4d

Question 1

if u have a complex with 2 isomers,, 1 more symmetric than the other,, what one will we predict has more IR abs bands

Answer 1

the less symmetric one will have more IR abs bands!!!

more symmetry = less abs bands

Question 2

3 ways we can synthesise metal carbonyls

Answer 2

direct combination

reductive carbonylation

ligand replacement

Question 3

ways of synthesising metal carbonyls: direct combination

give examples

Answer 3

Ni + 4CO –> Ni(CO)4

Fe + 5CO –> Fe(CO)5

only these 2 metals allow us to directly combine them with CO

Question 4

ways of synthesising metal carbonyls: reductive carbonylation

Answer 4

ReO2 + 17CO –> Re2(CO)10 + 7CO2

aka we have a salt and add CO to get a neutral metal + CO2.

Question 5

ways of synthesising metal carbonyls: ligand replacement

Answer 5

CO displaces other ligands and takes their place in complexes

Question 6

what counts as a phosphine ligand

Answer 6

litch anything with P being the donor part with the lone pair!!

the R chains dont matter but theres always 3 of them

Question 7

describe why phosphine is crazy

Answer 7

super toxic
super smelly
spontaneously fammable

Question 8

what shape // geometry does a phosphine ligand have

Answer 8

it has tetrahedral geometry

lone pair and the 3R chains

Question 9

when a phosphine ligand forms a sigma donation bond,, how many e- are donated

Answer 9

the lone pair,, aka,, 2 e-

Question 10

describe the phosphine M bonds and everything that happens with it

Answer 10

the P: is used for the sigma donation

the metal has a filled d orbital that donates e- into the P-C sigma* orbital!!!!!!!!
for backbonding!!!!

Question 11

what orbitals do Phosphine ligands accept the electrons from pi backbonding into

Answer 11

they accept them into the P-C sigma** orbital!!

not the P’s d orbital,, this is incorrect.

we still draw the backbonding as a p type orbital tho

Question 12

what about phosphine ligands is good when making complexes

Answer 12

theres a huge variety of phosphine ligands with diff sizes and diff sigma donor abilities,,, meaning we can pick which one we want to use and predict how this is gonna alter our complexxxx

Question 13

what about phosphine ligands can we use to customise things

Answer 13

• the phosphine ligands size: aka their tolman cone angle,, larger angles prevent many ligands from being bonded to the metal!! bc they take us smt space.
• its electric properties aka its sigma donor abilities

Question 14

how can we analyse the sigma donor abilities of a phosphine ligand

Answer 14

based on the 3 R groups its bonded to

if theyre electron withdrawing due to being electronegative,,, the P will be §+ while the R is §- : this weakens the sigma donor abilities of the ligand and theresfore strengthens the pi* backbonding interaction

if theyre electron donative via inductive effect,, this makes the p §- which increases its sigma donor bond,, and therefore weakens its pi* backbonding acceptor abilities.

Question 15

relationship between sigma donation and pi* backbonding

Answer 15

the better a ligand is at sigma donation,, the weaker it is at accepting pi* backbonding

theyre inversely proportional.

when theyre worse as sigma donor bonds,, theyre better at acception pi* backbonding abilities.

Question 16

are phosphines or carbonyls better at sigma donor bonds

Answer 16

phosphines are all better at sigma donor bonds accept for the PF3 phosphine ligands.

Question 17

the M-P bond with phsophine ligands is affected and determined by what

Answer 17

its determined by the metals identity and the identity of the ligands

if the metal is e- rich,, it probs wont want a good sigma donor ligand

if the metal is e- poor it probs will want a good sigma bond donor

e- poor metal will form a stronger MP bond with a good sigma donor ligand

e- rich metal will form a stronger MP bond with a good pi* backbonding acceptor ligand

Question 18

what can we use to identify phosphine ligands etc

Answer 18

31P NMR

shows diff environments,,, shows coupling constants etcccc

can show OS of metals,, ligand coordination environments and bond strengths

Question 19

what is a phosphine ligand

Answer 19

any ligand wiht a P as the 2e- donor atom

normally has 3 R groups attached to it

the type of R group it is doesnt matter

Question 20

a 2e- ligand can displace what

Answer 20

a 2e- ligand can displace other 2e- ligands

Question 21

a hydrogen directlyy bonded to a metal is called what

Answer 21

a hydride

bc its H-

Question 22

how many e- does a H-,, aka hydrode have

Answer 22

2e-

Question 23

bonding of hydrides,, what orbital does it have

Answer 23

it has a 1s orbital
which gives us a pure sigma bond

Question 24

can u have bridging Hydrides

Answer 24

yesss
H- bridging multiple metals

u overlap its s orbital with other orbitals

Question 25

MH IR stretch occurs wheree

Answer 25

2250 - 1700cm-1

Question 26

NMR shift of hydrides

Answer 26

0 --> -50ppm hydrides are very well shielded

Question 27

whats a dihydrogen complex

Answer 27

where u have the ethene bond type thing. like u have the Metal bonded to the bond that sits between 2H atoms.

Question 28

in dihydrogen,, where do the e- come from

Answer 28

the 2e- come from the H-H bond!!! aka the sigma donation comes from the 2e- in the dihydrogen bond. theyre orthogonal to eachother in a diagram.

Question 29

dihydrogen bonding explanation

Answer 29

its the in phase overlap of the 2 1s orbitals

Question 30

if the dihydrogen is made up of the in phase overlap of the 2 hydrogen 1s orbitals, what does that mean

Answer 30

that there also the out of phase 1s orbital overlap this is where the backbonding occurs. aka the 2e- from the sigma bond donate to the Metal,, and the metals d electrons donate via backbonding into the out of phase combo of 1s orbitals.

Question 31

backbonding itno dihydrogen causes what

Answer 31

it causes the HH bond to weaken it causes the HM bond to strengthen this occurs until the dihydrogen turns into dihydride: Metal is bonded to 2 separate hydrogens!!

Question 32

what are the dihydrogen hydrogens

Answer 32

theyre n2-H2 meaning theyre not independent from eachother

Question 33

what are the hydrogens of dihydride

Answer 33

theyre independent of eachother

Question 34

from dihydrogen complexes to dihydride complexes,, is it a spectrum or just 2 extremes

Answer 34

its a spectrum meaning complexes can be anywhere between them

Question 35

when u have a dihydrogen complex,, what happens to the oxidation state of the metal when sufficient backbonding occurs and causes dihydride complex to form

Answer 35

u get an n+2 complex aka u need to increase the metals oxidation state by 2. bc 2e- came from the dihydrogen bond and 2e- came from the metal via backbonding. so theres 2e- in each M-H- bond in dihydride complexes.

Question 36

whats the reaction called when u go from a dihydrogen complex to a dihydride complex,, increasing the oxidation state of the metal

Answer 36

its called an oxidative addition reaction

Question 37

in an oxidative addition reaction what doesnt change

Answer 37

the total amount of e- doesnt change

Question 38

how do u form hydrids: 4 diff ways

Answer 38

- oxidative addition of H2 ( dihydrogen complex oxidatively adds to form dihydride) - protonation of metal centre ( [Mn(CO)5]- + H+ --> [H-Mn(CO)5] - substitution with H- [BrMn(CO)5] + H- ---> [H-Mn(CO)5] + Br- - hydride elimination reactions

Question 39

remember that hydride is M-H,, so when trying to form them,, just try think of diff ways u can add a H to a metal: - the oxidative addition - protonation of the metal - substitution with H-

Answer 39

youve got this girl 💗