Insertion of terminal alkyne into Pt–N bond of the square planar [PtI₂(Me₂phen)] complex

Abstract

The reactivity of [PtX(Mephen)] complexes (X = Cl, Br, I; Mephen = 2,9-dimethyl-1,10-phenanthroline) with terminal alkynes has been investigated. Although the dichlorido species [PtCl(Mephen)] exhibits negligible reactivity, the bromido and iodido derivatives lead in short time to the formation of five-coordinate Pt(ii) complexes of the type [PtX(Mephen)(η-CH[triple bond, length as m-dash]CR)] (X = Br, I; R = Ph, n-Bu), in equilibrium with the starting reagents. Similar to analogous complexes with simple acetylene, the five coordinate species can also undergo dissociation of an halido ligand and formation of the transient square-planar cationic species [PtX(Mephen)(η-CH[triple bond, length as m-dash]CR)]. This latter can further evolve to give an unusual, sparingly soluble square planar product where the former terminal alkyne is converted into a :C[double bond, length as m-dash]C(H)(R) moiety with the α-carbon bridging the Pt(ii) core with one of the two N-donors of coordinated Mephen. The final product [PtX{κ-N,C-(Z)-N[combining low line]1-N10-C[combining low line][double bond, length as m-dash]C(H)(R)}] (N1-N10 = 2,9-dimethyl-1,10-phenanthroline; X = Br, I) contains a Pt-N-C-C-N-C six-membered chelate ring in a square planar Pt(ii) coordination environment.

Oxidative addition of 1,4‐dichloro‐2‐butyne to an organoplatinum complex: A new precursor for synthesis of ultrasmall Pt nanoparticles thin film at liquid/liquid interface as the electrocatalyst in methanol oxidation reaction

“…Although, the oxidative addition of alkyl and allyl halides to organoplatinum (II) complexes have been extensively studied but oxidative addition reaction of alkene or alkyne halides and their kinetic studies are rare . There are some reports about reaction of Pt (II) complexes with alkene and alkyne halides through formation of unsaturated five‐coordinate intermediates . Bidentate ligands with their steric hindrance reduces the transfer of negative charge on Pt (II) central metal and stabilizes this center toward oxidation reaction .…”

“…There are some reports about reaction of Pt (II) complexes with alkene and alkyne halides through formation of unsaturated five‐coordinate intermediates . Bidentate ligands with their steric hindrance reduces the transfer of negative charge on Pt (II) central metal and stabilizes this center toward oxidation reaction . Oxidative addition of various reagents, including alkyl and allyl halides to organoplatinum (II) complexes bearing diimine ligands such as bipy (2,2′‐bipyridine) and phen (1,10‐phenanthroline) leads to fabrication of organoplatinum (IV) complexes .…”

“…[5,6] Bidentate ligands with their steric hindrance reduces the transfer of negative charge on Pt (II) central metal and stabilizes this center toward oxidation reaction. [5] Oxidative addition of various reagents, including alkyl and allyl halides to organoplatinum (II) complexes bearing diimine ligands such as bipy (2,2′-bipyridine) and phen (1,10-phenanthroline) leads to fabrication of organoplatinum (IV) complexes. [7][8][9][10][11][12][13][14] Kinetic studies of colorful diimine Pt (II) complexes are facile due to characteristic sharp metal-to-ligand charge transfer (MLCT) bands in the visible region.…”