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The effective site-selective interaction between the π-bonds in the aromatic rings of the polyaniline and the graphitic structure of multiwall carbon nanotubes would strongly facilitate the charge-transfer reaction between the two components. We adopted multiwall carbon nanotubes (MWNTs) with minimal defects as templates and facilely fabricated carbon nanotube−polyaniline nanocomposites with uniform core−shell structures by ultrasonic assisted in situ polymerization. By varying the ratio of aniline monomers and carbon nanotubes, the thickness of polyaniline layers can be effectively controlled. The results indicated that the presence of carbon nanotubes with minimized defects induced the formation of a more planar conformation of polyaniline even when a high weight percent of aniline was loaded. As a result, macroscopically, great improvements in the electrical and electrochemical properties of the resulting nanocomposites were observed.

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Four different [PSiP]-pincer ligands L1–L4 ((2-Ph2PC6H4)2SiHR (R = H (L1) and Ph (L2)) and (2- i Pr2PC6H4)2SiHR′ (R′ = Ph (L3) and H (L4)) were used to investigate the effect of substituents at P and/or Si atom of the [PSiP] pincer ligands on the formation of silyl cobalt­(I) complexes by the reactions with CoMe­(PMe3)4 via Si–H cleavage. Two penta-coordinated silyl cobalt­(I) complexes, (2-Ph2PC6H4)2HSiCo­(PMe3)2 (1) and (2-Ph2PC6H4)2PhSiCo­(PMe3)2 (2), were obtained from the reactions of L1 and L2 with CoMe­(PMe3)4, respectively. Under similar reaction conditions, a tetra-coordinated cobalt­(I) complex (2- i Pr2PC6H4)2PhSiCo­(PMe3) (3) was isolated from the interaction of L3 with CoMe­(PMe3)4. It was found that, only in the case of ligand L4, silyl dinitrogen cobalt­(I) complex 4, [(2- i Pr2PC6H4)2HSiCo­(N2)­(PMe3)], was formed. Our results indicate that the increasing of electron cloud density at the Co center is beneficial for the formation of a dinitrogen cobalt complex because the large electron density at Co center leads to the enhancement of the π-backbonding from cobalt to the coordinated N2. It was found that silyl dinitrogen cobalt­(I) complex 4 is an effective catalyst for catalytic transformation of dinitrogen into silylamine. Among these four silyl cobalt­(I) complexes, complex 1 is the best catalyst for hydrosilylation of alkenes with excellent regioselectivity. For aromatic alkenes, catalyst 1 provided Markovnikov products, while for aliphatic alkenes, anti-Markovnikov products could be obtained. Both catalytic reaction mechanisms were proposed and discussed. The molecular structures of complexes 1–4 were confirmed by single-crystal X-ray diffraction.