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L1 exams > D-block > Flashcards

D-block Flashcards

1
Q

What is a transition metal

A

Elements w/ partially filled d/f-shells

Partially filled d/f-shell in most common compound

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2
Q

How to do you work out the number of d e-

A

No e- = group no. - metal OS

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3
Q

What are the trends in atomic radius

A

General contraction across period
∵ increasing Zeff

Increase from row 1 -> row 2
Row 2/3 metal in a triad
very similar radii
∵ lanthanide contraction
& increasing Zeff
w/ little shielding from ‘core’ 4f14 shell

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4
Q

What are the anomalies in atomic radius

A

Mn
∵ irregular solid state structure

Increase for Cu, Zn
∵ greater e- repulsion

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5
Q

What is the trend in ionic radius

A

Contraction left to right
Decrease Ti 2+ -> Cr 2+
Increase Cr 2+ -> Mn 2+
Decrease Mn 2+ -> Ni 2+
Increase Ni 2+ -> Zn 2+

Irregular
∵ effect d-orbital occupancy

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6
Q

What is the trend in IE

A

General rise across period
∵ increasing Zeff

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7
Q

What are the anomalies in IE

A

Dip for Mn+ -> Mn 2+ & Fe 2+ -> Fe 3+
both d6 -> d5
∴ removing paired e-
∴ experiencing repulsion

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8
Q

What is the trend in electronegativity

A

All relatively low
∵ metallic behaviour

General increase across period

Decrease down triad
in groups 3 -5
increases groups 6 - 12

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9
Q

What is the trend in atomisation energies

A

Higher than s-block metals
more valency e-
∴ stronger metallic bonds

Maxima at groups 5/6
most unpaired e-

Dip group 7
eg. Mn free atom is 3d5 4s2 & irregular structure

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10
Q

What is the trend in melting point

A

Stronger metallic bonding than s-block

Generally increase down group (triad)
larger 4d/5d orbitals
better overlap for bonding

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11
Q

What is an oxophilic metal

A

Metals that tend to be found as oxides

Left of d-block

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12
Q

What are chalcophilic metals

A

Metals that tend to be found as sulphides

Right of d-block

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13
Q

How can you determine max possible OS

A

Max possible OS = group number

High OS less common for Fe - Zn
∵ higher Zeff & IE

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14
Q

How do the OS for row 1 metal halides differ

A

F giver higher metal OS than Cl
∵ more 𝜒

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15
Q

What is the coordination chemistry of a metal cation in aq

A

Complex, hydrated ion
[M(OH2)6]n+

Ligand lewis base - metal lewis acid
∴ dative bond

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16
Q

What is the coordination chemistry of metal sulfate

A

MSO4 –H2O–> [M(OH2)6]n+ + SO4 2-
[M(OH2)6]n+ —> M(OH2)5SO4 crystallise
m(OH2)5SO4 –heat–> MSO4

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17
Q

What is the denticity of a ligand

A

No. donor atoms coordinated to metal

𝜅

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18
Q

What is the coordination number of a metal complex

A

CN = no. donor atoms attached to metal

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19
Q

When are CN > 6 more common

A

3rd row d-block & f-block

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20
Q

What are linkage isomers

A

Ambidentate
eg. NO2 - ligand coordinate through N or O

convert photochemically

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21
Q

What are ionisation isomers

A

Distinguished by chemical test

eg. [Co(NH3)5(SO4)]Br –Ag+–> AgBr
[Co(NH3)5(SO4)]SO4 –Ag+–> no reaction

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22
Q

What are hydrate isomers

A

Coordinated H2O vs. water of crystallisation

eg. [Cr(OH2)6]Cl3 vs.
[Cr(OH2)5]Cl2 . H2O

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23
Q

What are geometrical isomers

A

cis/trans isomers

facial (fac) - 3x z ligands cis to each other
/meridonal (mer) - 2x z ligands cis & 1x z ligand trans to p

24
Q

What are optical isomers

A

Two complexes that are
non-superimposable mirror images
& are enantiomers

25
Q

Why do some d-orbitals experience more repulsion

A

dz2 & dx2-y2
have lobes pointing along axes
∴ directly towards ligand
so more repulsion of e-

dxy, dxz & dyz
have lobes pointing between axes
∴ less repulsion of e-

26
Q

How do d-orbitals feel repulsion in a tetrahedral geometry

A

dz2 & dx2-y2
feel repulsion from ligands

27
Q

How does Δt compare to Δo

A

Δt ≈ 4/9 Δo

28
Q

How do high spin octahedral d-orbitals fill

A

All 5 d-orbitals singularly occupied before pairing

If Δo small
e- prefers high spin

29
Q

How do low spin octahedral d-orbitals fill

A

eg only occupied orbital
after t2g filled w/ 6e-

If Δo large
e- prefers low spin

30
Q

How do tetrahedral d-orbitals fill

A

High & low spin fill in the same ways as octahedral
(3x t2g orbitals at the bottom)

Low spin rare
∵ Δt usually small
∴ favours high spin

31
Q

What is the crystal field stabilisation energy

A

CFSE = change in energy resulting from splitting of d-orbitals

CFSE = E (w/ splitting) - E (w/out splitting)

32
Q

What is P in CFSE

A

Pairing energy
due to repulsion between paired e-

only count extra pairings due to splitting

33
Q

How does Δo/Δt compare to P

A

For d4 - d7
low spin if Δo > p
high spin if Δo < p

For d3 - d6
low spin if Δt > p
high spin if Δt < p

34
Q

How do octahedral and tetrahedral complexes compare

A

O strongly favour for
d3, d8, low spin d4 - d7

No CFSE difference for
d0, d5 high spin, d10

Small CFSE difference for
d1, d2, high spin d6, d7

35
Q

What is the effect of CFSE on hydration enthalpies of M2 ions

A

ΔhydH generally gets larger
across 3d row
ionic radius gets smaller
clear trend for d0, d5, d10 (0CFSE)

Deviation from smooth curve for other ions
∵ additional stabilisation of [M(OH2)6]2+
hydrated ions by CFSE

36
Q

What is ferromagnetism

A

Electron spins only align below curie temp
eg. 1043K for Fe

Above critical temp
material becomes paramagnetic

37
Q

What affects d-orbital splitting

A
  1. Charge (OS) of metal ion
    higher +ve change on M n+
    increases CFS
  2. Position of metal in d-block
    CFS increases down a group
    larger 4d/5d orbitals interact
    more w/ ligands
  3. Nature of ligand
    ligands can be ranked
    to spectrochemical series
     v. strong field ligand: CN-, CO
 strong field ligand: NH3
 weak field ligand: H2O, halogens
38
Q

What is the Jahn-Teller effect

A

Some octahedral complexes
9th e- could go into either dx2-y2 or dz2

Molecule in degenerate electronic state
undergo distortion to remove degeneracy

Causes further splitting
& lowers overall energy

39
Q

What are the distortions for octahedral complexes

A

1/3 e- in eg orbitals
large tetragonal
elongation or compression

1/4 e- t2g orbitals
small tetragonal compression

2/5 2- in t2g orbitals
small tetragonal elongation

d3, d8, d10, high spin d5, low spin d6
no distortion

40
Q

When is square planar favoured

A

For d8 complexes

41
Q

What are the comparisons of 4-coordinate d8 complexes

A

Square planar gives larger CFSE
especially for 2/3 metals
Rh(I), Ir(I), Pd(II), Pt(II), Au(III)

Tetrahedral minimises repulsion between ligands
eg. Ni(II) complexes w/ bulky ligands or weak field ligands

Tetrahedral = paramagnetic
Square planar = diamagnetic

42
Q

How can wavelength of complexes be calculated

A

ΔE = hv = hc/𝜆

43
Q

What are the selection rules

A
  1. Laporte Rule
    For transition to be allowed
    qn must change by ±1
    eg. s -> p or p -> d
  2. Spin selection rule
    e- cannot change its spin during transition
  3. Parity selection rule
    g -> g or u -> u forbidden
    g -> u allowed
44
Q

Are d -> d transitions allowed

A

Formally formatted by Laporte in octahedral complexes

Molecule w/ polyatomic ligands
not perfectly octahedral
vibrations mean centre of symmetry
can be temporarily lost
some mixing of orbital character can occur
∴ d -> d transitions can occur but relatively weak

45
Q

What is the affect of acid reaction of d-block metal ions in aq

A

Solutions [M(OH2)6]n+ are acidic

e- density pulled towards M n+ cation
M n+ polarises coordinated H2O
O-H polarity increases
depends on charge M n+

Proton transfer to solvent H2O raises acidity

46
Q

What happens when base is added to coordinated complexes

A

Deprotonation of coordinated water ligand
(not ligand exchange)

47
Q

What happens when NH3 is added to coordinated complexes

A

Deprotonation of coordinated water
(reversible reaction)

In excess NH3 ligand exchange occurs

48
Q

What are the types of ligand substitution

A

Anation = neutral replaced by anion

Aquation = any other ligand replaced by water

49
Q

What are the classifications of kinetics for ligand substitution

A

Labile = complexes undergo rapid substitution

Inert = complexes undergo slow substitution

row 2/3 [M(OH2)6]n+ generally more inert

50
Q

What is the K equation for ligand substitution

A

K = [MX5Yn-][X-] / [MX6][Y-]

51
Q

What is the stability constant

A

βn = k1 k2 k3 … kn = [MLn] / [M][L]^n

logβn = log (k1) + log (k2) + … + log (kn)

52
Q

What is the chelate effect

A

Enhanced stability of complexes
containing chelate ligands (eg. polydentate)
over one containing similar monodentate ligands

53
Q

How is ΔG calculated from the stability constant

A

ΔG = -RT x lnβ

ΔG = -RT x ln10 x logβ

54
Q

What is the macrocyclic effect

A

Complexes of macrocyclic ligands
show even greater stability

Donor atoms ‘pre-organised’

55
Q

What is the effect of chelate ring size on stability

A

As chelate ring size increase
logK generally decreases

largest k = most stable

56
Q

What is the Irving-Williams series

A

Trend of logβ where M is different metal ions

Peaks in -CFSE/Δo for d3 and d8
Trough for d0, d5, d10

∵ decreasing ionic radius left -> right
trend in CFSE for d5 -> d10
larger Δo in product [M(en)3]2+

57
Q

What are the interactions between hard/soft acids/bases

A

Hard acid-hard base
interactions more electrostatic in character
dominated by +/- charges

Soft acid-soft base
interactions more covalent in character
dominated by interactions of donor/acceptor orbitals

L1 exams (7 decks)

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