Review of variable Review of variable valence valence Transition metal ions have Transition metal ions have variable oxidation state variable oxidation state Electron configurations Electron configurations 4s 4s 2 3d 3d n with some exceptions with some exceptions
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Review of variable valence Transition metal ions have variable oxidation state Electron configurations 4s 2 3d n with some exceptions 4s 2 3d n with.
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Review of variable valenceReview of variable valence
Transition metal ions have variable oxidation Transition metal ions have variable oxidation statestate
Electron configurationsElectron configurations 4s4s223d3dnn with some exceptions with some exceptions
Isomerism – same atoms, different Isomerism – same atoms, different arrangementarrangement
Constitutional and stereoConstitutional and stereo
ConstitutionalConstitutional Different connections between the atomsDifferent connections between the atoms
Linkage isomers (choice of linkage atom)Linkage isomers (choice of linkage atom) Ionization isomers (different anion bonding)Ionization isomers (different anion bonding)
StereoisomersStereoisomers Same connections but different spatial Same connections but different spatial
Linkage isomersLinkage isomers The nitrite ion can use either the O or the N atom as the ligand The nitrite ion can use either the O or the N atom as the ligand
since both have non-bonding pairs.since both have non-bonding pairs. Indicate linkage in the name:Indicate linkage in the name:
Nitro (NONitro (NO22) links through N) links through N Nitrito (ONO) links through ONitrito (ONO) links through O
Obvious influence on physical propertiesObvious influence on physical properties
Ionization isomersIonization isomers
Different anions are linked to the central atomDifferent anions are linked to the central atom
In one, the free anion is SOIn one, the free anion is SO442-2-
In the second, the free anion is BrIn the second, the free anion is Br--
Same attachments but different arrangement Same attachments but different arrangement Cis- and trans- (analogous to bonding in alkenes)Cis- and trans- (analogous to bonding in alkenes)
Influences physical properties through different polarityInfluences physical properties through different polarity
Example with square planar: opposite or side-by-sideExample with square planar: opposite or side-by-side
Octahedral complexOctahedral complex
Not all complexes qualify for Not all complexes qualify for geometric isomersgeometric isomers
Square planar – Square planar – MLML22XX22 (cis and trans) (cis and trans)
MLML33X (none)X (none)
Tetrahedral – none with any compositionTetrahedral – none with any composition Octahedral –Octahedral –
MLML44XX22 (cis and trans) (cis and trans)
MLML33XX33
MLML55X (none)X (none)
More than two ligands…More than two ligands…
MLML22XY or MLXY or ML44XY can also have cis and trans XY can also have cis and trans
isomersisomers
Isomers or equal?Isomers or equal?
What hands are these…?What hands are these…?
Apparently all same connections and yet…Apparently all same connections and yet… Enantiomers are molecules or ions that form Enantiomers are molecules or ions that form
mirror images of each othermirror images of each other Tetrahedral C atoms with four different groupsTetrahedral C atoms with four different groups
Hands are enantiomers.Hands are enantiomers. They possess chiralityThey possess chirality Molecules that have no handedness are achiralMolecules that have no handedness are achiral
Testing for chiralityTesting for chirality
Presence of planes of symmetry – achiralPresence of planes of symmetry – achiral Absence of plane of symmetry – chiralAbsence of plane of symmetry – chiral
Handedness in complexes with Handedness in complexes with bidentate ligandsbidentate ligands
How many diastereoisomers and enantiomers are How many diastereoisomers and enantiomers are there of Co(en)there of Co(en)22ClCl22
++??
Getting a complex?Getting a complex?
Which are chiral?Which are chiral? Which are achiral?Which are achiral? What are the enantiomers?What are the enantiomers?