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Reaction of transition metal(II) salts with 2,2′-biimidazole (H2biim) and co-ligands formed a series of new complexes, [M(H2biim)2(bipy)2](NO3)2·2H2O (1–3) (M = Co, Ni, Zn), [Co(H2biim)2(bipy)](ClO4)2·3H2O (4), {[Cu(H2biim)2]3(μ-C3H3O4)2 (C3H2O4)2}·6H2O (5), [Co(H2biim)2(H2O)2](C3H3O4)2 (6) (bipy = 4,4′-bipyridine, C3H2O4 = malonate dianion, C3H3O4 = malonate anion). These complexes were characterized by single-crystal X-ray diffraction, and elemental analysis. All complexes except 4 were also characterized by luminescence spectra and thermogravimetric analysis. The crystal packing of these six complexes shows that cationic M(II)(2,2′-biimidazole) fragments are self-assembled to construct the 3D supramolecular networks by hydrogen bonding and π–π interactions. The 3D supramolecular networks are significantly affected by counter anion and co-ligands. In complexes 1–3, there are two sets of (4,4) nets which pass through each other to form inclined 2D interpenetration. Complex 4 is obtained by similar reactions as 1 Compared with 1, the only difference in 4 with the reactant Co(NO3)2·6H2O replaced by Co(ClO4)2·6H2O, but it has a very different structure. In 4, the 3D networks containing cavities of 23 × 23 A is formed. In complex 5, the uncoordinated waters form an infinite 1D pipe structure which is embedded in the 3D porous network. The acid–water ring and R22(9) synthons in complex 6 lead to the formation of (4,4) 2D network.

Reactions of transition metal(II) nitrate with 2,2′-biimidazole and 1,10-phenanthroline generated three new isostructural complexes, [Co(H2biim)3][Co(H2biim)2(phen)](NO3)4·2CH3OH·H2O (1), [Ni(H2biim)3][Ni(H2biim)2(phen)](NO3)4·3.5H2O (2), and [Zn(H2biim)3][Zn(H2biim)2(phen)](NO3)4·4H2O (3) (H2biim = 2,2′-biimidazole, phen = 1,10-phenanthroline). These complexes were characterized by single-crystal X-ray diffraction, elemental analysis, luminescent spectra and thermogravimetric analysis. The crystal packing of the complexes show that cationic [M(H2biim)3]2+ fragments are self-assembled to construct the 2-D supramolecular networks by hydrogen bonding and π–π interactions. The guest molecule [M(H2biim)2phen]2+ is well recognized by the N–H⋯O and O–H⋯O hydrogen bonds. In complexes 1–3, chiral guest molecules recognize the chirality of the host cations [M(H2biim)3]2+, which are assembled into 2-D nets with alternating Δ and Λ chirality resulting in the structure of racemates. The data observed in this paper suggest that the diverse hydrogen bonding modes between the nitrate and H2biim ligand identified here play a crucial role in the formation of 1–3.

The reactions of silver salts AgX [X = OTf (OTf = CF3SO3), ClO4 and BF4] and bis(diphenylphosphino)methane (dppm) with 4,4′-bipyridine (bipy) and its derivations [1,2-di(4-pyridyl)ethane (dpa), 1,2-di(4-pyridyl)ethylene (dpe), 1,3-bis(4-pyridyl)propane (bpp)] lead to six silver(I) complexes: {[Ag2(dppm)2(OTf)]2(μ-bipy)}(OTf)2·2CH3OH (1), {[Ag2(dppm)2(μ-bpp)(OTf)](OTf)·CH3OH}n (2), {[Ag2(dppm)2(CH3CN)]2(μ-dpa)}(ClO4)4·2CH3CN (3), [Ag2(dppm)3](ClO4)2 (4), {[Ag2(dppm)2(μ-bipy)(CH3CN)](BF4)2}n (5) and {[Ag2(dppm)2(μ-dpe)(CH3CN)](BF4)2}n (6). Complexes 1 and 3 are tetranuclear complexes with two eight-membered Ag2P4C2 rings bridged by bipy and dpa respectively. 2, 5 and 6 are of infinite chain structures formed by [Ag2(dppm)2] units linked by bpp, bipy and dpe respectively. 4 is a binuclear compound with two silver atoms bridged by three dppm ligands. All complexes are characterized by X-ray diffraction, fluorescence, 1H and 31P NMR spectroscopy and terahertz time-domain spectroscopy (THz-TDS).

The reactions of copper(I) halides with triphenylphosphine (PPh3) and mercaptan ligand [2-mercapto-6-nitrobenzothiazole (HMNBT), 2-amino-5-mercapto-1,3,4-thiadiazole (HAMTD) and 2-mercapto-5-methyl-benzimidazole (MMBD)] yielded seven complexes, [CuCl(HMNBT)(PPh3)2] (1), [CuX(HMNBT)(PPh3)]2 (X = Cl, Br) (2–3), [Cu(MNBT)(HMNBT)(PPh3)2] (4), [CuBr(HAMTD)(PPh3)2]·CH3OH (5) and [CuX(MMBD)(PPh3)2]·2CH3OH (X = Br, I) (6–7). These complexes were characterized by elemental analysis, X-ray diffraction, 1H NMR and 31P NMR spectroscopy. In these complexes the mercaptan ligands act as monodentate or bridged ligand with S as the coordination atom. In complexes 1 and 4, hydrogen bonds C H⋯X and weak interactions C H⋯π lead to the formation of chains and 2D network respectively, while complexes 2 and 3 are dinuclear. In 5–7, intramolecular hydrogen bonds link the [CuX(thione)(PPh3)2] molecules and the solvated methanol molecules into centrosymmetric dimers. Complexes 1–5 represent first copper(I) halide complexes of HMNBT and HAMTD. The complexes 1, 5, 6 and 7 exhibit interesting fluorescence in the solid state at room temperature and their terahertz (THz) time-domain spectroscopy was also studied.

Corporate restructuring was identified as a new industrial force that has great impact on economic values and that therefore has become central in daily financial decision making. This article investigates the optimal restructuring strategies under different dynamic factors and their numerous impacts on firm value. The concept of quasi-leverage is introduced and valuation models are built for corporate debt and equity under imperfect market conditions. The model’s input variables include the quasi-leverage and other firm-specific parameters, the output variables include multiple corporate security values. The restructuring cost is formulated in the form of exponential function, which allows us to observe the sensitivity of the variation in security values. The unified model and its analytical solution developed in this research allow us to examine the continuous changes of security values by dynamically changing the coupon rates, riskless interest rate, bankruptcy cost, quasi-leverage, personal tax rate, corporate taxes rate, transaction cost, firm risk, etc., so that the solutions provide useful guidance for financing and restructuring decisions.