Download Chem212,Quiz5,99

Chemistry 212, Quiz 5, 3/26/99
Name____________________________
Show your work and make your reasoning clear in each case.
Answer each of the following four questions.
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1. [5 points] For each ion in each pair of complex ions below, specify
• (1) the molecular geometry (octahedral, tetrahedral, square planar, etc.)
• (2) d-electron configuration (sketch the d-orbital splitting, label the orbitals, and fill in the
correct number of electrons)
• (3) expected ligand field splitting (strong or weak-field case)
• (4) expected spin type (high or low-spin configuration)
Compare and contrast the two ions in each of the sets.
(a) [2.5 points] [Fe(CO)6]3+ versus [Co(OH2)6]2+
(b) [2.5 points] [CoCl4]2- versus [PtCl4]2______________________________________________________________________________
2. [2 x 2.5 = 5 points] Show your understanding of any two of the following five terms by giving
a brief description of the term and the context in which it is used. Give an example to illustrate
your point and identify any symbols used in your answers.
(a) chelating ligands
(b) spectrochemical series
(c) chiral complex
(d) spin-only paramagnetism
(e) ligand field stabilization energy (LFSE)
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3. [4 x 1.25 = 5 points] For any four of the following six complexes below,
• (1) give the formula corresponding to the name, or the name corresponding to the formula
• (2) draw a sketch illustrating the geometry of the complex.
(a) trans-dichlorobis(ethylenediamine)ruthenium(III)
(b) fac-[FeBr3(NH3)3]
(c) tris(2,2’-bipyridine)ruthenium(II)
(d) [Co(en)3]3+
(e) tetracyanonickelate(II)
(f) cis-[RhCl2(NH3)4]+
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4. [2 x 2.5 = 5 points] Explain with reference to ligand field theory how any two of the
following three types of ligands affect the crystal field splitting of the d orbitals in an octahedral
complex.
 π-donor ligand
 - donor ligand
 π-acceptor ligand
In your answers discuss the type of orbital interaction between the ligand orbitals and the d
orbitals of the metal ion, and the manner in which the interaction affects the splitting. In each
case give an example of a ligand that belongs to the class, and estimate where you expect the
ligand to be on the spectrochemical series (i.e., low, middle, or high).
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Total points = 20
I Pledge__________________________