Formation of 2‑Azaallyl Cobalt(I) Complexes by Csp³–H Bond Activation

Three novel unsymmetrical η³-2-azaallyl cobalt­(I) complexes, [(2-PPh₂)­C₆H₄]­CHN­[CHC₆H₄­(4-R)]­Co­(PMe₃)₂ (<b>4</b>–<b>6</b>) (R = H (<b>4</b>); Cl (<b>5</b>); and OMe (<b>6</b>)), were synthesized by the reactions of Schiff base ligands [(2-PPh₂)­C₆H₄]­CHN­[CH₂C₆H₄­(4-R)] (<b>1</b>–<b>3</b>) (R = H (<b>1</b>); Cl (<b>2</b>); and OMe (<b>3</b>)) with CoMe­(PMe₃)₄ via sp³ C–H bond activation under mild reaction conditions. Complex {[(2-PPh₂)­C₆H₄]­CHNCH₃­[CHC₆H₄­(4-R)]­Co­(PMe₃)₂}I (<b>7</b>) as an 18e cobalt­(III) salt was obtained through the reaction of <b>4</b> with iodomethane. The substitution reaction of complex <b>4</b> with carbon monoxide afforded the dicarbonyl cobalt­(I) complex [(2-PPh₂)­C₆H₄]­CH­[NCHC₆H₄­(4-R)]­Co­(CO)₂­(PMe₃) (<b>8</b>). The molecular structures of complexes <b>4</b>–<b>8</b> were determined by single crystal X-ray diffraction

Formation of 2‑Azaallyl Cobalt(I) Complexes by Csp³–H Bond Activation

Three novel unsymmetrical η³-2-azaallyl cobalt­(I) complexes, [(2-PPh₂)­C₆H₄]­CHN­[CHC₆H₄­(4-R)]­Co­(PMe₃)₂ (<b>4</b>–<b>6</b>) (R = H (<b>4</b>); Cl (<b>5</b>); and OMe (<b>6</b>)), were synthesized by the reactions of Schiff base ligands [(2-PPh₂)­C₆H₄]­CHN­[CH₂C₆H₄­(4-R)] (<b>1</b>–<b>3</b>) (R = H (<b>1</b>); Cl (<b>2</b>); and OMe (<b>3</b>)) with CoMe­(PMe₃)₄ via sp³ C–H bond activation under mild reaction conditions. Complex {[(2-PPh₂)­C₆H₄]­CHNCH₃­[CHC₆H₄­(4-R)]­Co­(PMe₃)₂}I (<b>7</b>) as an 18e cobalt­(III) salt was obtained through the reaction of <b>4</b> with iodomethane. The substitution reaction of complex <b>4</b> with carbon monoxide afforded the dicarbonyl cobalt­(I) complex [(2-PPh₂)­C₆H₄]­CH­[NCHC₆H₄­(4-R)]­Co­(CO)₂­(PMe₃) (<b>8</b>). The molecular structures of complexes <b>4</b>–<b>8</b> were determined by single crystal X-ray diffraction

Selective C–F and C–H Activation of Fluoroarenes by Fe(PMe₃)₄ and Catalytic Performance of Iron Hydride in Hydrosilylation of Carbonyl Compounds

The reactions of perfluorinated toluene (CF3C6F5), pentafluoropyridine (C5NF5), and hexafluorobenzene (C6F6) with the iron(0) complex Fe­(PMe3)4 were investigated. The Fe­(I) complexes (4-CF3C6F4)­Fe­(PMe3)4 (1), (4-C5NF4)­Fe­(PMe3)4 (2), and (C6F5)­Fe­(PMe3)4 (3) were obtained by selective activation of the C–F bonds. However, under similar reaction conditions, the reaction of Fe­(PMe3)4 with perfluoronaphthalene (C10F8) afforded a π-coordinated Fe(0) complex, (η4-1,2,3,4-C10F8)­Fe­(PMe3)3 (4), and the expected C–F bond activation reaction was not observed. The expected iron hydride (C6F5)­FeH­(PMe3)4 (6) could be obtained in a yield of 80% by the reaction of bromopentafluorobenzene with Fe­(PMe3)4 and subsequent reduction with NaBH4. The molecular structures of complexes 2, 4, and 6 were determined by single-crystal X-ray diffraction. Complexes 1–4 and 6 could be used as catalysts for the hydrosilylation of carbonyl compounds. Among them, complex 6 is the best catalyst. The selective reduction of carbonyl groups of α,β-unsaturated aldehydes and ketones was also realized with 6 as catalyst

Selective C–F and C–H Activation of Fluoroarenes by Fe(PMe₃)₄ and Catalytic Performance of Iron Hydride in Hydrosilylation of Carbonyl Compounds

The reactions of perfluorinated toluene (CF₃C₆F₅), pentafluoropyridine (C₅NF₅), and hexafluorobenzene (C₆F₆) with the iron(0) complex Fe­(PMe₃)₄ were investigated. The Fe­(I) complexes (4-CF₃C₆F₄)­Fe­(PMe₃)₄ (<b>1</b>), (4-C₅NF₄)­Fe­(PMe₃)₄ (<b>2</b>), and (C₆F₅)­Fe­(PMe₃)₄ (<b>3</b>) were obtained by selective activation of the C–F bonds. However, under similar reaction conditions, the reaction of Fe­(PMe₃)₄ with perfluoronaphthalene (C₁₀F₈) afforded a π-coordinated Fe(0) complex, (η⁴-1,2,3,4-C₁₀F₈)­Fe­(PMe₃)₃ (<b>4</b>), and the expected C–F bond activation reaction was not observed. The expected iron hydride (C₆F₅)­FeH­(PMe₃)₄ (<b>6</b>) could be obtained in a yield of 80% by the reaction of bromopentafluorobenzene with Fe­(PMe₃)₄ and subsequent reduction with NaBH₄. The molecular structures of complexes <b>2</b>, <b>4</b>, and <b>6</b> were determined by single-crystal X-ray diffraction. Complexes <b>1</b>–<b>4</b> and <b>6</b> could be used as catalysts for the hydrosilylation of carbonyl compounds. Among them, complex <b>6</b> is the best catalyst. The selective reduction of carbonyl groups of α,β-unsaturated aldehydes and ketones was also realized with <b>6</b> as catalyst