Three new dihydrocarbyl LPt IV Me(Y) complexes (6−8; Y = Cl, I, OCH 2 CF 3 ) supported by the sulfonated CNN pincer ligand L have been prepared and characterized. The reaction of these complexes with a number of nucleophiles (H 2 O, CF 3 CO 2 − , Me 2 SO, PhNMe 2 ) resulting in the formation of corresponding C−X coupled products CH 3 −X has been studied in 2,2,2-trifluoroethanol (TFE) and DMSO. In TFE or DMSO solutions at 22 °C, in the presence of PhNMe 2 , a quantitative formation of a C−N coupled product, PhNMe 3 + , was observed for 6−8, with the reactivity decreasing in the order 6 > 7 > 8. The use of NaO 2 CCF 3 in TFE solutions was less efficient, leading to the production of MeO 2 CCF 3 in 60% yield after 22 h at 70 °C. In DMSO the C−O coupling was high yielding when aqueous trifluoroacetic acid was used to produce methanol (87% after 3 h at 80 °C) or when NaO 2 CCF 3 was used to form MeO 2 CCF 3 (80% after 1.5 h at 80 °C), with Me 3 SO + being a minor byproduct. The kinetics study of the reaction between 6−8 and PhNMe 2 in TFE has revealed an overall second-order rate law, d[PhNMe 3 + ]/dt = k 2 [6, 7 or 8][PhNMe 2 ], consistent with the realization of an S N 2type process. A DFT modeling of several alternative pathways of reaction between 7 and PhNMe 2 in TFE supported the direct nucleophilic attack of PhNMe 2 at the methyl group carbon of 7 as the most likely mechanism of this transformation.

A novel macrocyclic 1,7-dioxa-[2.1.1]-(2,6)-pyridinophane ligand has been synthesized and crystallographically characterized. Two derived metal complexes, dichloropalladium­(II) and chlorocopper­(I), were prepared. In the palladium­(II) complex LPdCl2, both in the solid state, according to its crystallographic characterization, and in CH2Cl2 solutions at −40 °C, according to 1H NMR spectroscopy, the ligand adapts a C 1-symmetric κ2-N,N-coordination mode in which the metal atom binds to two nonequivalent pyridine fragments of the macrocycle. The complex is fluxional at 20 °C. In the crystalline copper­(I) complex LCuCl, the macrocyclic ligand is also κ2-N,N-coordinated to the metal, but it utilizes two equivalent pyridine fragments for the binding. The copper­(I) complex is fluxional in CH2Cl2 solutions in the temperature range between 20 and −70 °C and is proposed to be involved in a fast intermolecular macrocyclic ligand exchange which is slowed down below −40 °C. DFT calculations predict a lower thermodynamic stability of the dioxapyridinophane-derived complexes LPdCl2 and LCuCl, as compared to their [2.1.1]-(2,6)-pyridinophane analogs containing bridging CH2 groups instead of the oxygen atoms. The electron poor dioxapyridinophane chlorocopper­(I) complex, in combination with NaBArF 4 (BArF 4 = tetrakis­[3,5-bis­(tri­fluoro­methyl)­phenyl]­borate) in dichloromethane solutions, can serve as an efficient catalyst for aziridination of various olefins with PhINTs at 0–22 °C.

Two sulfonated CNN-pincer ligands L1 and L2 were used to explore the oxidative functionalization of the Pt II -Me bond in derived K[(L)Pt II Me] complexes (L = L1 and L2) using O 2 and H 2 O 2 as oxidants (HL1 − = (6-phenylpyrid-2-yl)(pyrid-2yl)methanesulfonate; HL2 − = (6-phenylpyrid-2-yl)-6,7-dihydro-5H-cyclopenta [b]pyridine-7-sulfonate). Oxidation with O 2 of K[(L1)Pt II Me] in MeOH produced a single high-valent platinum complex, (L1)Pt IV Me 2 , whereas the use of H 2 O 2 led to (L1)Pt IV Me(OH), 10c, and (L1) 2 Pt IV 2 Me 2 (μ-OH) 2 , 14, having different configurations of a Pt IV center. Oxidation of a more rigid analog, K[(L2)Pt II Me], with O 2 led to diastereomeric complexes (L2)Pt IV Me(OH), 11d, in MeOH and 11a (detected as an adduct with the CF 3 CH 2 O − anion) in acetone/2,2,2-trifluoroethanol mixtures. The use of H 2 O 2 led to (L2)Pt IV Me(OH), 11c, and (L2) 2 Pt IV 2 Me 2 (μ-OH) 2 , 15, the analogs of 10c and 14, respectively. When heated with CF 3 CO 2 H in aqueous DMSO, MeOH, or acetone at 80 °C, (L)Pt IV Me(OH) complexes produced in high yield either MeOH and MeO 2 CCF 3 or C(sp 2 )-C(sp 3 ) coupled products involving a carbon atom of pincer ligands. DFT calculations were used to analyze the observed reactivity. It was concluded that the key factors favoring the C(sp 3 )-O coupling are the trans-arrangement of the methyl ligand and the sulfonate group, the use of CF 3 CO 2 − as an O-nucleophile and DMSO as a solvent favoring the generation of highly electrophilic Pt IV Me intermediates.

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