TopHat Chapter 14

Trigonal Prismatic/Anti Possible Conformers

1) 3 Methyl Group on one side completely elipse or block three methyl group on opposite side 2) Two pyramids are staggered--this one more stable since gives optimum distance between opposite facing methyl groups

To calculate CFSE for octahedral

1) Write out orbitals 2) spread out electrons (one per orbital on bottom then double up then one per top then double up) 3) Then find number of electrons on top and bottom and plug into equation: (# on bottom)(-0.4) + (# on top)(+0.6)

For octahedron, how many orbitals on top and bottom?

_______ ________ 2 on top ______ _____ ______ 3 on bottom

Orbital mapping of square planar

________ dx2-y2 _________dxy _________dz2 ________ dxz _________dyz

Atomic Trend for Energy Difference

As size of transition metal increases, the energy difference increases

Does charge or size trend take dominance?

CHARGE

Coordination Number 7

Capped octahedron Pentagonal biprism-- 1 lone

Two major components

Complex ion and Counter Ion

Complex Ion

Contains the metal atoms/ions and any attached atoms/ions -Contains a central metal cation bonded to one o r more molecules or ions

For coordination compounds, the term _____________________ ____________________ is often used in place of steric number of electron domains

Coordination Number

For octahedral, where is the following located? dxy

In between x and y axes

For octahedral, where is the following located? dxz

In between x and z axes

For octahedral, where is the following located? dyz

In between y and z axes

Flaws of crystal field theory

Is strictly electrostatic model with the -attraction between metal nucleus and ligand electrons -the repulsion of the metal electrons with ligand electron *No covalent character

For octahedral, where is the following located? dz2

Lies directly on z axis

For octahedral, where is the following located? dx2-y2

Lies on the x and y axes

Coordination Number 2

Linear

Large Splitting

Lower energy d orbitals are filled before higher energy orbitals are occupied

High Spin

Occupy one electron in EACH orbital (one in each top and bottom) before doubling up

Low Spin

Occupy one in each bottom, then double the bottom, then one in each top, then double the top

Coordination 6 common geometry

Octahedral

Coordination Number 6

Octahedron Pseudo-octahedal--1 lone Anti-prism-- 2 lone

Coordination

Refers to the bonds between transition elements and molecules/ions

VSEPR

Shows common molecular geometries for compounds based on bonding and nonbonding electron pairs around central atom

Octahedral without any ligand electron domains along z-axis

Square Planar

Coordination 4 common geometry

Tetrahedral

Coordination Number 4

Tetrahedron Square Planar-- 2 lone

Oxidation States for Energy Difference

The HIGHER the metal's oxidation state, the LARGER the CFSE

Crystal Field Stabilization Energy

The difference in energy between having all electrons in a spherical field and arranged in an octahedral field

CFT is unable to explain why certain ligands...

bind more strongly in coordination compounds

Complex ion is always enclosed in

brackets

charge of ligands can be...

positive, negative, or neutral

Major difference between compounds focused on previously and transition metal complexes is:

presence of occupied "d" orbitals (similar in energy to valence orbitals of the atom)

What does CFT provide?

rationale for prediction of color and magnetism of coordination compounds

Like charges (repel/don't repel)

repel

CFT is not truly a bonding theory, but allows us to account for...

shape, color, bond strength, and magnetic behavior of coordination compound

Therefore, ΔO is small enough such that it is more favorable to ...

single occupy all 5 metal d orbitals before pairing up

As electron donating and withdrawing groups are added, there is a (smaller/larger) HOMO/LUMO gap

smaller

Larger gap between HOMO/LUMO= (larger/smaller) wavelength

smaller

Therefore, (smaller/larger) volume for pair of electrons to occupy so pairing energy that arises due to electron pair (is/is not) significant for 3d complexes

smaller, is

Purple has (smallest/largest) wavelength reflected and red has (smallest/largest)

smallest, largest

Common alternative to tetrahedral is the ______________ _________________

square planar

0.4 is always multiplier for (t2g.eg)

t2g

dxy, dyz, dxz are known as _______ orbitals

t2g

In crystal field theory, the energetic effects of the ligands on the d orbitals of the metal are determined based on the ...

the geometry of the compound

Therefore, ΔO tends to be (small/large) enough such that _______________________________________________________________ is more favorable

the pairing of electrons

Charge of ligand is...

charge of molecule that forms ligand when electrons from ligand-metal bond are associated with the ligand

Counter Ions are required any time the primary coordination sphere is ________________

charged

The charge of the complex ion can be determined by the _____________ of the components of the coordination sphere

charges

___________ and ___________ of coordination compounds can often be predicted

color and magnetism

Complex ion is also known as primary

coordination sphere

__________________ _______________ ______________ extends bonding theory to coordination compound

crystal field theory

The extent of splitting between d orbitals (magnitude of Δ) influences the ______________ _____________________ within the orbitals

electron configuration

Ligand donates one or more electron pairs to the metal atom or cation and therefore acts as a...

electron pair acceptor

Crystal Field Theory is an ___________________ approach to orbital energies

electrostatic

When d orbitals of transition metals are surrounded by ligands, experience ____________________ ____________________ due to proximity to electrons

electrostatic repulsion

ΔO=

energy difference between upper set of d orbitals and the lower set

Barycenter=

energy level of five degenerate d orbitals in a perfectly spherical ligand environment

Unlike structures of coordination number 4, octahedral complexes are prevalent throughout _______________ _________ electron count

entire d

For 4d/5d orbitals, there is (greater/less) volume of space so (more/less) accommodating of electron pair and pairing energy (is/is not) significant

greater, more, is not

Experiments show... 3d transition metal complexes tend to favor (high/low) spin configurations 4d and 5d transition metal complexes tend to favor (high/low) spin configurations

high, low

Unique aspect of coordination complexes is that they are (higher/lower)

higher

In addition to geometry identity of the metal ion, the ________________________________________________ also affect the magnitude of the crystal splitting

identity of the ligand and ligands that bond to the metal

t2g orbitals lie (on/inbetween) axes

inbetween axes

For tetrahedral, eg orbitals lie (on/inbetween) ligand axes t2g orbitals lie (on/inbetween) axes

inbetween, on

However any transition metal d orbitals that lie along the ligand axes will (increase/decrease) in energy due to close proximity of ligand electrons

increase

If all ligands uniformly surround the d orbitals equally in a spherical arrangement, then all 5 of the d orbitals experience same (increase/decrease) in energy

increase

In octahedral, eg orbitals (increase/decrease) in energy

increase

For tetrahedral, t2g orbitals (increase/decrease) in energy by __________

increase, 0.4

Energy and Wavelength have a (direct/inverse) relationship

inverse

3d orbitals are (larger/smaller)

larger

In octahedral field, dz2 and dx2-y2 orbitals will undergo a (smaller/larger) increase in energy for...

larger, highly charged transition metals

In high spin, (more/less) electron repulsion which (increases/decreases) energy of the system so ΔO is (more/less) than energy associated with electron/electron repulsion

less, decreases, less

Fewer ligand electron regions= electron electron repulsion is (more/less) severe= split (more/less)

less, less

Tetrahedral has (more/fewer) ligand electron regions so electron repulsion is (more/less) severe

less, less

Therefore, metal d orbitals split (more/less) in tetrahedral so ΔT (greater than/less than) ΔO

less, less than

Every ligand's point of attachment to the metal contains at least one...

lone pair of electrons

Unlike main group elements, coordination compounds do NOT have...

lone pairs above and below plane of the square

With large CFSE, is greater tendency for (high/low) spin

low

CFT never addresses the interaction between...

metal d orbitals and ligand orbitals

For Pseudo-octahedral, an example of class of compounds known as _______________ consists of two cyclopentadienyl rings are perpendicular to the center axis and will sandwich the metal center

metallocenes

Both __________ and ___________ can contain charges that contribute to the overall charge

metals and ligands

When ligand electron domains are removed along the z-axis, repulsion is (maximized/minimized) in this spacial direction only

minimized

Octahedral can be obtained using ________, _________ or ______________

mono, bi or poly

As the charge of transition metal increases, ligand electrons are (more/less) strongly attracted to the metal's nucleus

more

In low spin, (more/less) electron repulsion which (increases/decreases) energy of the system so ΔO is (more/less) than energy associated with electron/electron repulsion

more, increases, greater

CFT considers bonding electrons in ligands as (positive/negative) point charges

negative

d complexes

number of electrons residing in metal d orbitals of these complexes

When hemoglobin becomes oxygenated to become oxyheme, ___________________ geometry is observed

octahedral

eg orbitals lie (on/inbetween) axes

on the axes

For octahedral, Each t2g electron contributes... Each eg electron contributes...

-0.4 ΔO 0.6 ΔO

Factors affecting crystal field splitting (Δ)

-Identity of the transition metal -Oxidation state of the transition metal -Identity of the ligand -Geometric ligand field surrounding the metal cation

Ligand

-The molecules or ions that surround the metal in a complex ion -Coordinate to the metal by donating one or more electron pairs to the metal atom or cation

Lower set of d orbitals decrease in energy from barycenter by ____________ ΔO

0.4

Upper set of d orbitals increase in energy from barycenter by _________ . ΔO

0.6

How many ligand electron regions in each? Tetrahedral? Octahedral?

4, 6

There are _____ d orbitals that each have a different...

5, orientation around the atom

When transition metals are solvated by water molecules, most common coordination involves ________ aqua ligands surrounding metal ion

6

Interest in coordination chemistry is because...

Their colors, their magnetic properties, and many biomolecules are coordination compounds

Coordination Number 3

Trigonal T-Shaped -- 1 lone

Coordination Number 5

Trigonal Bypyramidal Square-based Pyramids--1 lone

This is due to ...

atomic size trend

Which must be high spin?

d1, d2, d3, d8, d9, d10

Which can be high spin or low spin?

d4, d5, d6, d7

In octahedral, t2g orbitals (increase/decrease) in energy

decrease

Therefore, any metal d orbital containing z-axis will (increase/decrease) in energy relative to octahedral field

decrease

For tetrahedral, eg orbitals (increase/decrease) in energy by _________

decrease, -0.6

z-axis

defined as axis going through metal center containing axial groups

However, if 6 equivalent negative point charges occupy corners of octahedron, d orbitals experience the (same/different) change in energy

different

Which orbitals decrease and which increase?

dxz, dyz, dz2 decrease dxy, dx2-y2 increase

Just as trigonal prismatic/antiprismatic, ______________ and _______________ conformations exist as metallocenes and are (more/less) stable

eclipsed, staggered, more

0.6 is always multiplier for (t2g/eg)

eg

dz2 and dx2-y2 are known as _______ orbitals

eg