6d

Question 1

describe a cyclobutadiene

Answer 1

butane but with double bonds and cyclic

Question 2

what is the huckels rule for

Answer 2

• to see if smt is aromatic
• 4n+2
  is the amount of pi electrons it needs

should be an integer

Question 3

how many pi electrons does butadiene have

Answer 3

butane with 2 double bonds

so 4 pi electrons
doesnt fit huckels rule do cyclobutadiene and butaniene are not aromatic!!!

Question 4

bonds lengths of butaniene and cyclobutandiene due to it not being aromatic

Answer 4

it doesnt have identical bond lengths!!

so cyclobutaiene isnt a square but more of a rectangle shape,, theres distortion

Question 5

describe the MO of the pi system of cyclobutadiene and explain why the bonds arent all the same length

Answer 5

u always start with the fully bonding one where all the p orbitals are in phase. this mo is fully bonding and most stable

then u have 2 mo’s, which both have one node and these are nonbonding bc the inphase and out of phase interactions cancel out!

then u have the full antibonding one where u have 2 nodes.

the bond lengths arent the same bc the nonbonding orbitals become either bonding or nonbonding bc distortion occurs bc they arent filled equally. distortion removed degeneracy.

increasing the bond length reduces either the antibonding or bonding interaction depending on where the node is,, allowing the other interaction to be more prevalent.

Question 6

the fully bonding mo of cyclobutadiene overlaps with what d orbital

Answer 6

the dz^2 one !!

Question 7

the 2nd energy mo of cyclobutadiene interacts with what d orbital..

Answer 7

look at the bottom of the p orbitals and see if theyre filled or not and then make a d orbital that fits to this.. its normaly the dzy and this is where pi donation occurs

this one has more bonding character after distoriton occurs

Question 8

whats the 3rd mo of energy in cyclobutadiene

Answer 8

its the dzx
with the distortion causes the antibonidng nteraction to be strenghtened.

Question 9

whats the highest energy mo of cycobutadiene interacting with what d orbital

Answer 9

the dxy this is where delat backbonding occurs!!!

Question 10

when is distortion favoured and what electron count do these molecules usually have

Answer 10

favoured for ANTIAROMATICS AKA COMPOUNDS WHERE THE E- COUNT DOESNT RESPECT HUCKELS RULE

DISTORTION IS FAVOURED

Question 11

WHEN IS THE PROPER STRUCTURE WITH NO DISTORTION FAVOURED

Answer 11

when they respect huckels rule!!!!!! when theres no distortion bc the orbitals are filled equally.

Question 12

describe the order in which d orbitals overlap for backbonding

Answer 12

dz^2 : sigma bonation
dyz : pi donation
dzx : pi backbonding
dyx : delta backbonding

Question 13

all known complexes of butadiene have what ring structure

Answer 13

they all have a C4 square ring

Question 14

what do we treat cyclobutadiene as

Answer 14

a neutral 4 e- donor

Question 15

how can we synth complexes with cyclobutadiene

Answer 15

cyclobutane with a double bond on one side and 2Cl’2 on the other + Fe(CO)9 —> cyclobutadiene structure eith Fe in the middle and the (CO)3 at the bottom : ferrocene looking molecule + FeCl2 + 6CO

Question 16

second way of synthesising complexes with cyclobutadiene:

Answer 16

u have Cl- Co - PPh3 bonded to 2 alkynes with ph on each end

Question 17

whats cyclooctatetraene,, descibr it and what is the small name for it

Answer 17

its called COT

its cyclooctane aka an octane but in a circle with 4 conjugated double bonds

Question 18

is cyclooctatetraene aromatic

Answer 18

it has 4 double bonds meaning it has 8 pi e-.

4n+2 = 8
nope
its antiaromatic meaning its onlyt aromatic and all bonds will be the same length once u coordinate it,, bc then it gets 2e- from the metal.

u have the bonding and antibonding and then the other ones are paired up with nodes between them

Question 19

cyclobutadiene is a long.n type of ligands,, what number tho

Answer 19

long.n 4

bc the 4 carbons are not independent

Question 20

cyclooctatetraene is what type of long.n ligands

Answer 20

a long.n 8 ligand

bc the 8 carbonds are not independent

Question 21

what do we treat cyclooctatetraene ligand as

Answer 21

a 10e- C8R8 ^-2 donor ligand

Question 22

whats wrong with the cyclooctatetraene ligand tho

Answer 22

its hella big when planar

meaning it only coordiantes with metals in the f row!!!

aka the actinides

Question 23

what metals can COT aka cyclooctatetraene complex with

Answer 23

we see it complex with uranium!!!

u have COT - U - COT

aka bis(COT)U

Question 24

whats the electron count of bis(COT) U

Answer 24

COT - U - COT

COT = C8H8 ^-2 (10e-)
U = 4+ (2e-)
COT = C8H8 ^-2 (10e-)

u have 22e- in total !!!

18e- rule isnt applied to this complex bc its not using a d block metal,, but an f block metal.

Question 25

when u have COT,, its obvs a long.n 8 ligand but what else can it be and how can we do it

Answer 25

it can be a long.n 4 and long.n 2 ligand this is done by only using some double bonds to coordinate with the metal. when double boonds arent in conjugation and are bonded to the same metal,, they count as separate bc theyre not in conjugation. so when its bent like a taco holder with the double bonds at the top and at the bottom its a 4 x 2e- donor bc all the double bonds are independednt when its just kinda bent /// slanted like a stair in the staircase its a 2 x 4e- ligand bc the pair of double bonds coordinated to the same ligand are in conjugation.

Question 26

when do we distort energy levels

Answer 26

when energy levels arent equally populated // when orbitals arent equally populated

Question 27

benzene has how many pi electrons

Answer 27

6e-

Question 28

is benzen aromatic or antiaromatic what will happen if it was benzene 2+

Answer 28

benzene is aromatic bc it fits huckels rule if it was antiaromatic it would be benzene2+ bc that would mean u have 4e- and that doesnt fit huckels rule. bc its aromatic,, the orbitals are filled equally so theres no need for distortio n

Question 29

describe the mo diagrams of benzene and the order of d orbitals and interactions between them.

Answer 29

fully bonding one = dz^2 = sigma donation bonding 1 node : dyz, dzx : pi donation to each depending on orbital symmetry and where the node is 2 antibonding ones : 2 nodes : dxy and dx2-y2 = delta backbonding fully antibonding = no d block metal has an orbital whos symmetry matches it and can lead to an interaction

Question 30

in benzene,, does the sigma interaction or pi interaction larger

Answer 30

the pi interaction is larger bc theres 2 mo's that mave pi interaction (the bonding ones with one node) compared to the one sigma donation (the fully bonding one with no nodes)

Question 31

benzene is a what long.n ligand

Answer 31

its an n.long 6 bc all the carbons are not independednt from one another. they work as a group.

Question 32

so what 3 interactions does benzene as a ligand have with its metal

Answer 32

sigma donation pi donation delta backbonding and these all give the same amount of e- : aka take // give 2e- to bonding and antibonding orbitals. so all c-c bonds are equal in legnth

Question 33

why are the cc bonds in benzene equal in length

Answer 33

bc sigma bonding // pi bonding and delta backbonding occur in a way that keeps all the orbitals degenerate in terms of how many e- are in each of them - allowing degenerate orbitals to have the same amount of e- so theres no need for distortion!!

Question 34

a long.n 6 arene ligand maintains what

Answer 34

it maintains equal CC bonds

Question 35

is benzene a good ligand

Answer 35

yess!! benzene is a good ligand

Question 36

describe a ligand with benzene in it and how to make it

Answer 36

benzene - Cr - benzene 6e- + 6e- + 6e- = 18e- Cr gas + 2C6H6 sandwich structure its a very stable compound

Question 37

how can benzene be added to a metal for it to form a complex and be a ligand

Answer 37

Cr(CO)6 + benzene - OMe 3(CO)Cr - benzene - OMe still 18 e- (CO give 2e- each)

Question 38

a CO ligand gives how many e-

Answer 38

gives 2e-

Question 39

whats an arene

Answer 39

an aromatic hydrocarbon

Question 40

can u have long.n4 and long.n 2 arenes // benzene

Answer 40

yes!! just depends on how many Carbonds and double bonds u want to use to bond to ur metal . 1 double bond = long.n 2 bc ur using 2 C to become besties using 2 double bonds that are conjugated together = long.u 4 bc ur using 4 carbons to be besties and coordinate to the metal