Chapter 15 Group 15 Elements

Occurrence and extraction Physical Properties Metals Halides, oxides, hydroxides, salts of oxoacids Phosphoacids Sulfides and selenides

1 http://www.cpsc.gov//PageFiles/122137/270.pdf

http://www.semiconductor-today.com/news_items/2012/APRIL/YOLE_170412.html

Relative abundances of the group The main components (by percentage 15 elements in the Earth’s crust. volume) of the Earth’s atmosphere

2 Phosphorus containing nerve agents.

Destruction of the nerve agents

Selected low-temperature baths involving liquid N2.

3 covalent bond enthalpy terms (kJ mol1)

vs.

4 Schematic representation of the electronic

repulsion, believed to weaken the FF bond in F2.

Composition of air N2 - dinitrogen

Methods to produce Fractional distillation N2 on a small scale

Membrane separation

http://www.mvsengg.com/products/nitr http://www.bbc.co.uk/schools/gcsebites ogen/membranenitrogen/membrane_pr ize/science/edexcel_pre_2011/oneearth/ ocess_detail/ usefulproductsrev2.shtml

5 Phosphorus

tetrahedral P4

Part of one of the chain- like arrays of atoms present in the infinite http://en.wikipedia.org/wiki/File:PhosphComby.jpg lattice of Hittorf’s phosphorus

http://en.wikipedia.org/wiki/File:PhosphorusAllotropes.svg

Part of one layer of puckered 6-membered rings present in black phosphorus

Arsenic, antimony, and Arsenic bismuth in the solid state Vapor phase

4M + 3O2  2M2O3 (M = As, Sb, Bi)

2As + 6NaOH  2Na3AsO3 + 3H2

6 http://www.yetterco.com/media-library/videos/preview/12.jpg

7 Chemistry of ammonia (NH3)

barrier to inversion is low, 24 kJ mol-1

4NH + 3O 2N + 6H 3 2  2 2 Oxidation products depend on conditions 4NH3 + 5O2 ––Pt/Rh 4NO + 6H2O

+ - -5 NH3(aq) + H2O(l) ⇌ [NH4] (aq) + [OH] (aq) Kb = 1.8x10

+ + -10 [NH4] (aq) + H2O(l) ⇌ [H3O] (aq) + NH3(aq) Ka = 5.6x10

NH3 + HBr  NH4Br

CaSO4 + 2NH3 + CO2 + H2O  CaCO3 + [NH4]2SO4

NH3 + HNO3  NH4NO3

Chemistry of phosphine/phosphane (PH3)

liquid NH3 + - K + PH3 K + [PH2] + 1/2H2

HX + PH3 PH4X

+ + [PH4] + H2O  PH3 + [H3O]

PH3 acts as a Lewis base, forms a range of adducts:

H3B·PH3Cl3B·PH3 Ni(PH3)4 Ni(PH3)2(CO)2

PH3 + 2O2 --Δ H3PO4

8 Hydrides E2H4 (E = N, P, As)

NH3 + NaOCl  NH2Cl + NaOH fast

NH3 + NH2Cl + NaOH  N2H4 + NaCl + H2O slow

Hydrazine (N2H4) is kinetically stable with respect to N2 and H2. -1 ΔfH(298K) = +50.6 kJ mol

Removes O2 from industrial boilers (forms N2H4 + O2  N2 + 2H2O)

Alkyl derivatives used with N2O4 as rocket fuel. (a) The structure of N2H4, and Newman projections showing (b) the observed gauche conformation, and (c) the possible staggered conformation. An eclipsed conformation is also possible.

High Energy Density Materials

5,5'-azotetrazolate dianion

Ba2+ (2+) + [N2H5]2[SO4] [N2H5]2 ·2H2O

373 K, in vacuo (2+) (2+) [N2H5]2 ·2H2O [N2H5]2

ΔfH(s, 298 K) = +858 kJ/mol (3.7 kJ/g)

9 2- [P3H3]

Potential diagram for nitrogen at pH = 0.

Latimer (or reduction potential diagrams) show the standard reduction potentials connecting various oxidation states of an element.

+ Is hydroxlamine [NH3OH] stable with respect to disproportionation + + to N2 and [N2H5] & [NH4] ?

10 HN3

 [N3]

[PPh4][N3] + Me3SiN3 + EtOH  [PPh4][N3HN3] + Me3SiOEt

 [N3HN3]

11 Metal and non-metal azide compounds

 2- trans- [Ru(en)2(N2)(N3)] [Sn(N3)6]

(i) Liquid HF, 195 K N2 : isolated 1790 (ii) Warm to 298 K - [N F]+[SbF ] + HN [N ]+[SbF ]- + HF N3 : synthesized 1890 2 6 3 5 6 + N5 : synthesized 1999

+ - [NO] [SbF6] + 2.5N2 NO

NO + - 2 + - [N5] [SbF6] [NO2] [SbF6] + 2.5N2

Br2

+ - [Br2] [SbF6] + 2.5N2

12 Nitrides: titanium nitride coated saw blades

Li3N, Na3N, Be3N2, Mg3N2, Ca3N2, Ba3N2 and AlN.

•Hydrolysis of saline hydrides liberates NH3

•Na3N is hygroscopic

Na3N + 3H2O  3NaOH + NH3 •Nitrides of d-block metals are hard, inert solids with high melting points and electrical conductivities.

2- Pernitrides [N2] are known for Sr, Ba.

•Conditions of 5600 bar of N2 at 920 K for BaN2.

Si3N4 are used in glow plugs.

Phosphides Most elements (except Hg, Pb, As, Te) combine with P to form phosphides • Variety of solid state structures • Phosphides with d-block metals tend to be inert, metallic looking, with high melting point and electrical conductivities.

• Group 1 metals form M3P and Group 2 metals form M3P2 • Are hydrolyzed by water

and can be considered http://pubs.rsc.org/en/conten t/articlelanding/2010/cs/b916 ionic 787k#!divAbstract • The alkali metals can also form phosphides which contain groups of 3- 3- P atoms (e.g. [P7] and [P11] ) as chains or cages.

13 Gallium Arsenide

• Important group III-V semiconductor that crystallizes with zinc-blende structure • Band gap of 1.42 eV, thus can be used to make devices that emit light in the infrared region.

• Exhibits high electron mobility, 8500 cm2V-1s-1 vs. silicon 1500 cm2V-1s-1

• Disadvantages of GaAs vs Si: • Expensive • Brittle • Lower Thermal Conductivity

• Highest-efficiency single-junction solar cell at 28.8% • http://dx.doi.org/10.1109%2FPVSC.2012.6317891

NiAs (nickel arsenide)

Unit cell of NiAs

14 [Sb ]2 or [Bi ]2 Pd-centered pentagonal 8 8 antiprismatic structure of 4 [[email protected]]

15 Selected reactions of PCl5.

{SbF5}4

 [Sb2F11] 2 [As6I8]

16 [BiCl3(15-crown-5)] [BiCl3L]

Oxides of Nitrogen

17 2- [N2O2]

18 HNO3

- NO3

19 oxoacids of phosphorus

20 4 [W3(OH2)9NiSe4{PH(OH)2}]

21 enantiomers (non-superimposable mirror images)

unit cell of FeSb2O6 unit cell of NaSbO3

22  [Cl3PNPCl2NPCl3]

Proposed reaction scheme for  the formation of the cyclic [Cl3PN(PCl2N)2PCl3] phosphazene (NPCl2)3

phosphazenes (NPX2)3 P4N4 ring conformations

+ N- P P+ N- P+ N-

23 2 (R)-[Sb(O2CCF3)3] Bi2(O2CCF3)4 [Bi2(C6H4O2)4]