Autocatalytic Alkyne Cycloadditions:  Evidence for Colloidal Pt Catalysis

Abstract

Treatment of the four-membered platinacycle L2Pt(1,8-naphthalendiyl) (1) or the five-membered platinacycle L2Pt(1,12-triphenylendiyl) with excess PhCCPh at 120-150 degrees C gives the coupling products 1,2-diphenylacenaphthalene or 4,5-diphenylbenzo[e]pyrene and the alkyne complex L2Pt(eta2-PhCCPh). Both reactions show an accelerating rate, which has been traced to catalysis of the reaction by colloidal platinum formed by the reaction of O2 with L2Pt(eta2-PhCCPh).

Phenanthriporphyrin: An Antiaromatic Aceneporphyrinoid as a Ligand for a Hypervalent Organophosphorus(V) Moiety

“…A phenanthrene motif built into a chelating ligand has been very rarely encountered 24. 25 Nevertheless, the binding component where the C(4) and C(5) carbon atoms of phenanthrene (where the numbers refer to “free” phenanthrene) are simultaneously bound has been recognized in silylated phenanthrenes26 and metalated triphenylene derivatives 27–29…”

“…Previously an incorporation of ap hosphorus(V) center into the {CNN} coordination core of carbaporphyrinoid has been reported for N-fused dihydrotelluraporphyrin. [27][28][29] Them ethoxide ligands at the phosphorus(V) center are readily exchangeable for hydroxides during chromatography on basic alumina or if traces of water are present in asolvent as documented by 1 HNMR spectroscopy ( Figure S25). [24,25] Nevertheless,t he binding component where the C(4) and C(5) carbon atoms of phenanthrene (where the numbers refer to "free" phenanthrene) are simultaneously bound has been recognized in silylated phenanthrenes [26] and metalated triphenylene derivatives.…”

Autocatalysis: Kinetics, Mechanisms and Design

“…The byproduct of this reaction, Pt‐alkyne complex, reacts with oxygen, and produces Pt metal. Authors suggest that Pt colloids act as a heterogeneous autocatalyst in these reactions [118] …”

“…Authors suggest that Pt colloids act as a heterogeneous autocatalyst in these reactions. [118] The rhodium-catalyzed dehydrogenation of H 3 BÀ NMe 2 H to cyclic (H 2 BÀ NMe 2 ) 2 is another example of a transition-metalbased autocatalytic reaction. The mechanism underlying this reaction involves multiple intermediates and was discussed in detail by Sewell et al [123] Despite the opportunity to design organometallic autocatalytic reactions based on the formation of catalytically active ligands, all reactions that we discussed in this section are the result of serendipitous discoveries.…”

Phenanthriporphyrin: An Antiaromatic Aceneporphyrinoid as a Ligand for a Hypervalent Organophosphorus(V) Moiety

“…[24,25] Nevertheless,t he binding component where the C(4) and C(5) carbon atoms of phenanthrene (where the numbers refer to "free" phenanthrene) are simultaneously bound has been recognized in silylated phenanthrenes [26] and metalated triphenylene derivatives. [27][28][29] Them ethoxide ligands at the phosphorus(V) center are readily exchangeable for hydroxides during chromatography on basic alumina or if traces of water are present in asolvent as documented by 1 HNMR spectroscopy ( Figure S25). Consequently,i tw as crucial for any characterization that the sample was recrystallized just before measurements and that all experiments were carried out in an inert atmosphere.…”