Transcript Slide 1

Transition Metal Chemistry:
Crystal Field Theory
Jessica Comstock
Kata Haeberlin
Kelsey Fisher
Transition Metals
• elements in which the d and f subshells
are progressively filled
• 50 elements
• transition elements with incomplete d
subshells tend to form complex ions
(Chang 935)
Periodic Trends
• Going across a period, the valence
doesn't change.
• As a result, the electron being added to
an atom goes to the inner shell, not
outer shell, strengthening the shield.
• Why are they called transition metals ?
• The elements represent the
successive addition of electrons to
the d orbitals of the atoms. Transition
metals represent the transition
between group 2 and 13 elements.
high tensile strength
high density
high melting and boiling points
often form colored compounds
solid at room temperature (except
• form complex ions
• often paramagnetic
Oxidation States
• Unlike group 1 and group 2 metals,
transition element ions can have multiple
stable oxidation states.
• They can lose d electrons without a high
energetic penalty (Wikipedia).
Crystal Field Theory
• Developed in the 1930’s by Hans Bethe and
John Hasbrouck van Vleck
• Model that describes electronic structure
of transition metal compounds
• Accounts for
• Some Magnetic Properties
• Colors
• Hydration Enthalpies
• Spinal Structure of Transition Metals
• Attraction between positively charged
metal cation and negatively charged
electrons of the ligand
• Repulsion of electrons
• Splitting affected by
• Nature of metal ion
• Oxidation State
• Arrangement of ligands around the
metal ion
• Nature of the ligands
Spectrochemical Series
• Energy difference ∆ depends on
• Ligands
• Geometry of the complex
I− < Br− < S2− < SCN− < Cl− < NO3−
< N3− < F− < OH− < C2O42− < H2O
< NCS− < CH3CN < py < NH3 < en <
phen < NO2− < PPh3 < CN− < CO
High / Low Spin
• Low Spin
• Large ∆
• Strong-Field
• Cn-, Co
• High Spin
• Small∆
• Weak-Field
• I-, Br-
Change in energy is
equal to energy of
the absorbed
Energy of absorbed
photon is opposite
of the color
• Chang, Raymond. Chemistry;
McGraw-Hill: San Fransisco,