Inorganic Chemistry Exam 2
UPDATED Study Guide QUESTIONS
AND CORRECT ANSWERS
- What are the two designations used to denote the chirality of chelate
rings? - CORRECT ANSWERS Left-handed
(counterclockwiese): Λ
Right-handed (clockwise): Δ
Another Way to Identify Λ and Δ Propellers - CORRECT ANSWERS
Left-handed propeller: spinning counterclockwise would move
object away from us (or push air towards us)
Right-handed propeller: spinning clockwise would move object away
from us (or push air towards us)
What is the textbook method of identifying the chirality of chelate
rings? - CORRECT ANSWERS Rotate the structure to place
one ring horizontally across the back at the top of the triangular face
-image the front ring as being parallel to the back ring (eclipsed
structure); determine what rotation of the front ring is required to
obtain the actual structure
-if the rotation in Step 2 is counterclockwise, the structure is
designated as lambda Λ; if the rotation in Step 2 is clockwise, the
structure is designated as delta Δ
Identifying Chelate Ring Chirality 2 - CORRECT ANSWERS
Picture
,What are structural/constitutional isomers? What are 4 types? How do
diastereomers and constitutional isomers compare in physical
properties vs how enantiomers compare? - CORRECT ANSWERS
Molecules that have the same molecular formula but different
atom connectivity
-hydrate isomers: H2O is a ligand or an additional occupant within the
crystal; [Co(NH3)4(H2O)Cl]Cl2 (where H2O is a ligand) vs
[Co(NH3)4Cl2]Cl⋅H2O (where H2O is the solvate but incorporated
into the crystal structure)
-ionization isomers: compounds w/ same formula but give different
isomers upon isomerization; [Co(NH3)4(NO2)Cl]Cl vs
[Co(NH3)4Cl2]NO2 (different counterions), [Co(NH3)4(H2O)Cl]Cl2
vs [Co(NH3)4Cl2]Cl⋅H2O (examples of both hydrate and ionization
isomers), etc.
-coordination isomers: coordination compounds where the metal
cations and anions switch ligands, ligands attached to a specific metal
ion change, or metals change oxidation states; for ex,
[Zn(NH3)4][CuCl4] and [Cu(NH3)4][ZnCl4], [Pt(NH3)4][PtCl6] and
[Pt(NH3)4Cl2][PtCl4], and Pt(II)Pt(IV) and Pt(IV)Pt(II)
-linkage isomers: where the same compound has different
connectivity due to an ambidentate ligand, meaning one that can
donate a lone pair of electrons to a central metal atom through more
than one donor atom; for ex, [Co(NH3)5(NO2)]^2+ exists as 2
linkage isomers, one where the nitrite is bound through nitrogen and
another where it's bound via oxygen
Diastereomers and constitutional isomers have different solubilities,
different X-ray diffraction patterns, and different IR spectra, while
enantiomers won't normally by XRD, IR and Raman, etc.
What is Magnus's Green salt? - CORRECT ANSWERS The
first known platinum ammine; used as a research material in materials
science for developing new electronics
, What is the primary way we determine bond lengths and bond angles
for inorganic compounds? - CORRECT ANSWERS Single-
crystal X-ray diffraction
-monochromatic X-rays irradiate the crystal; the X-rays scatter off the
periodic electron density in the crystal
-the X-rays diffract at specific angles related to the shape and size of
the unit cell, and the diffraction angles can then be related to the
periodic spacing of atoms in the crystals
Under what circumstances do enantiomers differ in physical and
chemical properties? What is enantioselectivity? - CORRECT
ANSWERS Enantiomers usually have the same chemical
properties unless it's interacting w a chiral thing like object, light, and
surfaces
-for ex, [Rh(en)3]^3+ can be used to resolve chiral anions like tartrate
(TA)
-enantioselectivity is preferential formation of one enantiomer over
another in a chemical reaction
What is the best way to separate enantiomers? - CORRECT
ANSWERS If you want to separate two enantiomers, you can
try to crystallize them by coordinating them with an enantiomerically
pure counterion (or by making a Lewis acid-base adduct as shown), as
when 2 enantiomers of opposite chirality are each bound to a second
molecule or ion that is also chiral (and only one enantiomer of the 2nd
species is present), they become diastereomers with different
solubilities
-for ex, 1-Phenylethylamine/methyl benzylamine (MBA) can form
diastereomeric salts when it reacts with chiral acids: (R,R)-TA with R-
UPDATED Study Guide QUESTIONS
AND CORRECT ANSWERS
- What are the two designations used to denote the chirality of chelate
rings? - CORRECT ANSWERS Left-handed
(counterclockwiese): Λ
Right-handed (clockwise): Δ
Another Way to Identify Λ and Δ Propellers - CORRECT ANSWERS
Left-handed propeller: spinning counterclockwise would move
object away from us (or push air towards us)
Right-handed propeller: spinning clockwise would move object away
from us (or push air towards us)
What is the textbook method of identifying the chirality of chelate
rings? - CORRECT ANSWERS Rotate the structure to place
one ring horizontally across the back at the top of the triangular face
-image the front ring as being parallel to the back ring (eclipsed
structure); determine what rotation of the front ring is required to
obtain the actual structure
-if the rotation in Step 2 is counterclockwise, the structure is
designated as lambda Λ; if the rotation in Step 2 is clockwise, the
structure is designated as delta Δ
Identifying Chelate Ring Chirality 2 - CORRECT ANSWERS
Picture
,What are structural/constitutional isomers? What are 4 types? How do
diastereomers and constitutional isomers compare in physical
properties vs how enantiomers compare? - CORRECT ANSWERS
Molecules that have the same molecular formula but different
atom connectivity
-hydrate isomers: H2O is a ligand or an additional occupant within the
crystal; [Co(NH3)4(H2O)Cl]Cl2 (where H2O is a ligand) vs
[Co(NH3)4Cl2]Cl⋅H2O (where H2O is the solvate but incorporated
into the crystal structure)
-ionization isomers: compounds w/ same formula but give different
isomers upon isomerization; [Co(NH3)4(NO2)Cl]Cl vs
[Co(NH3)4Cl2]NO2 (different counterions), [Co(NH3)4(H2O)Cl]Cl2
vs [Co(NH3)4Cl2]Cl⋅H2O (examples of both hydrate and ionization
isomers), etc.
-coordination isomers: coordination compounds where the metal
cations and anions switch ligands, ligands attached to a specific metal
ion change, or metals change oxidation states; for ex,
[Zn(NH3)4][CuCl4] and [Cu(NH3)4][ZnCl4], [Pt(NH3)4][PtCl6] and
[Pt(NH3)4Cl2][PtCl4], and Pt(II)Pt(IV) and Pt(IV)Pt(II)
-linkage isomers: where the same compound has different
connectivity due to an ambidentate ligand, meaning one that can
donate a lone pair of electrons to a central metal atom through more
than one donor atom; for ex, [Co(NH3)5(NO2)]^2+ exists as 2
linkage isomers, one where the nitrite is bound through nitrogen and
another where it's bound via oxygen
Diastereomers and constitutional isomers have different solubilities,
different X-ray diffraction patterns, and different IR spectra, while
enantiomers won't normally by XRD, IR and Raman, etc.
What is Magnus's Green salt? - CORRECT ANSWERS The
first known platinum ammine; used as a research material in materials
science for developing new electronics
, What is the primary way we determine bond lengths and bond angles
for inorganic compounds? - CORRECT ANSWERS Single-
crystal X-ray diffraction
-monochromatic X-rays irradiate the crystal; the X-rays scatter off the
periodic electron density in the crystal
-the X-rays diffract at specific angles related to the shape and size of
the unit cell, and the diffraction angles can then be related to the
periodic spacing of atoms in the crystals
Under what circumstances do enantiomers differ in physical and
chemical properties? What is enantioselectivity? - CORRECT
ANSWERS Enantiomers usually have the same chemical
properties unless it's interacting w a chiral thing like object, light, and
surfaces
-for ex, [Rh(en)3]^3+ can be used to resolve chiral anions like tartrate
(TA)
-enantioselectivity is preferential formation of one enantiomer over
another in a chemical reaction
What is the best way to separate enantiomers? - CORRECT
ANSWERS If you want to separate two enantiomers, you can
try to crystallize them by coordinating them with an enantiomerically
pure counterion (or by making a Lewis acid-base adduct as shown), as
when 2 enantiomers of opposite chirality are each bound to a second
molecule or ion that is also chiral (and only one enantiomer of the 2nd
species is present), they become diastereomers with different
solubilities
-for ex, 1-Phenylethylamine/methyl benzylamine (MBA) can form
diastereomeric salts when it reacts with chiral acids: (R,R)-TA with R-
