Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
 
Characterization and Phenylacetylene-Assisted Cyclometalation of an Isolable Hydrido–Selenolato PtII Complex Having Phosphite Ligands, cis-[PtH(SeTrip){P(OPh)3}2]
Hitomi KamonYutaro AokiNorio NakataAkihiko Ishii
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Volume 87 (2014) Issue 2 Pages 274-282

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Abstract

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 [Pt{P(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(κC1Se9-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)-[Pt{κCP-(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.

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© 2014 The Chemical Society of Japan
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