The development of high-performance shielding materials against electromagnetic pollution requires mobile charge carriers and magnetic dipoles. Herein, we meet the challenge by building a three-dimensional (3D) nanostructure consisting of chemically modified graphene/Fe3O4(GF) incorporated polyaniline. Intercalated GF was synthesized by the in situ generation of Fe3O4 nanoparticles in a graphene oxide suspension followed by hydrazine reduction, and further in situ polymerization with aniline to form a polyaniline composite. Spectroscopic analysis demonstrates that the presence of GF hybrid structures facilitates strong polarization due to the formation of a solid-state charge-transfer complex between graphene and polyaniline. This provides proper impedance matching and higher dipole interaction, which leads to the high microwave absorption properties. The higher dielectric loss (ε'' = 30) and magnetic loss (μ'' = 0.2) contribute to the microwave absorption value of 26 dB (>99.7% attenuation), which was found to depend on the concentration of GF in the polyaniline matrix. Moreover, the interactions between Fe3O4, graphene and polyaniline are responsible for superior material characteristics, such as excellent environmental (chemical and thermal) degradation stability and good electric conductivity (as high as 260 S m(-1)).

Hydrotris(triazolyl)borate (Ttz) ligands form CuNO(x) (x = 2, 3) complexes for structural and functional models of copper nitrite reductase. These complexes have distinct properties relative to complexes of hydrotris(pyrazolyl)borate (Tp) and neutral tridentate N-donor ligands. The electron paramagnetic resonance spectra of five-coordinate copper complexes show rare nitrogen superhyperfine couplings with the Ttz ligand, indicating strong σ donation. The copper(I) nitrite complex [PPN](+)[(Ttz(tBu,Me))Cu(I)NO(2)](-) has been synthesized and characterized and allows for the stoichiometric reduction of NO(2)(-) to NO with H(+) addition. Anionic Cu(I) nitrite complexes are unusual and are stabilized here for the first time because Ttz is a good π acceptor.

N-heterocyclic carbene (NHC) based ruthenium complexes were studied as catalysts for the transfer hydrogenation of ketones. Variations in the catalyst structure were investigated for their impact on hydrogenation and catalyst stability. Catalyst attributes included bis-or mono-NHC ligands, pendant ether groups in some cases, and arene ligands of varied bulk and donor strength. Ruthenium complexes were synthesized and fully characterized, including complexes with a monodentate NHC ligand containing a tethered ether N substituent (Im Et,CH2CH2OEt RuCl 2 (η 6 -arene); arene = benzene (4), p-cymene (5), hexamethylbenzene (6)), a complex with a monodentate NHC ligand with solely alkyl N substituents (Im Et,Pentyl RuCl 2 (η 6 -p-cymene) ( 8)), and a complex with a bis-NHC ligand ([RuCl(methylenebis(Im Et ) 2 )(η 6 -p-cymene)]PF 6 ( 7)) (Im = imidazole-derived NHC; superscripts indicate N substituents). X-ray crystal structures were obtained for 4, 5, 7, and 8. All of the ruthenium complexes were tested and found to be active transfer hydrogenation catalysts for the reduction of acetophenone to 1-phenylethanol in basic 2-propanol. Precatalyst 4, which contains a tethered ether group and benzene ligand, was found to be the most active catalyst. Variabletemperature 1 H NMR studies of complexes 4−6 show that arene lability increases in the order C 6 Me 6 < cymene < benzene, and this lability is directly correlated with catalytic activity. The catalysis appears to be homogeneous, and a mechanism invoking arene loss is proposed. Precatalyst 4 reduced electron-deficient ketones most easily, and 4′-nitroacetophenone was reduced under base-free conditions. The highest TOF (turnover frequency) and TON (turnover number) values obtained were 3003 h −1 and 845, respectively, for ketone reduction with catalyst 4.

Alkylzinc complexes, (Ttz(R,Me))ZnR' (R = tBu, Ph; R' = Me, Et), show interesting reactivity with acids, bases and water. With acids (e.g. fluorinated alcohols, phenols, thiophenol, acetylacetone, acetic acid, HCl and triflic acid) zinc complexes of the conjugate base (CB), (Ttz(R,Me))ZnCB, are generated. Thus the B-N bonds in Ttz ligands are acid stable. (Ttz(R,Me))ZnCB complexes were characterized by (1)H, (13)C-NMR, IR, MS, elemental analysis, and, in most cases, single crystal X-ray diffraction. The four coordinate crystal structures included (Ttz(R,Me))Zn(CB) [where R = Ph, CB (conjugate base) = OCH(2)CF(3) (2), OPh (6), SPh (8), p-OC(6)H(4)(NO(2)) (10); R = tBu, CB = OCH(CF(3))(2) (3), OPh (5), SPh (7)*, p-OC(6)H(4)(NO(2)) (9) (* indicates a rearranged Ttz ligand)]. The use of bidentate ligands resulted in structures [(Ttz(Ph,Me))Zn(CB) (CB = acac (12), OAc (14))] in which the coordination geometries are five, and intermediate between four and five, respectively. Interestingly, three forms of (Ttz(Ph,Me))Zn(p-OC(6)H(4)(NO(2))) (10) were analyzed crystallographically including a Zn coordinated water molecule in 10(H(2)O), a coordination polymer in 10(CP), and a p-nitrophenol molecule hydrogen bonded to a triazole ring in 10(Nit). Ttz ligands are flexible since they are capable of providing κ(3) or κ(2) metal binding and intermolecular interactions with either a metal center or H through the four position nitrogen (e.g. in 10(CP) and HTtz(tBu,Me)·H(2)O, respectively). Preliminary kinetic studies on the protonolysis of LZnEt (L = Ttz(tBu,Me), Tp(tBu,Me)) with p-nitrophenol in toluene at 95 °C show that these reactions are zero order in acid and first order in the LZnEt.

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