transition metal complexes part 1

Question 1

what are ligands?

Answer 1

Lewis Base
Electron donors

Question 2

what are metal centers?

Answer 2

Lewis Acids
Electron acceptors

Question 3

Adduct

Answer 3

the product of a Lewis acid-base reaction

Question 4

coordination number

Answer 4

number of ligand binding sites on metal center

Question 5

coordination sphere

Answer 5

central metal and ligands that are closely attached to it are enclosed in a square bracket

Question 6

most transition metal complexes are either # or # coordinate
CN= #

Answer 6

4 or 6
CN=2

Question 7

multi-dentate ligands
dentate - greek for ?

Answer 7

ligands that can bind through multiple donor atoms
greek for tooth

Question 8

ligands that stabilize low oxidation state

Answer 8

CO, CN-, [Fe(CO)5]

Question 9

ligands that stabilize normal oxidation states

Answer 9

water, ammonia, halides, [Fe(H2O)6]2+, Fe(H2O)6]3+

Question 10

ligands that stabilize high oxidation state

Answer 10

fluoride, oxide [CoF6]2-, [FeO4]2-

Question 11

ligands can stabilize low oxidation metal centers, but it is not possible with…
stable compound with iron(0):
? compounds cannot be formed:

Answer 11

not possible with main group metals
Fe(CO)5
Ca(0)… Ca(CO)5

Question 12

interesting magnetic properties
NiCl4 2-
Ni(CN)4 2-

Answer 12

paramagnetic Ni2+ complex
diamagnetic Ni2+ complex

Question 13

interesting optical properties
cis-Co(NH3)4Cl2
trans-Co(NH3)4Cl2

Answer 13

green
violet

Question 14

interesting electrical properties
cannot conduct electricity
conducts electricity

Answer 14

NiO2
TiO2

Question 15

Valence bond theory:

Answer 15

hybridization of orbitals

Question 16

each covalent bond is formed by…
the individual orbital identity is…
the bond strength is…

Answer 16

an overlap of atomic orbitals from each atom
retained
proportional to the amount of orbital overlap

Question 17

Bonding in coordination compounds

Answer 17

Valence bond theory
filled orbital on ligand
empty orbital on metal cation

Question 18

the original atomic orbitals are mixed together and transformed into a new set of ? that match the ? for bonding

Answer 18

hybrid orbitals
directional requirements

Question 19

a drawback of the valence bond theory

Answer 19

VB theory can ‘t explain color and magnetism of coordination compound

Question 20

crystal field theory

Answer 20

the d-orbitals are degenerate in free atoms
all orbitals have the same energy

Question 21

upon entering a repulsion field, the d-orbitals…

Answer 21

lose their degeneracy

Question 22

incoming ligands ? electrons in orbitals

Answer 22

repel

Question 23

the closer the proximity of the ligands…

Answer 23

the more repulsion

Question 24

ligands directed between orbitals have

Answer 24

low energy

Question 25

orbitals facing incoming ligands

Answer 25

high energy

Question 26

incoming ligands generate an ? on the ?

Answer 26

"electronic repulsion field" on the transition metal orbitals

Question 27

octahedral field

Answer 27

six ligand donor atoms approach in an Oh symmetry

Question 28

four ligand donor atoms approach in an Td symmetry

Answer 28

tetrahedral field

Question 29

dxy, dxz, dyz face between ...

Answer 29

incoming ligands and relative energy decreases

Question 30

dx2-y2 and dz2 face directly at ...

Answer 30

incoming ligands and relative energy increases

Question 31

eg

Answer 31

dx2-y2 and dz2 orbitals

Question 32

t2g

Answer 32

dxy, dxz, and dyz orbitals

Question 33

factors that affect crystal field splitting

Answer 33

the identity of the transition metal oxidation state of metal number of ligands, more ligands, more splitting nature of the ligands

Question 34

I- < Br- < Cl- < F- < OH- < OH2 < NH3

Answer 34

spectrochemical series weak field/high spin to strong field/ low spin

Question 35

strong field case weak field case

Answer 35

the splitting energy is large the splitting energy is small

Question 36

low spin complexes tend to be ? while high spin complexes tend to be ?

Answer 36

diamagnetic paramagnetic

Question 37

d5 metal in gas phase d5 metal in weak field d5 metal in strong field

Answer 37

5-fold degeneracy weak field: high spin strong field: low spin

Question 38

electron pairing energy more than splitting energy electron pairing energy less than splitting energy

Answer 38

high spin low spin

Question 39

d1-d3 and d8-d10

Answer 39

the number of unpaired electrons are the same for strong and weak fields

Question 40

the number unpaired electrons are not equivalent between strong and weak fields

Answer 40

d4-d7

Question 41

d0 and d10

Answer 41

the transition metal acts like a main-group metal

Question 42

crystal field stabilization energy: the lower energy orbitals are more stable than the ... electrons in t2g orbitals the net change in orbital energies after splitting is

Answer 42

higher energy orbitals impart extra stability zero

Question 43

what is Dq?

Answer 43

differential quanta which comes from quantum mechanics

Question 44

each electron in t2g decreases energy by each electron in eg increases energy by

Answer 44

4/10 6/10

Question 45

tetrahedral complexes t2g orbitals are ? by incoming ligands eg orbitals are ? by incoming ligands

Answer 45

repelled not repelled

Question 46

tetrahedral ligand field splitting is ... octahedral ligand field splitting always ? field

Answer 46

opposite always weak field

Question 47

electrons in the incompletely filled d orbitals can be ...

Answer 47

excited from lower occupied to higher unoccupied orbitals

Question 48

delta = hc/wavelength

Answer 48

the frequency of the absorption is proportional to the crystal field splitting

Question 49

when the excited state relaxes to the ground, ?

Answer 49

light is emitted

Question 50

what are the drawbacks of crystal field theory?

Answer 50

-considers only the metal ion d orbitals and give no consideration at all to other metal orbitals like s,p -unable to account for the relative strength of ligands -bond between metal and ligands purely ionic. it gives no account to partial covalent nature of the metal-ligand bond