Chem 107 Final Review

VBT

starts by hybridizing atomic orbitals on a central atom, and uses these hybrids to form bonds to nearby substituents

Fine Structure

refers to the splitting of spectral lines of atoms due to electron spin and relativistic effects. Due to vibronic coupling

Diamagnetic

characterized by paired electrons that are not attracted to a magnetic field

Paramagnetic

characterized by unpaired electrons that are attracted to a magnetic field.

Molecular Orbital Theory

assumes that the valence elctrons of atoms within a molecule will form orbital overlaps and become delocalized as allowed by symmetry rules

Three Conditions for AOs to interact and form MOs

Same symmetry, similar energy, spatial overlap

Non-bonding Combinations

Orbitals with differing numbers of internuclear nodes cannot form overlaps, and result in non-bonding combinations

Gerada

symmetrical with respect to inversion

Ungerada

unsymmetrical with respect to inversion

sp Mixing

When orbitals of the same symmetry (sigma or pi, g or u) are of a similar energy, they can undergo a further interaction. The more stable orbital is further stabilized, while the less stable orbital is further destabilized

Effective Nuclear Charge

the positive charge experienced by the valence electrons of an atom or molecule. As you move right on periodic table, Zeff increases because there are more protons in the nucleus. s-type orbitals are more sensitive to increases in Zeff because they have more electron density

Molecules with sp-mixing

Li2, Be2, B2, C2, N2

Molecules without sp mixing

O2, F2, Ne2

Crystal Field Theory

a simple explanation for how d-electrons are perturbed by the ligands that surround a metal. the point charges are the ligands themselves, which function as repulsive electron clouds

Ligand Field Theory

combines ideas of CFT and MO theory to describe the interactions of metal valence orbitals with frontier MOs of the ligands

3dz²

3dx²-y²

3dyz

3dxz

3dxy

Octahedral crystal field splitting

From top to bottom: (dz²,dx²-y²), (dxy,dyz,dxz)

Tetrahedral crystal field splitting

From top to bottom: (dxy,dyz,dxz), (dz²,dx²-y²)

Square planar crystal field splitting

From top to bottom: (dx²-y²), (dxy), (dz²), (dxz,dyz)

ML5, D3h crystal field splitting

From top to bottom: (dxy, dx²-y²), (dz²) higher energy, (dxz,dyz)

D3h, ML3 crystal field splitting

From top to bottom: (dxy, dx²-y²), (dz²) lower energy, (dxz, dyz)

Order of crystal field splitting energies

Delta sp > Delta O > Delta T 

Tetrahedral splitting, high or low spin

high spin

Square planar, high or low spin

low spin

Octahedral, high or low spin

either or, depends on ligand

Multiplicity

count unpaired electrons, add one

Noble d8 metal compounds are usually tetrahedral or square planar?

Square planar; if tetrahedral, more electrons placed in higher energy level compared to square planar diagram

Pi donor or acceptors: Cl-, Br-, I- 

Pi donors

Pi donor or acceptors: OR-, SR-

Pi donors

Pi donor or acceptor: NR^2-

Pi donor

Pi donor or acceptor: O^2-

Pi donor

Pi donor or acceptors: NR₂ -

Pi donor

N^3-

Pi donor

Pi donor or acceptor: H2O

regular sigma donor!

Pi donor or acceptors: NH3

regular sigma donor!

Pi donor or acceptors: en (ethylenediamine)

regular sigma donor!

Pi donor or acceptors: PMe₃

regular sigma donor!

Pi donor or acceptors: CO

pi acceptor

Pi donor or acceptors: CN-

pi acceptor

Pi donor or acceptors: NO+

pi acceptor

Pi donor or acceptors: pyridine

pi acceptor

High or low spin for pi acceptor

low spin

high or low spin for pi donor

high spin

Geometries for 3-coordinate complexes

t-shaped, pyramidal, trigonal planar

Geometries for 5-coordinate complexes

trigonal bipyramidal, square pyramidal

Geometries for 6-coordinate complexes

tetragonally distorted, octahedral, trigonal prisms

Seven coordinate geometry

Pentagonal bipyramid

Eight coordinate geometry

square antiprismatic, bicapped trigonal prismatic

Coordinate covalent bond

a bond in which both electrons are donated from one of the atoms/groups. AKA dative bond. ONLY applies to neutral ligands

Nomenclature: H2O

aquo

Nomenclature: NH3

ammine

Nomenclature: OH-

hydroxo

Nomenclature: H

hydrido

Nomenclature: CN-

cyano

Nomenclature: NO2-

nitro

Nomenclature: O^2-

oxo

Nomenclature: —SCN-

thiocyano

Nomenclature: —NCS-

isothiocyano

Nomenclature: anionic complexes

get -ate suffix to metal.

Some use greek name, ex:

Fe: ferrate Ag: Argenate Pb: Plumbate

Au: Aurate Sn: Stanate

Nomenclature: bridging ligands

prefix µⁿ-

(where n is # of metals bridged)

Nomenclature: PR3

phosphine

Nomenclature: NR₂^-

amido

Nomenclature: NR^2-

imido

Denticity

number of donor atoms on a ligand

ex.

monodentate: phosphine

bidentate: bipy

bipy

ortho-phenanthroline (ophen)

diethylenetriamine (dien)

triethylenetetraamine (trien)

tris-(2-aminoethyl)amine (tren)

terpy

terpyridine (bipy + another pyridine)

Chelation

binding of a metal by a ligand through 2 or more donor atoms, forming a ring(s)

Thermodynaic Chelate effect

chelating ligands form more thermodynamically stable complexes than with non-chelating ligands. it’s primarily an entropic effect

Kinetic chelate effect

the probability of a dissociated ligand binding back to the metal is increased when that ligand is held on by a “tether”. if the chelated ligand partially dissociates, reassociation is facile because it remains partially bound.

However, if ring is too large, effect is reduced.

Hydrate (solvent) isomerism

occurs when water (or another solvent) can appear within the primary or secondary coordinate sphere of a metal ion; e.g. [Cr(H₂O)₆]Cl₃ vs. [CrCl(H₂O)₅]Cl₂ . H₂O

Ionization isomers

the same formulae, but differ in which ions are present in the primary and secondary coordination spheres; e.g. [Co(NH₃)₅(SO₄)][NO₃] vs. [Co(NH₃)₅(NO₃)][SO₄]

Coordination isomerism

occurs when ligands can be distributed differently between two or more metals

Linkage isomerism 

occurs when ligands use different donor atoms to bind to a metal center

fac or mer?

mer

fac or mer?

fac

Λ or ∆?

lambda

Λ or ∆?

delta

Symmetry of p-orbital

C∞v

Symmetry of d-orbitals (not z²)

D2h

Symmetry of f-orbitals

Td

Chiral or achiral?: C1, Cn, Dn

chiral

How to determine point group

what is ∆E approximately equal to

∆o. Therefore, incresing ∆o, decreases wavelength (lambda) absorbed

Laporte selection rule

selection rule explaining transitions between different orbitals (d→p allowed, d→d not allowed)

(can also think of g→u allowed, g→g not allowed)

spin selection rule

A transition is allowed if the starting and final states have the same multiplicity (∆S=0)

(Basically can’t pair spin up and spin up, gotta be up and down pairing)

strongly colored, somewhat colored, or colorless: spin and laporte allowed

strongly colored

strongly colored, somewhat colored, or colorless: spin forbidden, laporte allowed (or vice versa)

somewhat colored

strongly colored, somewhat colored, or colorless: spin and laporte forbidden

colorless

Jahn-Teller Theorem

a system with unequal occupation of degenerate electronic states will undergo a structural distortion, removing that degeneracy

Weak or strong Jahn Teller: high spin d4

strong

Weak or strong Jahn Teller: low spin d7

strong

Weak or strong Jahn Teller: d9

strong