Square Planar Cobalt(II) Hydride versus T-Shaped Cobalt(I): Structural Characterization and Dihydrogen Activation with PNP-Cobalt Pincer Complexes.

The carbazole-based pincer ligand R(CbzPNP)H (R = iPr, tBu) has been used for the synthesis and characterization of various low- and high-spin cobalt complexes. Upon treatment of the high-spin complexes R(CbzPNP)CoCl (2R-CoIICl) with NaHBEt3, the selective formation of cobalt(II) hydride 3 iPr-CoIIH and T-shaped cobalt(I) complex 4 tBu-CoI was observed, depending on the substituents at the phosphorus atoms. For an unambiguous characterization of the reaction products, a density functional theory (DFT) supported paramagnetic NMR analysis was carried out, which established the electron configuration and the oxidation states of the metal atoms, thus demonstrating the significant impact of ligand substitution on the outcome of the reaction. A distinct one-electron reactivity was found for 4 tBu-CoI in the dehalogenation of tBuCl and cleavage of PhSSPh. On the other hand, the CoI species displayed two-electron redox behavior in the oxidative addition of dihydrogen. The resulting dihydride complex 6 tBu-CoIII(H)2 was found to display sluggish reactivity toward alkenes, whereas the cobalt(II) hydride 3 iPr-CoIIH was successfully employed in the catalytic hydrogenation of unhindered alkenes. The stoichiometric hydrogenolysis of 8 iPr-CoIIBn at elevated pressure (10 bar) led to a rapid cleavage of the Co-C bond to yield hydride complex 3 iPr-CoIIH. On the other hand, treatment of 2 iPr-CoIICl with phenethylmagnesium chloride directly resulted in the formation of 3 iPr-CoIIH, indicating facile ß-H elimination of the alkene insertion product (reversibly) generated in the catalytic hydrogenation. On the basis of these observations, a mechanistic pathway involving a key σ-bond metathesis step of the CoII-alkyl species is proposed.

Quality of life and comorbidity among older home care clients: role of positive attitudes toward aging.

PURPOSE: Comorbidity has a negative impact on quality of life (QoL). This study aimed to investigate whether the impact of comorbidity on QoL is lower in older home care clients with positive attitudes toward aging. METHODS: Totally, 361 older adults aged 50-91 years who were clients of 14 home care agencies in two regions in the Czech Republic gave an in-person interview to research nurses and completed the WHOQOL-BREF, the WHOQOL-OLD, and the Attitudes to Aging Questionnaire. The Charlson comorbidity index was calculated using ICD-10 codes. To address possible interaction between comorbidity and attitudes toward aging for QoL, the presence of additive interaction between comorbidity and attitudes toward aging on QoL was examined by synergy index. All analyses were adjusted by age, gender, education, and living arrangement. RESULTS: A higher comorbidity index was significantly associated with lower scores of both QoL measures; one index increase was associated with 3.7 [95 % confidence interval (CI) 1.5: 5.9] decreases in generic QoL and 3.6 (95 % CI 1.3: 5.9) decreases in older-specific QoL. In stratified analyses by attitudes toward aging, comorbidity showed no association with QoL among those with positive attitudes, while it was significantly associated with low QoL in those without positive attitudes. The presence of additive interactions between comorbidity and less than positive attitudes on falling in low QoL was clearly suggested. CONCLUSIONS: The negative impact of comorbidity on QoL might be mitigated by promoting a positive self-perception of aging in older people.

CIMT 2022: Report on the 19th Annual Meeting of the Association for Cancer Immunotherapy.

The 19th Annual Meeting of the Association for Cancer Immunotherapy (CIMT), Europe's cancer immunotherapy meeting, was the first in-person event organized by CIMT since the beginning of the COVID-19 pandemic. As a hybrid event from May 10-12, the meeting attracted 920 academic and clinical professionals from over 40 countries, who met to discuss the latest advances in cancer immunology and immunotherapy research. This report summarizes the highlights of CIMT2022.

Dehydrogenative coupling of 4-substituted pyridines mediated by a zirconium(ii) synthon: reaction pathways and dead ends.

The mechanism of the reductive homocoupling of pyridine derivatives mediated by the ZrII synthon [(PNP)Zr(η6-toluene)Cl] (1) has been investigated. Selective transformation into three different types of product complexes has been observed, depending on the N-heterocyclic substrate employed: the bipyridyl complexes 3-R (R = Me, Et, t Bu, Bn, Ph, CHCHPh), which are the homocoupling products, the η2-((4-dimethylamino)pyridyl) complex 4 as well as the bis(isoquinolinyl) complex 5. By deuterium labelling experiments the participation of the ligand backbone in the pyridine coupling reaction via potential cyclometallation steps was ruled out. Based on DFT modelling of the possible reaction sequences a reaction mechanism for the coupling sequence could be identified. The latter is initiated by a reductive syn C-C coupling rather than based on an initial C-H activation of the pyridine substrate.