The elements
o N2 a colourless gas (bp: -196 C) o P4 yellow mp: 44 C d: 1.84 red mp: 600 oC d: 2.16 chains of tetrahedra o o black mp: 610 C d: 3.56 6:6, r1 2.23, r2 3.32 >90 Group 15 As gray solid, black P-structure Sb gray solid, black P-structure N, P, As, Sb, Bi Bi gray solid, black P-structure N P As Sb Bi Abundance ppm 300 800 5 1 .2 Electronegativity (H:2.2) 3.0 2.2 2.2 2.1 2.0
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The atmosphere 1890’s: discovery of noble gases
N2 O2 Ar CO2 Ne H2 He Kr Xe Density of atmospheric gas
Bp minus H2O, CO2 and O2 77.2 90.1 87.2 194.7 27.2 20.2 4.2 119.2 165.1 /K different from
-4 -5 -5 -6 -7 -8 NH NO → N +2H O αvol .7803 .2099 .0093 3·10 2·10 1·10 5·10 1·10 8·10 4 2 2 2 2NaN3 → 2N2 + 2Na
Bnot pure N2
Last step N2 + Mg → Mg3N2 left are Ar and other Noble gases of the atmosphere
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o -1 ΔH diss /kJ·mol Nitrogen fixation
•N 945 2 ≡ = - N2 + 3H2 ' 2NH3 o •O2 495 metal oxide catalyst gas (400 C, 100+ atm)
•F2 159 CC 810 600 350 •Cl 242 + - + 2 N2 + 10H + 8e ' 2NH4 + H2 CN 850 620 240 o •H2 436 nitrogenases gas/sol (10 C, 0.8 atm)
CO 1050 700 360 + - N2+O2 ' NO/NO2 (gas) → NH4 /NO3 NN 945 400 160 lightening gas (high energy,0.8/0.2 atm)
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1 :N:::N: Nitrogen reactions
Nitrogen fixation by bacteria MgADP+HPO 2- 4 Mg or Li + N2 → Metal nitride + Fdred [Fe-prot]ox [Fe-Mo-p]red 8H + N2 Mg3N2 + 6H2O → 3Mg(OH)2 + 2NH3
Fdoc [Fe-prot]red [Fe-Mo-p]ox H2 + 2NH3 MgATP 1960’s: 2+ 2+ [Ru(NH3)5N2] + H2O ' [Ru(NH3)5H2O] +N2 [4Fe-4S] [Fe-Mo-S-proteins] Mo-N≡N
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Amines N - H
+ + - 2- 3- - - NH4 'H + NH3 9.25 NH2 NH N NH3 +OCl → NH2Cl + OH + + chloramine RNH 'H + RNH 10+ R NH R N 3 2 2 3 - - + + NH2Cl + OH + NH3 → H2NNH2 + H2O + Cl ArNH3 'H +ArNH2 9- hydrazine + + N2H5 ' N2H4 + H pK~7.95
2NaNH2 + N2O → NaN3 + NaOH + NH3 - + HN3 ' N3 + H pK~4.75 ……etc Hydrazoic acid (hydrogen azide)
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N – O Acids
NH NO nitrous oxide N2O 4 3 laugh N=N=O + + HONO + H → H2O + N≡O nitrosonium ion nitric oxide* - NO N2+O2 radical ·N=O pK~3.35 NO2 nitrito (O) or nitro (N) (nitrosyl as a ligand) O-+ nitrogen NO2 N2+O2 brown ·N=O dioxide + + HONO2 + H → H2O + O=N =O nitronium ion colour O O dinitrogen N O 2NO N - N 2 4 2 less O O tetraoxide HO hyponitrous acid O O dinitrogen N – N pK’s 6.9 , 11.6 blue l N - N OH N2O3 HNO2 O trioxide colour O O dinitrogen HO N O HNO N-O-N 2 5 3 less O O pentaoxide N – N pK 6.6 nitramide HO (nitric acid amide) * Short living signal molecule causing dilation of blood vessels
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2 Other N functions P-O-H
+ RNH2 + H +HNO2 → RN≡N diazonium ions •P4 + 3O2 → P4O6 + H2O → HP(OH)2O
+ 2O2 → P4O10 R2NH + HNO2 → R2N-N=O N-nitrosamines P4O10 +H2O → P(OH)3O RNH2 + O=CR2 → RN=CR2 Schiff bases
HONH2 + O=CR2 → HON=CR2 oximes hydroxylamine HxPyOz: P tetrahedral! NH-C-R hydroxamic acids O OO e.g. H P O HOPOPPOH HO O 5 3 9 O OO H HH
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N – halides Halides
•3F2+ 4 NH3 → 3NH4F + NF3 pyradimal (stable gas)
•NHCl +3Cl → NCl + 4HCl explosive yellow liquid 4 2 3 •2P + 3Cl2 → PCl3 stable liquid: chlorinating agent aqueous solutions insoluble high yield: 20oC, 2 M acid solution • P + xsCl2 → PCl5 : [PCl4][PCl6]s → PCl5 g • [PBr4]Br •NH3 + I2 → NI3·NH3 extremely explosive brown solid
• AsCl3 l,SbCl3 s, BiCl3 s,
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Trihydrides Other ligands
[Cr(Das)2Br2]ClO4 NH PH AsH SbH BiH 3 3 3 3 3 1,2-bis(dimethylarsino)benzen Name Ammonia phospine arsine stibine Bismuthane systematic (azane) phosphane arsane stibane PPPAs o Bp C -34.5 -87.5 -62.4 -18.4 H H H Me Me Me φφφ φφφ Dipol 1.47 0.57 0.2 0.12 moment 2- 2- medium, soft, soft, soft, soft, ATP ROPO3 RPO3 ligand strong weak more weak weaker very weak cyclic or linear poly phosphates phosphate esters phosphonates
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