Hitomi Kamon、Yutaro Aoki、Norio Nakata、Akihiko Ishii
DOI:10.1246/bcsj.20130295
日期:2014.2.15
A hydrido–selenolato PtII complex having P(OPh)3 ligands, cis-[PtH(SeTrip)P(OPh)3}2] (Trip: 9-triptycyl), was synthesized by the reaction of TripSeH with [PtP(OPh)3}2]. The structure was characterized by NMR spectroscopy and X-ray crystallography in comparison with the corresponding PPh3 complex, cis-[PtH(SeTrip)(PPh3)2], indicating the stronger coordination of P(OPh)3 to the Pt center than that of PPh3. On heating at 130 °C in xylene for 17 h, cis-[PtH(SeTrip)P(OPh)3}2] was converted to the corresponding 1,2-selenaplatinacycle (SP-4–2)-[Pt(κC1,κSe9-TripSe(2−))P(OPh)3}2] through an intramolecular cyclization (cyclometalation). The reaction with dimethyl acetylenedicarboxylate (DMAD) gave a mixture of hydroselenation products (E)- and (Z)-(MeO2C)CH=C(SeTrip)CO2Me non-stereoselectively together with 1H-2-benzoselenin, dimethyl 7H-7,11b[1′,2′]-benzenoanthra[9,1-bc]selenin-2,3-dicarboxylate. In the reaction with phenylacetylene in toluene at 110 °C, phenylacetylene served as a hydrogen acceptor to form the 1,2-selenaplatinacycle and styrene. Based on the results of controlled experiments using cis-[PtD(SeTrip)P(OPh)3}2] and phenylacetylene-d, the mechanism of the cyclometalation was proposed as the 1,2- (major) and 2,1- (minor) insertions of phenylacetylene into the Pt–H bond followed by cyclometalation between the Pt center and the triptycyl group. The reaction with phenylacetylene in the presence of excess P(OPh)3 furnished a 1,2,3-oxaphosphaplatinacycle, (SP-4–2)-[PtκC,κP-(Z)-CH=C(Ph)OP(OPh)2}(SeTrip)P(OPh)3}], as a minor product, together with the 1,2-selenaplatinacycle in a decreased yield.
一种氢化-硒醇铂(II)配合物,cis-[PtH(SeTrip)P(OPh)3}2](Trip:9-三苯基),通过TripSeH与[PtP(OPh)3}2]的反应合成。该结构通过NMR谱和X射线晶体学与相应的PPh3配合物cis-[PtH(SeTrip)(PPh3)2]进行了比较,表明P(OPh)3对铂中心的配位强于PPh3。在130°C下在二甲苯中加热17小时后,cis-[PtH(SeTrip)P(OPh)3}2]通过分子内环化(环金属化)转化为相应的1,2-硒铂环(SP-4–2)-[Pt(κC1,κSe9-TripSe(2−))P(OPh)3}2]。与二甲基炔二羧酸酯(DMAD)的反应产生了非立体选择性地生成的氢硒化产物(E)和(Z)-(MeO2C)CH=C(SeTrip)CO2Me,以及1H-2-苯并硒啉、二甲基7H-7,11b[1′,2′]-苯并蒽[9,1-bc]硒烯-2,3-二羧酸酯。在110°C的甲苯中与苯炔的反应中,苯炔作为氢受体,形成了1,2-硒铂环和苯乙烯。根据使用cis-[PtD(SeTrip)P(OPh)3}2]和苯炔-d的控制实验结果,提出了环金属化的机制,认为是苯炔在铂–氢键中进行1,2-(主要)和2,1-(次要)插入后与三苯基基团进行环金属化。在过量P(OPh)3存在下与苯炔的反应中,生成了1,2,3-氧磷铂环(SP-4–2)-[PtκC,κP-(Z)-CH=C(Ph)OP(OPh)2}(SeTrip)P(OPh)3}],作为次要产物,同时1,2-硒铂环的产率降低。