Synthesis and properties of novel ortho-metalated cobalt(I) and iron(II) complexes through Csp2–H bond activation of dibenzylphenylphosphine

Dibenzylphenylphosphine in the reaction with CoMe(PMe3)4 afforded complex [(Me3P)3Co((ortho-C6H4)∩P(C6H5)(CH2C6H5))] (1) by Csp2–H activation via ortho-metalation with P atom as anchoring group. An unexpected dinitrogen iron(II) complex [(Me3P)2(N2)Fe((ortho-C6H4)2∩P(C6H5))] (2) stabilized by two five-membered chelate rings as [CPC]-pincer ligand was formed through the reaction of dibenzylphenylphosphine with FeMe2(PMe3)4 via double Csp2–H activation. The reactions of complexes 1 and 2 with carbon monoxide delivered carbonyl complexes [(Me3P)(CO)2Co((ortho-C6H4)∩P(C6H5)(CH2C6H5))] (3) and [(Me3P)2(CO)Fe((ortho-C6H4)2∩P(C6H5))] (4). An iodo methyl cobalt(III) complex [(Me3P)2(Me)(I)Co((ortho-C6H4)∩P(C6H5)(CH2C6H5))] (5) was isolated through the reaction of 1 with iodomethane. The structures of 1, 2, 3, 4 and 5 were determined by X-ray diffraction.

Graphical abstractDibenzylphenylphosphine in the reaction with CoMe(PMe3)4 afforded complex 1 by Csp2–H activation via ortho-metalation. An unexpected dinitrogen iron(II) complex 2 stabilized by two five-membered chelate rings as [CPC]-pincer ligand was formed through the reaction of dibenzylphenylphosphine with FeMe2(PMe3)4 via double Csp2–H activation. The reactions of complexes 1 and 2 with CO delivered carbonyl complexes 3 and 4. An iodo methyl cobalt(III) complex 5 was isolated through the reaction of 1 with iodomethane. The structures of 1, 2, 3, 4 and 5 were determined by X-ray diffraction.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► C–H bond activation mediated by iron and cobalt complexes. ► ortho-metalation of dibenzylphenylphosphine by iron and cobalt complexes. ► electron-rich low-valent iron and cobalt complexes supported by trimethylphosphine.