Search

In this study, two [PCP] pincer silylene cobalt(I) complexes [((Ph2POCH2)2CH)Co(PMe3)(SiCl((NtBu)2CAr))] (Ar = Ph (2) and 4-MePh (3)) were synthesized through the substitution reaction of the [PCP] pincer cobalt(I) complex [((Ph2POCH2)2CH)Co(PMe3)2] (1) with silylene ligands: SiCl((NtBu)2CAr) (Ar = Ph (L1) and 4-MePh (L2)). The reaction of complex 2 with CO afforded the carbonyl silylene cobalt(I) complex [((Ph2POCH2)2CH)Co(CO)(SiCl((NtBu)2CPh))] (4), while complex 2 reacted with CH3I to give rise to cobalt(II) iodide [((Ph2POCH2)2CH)Co(I)(PMe3)] (6). With a catalyst loading of 2 mol%, complex 6 displayed efficient catalytic activity for hydrosilylation of alkenes by using Ph2SiH2 as the hydrogen source under mild conditions. The molecular structures of complexes 2, 3, 4 and 6 were determined by single crystal X-ray diffraction analysis. [ABSTRACT FROM AUTHOR]

The hydrido silyl iron complex (o-Ph2PC6H4SiMe2)Fe(PMe3)3H (2) was obtained via the activation of the Si–H bond of the bidentate silyl ligand o-Ph2P(C6H4)SiMe2H (1) by Fe(PMe3)4. 2 showed good to excellent catalytic activity in both the reduction of aldehydes/ketones and the dehydration of benzamide. In addition, with complex 2 as a catalyst, α,β-unsaturated carbonyls could be selectively reduced to the corresponding α,β-unsaturated alcohols. The mechanisms of the formation of 2 and the catalytic dehydration process are proposed and partly experimentally verified. [ABSTRACT FROM AUTHOR]

Two novel cobalt Schiff base complexes 3 and 4, ((2-PPh2)C6H4)C=N(C10H7)Co(PMe3)2 (3) and ((2-PPh2)C6H4)CH=N(C6H5)Co(PMe3)2 (4) with η2(C–H) coordination, were synthesized by the reactions of Schiff base preligands ((2-PPh2)C6H4)CH=N(C10H7) (1) and ((2-PPh2)C6H4)CH=N(C6H5) (2) with CoMe(PMe3)4via sp2 C–H bond activation. Under similar reaction conditions, the reactions of Co(PMe3)4 with 1 and 2 gave rise to the simple π-(C=N)-coordinated cobalt(0) complexes ((2-PPh2)C6H4)CH=N(C10H7)Co(PMe3)2 (5) and ((2-PPh2)C6H4)CH=N(C6H5)Co(PMe3)2 (6). Complex ((2-PPh2)C6H4)C=N(C10H6)CoI(PMe3)2 (7) was obtained through the reaction of 3 with iodomethane via the activation of the second C–H bond in 1. The substitution reaction of complex 3 with carbon monoxide afforded the dicarbonyl cobalt(i) complex ((2-PPh2)C6H4)C=N(C10H7)Co(CO)2(PMe3) (8). The molecular structures of 4, 5, 7 and 8 were determined by single-crystal X-ray diffraction. [ABSTRACT FROM AUTHOR]