Early developments in lanthanide-based dinitrogen reduction chemistry

2005 ◽  
Vol 83 (4) ◽  
pp. 375-384 ◽  
Author(s):  
William J Evans ◽  
David S Lee
Keyword(s):  
Nitrogen Fixation ◽  
Alkali Metal ◽  
Key Words ◽  
Entire Series ◽  
Dinitrogen Reduction ◽  
Dinitrogen Complex

Although the first crystallographically characterized lanthanide dinitrogen complex was reported in 1988 with samarium, it is only in recent years that this field has expanded to include fully characterized examples for the entire series of lanthanides. The development of lanthanide dinitrogen chemistry has been aided by a series of unexpected results that present some good lessons in the development of science. This review presents a chronological account of the lanthanide dinitrogen chemistry discovered in our laboratory through the summer of 2004.Key words: lanthanides, dinitrogen, reduction, alkali metal, nitrogen fixation, diazenido.

Synthesis and structure of a terminal dinitrogen complex of nickel

2005 ◽  
Vol 83 (4) ◽  
pp. 328-331 ◽  
Author(s):  
Rory Waterman ◽  
Gregory L Hillhouse
Keyword(s):  
Crystal Structure ◽  
Petroleum Ether ◽  
Key Words ◽  
X Ray ◽  
Dinitrogen Complex

Reaction of petroleum ether solutions of [(dtbpe)Ni]2(η2,µ-C6H6) (1, dtbpe = 1,2-bis(di-tert-butylphosphino)ethane) with triphenylphosphine under a dinitrogen atmosphere gives the Ni(0) dinitrogen adduct (dtbpe)Ni(N2)(PPh3) (2), which can be isolated as dark red crystals in 87% yield. The X-ray crystal structure of 2 reveals pseudotetrahedral geometry about Ni and a terminal dinitrogen ligand with Ni—N(1) = 1.830(2) Å, N(1)—N(2) = 1.112(2) Å, and Ni-N(1)-N(2) = 177.5(2)°. Key words: dinitrogen, nickel, X-ray.

Nucleation during primary succession in the Canadian Rockies

1993 ◽  
Vol 71 (8) ◽  
pp. 1093-1096 ◽  
Author(s):  
D. J. Blundon ◽  
D. A. MacIsaac ◽  
M. R. T. Dale
Keyword(s):  
British Columbia ◽  
Nitrogen Fixation ◽  
Key Words ◽  
Rocky Mountains ◽  
Primary Succession ◽  
The Other ◽  
Pioneer Species ◽  
Canadian Rocky Mountains ◽  
Successional Species ◽  
Key Words Colonization

A study of nucleation during primary succession was carried out on age sequences of communities at two sites in the Canadian Rocky Mountains: one at the Mount Robson moraines, British Columbia, the other at Southeast Lyell Glacier, Alberta. The study concentrated on the associations of species with the nitrogen-fixing plants Hedysarum boreale var. mackenzii at Mount Robson moraines and Dryas drummondii at Southeast Lyell Glacier because those plants might serve as nuclei for colonization by other species, thus facilitating succession. The data show that recruitment of later successional species is greater in patches of the two pioneer species, but the fact that recruitment takes place away from the plants also suggests that although there is nucleation, it is not necessary for succession at these sites. Key words: colonization, nitrogen fixation, nucleation, succession.

Chemical nitrogen fixation by using molybdenum and tungsten complexes

2001 ◽  
Vol 73 (2) ◽  
pp. 261-263 ◽  
Author(s):  
Masanobu Hidai ◽  
Yasushi Mizobe
Keyword(s):  
Nitrogen Fixation ◽  
The Other ◽  
Nucleophilic Attack ◽  
Dinuclear Complexes ◽  
Tungsten Complexes ◽  
Other Hand ◽  
Dinitrogen Complexes ◽  
Dinitrogen Complex ◽  
Moderate Yield ◽  
And Tungsten

Dinitrogen complex cis-[W (N2) 2 (PMe2Ph) 4] reacts with an excess of acidic dihydrogen complexes such as trans-[RuCl (h2-H2) (dppe) 2]BF4 (dppe = 1,2-bis (diphenylphosphino) ethane) at 55 °C under 1 atm of H2 to form ammonia in moderate yield. The reaction is presumed to proceed through nucleophilic attack of the remote nitrogen of the coordinated dinitrogen on the dihydrogen ligand. The coordinated dinitrogen is also protonated by treatment with hydrosulfido-bridged dinuclear complexes such as [Cp*Ir (m-SH) 3IrCp*]Cl (Cp* = h5-C5Me5) to afford ammonia. On the other hand, the synthetic cycle for the formation of pyrrole and N-aminopyrrole from dinitrogen and 2,5-dimethoxytetrahydrofuran has been established starting from dinitrogen complexes of the type trans-[M (N2) 2 (dppe) 2 ] (M = Mo, W).

Activation and cleavage of alkynes by the dinuclear tantalum complexes ([NPN]Ta)2(µ-H)4 and ([NPN]Ta)2(µ-η1:η2-N2)(µ-H)2 (where NPN = PhP(CH2SiMe2NPh)2)

2005 ◽  
Vol 83 (6-7) ◽  
pp. 652-660 ◽  
Author(s):  
Michael P Shaver ◽  
Samuel A Johnson ◽  
Michael D Fryzuk
Keyword(s):  
Small Molecules ◽  
Key Words ◽  
Crystallographic Analysis ◽  
Terminal Alkynes ◽  
Dinitrogen Complex

Reaction of phenylacetylene with the dinuclear tetrahydride complex ([NPN]Ta)2(µ-H)4 gives the product ([NPN]Ta)2(µ-PhCCH)(µ-H)2 (where NPN is PhP(CH2SiMe2NPh)2). Activation of other terminal alkynes by ([NPN]Ta)2(µ-H)4 accesses ([NPN]Ta)2(µ-RCCH)(µ-H)2 (R = n-Pr, t-Bu). Crystallographic analysis of the R = Ph derivative showed it to be a bis(µ-alkylidene) bound asymmetrically to the two tantalum centres. Storage of solutions of ([NPN]Ta)2(µ-PhCCH)(µ-H)2 under vacuum promotes the loss of H2 and cleavage of the C—C bond to give a bis(µ-alkylidyne) complex, ([NPN]Ta)2(µ-CPh)(µ-CH). Addition of diphenylacetylene did not give the desired ([NPN]Ta)2(µ-CPh)2, but rather promotes a complex decomposition of the supporting [NPN] ligands. Reaction of phenylacetylene with the dinitrogen complex ([NPN]Ta)2(µ-η1:η2-N2)(µ-H)2 results in the dissociation of the bound dinitrogen and the formation of ([NPN]Ta)2(µ-PhCCH)(µ-H)2, which is identical to that derived from the reaction with the dinuclear tetrahydride. Key words: tantalum, alkyne, alkylidene, alkylidyne, amidodiphosphine, dinuclear hydride dinitrogen, activation of small molecules.

scholarly journals Nitrification and denitrification in pond

2011 ◽  
Vol 10 (1) ◽  
pp. 89 ◽  
Author(s):  
Yuni Puji Pujihastuti
Keyword(s):  
Nitrogen Fixation ◽  
Survival Rate ◽  
Key Words ◽  
Nitrogen Assimilation ◽  
Inorganic Nitrogen ◽  
Aerobic Condition ◽  
Nitrification Process ◽  
Preparation Step ◽  
Nitrification And Denitrification ◽  
The One

<p>More of waste than pond aquacultutre system produced, will increase sedimentation in the bottom.  Ammonium and nitrite compounds are other forms of inorganic nitrogen in the pond. Nitrogen anorganic consist of ammonia, ammonium, nitrit, nitrat and nitrogen. Degradation of process metabolic biota culture waste can biologically be nitrat compound one of the forms that are not toxic in the nitrification process.  Five process of nitrogen biogeochemical cycle in the container cultivation is the amonification, nitrification, nitrogen assimilation, denitrification and nitrogen fixation. Nitrogen is the one of the compound in the overlay/ top stratification sediment.  Improvement of speed degradation will be success if the pond bottom on aerobic condition. Survival rate of tiger shrimp in the laboratory scale can be increase by administration of nitrification and denitrification bacteria should not just in the water kolom of pond engineering but also at the bottom pond layer at the preparation step.  Depht of the sediment 15 cm in day zero, intensive pond have been produced of nitrit and ammonium with the producing bacteria.  Application of nitrification and denitrification bacteria in the sediment and water coloum can be performed as the measurenment and evaluation nitrit, nitrat and ammonium abudance.</p> <p>Key words:  ponds, nitrogen inorganic, nitrification, denitrification</p> <p><em> </em></p> <p>ABSTRAK</p> <p>Semakin banyak limbah kegiatan yang dihasilkan dalam sistem budidaya tambak, akan meningkatkan sedimentasi dalam dasar tambak.  Senyawa amonium dan nitrit merupakan bentuk lain dari nitrogen anorganik dalam tambak. Nitrogen anorganik terdiri terdiri dari amonia (NH<sub>3</sub><sup>-</sup>), amonium (NH<sub>4</sub><sup>+</sup>), nitrit (NO<sub>2</sub><sup>-</sup>), dan nitrogen (N<sub>2</sub>). Secara biologis, proses perombakan sisa metabolisme biota budidaya dapat menjadi nitrat (NO<sub>3</sub>), suatu bentuk yang tidak berbahaya dalam proses nitrifikasi.  Lima proses siklus biogeokimia nitrogen yang terjadi di wadah budidaya adalah amonifikasi, nitrifikasi, asimilasi nitrogen, denitrifikasi, dan fiksasi nitrogen. Nitrogen merupakan senyawa yang biasanya terletak di lapisan paling atas dalam sedimen.  Peningkatan kecepatan degradasi akan dapat dicapai jika sedimen berada dalam kondisi aerobik. Tingkat kelangsungan hidup udang pada uji skala laboratorium memperlihatkan bahwa penambahan bakteri nitrifikasi dan denitrifikasi terseleksi dapat meningkatkan kelangsungan hidup udang windu Aplikasi pemberian bakteri nitrifikasi dan denitrifikasi tidak seharusnya hanya dalam air saja, namun juga dalam pengolahan tanah dasar tambak.  Pada kedalaman sedimen 15 cm hari ke-0, tambak intensif telah terdapat bakteri penghasil nitrit dan amonium dan kelimpahannya semakin meningkat seiring dengan bertambahnya umur udang.  Aplikasi pemberian bakteri nitrifikasi dan denitrifikasi di sedimen dan kolom perairan dapat dilakukan seiring dengan pengukuran dan evaluasi kondisi nitrit, nitrat dan ammoniumnya.  Secara alami,  dalam kolom perairan telah terdapat senyawa nitrit, nitrat dan amonium, seberapapun itu perlu diimbangi dengan kebijakan dalam pemberian bakteri dari luar.</p> <p>Kata kunci: tambak, nitrogen anorganik, nitrifikasi, denitrifikasi</p>

The ecology of four annual clovers adventive in New Zealand grasslands

2003 ◽  
Vol 11 ◽  
pp. 175-184
Author(s):  
C.C. Boswell ◽  
R.J. Lucas ◽  
M. Lonati ◽  
A. Fletcher ◽  
D.J. Moot
Keyword(s):  
Nitrogen Fixation ◽  
Soil Moisture ◽  
New Zealand ◽  
Key Words ◽  
N Fixation ◽  
Hard Seeds ◽  
Drought Conditions ◽  
Trifolium Arvense ◽  
Arid Grasslands ◽  
Semi Arid

Four annual clovers have become adapted to the dry and semi-arid grasslands in New Zealand. In the absence of competition from perennial clovers, which are adapted to sub-humid and humid environments, further spread is likely to continue. Annuals rely on high numbers of small and hard seeds for survival. Their germination is dependent on a combination of adequate soil moisture and favourable temperatures, with no evidence of a prechilling treatment required. For striated clover, germination results highlight their adaptation to cool moist autumn conditions during germination. The benefits of adventive clovers for N fixation (0.2-100 kg N ha-1) are greatest where sulphur fertiliser has been applied, the clover population is dense, and soil moisture ideal over several months, but may be nil in drought conditions. Key words: annual clovers, germination, nitrogen fixation, semi-arid grassland, Trifolium arvense, T. dubium, T. glomeratum, T. striatum

Cultivation of Bradyrhizobium CB756 on sucrose prefermented by yeast

1992 ◽  
Vol 38 (6) ◽  
pp. 569-572 ◽  
Author(s):  
T. A. Lie ◽  
Martin Muilenburg ◽  
Nguyen Huu Hiep ◽  
Kamuran Ayhan
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Nitrogen Fixation ◽  
Key Words ◽  
Yeast Cells ◽  
Basal Salts

Saccharomyces cerevisiae, grown with sucrose as a substrate, converts the sucrose to glycerol and produces yeast cells. The yield of glycerol was doubled by adding CaCO3. The fermented medium, containing glycerol and yeast cells, was an excellent medium for the cultivation of Bradyrhizobium CB756. Best results were obtained after dilution of the fermented medium to 10% (v/v) with a basal salts solution, but even with dilutions of 5 and 2.5%, high numbers of Bradyrhizobium CB756 cells were obtained. Key words: Bradyrhizobium, glycerol, nitrogen fixation, inoculants.

Ligand-assisted reduction of Co(II) to Co(I) and subsequent coordination of dinitrogen

2005 ◽  
Vol 83 (4) ◽  
pp. 279-285 ◽  
Author(s):  
Jennifer Scott ◽  
Sandro Gambarotta ◽  
Ilia Korobkov
Keyword(s):  
Key Words ◽  
Bond Formation ◽  
Nitrogen Atmosphere ◽  
Dinitrogen Fixation ◽  
Dinuclear Complex ◽  
Methylene Carbon ◽  
Low Valent ◽  
Dinitrogen Complex ◽  
Identical Unit

Reaction of the bis-aminopyridine dianion {[2,6-[2,6-(i-Pr)2PhN-C=(CH2)]2(C5H3N)]Li(THF)}{Li(THF)4} with CoCl2(THF)1.5 under Ar afforded the dinuclear complex {[2,6-(i-Pr)2PhN-C=(CH2)](C5H3N)[2,6-(i-Pr)2PhN=C(CH2)]}2[Co(µ-Cl)Li(THF)3]2·4(THF) (1) in which the ligand is coupled to a second identical unit at a terminal methylene carbon. In turn, the C—C bond formation caused reduction of the Co(II) center to the monovalent state. The same reaction performed under a nitrogen atmosphere afforded the double dinitrogen complex {[2,6-(i-Pr)2PhN-C=(CH2)](C5H3N)[2,6-(i-Pr)2PhN=C(CH2)]}2[Co(N2)]2·2(toluene) (2). Key words: low-valent Co, diiminopyridinato, dinitrogen fixation.

Rahnella aquatilis, a nitrogen-fixing enteric bacterium associated with the rhizosphere of wheat and maize

1991 ◽  
Vol 37 (3) ◽  
pp. 195-203 ◽  
Author(s):  
Odile Berge ◽  
Thierry Heulin ◽  
Wafa Achouak ◽  
Claude Richard ◽  
Rene Bally ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Key Words ◽  
Dna Hybridization ◽  
Pure Culture ◽  
Tween 80 ◽  
Decarboxylase Activity ◽  
Enteric Bacterium ◽  
Diazotrophic Bacteria ◽  
Rahnella Aquatilis ◽  
First Time

In a study of dominant diazotrophic bacteria present in the rhizosphere of wheat and maize, 28 strains of Enterobacteriaceae were isolated. They were all Voges-Proskauer positive, motile at 28 °C but not at 37 °C, and they produced a Tween-80 esterase and did not exhibit decarboxylase activity. This fits well with the description of Rahnella aquatilis. The ability of these strains to reduce acetylene in pure culture and in association with their host plant and the DNA hybridization with a nifHDK probe are described. This is the first time that R. aquatilis is reported as a rhizosphere-associated bacterium and also a nitrogen fixer. Key words: Rahnella aquatilis, rhizosphere, wheat, maize, nitrogen fixation.

Sign in / Sign up

Export Citation Format

Share Document