The reaction of (cod)PtMe2 (cod = 1,5-cyclooctadiene) with trifluoroacetic acid to release methane is an important system because it represents the microscopic reverse of desirable methane activation and because it has an unusually large kinetic isotope effect (KIE) that has been tentatively attributed to proton tunneling. A detailed kinetic and mechanistic investigation of this system was conducted using stopped-flow and traditional time-dependent UV–vis spectroscopy, supported by NMR and density functional theory studies. Consistently large KIE values (∼14) in line with previous reports were obtained over a large range of reactant concentrations (0.1–1.6 mM (cod)PtMe2 and 3.2 mM to 6.0 M acid). At lower concentrations of acid, the KIE decreased significantly (KIE = ∼6 for 0.1 mM (cod)PtMe2 and 0.2 mM acid). This concentration-dependent KIE suggests a multistep reaction mechanism, eliminating the need to invoke proton tunneling. The reaction exhibits first-order dependence on (cod)PtMe2 and approximately second-order dependence on acid, with at least 2 equiv of acid required for complete conversion. Overall, the kinetic data indicate a multimolecular, multistep reaction mechanism for the protonolysis of (cod)PtMe2, thus ruling out the previously accepted bimolecular single-step mechanism. A mechanistic alternative consistent with the kinetic data is proposed, in which sequential oxidative addition and reductive elimination occur, and the second equivalent of acid serves to stabilize the trifluoroacetate anion in solution.

The reaction of (cod)PtMe2 (cod = 1,5-cyclooctadiene) with trifluoroacetic acid (TFAH) to release methane is an important system because it represents the microscopic reverse of desirable methane activation, and because it has an unusually large kinetic isotope effect (KIE) that has been tentatively attributed to proton tunneling. A detailed kinetic and mechanistic inves-tigation of this system was conducted using stopped-flow and traditional time-dependent UV-vis spectroscopy, supported by NMR and DFT studies. Consistently large KIE values (~14) in line with previous reports were obtained over a large range of reactant concentrations (0.1 – 1.6 mM (cod)PtMe2 and 3.2 mM to 6.0 M acid). At lower concentrations of acid, the KIE decreased significantly (KIE = ~6 for 0.1 mM (cod)PtMe2 and 0.2 mM acid). This concentration-dependent KIE suggests a multi-step reaction mechanism, eliminating the need to invoke proton tunneling. The reaction exhibits first-order dependence on (cod)PtMe2 and approximately second-order dependence on acid, with at least 2 equivalents of acid required for complete conversion. Overall, the kinetic data indicate a multi-molecular, multi-step reaction mechanism for the protonolysis of (cod)PtMe2, thus ruling out the previously accepted bimolecular single-step mechanism. A mechanistic alternative consistent with the kinetic data is proposed, in which sequential oxidative addition and reductive elimination occur, and the second equivalent of acid serves to stabilize trifluoroacetate anion in solution.

Objective: The purpose of this study was to investigate whether service losses during the coronavirus disease 2019 (COVID-19) pandemic were associated with worsened parent mental health or child behavioral health among families of children with autism spectrum disorder and to identify factors associated with favorable parent appraisals of habilitative teletherapy (applied behavior analysis; speech, occupational, physical therapy) for their child. Method: This web-based survey study was conducted from May to July 2021 with parents whose children were receiving habilitative therapy for autism from an integrated health system. A total of 322 parents responded to the survey (20% response rate). The outcome variables were pandemic-related parent mental health, pandemic-related child behavioral health, and appraisal of habilitative teletherapy. Predictors were COVID-19-related services changes in health care or child care, COVID-19 history (COVID-19 stress, testing positive for COVID-19), and child autism factors (autistic behaviors, caregiving strain). Results: Loss of regular child care was associated with higher odds of worsened parent mental health (odds ratio [OR] 5 2.7, 95% confidence interval [CI] 5 1.5-4.8); higher levels of caregiving strain were associated with worsened child behavioral health (OR 5 2.3, 95% CI 5 1.4-3.8). Higher levels of COVID-19 stress were associated with more favorable appraisals of telehealth (b 5 0.4, p < 0.01), whereas higher caregiving strain scores were associated with less favorable appraisals of telehealth (b 5 20.2, p < 0.01). Conclusion: During COVID-19, caregiving factors were associated with worsened parent mental health and worsened child behavioral health, and telehealth is not preferred by all families. Policy interventions to support caregivers, such as affordable, high-quality child care and paid family leave, are a high priority.

The reaction of (cod)PtMe2 (cod = 1,5-cyclooctadiene) with trifluoroacetic acid (TFAH) to release methane is an important system because it represents the microscopic reverse of desirable methane activation, and because it has an unusually large kinetic isotope effect (KIE) that has been tentatively attributed to proton tunneling. A detailed kinetic and mechanistic inves-tigation of this system was conducted using stopped-flow and traditional time-dependent UV-vis spectroscopy, supported by NMR and DFT studies. Consistently large KIE values (~14) in line with previous reports were obtained over a large range of reactant concentrations (0.1 – 1.6 mM (cod)PtMe2 and 3.2 mM to 6.0 M acid). At lower concentrations of acid, the KIE decreased significantly (KIE = ~6 for 0.1 mM (cod)PtMe2 and 0.2 mM acid). This concentration-dependent KIE suggests a multi-step reaction mechanism, eliminating the need to invoke proton tunneling. The reaction exhibits first-order dependence on (cod)PtMe2 and approximately second-order dependence on acid, with at least 2 equivalents of acid required for complete conversion. Overall, the kinetic data indicate a multi-molecular, multi-step reaction mechanism for the protonolysis of (cod)PtMe2, thus ruling out the previously accepted bimolecular single-step mechanism. A mechanistic alternative consistent with the kinetic data is proposed, in which sequential oxidative addition and reductive elimination occur, and the second equivalent of acid serves to stabilize trifluoroacetate anion in solution.