N. M. Nanje Gowda

Effect of concentration, temperature, moisture, liming and organic matter on the efficacy of the nitrification inhibitors benzotriazole, o-nitrophenol, m-nitroaniline and dicyandiamide

Laboratory experiments were carried out to study the effect of various factors that affect the efficacy of the nitrification inhibitors, benzotriazole, o-nitrophenol, m-nitroaniline and dicyandiamide. In a Paleustalf, increasing concentrations of the inhibitors from 0 to 15 mg/kg soil prolonged the nitrification up to 60 days. Increase in temperature from 10 to 30°C decreased the efficacy of all four nitrification inhibitors (by 6–62% at 30 days). Benzotriazole was equally effective in soil moisture conditions ranging from 40 to 80% of the maximum water holding capacity of the soil (WHC). o-Nitrophenol and m-nitroaniline were more effective at 60% WHC, while the efficacy of DCD was more at 40% WHC. Addition of 1000 mg/kg soil of fresh organic matter reduced the efficacies of o-nitrophenol, m-nitroaniline and benzotriazole by 55, 65 and 22%, respectively while the reduction in the efficacy of dicyandiamide was non-significant. Liming an acidic soil (Kandiustalf) to change the pH from 5.4 to 8.3 decreased the efficacies of the nitrification inhibitors and decreased the ammonium content in the soil at 30 days from 55 to 9 mg/kg in case of o-nitrophenol and m-nitroaniline and from 53 to 35 mg/kg in case of benzotriazole and dicyandiamide.

Cyclometallation of bis-benzimidazole derivatives with rhodium(III) halides

Abstract Treatment of rhodium(III) halides with the N-heterocycles (LH), 1,3-bis(benzimidazolyl)benzene (bBzlH 2 bzH; Ia ) and its N-methyl derivative (bBzlMe 2 bzH; Ib ) in methanol gave halobridged binuclear cyclometallated products of the composition [RhX 2 L] 2 (X=Cl, Br or I). The chloro complex undergoes halobridge cleavage reactions to yield several new mononuclear complexes of the types RhCl 2 (bBzlH 2 bz)(AsPh 3 ), RhCl(bBzlH 2 bz)(OClO 3 )(L′/N-N) (L′=AsPh 3 ; N-N=2,2′-bipyridine or 1,10-phenanthroline) and the heterocycle bridged binuclear complexes of the composition [RhCl 2 (bBzlH 2 bz)] 2 ( μ -N-N) (N-N=pyrazine or 4,4′-bipyridine). Passage of CO through [RhCl 2 (bBzlH 2 bz)] 2 in DMF yielded mononuclear carbonyl complex RhCl 2 (CO)(bBzlH 2 bz)·2H 2 O. Treatment of carbonylated solution of rhodium trichloride with Ia produced non-cyclometallated mononuclear complex of the type [Rh(CO) 2 (bBzlH 2 bzH)]Cl. The complexes are characterised by 1 H, 13 C NMR, IR, Far-IR, electronic and FAB-mass spectral studies.

Reactions of rhodium and iridium salts with multidentate N-heterocycles

Abstract Complexes of rhodium and iridium of the types MX 3 L, MX(CO) 2 L and MX 3 (CO)L (X = halide) containing multidentate N -heterocycles (L),2,6-bis(benzimidazolyl)pyridine(bBzlH 2 py) and 2,6-bis( N -methyl-benzimidazolyl)pyridine (bBzlMe 2 py) have been prepared and characterized by IR, electronic and 1 H and 13 C NMR spectral data. RhX(CO) 2 L, on treatment with alcoholic solvents or DMF undergoes reversible decarbonylation to produce RhXL·2H 2 O. Passage of NO or O 2 through the carbonyl suspended in hot 2-methoxyethanol releases CO 2 .

Synthesis and NMR spectral assignments of novel nitrogen and sulfur heterocyclic compounds

Synthesis and NMR spectral studies of multidentate N and S heterocycles, 1,3,5‐tris(N‐methylbenzimidazolyl)benzene, 1,3,5‐tris(benzimidazolyl)benzene,1,3,5‐tris(benzothiazolyl) benzene, 2,2′‐bipyridine 3,3′‐bis(benzothiazolyl)benzene and 1,2,4,5‐tetrakis(benzothiazolyl) benzene have been carried out. 2D 1H1H PFG‐COSY as well as 1H13C single and multiple bond correlated (2D GRASP‐HSQC and GRASP‐HMBC) experiments have been employed to characterize the compounds. 1D NOE experiments have been useful in understanding the structure of 1,3,5‐tris(N‐methylenzimidazolyl)benzene. Copyright

Regulation of Nitrification by Benzotriazole, o-Nitrophenol, m-Nitroaniline and Dicyandiamide and Pattern of NH3 Emissions from Citronella Field Fertilized with Urea

Nitrification inhibitors areuseful for reducing fertilizer related environmentalpollution. Use of such nitrification inhibitors as,benzotriazole, o-nitrophenol, m-nitroaniline anddicyandiamide has effectively regulated nitrification in acitronella (Cymbopogon winterianus Jowitt.) fieldfertilized with urea. At 450 kg N ha-1 yr-1, there wassubstantially higher accumulation of NH+4-N in thesoil. Proper placement (5 cm below soil surface) offertilizers have minimized NH3 emissions even fromnitrification inhibitor treated urea plots. Thus, thenitrification inhibitors can potentially reduceenvironmental pollution connected to NO-3 in soilwhile maintaining low NH3 gas emissions, if thefertilizer is properly placed.

Evaluation of nitrification inhibitors for use under tropical conditions

Abstract Six simple chemical compounds were evaluated for inhibition of nitrification. The compounds of o‐nitroaniline, m‐nitroaniline, o‐nitrophenol, benzotriazole, and 2,4,6‐trinitrophenol were compared with dicyandiamide by adding 10 μg inhibitor/g of a sandy loam soil, incubating for 30 days at 30°C and analyzing for NH+ 4, NO‐ 2, and NO‐ 3 formation. The results indicated that benzotriazole, o‐nitrophenol, and m‐nitroaniline were very effective nitrification inhibitors.

Thermal and toughness property studies on a polybenzimidazole-modified epoxy resin system

The effect of polybenzimidazole (Pill) on a silica-filled epoxy resin matrix has been investigated. Polybenzimidazole (PBI) was incorporated into a difunctional epoxy resin matrix to the extent of 10%, before being cured with an anhydride hardener. The effects of Pill on the curing reaction and glass transition temperature (Tg) and on the toughness of the cured epoxy matrix have been studied using differential scanning calorimetry (OSC), thermogravimetric ctric analysis (TGA) and a universal testing machine (Instron). The results indicate that the PBI modifier enhanced not only the glass transition temperature of the difunctional epoxy m.atrix but also its toughness, by its catalytic action. Further investigations have been carried out on the fractured specimens, using scanning electron microscopy (SEM) to support the enhanced toughness property of the epoxy matrix.

Complexes of ruthenium(II) and ruthenium(III) with tertiary arsines

Abstract Ruthenium trichloride reacts with stoichiometric amounts of tertiary arsines in boiling ethanol to give paramagnetic complexes, RuCl 3 (Ph 2 RAs) 3 (R = Me, Et, Pr, Bu), which react further with 2,2′-bipyridyl(bipy) and o -phenanthroline(phen) to yield brick red crystalline products, RuCl 3 (N-N)(Ph 2 RAs) (N-N = bipy, phen). In the presence of excess arsine Ru(III) is reduced to Ru(II), and trichloro-bridged complexes of the formula [Ru 2 Cl 3 (Ph 2 RAs) 6 ]Cl are formed. These on treatment with carbonylated solutions of rhodium chloride produce yellow crystals of [Ru 2 Cl 3 (Ph 2 RAs) 6 ][RhCl 2 (CO) 2 ] containing Ru(II) and Rh(I). Several dicarbonyl complexes cis -RuX 2 (CO) 2 (Ph 2 RAs) 2 (X = Cl, Br; R = Pr, Bu) have also been isolated.

Unidentate coordination of 2,2?-bipyridine and 1,10-phenanthroline in a cyclometallated rhodium(III) complex. Evidence from1H and13C NMR spectra

The binuclear cyclometallated complex [RhCl(µ‐Cl)(bBzlH2bz)]2 [bBzlH2bzH = 1,3‐bis(benzimidazolyl)benzene] undergoes a dichloro bridge cleavage reaction with 2,2′‐bipyridine (bipy) or 1,10‐phenanthroline (phen) in the presence of perchlorate to yield a mononuclear complex of the type RhCl(OClO3)(bBzlH2bz)(N‐N) (N‐N = bipy or phen). Surprisingly, the N‐heterocycle, bipy or phen, is neither chelating nor bridging bidentate in the complex. Such a monodentate coordination of bipy or phen was detected using two‐dimensional 1H–1H correlated and NOE experiments (DQF‐COSY and ROESY), 1H–13C single‐ and multiple‐bond correlated two‐dimensional NMR experiments (PFG‐HSQC and PFG‐HMBC) and 1H,13C spin–lattice relaxation time measurements. The non‐coordination of the pendant nitrogen of the heterocycle bipy or phen is evidenced by the observation of two sets of signals together with the presence of interligand NOEs only between the coordinated part of the heterocycle and the bisbenzimidazole as seen in the corresponding ROESY spectrum. Further, the 1H and 13C spin–lattice relaxation times show lower values for the nuclei in the coordinated part of the heterocycle, bipy or phen, than for the uncoordinated parts, supporting the fact that only one of the two nitrogens of the heterocycle has coordinated to the metal and thus behaves as monodentate ligand. Copyright

Hydride and related complexes of rhodium(III) with nitrogen donor ligands

Abstract The reactions of the two isomeric series (α and β) of complex hydrides of rhodium of the type RhH X 2 L 3 ( X is a halogen and L is a tertiary arsine or phosphine) with the nitrogen donor ligands 2,2′-dipyridyl ( N - N ) and 1,10-phenanthroline ( N - N ) have been investigated. In presence of perchloric acid the α hydrides give new hydrido compounds of the type [RhH X ( N - N ) L 2 ]ClO 4 , while the β hydrides give complexes of the type [Rh X 2 ( N - N ) L 2 ]ClO 4 . Under similar conditions trihalo compounds of rhodium of the type Rh X 3 L 3 also give compounds similar to those obtained from the corresponding β hydrides. Configurations for the cationic species have been assigned on the basis of results of i.r. and NMR measurements.