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Core 4b > Metal-Ligand Bonding > Flashcards

Metal-Ligand Bonding Flashcards

1
Q

What is the Electropositive trend of the transition metals?

A

Electropositivity increases from right to left and down a group

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2
Q

What is hapticity η?

A

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

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3
Q

What is denticity κ?

A

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

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4
Q

What is µ?

A

Number of metal atoms bridged by a ligand

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5
Q

How do you find the oxidation state?

A

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

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6
Q

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

A

+1 (NO+)
donates 3 electrons

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7
Q

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

A

-1 (NO-)
Donates 1 electron

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8
Q

How can you work out the ligand charge?

A

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

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9
Q

What is the electroneutrality principle?

A

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

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10
Q

How do you find the d-electron count?

A

d-electron count = group number - oxidation state

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11
Q

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

A

TVEC = d-electron count + electrons donated by ligands

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12
Q

What is the ionic formalism?

A

M-L -> M+ + L-

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13
Q

u

A
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14
Q

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

A

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

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15
Q

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

A

TM - 6 ligands
Lanthanides - 9 Ligands

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16
Q

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

A

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

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17
Q

What is a sigma donor?

A

Has a lone pair of electrons to donate to the metal

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18
Q

What is a Sigma donor, Pi acceptor?

A

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

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19
Q

What is a sigma donor, pi donor?

A

Has multiple lone pairs to donate to the metal

20
Q

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

A

Crystal Field Theory

21
Q

What orbitals are the bonding to a metal determined by?

A

HOMO/LUMO

22
Q

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

A

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

23
Q

What can occupying the antibonding orbitals do to the bond?

A

Break the bond

24
Q

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

A

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

25
Q

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

A

empty d orbitals

26
Q

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

A

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

27
Q

What is the spectrochemical series?

A

A list of ligands in order of increasing field strength.

28
Q

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

A

CO > CN- > PPh3

29
Q

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

A

NH3 > H2O > OH- > F-

30
Q

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

A

Cl- > S2- > Br- > I-

31
Q

Put these in order of increasing field strength:

pi-acceptors
sigma only
pi-donors

A

pi-acceptor > sigma only > pi-donors

32
Q

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?

A

In an Oh field eg is sigma star

less overlap

slower speed of electron transfer

33
Q

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?

A

t2g in an octahedral is pi/pi star/ non bonding

faster elcetron transfer

more overlap

34
Q

how does large bond length change effect speed of reaction?

A

slows reaction with larger bond length change

35
Q

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

A

relax the bonds and then transfer the electrons

36
Q

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

A

you cannot just spontaneously transfer electrons as it violates the conservation of energy

a photon could be used for vertical transition

37
Q

what is delta r?

A

Metal - Ligand bond length difference between the oxidant and reductant

38
Q

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

A

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

39
Q

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

A

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

40
Q

hiw can you determine the probability of a reaction?

A

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)

41
Q

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

A

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

42
Q

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

A

delta G dagger proportional to delta r squared

bigger changes im bind lengths equals bigger delta G ( activation energy) so slower reaction

43
Q

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

A

fast

44
Q

go over the equation on page 57

A

lololololol

45
Q

rate gets slower if activation energy increases

A
46
Q

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

A

trollolololol

47
Q

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

A

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

Core 4b (4 decks)

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