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AP Notes Chapter 22
Transition Metals Their
Coordination Compounds &
Isomers
Transition Elements
Metals capable of taking on multiple oxidation numbers.
Exist in 3 series 1st the 3d 2nd the 4d and the 3rd 5d
The 2nd and 3rd series are almost identical in radii size
due to the 4f and 5f orbitals, the addition of these 14
protons and little shielding effect cause the similarity in
size this is called the lanthanide contraction.
Transition Elements
Atomic Radii decrease from left to right, with a
slight increase at the right end.
As Nuclear charge increases the s outer
electrons are pulled closer initially making the
atom smaller, near the end increased electron
repulsion causes the slight increase.
Coordination Compounds or complex ions
Usually consist of a transition metal and the
attraction of a unit called a Ligand with a
coordinate covalent bond.
They take on a 3-D shape, those shapes or
geometries use the naming methods you
already know….and then add to them
Common coordination numbers are 2,4,and
6 they are associated with geometries linear,
tetrahedral, square planar and octahedral.
Coordination Compounds
Linear – [CuCl2]- , [Ag(NH3)2]+
Tetrahedral – [CoCl4]2- , [NiCl4]2[Ni(CO)4] , [Zn(NH3)4]2+
Square Planar – [Ni(CN)4]2-
Octahedral – Fe(H2O)6]2+ , [Co(NH3)6]3+
Coordination Compounds
Monodentate - Ligands with one lone pair of
electrons to donate
Polydentate – Ligands that have more than
one lone pair to danate, often on different
atoms (one bite)
Chelate ring – a polydentate ligand that
coordinate bonds to the same atom (two
bites)
Transition Elements
Melting Points increase toward the center of each
series where the d orbital is about half-filled, where
the largest number of unpaired electrons exist.
These metals can be isolated or extracted from ore
by processes we call metallurgy
Pyrometallurgy – involves high temperatures
Hydrometallurgy – involves aqueous solutions
Isomerization Flow Chart
Isomers
Structural or Constitutional
(Different Bonds or connectivity)
Coordination
(Different Bonds)
Stereoisomerism
(Different arrangement same connectivity)
Geometric or Achiral
(Without stereocenters)
Cis(Same side)
Linkage
(Different Connectivity)
Optical or Chiral
(With stereocenters)
Trans(Opposite side)
Enantiomers
(Mirror images
Non-superimposible)
Diastereoisomer
(Non-mirror images)
Constitutional isomers:
compounds that have the
same molecular formula but
different structural formulas
(connected differently)
CH3 CH2 CH2 CH3
Bu tane
(bp -0.5°C)
CH3
CH3 CHCH3
2-Methylp ropan e
(bp -11.6°C)
Cis- or Trans- isomers:
because of restricted rotation about a
carbon-carbon double bond, an alkene
with two different groups on each
carbon of the double bond shows cistrans isomerism
H
H
H
C C
H3 C
CH3
C C
CH3
cis -2-Butene
mp -139°C, b p 4°C
H3 C
H
t rans-2-Butene
mp -106°C, bp 1°C
Crystal Field Theory
All the d orbitals are equal in energy they
are said to be degenerate
Atomic bond theory and molecular orbital
theory cannot explain many complexes and
their behavior or bonding
The electrostatic field or ligand field exists
when the atom or ion is approached by a
legand.
Electrons lose degeneracy and are pushed
into higher and lower spins split by energy
Crystal Field Theory
Fe2+ has d6 electron configuration
Fe2+
[Fe(H2O)6]2+
[Fe(CN)6]4-
weak field
strong field
high spin
low spin
DE
Colors & Coordination Componds
Transition metal complexes absorb light causing
electrons to move from low to high energy levels.
The energy difference corresponds to a frequency in
the visible portion of the spectrum … they
appeared colored
Electron transition in the d orbital is responsible for
this color
Changes in the splitting of the d orbital changes the
observed color
Ligands ordered in ability to split d i.e. how strong
the ligands are, ordering = spectrochemical series