Chapter 15
Group 15 Elements
Occurrence and extraction
Physical Properties
Metals
Halides, oxides, hydroxides, salts of oxoacids
Phosphoacids
Sulfides and selenides
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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
15 elements in the Earth’s crust.
The main components (by percentage
volume) of the Earth’s atmosphere
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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
Fractional distillation
Methods to produce
N2 on a small scale
Membrane separation
http://www.mvsengg.com/products/nitr
ogen/membranenitrogen/membrane_pr
ocess_detail/
http://www.bbc.co.uk/schools/gcsebites
ize/science/edexcel_pre_2011/oneearth/
usefulproductsrev2.shtml
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Phosphorus
tetrahedral P4
Part of one of the chainlike arrays of atoms
present in the infinite
lattice of Hittorf’s
phosphorus
http://en.wikipedia.org/wiki/File:PhosphComby.jpg
http://en.wikipedia.org/wiki/File:PhosphorusAllotropes.svg
Part of one layer of
puckered 6-membered
rings present in black
phosphorus
Arsenic
Vapor phase
Arsenic, antimony, and
bismuth in the solid state
4M + 3O2  2M2O3
(M = As, Sb, Bi)
2As + 6NaOH  2Na3AsO3 + 3H2
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http://www.yetterco.com/media-library/videos/preview/12.jpg
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Chemistry of ammonia (NH3)
barrier to inversion is
low, 24 kJ mol-1
4NH3 + 3O2 
2N2 + 6H2
4NH3 + 5O2 ––Pt/Rh
NH3(aq) + H2O(l)
Oxidation products
depend on conditions
4NO + 6H2O
⇌ [NH4]+(aq) + [OH]-(aq)
[NH4]+(aq) + H2O(l) ⇌ [H3O]+(aq) + NH3(aq)
NH3 + HBr 
Kb = 1.8x10-5
Ka = 5.6x10-10
NH4Br
CaSO4 + 2NH3 + CO2 + H2O  CaCO3 + [NH4]2SO4
NH3 + HNO3  NH4NO3
Chemistry of phosphine/phosphane (PH3)
K + PH3
liquid NH3
HX + PH3
K+ + [PH2]- + 1/2H2
PH4X
[PH4]+ + H2O  PH3 + [H3O]+
PH3 acts as a Lewis base, forms a range of adducts:
H3B·PH3Cl3B·PH3
PH3 + 2O2 --Δ
Ni(PH3)4
Ni(PH3)2(CO)2
H3PO4
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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.
ΔfH(298K) = +50.6 kJ mol-1
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+
+ [N2H5]2[SO4]
[N2H5]2(2+)
373 K, in vacuo
[N2H5]2
(2+)
·2H2O
·2H2O
[N2H5]2(2+)
ΔfH(s, 298 K) = +858 kJ/mol
(3.7 kJ/g)
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[P3H3]2-
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]+?
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HN3
[N3]
[PPh4][N3] + Me3SiN3 + EtOH 
[PPh4][N3HN3] + Me3SiOEt
[N3HN3]
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Metal and non-metal azide compounds
[Sn(N3)6]2-
trans- [Ru(en)2(N2)(N3)]
N2 : isolated 1790
N3- : synthesized 1890
[N2F]+[SbF6]
+ HN3
(i)
(ii)
Liquid HF, 195 K
Warm to 298 K
[N5]+[SbF6]- + HF
N5+ : synthesized 1999
[NO]+[SbF6]- + 2.5N2
NO
[N5]+[SbF6]-
NO2
[NO2]+[SbF6]- + 2.5N2
Br2
[Br2]+[SbF6]- + 2.5N2
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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.
Pernitrides [N2]2- 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
ionic
http://pubs.rsc.org/en/conten
t/articlelanding/2010/cs/b916
787k#!divAbstract
• The alkali metals can also form phosphides which contain groups of
P atoms (e.g. [P7]3- and [P11]3-) as chains or cages.
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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)
Ni
As
Unit cell of NiAs
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[Sb8]2 or [Bi8]2
Pd-centered pentagonal
antiprismatic structure of
[Pd@Bi10]4
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Selected reactions of PCl5.
{SbF5}4
[Sb2F11]
[As6I8]2
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[BiCl3(15-crown-5)]
[BiCl3L]
Oxides of Nitrogen
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[N2O2]2-
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HNO3
NO3-
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oxoacids of phosphorus
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[W3(OH2)9NiSe4{PH(OH)2}]4
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enantiomers (non-superimposable mirror images)
unit cell of FeSb2O6
unit cell of NaSbO3
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[Cl3PNPCl2NPCl3]
Proposed reaction scheme for
the formation of the cyclic
phosphazene (NPCl2)3
phosphazenes (NPX2)3
N-
[Cl3PN(PCl2N)2PCl3]
P4N4 ring conformations
P+
P+
NN-
P+
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(R)-[Sb(O2CCF3)3]
Bi2(O2CCF3)4
[Bi2(C6H4O2)4]2
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