Metal-Ligand Bonding

Question 1

What is the Electropositive trend of the transition metals?

Answer 1

Electropositivity increases from right to left and down a group

Question 2

What is hapticity η?

Answer 2

The number of contiguous atoms of a ligand attached to a metal

Question 3

What is denticity κ?

Answer 3

The number of non-contiguous atoms coordinating from a ligand (often a. chelating ligand)

Question 4

What is µ?

Answer 4

Number of metal atoms bridged by a ligand

Question 5

How do you find the oxidation state?

Answer 5

Oxidation state = Charge on the complex - Sum of the charges of the ligands

Question 6

What charge does a linear NO ligand have and how many electrons does it donate?

Answer 6

+1 (NO+)
donates 3 electrons

Question 7

What charge does bent NO ligand have and how many electrons does it donate?

Answer 7

-1 (NO-)
Donates 1 electron

Question 8

How can you work out the ligand charge?

Answer 8

Determine how many H+ to add until the molecule is neutral

Question 9

What is the electroneutrality principle?

Answer 9

The formal charge is not the actual charge distribution. No atom will have an actual charge greater than + or - 1

Question 10

How do you find the d-electron count?

Answer 10

d-electron count = group number - oxidation state

Question 11

How do you find the Total Valence Electron Count (TVEC)?

Answer 11

TVEC = d-electron count + electrons donated by ligands

Question 12

What is the ionic formalism?

Answer 12

M-L -> M+ + L-

Question 13

u

Question 14

What is the trend of coordination numbers for early groups in transition metals?

Answer 14

In general, coordination numbers are greater for earlier TM groups (4-7). Coordination numbers for lanthanides are generally greater than TMs

Question 15

What area the steric limit for number of ligands on transition metals and lanthanides?

Answer 15

TM - 6 ligands
Lanthanides - 9 Ligands

Question 16

What are the 3 requirements of the orbitals for a bond to form?

Answer 16

1) Must have appropriate symmetry
2) Must overlap
3) Must be similar energy

Question 17

What is a sigma donor?

Answer 17

Has a lone pair of electrons to donate to the metal

Question 18

What is a Sigma donor, Pi acceptor?

Answer 18

Has lone pair to donate to met, aswell as another empty orbital to accept electron density from metal

Question 19

What is a sigma donor, pi donor?

Answer 19

Has multiple lone pairs to donate to the metal

Question 20

How can you find the ordering of the d-orbitals?

Answer 20

Crystal Field Theory

Question 21

What orbitals are the bonding to a metal determined by?

Answer 21

HOMO/LUMO

Question 22

What does the greater electronegativity around a carbon atom in CO do for the bonding and why?

Answer 22

Creates better overlap for the sigma donation via carbon atom to happen

Question 23

What can occupying the antibonding orbitals do to the bond?

Answer 23

Break the bond

Question 24

How can you decide whether the NO is bent or linear?

Answer 24

Work out the TVEC of the complex without the NO, and see if you need to add 3 (linear) or 1 (bent) electron to make the TVEC upto 18

Question 25

What is required for a pi donor interaction in terms of orbitals?

Answer 25

empty d orbitals

Question 26

Why don't pi donor systems always obey the 18 electron rule?

Answer 26

The pi donor ligands and the t2g orbitals are now pi antibonding and is therefore less energrtically favourible to fill them

Question 27

What is the spectrochemical series?

Answer 27

A list of ligands in order of increasing field strength.

Question 28

What are examples of pi-acceptor ligands in order of increasing field strength?

Answer 28

CO > CN- > PPh3

Question 29

What are examples of sigma-only ligands in order of increasing field strength?

Answer 29

NH3 > H2O > OH- > F-

Question 30

What are examples of pi-donor ligands in order of increasing field strength?

Answer 30

Cl- > S2- > Br- > I-

Question 31

Put these in order of increasing field strength: pi-acceptors sigma only pi-donors

Answer 31

pi-acceptor > sigma only > pi-donors

Question 32

why is the eg to eg transfer in an octahedral field a large change in bomd lentgh? and how does this effect speed ov electron transfer and overlap?

Answer 32

In an Oh field eg is sigma star less overlap slower speed of electron transfer

Question 33

why is the t2g to t2g transfer in an octahedral field a small change in bond length? and how does this effect speed of electron transfer and overlap?

Answer 33

t2g in an octahedral is pi/pi star/ non bonding faster elcetron transfer more overlap

Question 34

how does large bond length change effect speed of reaction?

Answer 34

slows reaction with larger bond length change

Question 35

In an electron transfer do you relax the bomd first or transfer the elctron first?

Answer 35

relax the bonds and then transfer the electrons

Question 36

why not transfer electron and then relax bonds? and what could be used to make it happen?

Answer 36

you cannot just spontaneously transfer electrons as it violates the conservation of energy a photon could be used for vertical transition

Question 37

what is delta r?

Answer 37

Metal - Ligand bond length difference between the oxidant and reductant

Question 38

how do you find the delta G from a delta r diagram

Answer 38

the distance between the starting delta r and the intersection pf the 2 parabolas

Question 39

What does the intersection of 2 parabolas in a reaction coordinat transition state diagram show?

Answer 39

the requirement of equal orbital energies is met, and this allows the possibility of electron transfer

Question 40

hiw can you determine the probability of a reaction?

Answer 40

draw the 2 parabolas but without the intersectuon (looksmlike a normal reaction coordinate) and the size of the gap (delta Ec) determines probability (larger the more probable)

Question 41

in the normal region what is ghe relation between activation energy (delta G dagger) and driving force (delta G o)?

Answer 41

delta G dagger is proportional to 1/delta G o squared

Question 42

what is the relation between delta G dagger (activation energy) and delta r?

Answer 42

delta G dagger proportional to delta r squared bigger changes im bind lengths equals bigger delta G ( activation energy) so slower reaction

Question 43

are reactions fast or slow if they have simmilar bond lengths?

Answer 43

fast

Question 44

go over the equation on page 57

Answer 44

lololololol

Question 45

rate gets slower if activation energy increases

Question 46

learn the activation enrrgy and lander rules (there is 3)

Answer 46

trollolololol

Question 47

how does rate (k) relate to thermodynamic driving force (delta G o) in the inverted region?

Answer 47

rate (k) decreases as the thermodynamic driving force increases (inverted region)