Platinum Complexes of Bicyclopropylidene and Related Ligands

<p>The coordination chemistry of the cyclopropyl-substituted alkenes, bicyclopropylidene (BCP) and methylenecyclopropane (MCP), with platinum was explored. A range of complexes with ŋ²-alkene ligands were synthesised by the displacement of a ligand, typically ethene, from a precursor complex. These complexes are [Pt(L)(P—P)] (L = BCP, MCP; P—P = Ph₂P(CH₂)₃PPh₂, Cy₂P(CH₂)₂PCy₂, ᵗBu₂P(CH₂)₂PᵗBu₂, ᵗBu₂PCH₂(o-C₆H₄)₂PᵗBu₂), [Pt(L)(P—S)] (L = BCP, MCP; P—S = ᵗBu₂PCH₂(o-₆H4)CH₂SᵗBu), [Pt(C₂H4)(L)(PR₃)] (L = BCP, MCP; PR₃ = PPh₃, PCy₃), [Pt(MCP)₂(PR₃)] (PR₃ = PPh₃, PCy₃) and [PtCl₂(L)(L′)] (L = BCP, MCP; L′ = Py, DMSO). These were the first examples of platinum complexes with ŋ²-BCP ligands, and the first bis-MCP Pt complexes. BCP underwent ring-opening reactions with both Pt(0) and Pt(II) complexes to form the 1,3-diene allylidenecyclopropane (ACP). The first transition metal complexes of ACP [Pt(ACP)(P—P)] (P—P = Ph₂P(CH₂)₃PPh₂, Cy₂P(CH₂)₂PCy₂, ᵗBu₂P(CH₂)₂PᵗBu₂) were synthesised. Some of these complexes rearranged to form ŋ²:σ²-metallacyclopentene complexes, the first instances of the formation of ŋ²:σ²-metallacyclopentene complexes from ŋ²:π-diene complexes. With MCP, the ring-opening reaction only occurred with [₂(COD)], as a result of the anti-Markovnikov addition of Pt–H, generated by the β-hydride elimination of an Et group, across the double-bond. The major products of this reaction were the 1-methylcyclopropyl complexes [Pt(C(CH₂)₂CH₃)Et(COD)] and [Pt(C(CH₂)₂CH₃)₂(COD)], the first examples of such complexes. Protonation of [Pt(L)(P—P)] resulted in a ring-opening reaction to form both the 2-substituted and 1-methyl allyl complexes, [Pt(ŋ³-CH₂CRCH₂)(P—P)]⁺ (R = ᶜPr, Me; P—P = Ph₂P(CH₂)₃PPh₂, ᵗBu₂PCH₂(o-C₆H₄)CH₂PᵗBu₂) and [Pt(ŋ³-CR₂CHCHMe)(P—P)]⁺ (R = cPr, Me; P—P = Ph₂P(CH₂)₃PPh₂, ᵗBuPCH₂(o-C₆H₄)CH₂PᵗBu₂). The analogous 1-methyl complexes were also formed from [Pt(L)(P—S)], wherein the alkene reacted with a hydride formed by the ortho-metallation of the P—S ligand. Computational models were used to investigate the formation of the allyl structures and it was found that the activation energy had a more significant effect than complex stability on product distributions. Complexes with β-chloroalkyl ligands [Pt(C(CH₂)₂CR₂Cl)Cl(L)₂] (R = CH₂, H, L = SEt₂, NCᵗBu, Py) were formed by the addition of Pt–Cl across the alkene double bond. Phosphine complexes were formed by the displacement of a ligand from cis–[Pt(C(CH₂)₂CR₂Cl)Cl(Py)₂] (R = CH₂, H). These are the first examples of stable Pt(II) β-haloalkyl complexes. It was found using computational models that the presence of cyclopropyl rings had a stabilising effect on these complexes.</p>

Platinum Complexes of Bicyclopropylidene and Related Ligands

<p>The coordination chemistry of the cyclopropyl-substituted alkenes, bicyclopropylidene (BCP) and methylenecyclopropane (MCP), with platinum was explored. A range of complexes with ŋ²-alkene ligands were synthesised by the displacement of a ligand, typically ethene, from a precursor complex. These complexes are [Pt(L)(P—P)] (L = BCP, MCP; P—P = Ph₂P(CH₂)₃PPh₂, Cy₂P(CH₂)₂PCy₂, ᵗBu₂P(CH₂)₂PᵗBu₂, ᵗBu₂PCH₂(o-C₆H₄)₂PᵗBu₂), [Pt(L)(P—S)] (L = BCP, MCP; P—S = ᵗBu₂PCH₂(o-₆H4)CH₂SᵗBu), [Pt(C₂H4)(L)(PR₃)] (L = BCP, MCP; PR₃ = PPh₃, PCy₃), [Pt(MCP)₂(PR₃)] (PR₃ = PPh₃, PCy₃) and [PtCl₂(L)(L′)] (L = BCP, MCP; L′ = Py, DMSO). These were the first examples of platinum complexes with ŋ²-BCP ligands, and the first bis-MCP Pt complexes. BCP underwent ring-opening reactions with both Pt(0) and Pt(II) complexes to form the 1,3-diene allylidenecyclopropane (ACP). The first transition metal complexes of ACP [Pt(ACP)(P—P)] (P—P = Ph₂P(CH₂)₃PPh₂, Cy₂P(CH₂)₂PCy₂, ᵗBu₂P(CH₂)₂PᵗBu₂) were synthesised. Some of these complexes rearranged to form ŋ²:σ²-metallacyclopentene complexes, the first instances of the formation of ŋ²:σ²-metallacyclopentene complexes from ŋ²:π-diene complexes. With MCP, the ring-opening reaction only occurred with [₂(COD)], as a result of the anti-Markovnikov addition of Pt–H, generated by the β-hydride elimination of an Et group, across the double-bond. The major products of this reaction were the 1-methylcyclopropyl complexes [Pt(C(CH₂)₂CH₃)Et(COD)] and [Pt(C(CH₂)₂CH₃)₂(COD)], the first examples of such complexes. Protonation of [Pt(L)(P—P)] resulted in a ring-opening reaction to form both the 2-substituted and 1-methyl allyl complexes, [Pt(ŋ³-CH₂CRCH₂)(P—P)]⁺ (R = ᶜPr, Me; P—P = Ph₂P(CH₂)₃PPh₂, ᵗBu₂PCH₂(o-C₆H₄)CH₂PᵗBu₂) and [Pt(ŋ³-CR₂CHCHMe)(P—P)]⁺ (R = cPr, Me; P—P = Ph₂P(CH₂)₃PPh₂, ᵗBuPCH₂(o-C₆H₄)CH₂PᵗBu₂). The analogous 1-methyl complexes were also formed from [Pt(L)(P—S)], wherein the alkene reacted with a hydride formed by the ortho-metallation of the P—S ligand. Computational models were used to investigate the formation of the allyl structures and it was found that the activation energy had a more significant effect than complex stability on product distributions. Complexes with β-chloroalkyl ligands [Pt(C(CH₂)₂CR₂Cl)Cl(L)₂] (R = CH₂, H, L = SEt₂, NCᵗBu, Py) were formed by the addition of Pt–Cl across the alkene double bond. Phosphine complexes were formed by the displacement of a ligand from cis–[Pt(C(CH₂)₂CR₂Cl)Cl(Py)₂] (R = CH₂, H). These are the first examples of stable Pt(II) β-haloalkyl complexes. It was found using computational models that the presence of cyclopropyl rings had a stabilising effect on these complexes.</p>

Digital transformation readiness: How ‘Sonjo Pangan’ movement assists SMEs’ product distributions during COVID-19 Pandemic

COVID-19 was initially discovered in China on December 31, 2019. One of the impacts of the COVID-19 pandemic in several countries includes the enactment of policies to restrict human activities which caused economic problems for SMEs. The government efforts to tackle this issue are various such as launched a smartphone application for SMEs. Sonjo Pangan (Sonjo Food) refers to a movement initiated by a group of people expecting to help SMEs who are vulnerable to COVID-19. Sonjo assisted SMEs to sell their product online. This research aims to measure the digital readiness level of Sonjo Pangan SMEs and to explore how Sonjo Pangan helps SMEs during pandemic. Data had been collected by online questionnaire shared in their main media platform such as WhatsApp Group. Analysis was conducted by mix-method analysis. The result of this research indicated that Sonjo Pangan assisted SMEs to distribute their product in the city, intercity, even inter-island by WA group and through a free online platform. Sonjo Pangan SMEs thus obtained the advantages such as improvements in technology skills and development of social capital.

Highly oxygenated organic molecules produced by the oxidation of benzene and toluene in a wide range of OH exposure and NO_<i>x</i> conditions

Oxidation of aromatic volatile organic compounds (VOCs) leads to the formation of tropospheric ozone and secondary organic aerosol, for which gaseous oxygenated products are important intermediates. We show, herein, the experimental results of highly oxygenated organic molecules (HOMs) produced by the oxidation of benzene and toluene in a wide range of OH exposure and NOx conditions. The results suggest that multigeneration OH oxidation plays an important role in the product distribution, which likely proceeds more preferably via H subtraction than OH addition for early generation products from light aromatics. More oxygenated products present in our study than in previous flow tube studies, highlighting the impact of experimental conditions on product distributions. The formation of dimeric products, however, was suppressed and might be unfavorable under conditions of high OH exposure and low NOx in toluene oxidation. Under high-NOx conditions, nitrogen-containing multifunctional products are formed, while the formation of other HOMs is suppressed. Products containing two nitrogen atoms become more important as the NOx level increases, and the concentrations of these compounds depend significantly on NO2. The highly oxygenated nitrogen-containing products might be peroxyacyl nitrates, implying a prolonged effective lifetime of RO2 that facilitates regional pollution. Our results call for further investigation on the roles of high-NO2 conditions in the oxidation of aromatic VOCs.