Unit 3 | Coordination Chemistry

Question 1

exceptions to electron stability for electron configuration

Answer 1

group 6 and 11 have a stability exception
half-shell is more stable than not
don’t apply to ion

Question 2

what is the first in first out rule for electron configuration

Answer 2

3d subshell is significantly lower in energy than 4s meaning the 4s e-s before the 3d e-s
to form an ion, 4s electrons are lost first

Question 3

coordination compounds

Answer 3

metal ion (electropositive and lewis acid) surrounded by molecules and/or anions with lone pairs (lewis bases) called ligands

Question 4

what do the counter ions do for the complex ion

Answer 4

they are not bonded to the metal ion, they dissolve in aqueous solution and maintain the charge neutrality and are used for calculating the charge of the complex ion

Question 5

geometries of complex ions

Answer 5

CN 2: Linear (least common)
4: Square planar
4: tetrahedral
6: octahedral (most common)

Question 6

What is coordination number?

Answer 6

number of bonds b/w the metal ion and the ligands

Question 7

When to choose a square planar or tetrahedral

Answer 7

square planar: most nd8 e- configuration
tetrahedral: for (most) all other metal ions with CN=4

Question 8

what is a ligand

Answer 8

a neutral molecule or an ion with a lone pair of e- that can be used to form a bond to the metal ion
bond is often called a coordinate covalent bond

Question 9

Monodentate ligands

Answer 9

attached to the metal by one bond

Question 10

Bi/Poly- dentate ligands

Answer 10

attached to the metal by more than one bond or pair of electrons
bi specifically - 2 pairs e-, takes two neighbouring spots on the metal, each ligan counts as two towards coordination #

Question 11

names of anionic: F-, Cl-, Br-, I-, CN-, OH-
names of neutral: H2O, NH3, CO, NO

Answer 11

fluoro, chloro, bromo, iodo, cyano, hydroxo
aqua, ammine, carbonyl, nitrosyl

Question 12

how much bonds in : (en), (ox), (dien), (EDTA)

Answer 12

ethylenediamine, 2
oxalate (oxalato), 2
diethylenetriamine, 3
ethylenediaminetetraacetate, 6

Question 13

metal exceptions for naming: Fe, Cu, Pb, Ag, Au, Sn

Answer 13

ferrate, cuprate, plumbate, argentate, aurate, stannate

Question 14

naming rules

Answer 14

name ligands before metal
neutral ligands, anionic ligands replace -ide with o
indicate number of ligands using prefixes; di,tri,tetra,penta,hexa
for ligands whose name already have the di-tri, use bis,tris,tetrakis
prefixes do NOT affect alphabetical order.

Question 15

Isomers

Answer 15

chemical composition (molecular formula) but are difference due to differences in bonding (structural isomers) or orientation (steroisomers) which can strongly influence compound properties such as colour, interaction with light, reactivity

Question 16

coordination isomers

Answer 16

a ligand and a counter- ion exchange position (or ligands and counter-ions)

Question 17

linkage isomers

Answer 17

ligand rearranges and bind through another atom (ambidentate ligands)
NO2-, SCN- OCN-

Question 18

geometric isomers (cis-trans and fac-mer)

Answer 18

cis - ligands are 90 apart
trans - ligands are 180 apart
fac -the same ligands are 90/90/90
mer - ligands are 180/90/90

Question 19

optical isomers (enantiomers)

Answer 19

molecules that rotate the plane of light are said to be optically active or chiral (asymmetry so that the mirror image and the original are non-superimposable)
can happen in tetrahedral - with 4 different ligands
octahedral - cis with at least one bidentate
square planar are not chiral! - meaning that it is symmetrical

Question 20

why doesn’t the valence bond theory work for explaining bonding in complex ions

Answer 20

bonds do NOT involve the orbitals containing d-electrons, no info is given about the energies of d-orbitals
doesn’t explain the magnetic properties
colours

Question 21

crystal field theory

Answer 21

focuses on the energies of d-orbitals
the ligands are approximated as negative point charges and the metal-ligan bond is ionic
electrostatic interactions b/w lone pair e- and the dorbitals e-s result in coordination

Question 22

eg set

Answer 22

dz2 amd dz2-y2

Question 23

t2g

Answer 23

dxy, dxz, dyz

Question 24

small delta - P (pairing energy) > delta

Answer 24

pairing is not favorable, small gap so will make the jump, filled the t2g and eg sets before pairing up
forms high- spin complexes

Question 25

large delta - P (pairing energy) < delta

Answer 25

pairing is favourable, large gaps so no jump, e- will first fill the t2g set and pair before jumping to eg set
from low spin complexes

Question 26

influence on delta(energy splitting crystal field splitting)’s magnitude

Answer 26

dependant on ligands, increases towards a more positive metal ion

Question 27

diamagnetic

Answer 27

all e-s are paired, not attracted by a magnetic field

Question 28

paramagnetic

Answer 28

has unpaired electrons, attracted by a magnetic field