Inorganic Concepts Flashcards

Question

What is the enthalpic contribution to chelate effect?

Answer 1

lp-lp repulsion between donor atoms overcome in chelate synthesis, so doesnt need to overcome during binding of multiple ligands Less desolvation energy for chelate ligands RNH₂ more basic than NH₃ due to inductive effect

Answer 2

After one site occupied then prob of second binding is greater when chelate as higher effective contribution of donor atoms in vicinity

Answer 3

Macrocycle ligand complexes more stable than open chain acyclic analogues Macrocycle - at least 3 donor atoms in cculic structure Enthalpic and entropic contributions

Answer 4

Initial enthalpy for macrocycle more +ve due to lp-lp repulsions stronger in cyclic Change in complexation larger and more -ve, so complexation more stable Less strongly solvated than acyclic analogues

Answer 5

Macro less conformationally flexible so lose fewer dof on complexation (S larger and more +ve than the acyclic) Coord of metal cation release solvent molecules (same for acyclic but still better than monodentate)

Answer 6

Ligand trans to leaving-group has an effect on rate of substitution Series orders ligands by their effect on rate const of sub

Answer 7

Most often for square planar, but can observed in Oct species Combination of sigma gs and π-TS effects

Answer 8

Ligand higher in series if raises E of gs - seen with strong σ-donor ligands Trans ligands bonded to same metal orbital as LG, so stronger the trans ligand the weaker the bond to LG This can then effect the rate or strength of the bond (completely different)

Answer 9

Bond-weaking effect due to the σ-bonding of a trans ligand to a leaving-group If high in trans influence then not necessarily high in trans effect - doesnt include π donor effectiveness and other factors

Answer 10

X-ray crystallography for M-X bond lengths IR stretching freq NMR coupling const

Answer 11

Must lower energy of TS to be high in series, done by π-acceptor ligands Because in TBP TS then LG and trans ligand share a d-orbital so extra e- density on metal on metal from new group accomodated by π-acceoptor of trans ligand Pi-acceptors are low in trans inflence as they dont weaken M-LG bond

Answer 12

Measure of interelectronic repulsion in a complex Smaller for complexes than free ions as e- have more atoms to spread over Smaller for 4/5d as e- further apart Increases across a period as higher Z_eff

Answer 13

Explains decrease in Racah (B) when TM free ion forms a complex Decreases for complexes as e- more spread out and ligands have -ve charge so decreases +ve charge on metal and orbitals expand

Answer 14

B reduced less for Mn²⁺ as prefers to keep electrons localised due to exchange stabilisation

Answer 15

Covalency delocaises e- Softer ligands therefore more delocalisation so reduced e- density Means small B and ligands high in nephelauxetic effect series

Answer 16

π-donors/acceptors high in nephelauxetic effect series as both spread the elec charge

Answer 17

Extent of reduction of B for different ligands

Answer 18

Chemistry of 1st row main group v different to later rows Effects: Oxn staes, hybridisation, multiple bonds, electronegative effects

Answer 19

Difference between 2p and later np is due to lack of radial nodes in 2p RDF Means 2p more sensitive to charge so stabilises rapidly on oxn compared to 3p Limits oxn states of 1st row as successive IE increase dramatically

Answer 20

More sp hybridisations with 1st row as 2s/p have similar radial extents (diverges down the group) Not favoured down the group as poorer size/energy match (decreasing S²/ΔE for hybridisations)

Answer 21

MeLi has tetramic with covalency, NaMe is ionic rocksalt Trans-bent structures of E₂R₂ Bond angle in H₂O larger than SH₂

Answer 22

π-overlap decreases faster than σ-ovelap down group Means multiple bonds rather than double bonds becomes more common

Answer 23

E(OH)_qO_p where E is non-metal or early TM

Answer 24

More χ makes O-H bond more polar and stabilises conj base Opposite to HX - which is based on bond strength

Answer 25

Inductive effect and increased stability of conj base as p increases, so more resonance structures

Answer 26

E(OH)_qO_p pKa = 8 - 5p As succesive ionisations, the pKa increases by 5 each time

Answer 27

H_{2_{CO_{3_{less acidic than expected, as in eqm with H_{2_{O + CO_{2_{Dont include solvation

HClO_{4_{more acidic than HClO_{3_{by a larger margin than expected. Due to VII oxn state much less stable than V, so Cl draws e- density towards itself, polarising OH bond & increasing acidity}}}}}}}}}}}}

Answer 28

Equation to calc lattice enthalpy

Answer 29

Derived from Born-Lande Define madelung constant A=0.87, account for repulsive interaction at short distance (1/n), and assume n=9 for rock-salt structure

Answer 30

Assumes ionic model: * hard, incompressible spheres * integer charges * only elecrostatic forces Breaks down when any covalency

Answer 31

* Stability trends of different compounds and oxn states * Solubilities - find in combination with born equation, solubility increases as the difference in the radii increases

Answer 32

Intercalation of guest species into a host lattice, which remains largely unchanged Weak vdW interactions between layers make intercalation possible

Answer 33

Graphite - semimetal, no bandgap but no density of states (dos) at Fermi. Can make into metal via two methods Empty states above fermi easily filled via reductive intercatalation (KC₈) Filled states below Ef emptied via oxidative intercalation (C₈Br)

Answer 34

Sulfides: TiS₂ + Na -> Na_xTiS₂ Others: C₆₀ ReO₃ and WO₃ Li-ion batteries

Answer 35

Solid C₆₀ has fcc K⁺ can occupy all Oh/Td sites within ccp array of C₆₀^3- Can measure redn of C₆₀ to C₆₀^3- via voltammetry Superconductor below 40K

Answer 36

2nd/3rd row TM oxides with ReO₃ can intercalate Li Li₂ReO₃ structural distortion converts 12-coord cavity into 2x edge-sharing 6-coord sites occupied by Li

Answer 37

Li insertion leads to: 12-coord cavity -> 4x planar 4-coord sites Lower level Li than ReO₃ But can have more Na inserted

Answer 38

Reversible electrochem oxn of LiCoO₂ <-> Li_0.5CoO₂ Reductive intercalation highly favourable and has an almost constant driving force, generates electric potential

Answer 39

Solids where the electrons are localised, whereby the band at the fermi level splits due to e- repulsion

Answer 40

Large number of crystal orbitals which are approx to be continuous Greater overlap of orbitals then the wider the band

Answer 41

e-s have random spins so experience greater e- e- repulsion than if on one atom Strength of repulsion measued by parameter U

Answer 42

Greater the length of box (in particle in a box) means lower curvature of wavefn so lower KE of e-s Strength of this favourable bonding is by W

Answer 43

Mott-hubbard insulator: W<`U` Simple-band so metallic: W>U

Answer 44

d orbitals contract as Z_eff increases This gives narrower bands and increased e-e- repulsion e.g. TiO/VO metallic and MnO/NiO Mott-hubbard insulating

Answer 45

4/5d unlikely to be Mott-Hubbard insulating As more radially diffuse orbital so better overlap (larger W) and wider bands (smaller U)

Answer 46

4f contracted in core so don't participate in bonding, and e- localised (U>>W) V. narrow band so this band is Mott-Hubbard insulating Only conduct when d-band contains e-

Answer 47

EuS: 4f⁷5d⁰ is insulating GdS: metallic, 4f⁷5d¹ is favouted over 4f⁸ due to pairing energy

Answer 48

Introduce mixed valency e.g. react NiO with O₂ to give Ni_1-xO, which has Ni³⁺ sites and e- can hop between them

Answer 49

Solid electrolytes - conductors with highly mobile ions Used in batteries and sensors

Answer 50

AgI Na₂O.nAl₂O₃ ZrO₂ Bi₂O₃

Answer 51

β-form is wurtzite Upon heating Ag+ "melts" to give α form - bcc of I^- and Ag⁺ distrbuted across different cation sites low activation energy for hopping between sites leads to increase in conductivity entropy change from β->α about 1/2 associated with melting of typical ionic solid Addition of Rb gives low T ionic conductivity

Answer 52

Spinel-like blocks of Al₂O₃ Al³⁺ in Td and Oh sites and every 5th layer has 3/4 O^2- missing Na⁺ in layer and mobile within it, makes it conducting Used in Na-S battery

Answer 53

7-coord at low T, distorted fluorite at high T Used in O sensors in ICE engines

Answer 54

Low T:γ-phase with low symm at low T High T: δ-phase, anion melts to adopt disordered array within fcc Bi cations Based on fluorites but AB_1.5 instead fo AB₂, as disordered anion vacancies O^2- occupy many frankel defect sites, polarizability of Bi leads to high anion mobility

Answer 55

Molar mag susceptibility of a complex containing a metal ion χ = C/T where C α effective mag moment Therefore T independent

Answer 56

Must obey spin-only formula (TM) or lande (lanthanides) so must be no thermally excited states 2nd order mixing can allow for obeying curie

Answer 57

No thermally excited states TM ions with A₂ E gs

Answer 58

2nd order mixing of es into gs by B when small ΔE A2 and E in TM are close in energy for this to occur

Answer 59

TM states which have gs orbital have L=1

Answer 60

A.m leads to spin-orbit coupling where different J levels have energy splitting ~ kT (as SO coupling const small) Boltzmann distribution amongst these levels so mag moment is T dependent χ^-1 against T plotted - curves up at low T (as μ increases with T) but straightens at high T as effects of SO equalise (all equal energy states)

Answer 61

Mostly do - even though gs orbital has am (4f contracted and not perturbed by ligand field) SO occurs but only ground J level is occupied as splitting between J levels is much larger than kT as λ α Z⁴

Answer 62

4f⁶ and 4f⁵ including Eu³⁺ or Sm²⁺ As have thermally accessible es so mag moments vary with T

Answer 63

Predicts mag moment of complexes with para metal ions n = unpaired e- S = spin quantum number

Answer 64

* L=0 in gs * No thermally accesible es * No 2nd order Zeeman effect in an applied mag field * No spin-orbit coupling

Answer 65

hs d⁵ and d⁷ (e.g. Fe³⁺)

Answer 66

Gs orbital am L=1 Leads to spin-orbit coupling so different J levels have similar energy splitting to kT Boltzmann distribution amongst those levels so mag moment T dependent

Answer 67

when d`<1/2 filled` then λ +ve and 2nd order spin-orbit coupling decreases effective mag moment below spin-only Counteracts TIP

Answer 68

as d>1/2 the λ is -ve and so the 2nd order spin orbit coupling increases mag moment above spin only enforces TIP

Answer 69

Requires a stereochem non-rigid molecule which has `<1` themally accessible structure and can pass between them under certain cond

Answer 70

Functionality interchange Berry pseudorotation Ring whizzing

Answer 71

k = rate const for exchange, and Δv = difference in shift between 2 forms when k>>Δv then fast exchange so indistinguishable when k<<Δv then slow exchange and they are distinguishable k ~ Δv then at coalescence point

Answer 72

Due to energy-time uncertainty principle Forms exist for shorter period of time, so uncertainty in their energy is greater

Answer 73

Can show if 1,2 or 1,3 ring shifts as the chemical environment that is maintained through a single shift differs

Answer 74

Fast technique so for rapid exchange processes E.g. berry pseudorotation

Answer 75

Doublet at all T - not complex splitting as expected Due to berry pseudorotation process which has a low Ea

Answer 76

Interchange between bridgind/terminal CO C NMR: Low T - 4 peaks, bridging and 3xterminal High T - 1 peak, all are equivalent

Answer 77

2xη-5 and 2xη-1 rings H NMR: Low T - 4 peaks High T -2 peaks, ring whizzing so all protons in η-1 rings are equivalent V high T - 1 peak, hapicity can change

Answer 78

p³, d⁵, f⁷ elements comparatively stable to ionisation and keep e- localised in compounds

Answer 79

Prefers to keep e- localised rather than delocalised so weaker metal bonding and easier atomisation MnO is mott-hubbard insulator whereas other early 3d MO are conductors due to this localisation

Answer 80

Predicts stability of compounds and reaction pathways Hard - small and charge dense, electrostatic Soft - large and charge diffuse, covalent bonding

Answer 81

Qualitative, is a big oversimplification Difficult to predict/compare reactivity of species on border between soft and hard - like TM

Answer 82

TM complexes kinetically stable when 18 VE Due to all M-L bonding and low-energy nb d orbitals filled Anti orbitals empty

Answer 83

9 valence MOs If σ-only ML_x: x bonding MOs x anti MOs 9-x nb MOs

Answer 84

Class 1: 3d metals and/or weak field ligands, t_2g nb and e_g anti so range of VE possible Class 2: 4/5d metals with weak field ligands and/or σ donors, t_2g nb but e_g strongly anti, only up to 18 VE Class 3: most organometallics, t_2g is π-bonding and e_g strongly anti, follows 18 VE

Answer 85

Low neutral VE so to form 18 VE would be difficult sterically best example being group 4 metallocenes (like Ti - which give 16/14 VE compounds)

Answer 86

pz not used in bonding (by D4h symm) so only 8xM-L bonding and metal based non-bonding MOs to fill Adds up to 16 VE Donation into this would cause strong steric repulsion from filled dz2, which is contracted

Answer 87

Directly analogus - but octet rules has almost no exceptions unlike 18 VE As 18 VE relies on using valence orbitals in bonding which is unrealistic due to different radial extent of the d orbitals to s/p Octet only relies on using valence s/p which have similar radial extents

Answer 88

Heavy main group elements where 6s contracted due to relativity so different to p Example of inter pair effect

Answer 89

Overlap (RDF) and electron occupancy Observed in TM as have more extended overlap Limited in s/f blocks are core-like orbitals which don't overlap

Answer 90

Orbitals down group get nodes and get more diffuse (with lower e-e- repulsion) Better overlap and greater bond strength when better overlap

Answer 91

3d - bridging COs 4/5d - M-M more common and fewer bridging CO Can find by IR - bridging CO have a lower stretching freq

Answer 92

Decreases as Z_eff, so more contracted d-orbitals so worse overlap and higher e- repulsion U>W across the period

Answer 93

Li 2s and 2p same radial extent so s-p mixing possible Gives directional hybrid orbitals with good overlap in a cluster Doesnt happen in MeCs which is ionic rocksalt

Answer 94

Term which describes the decrease in ionic radii across the lanthanide elements

Answer 95

Increased Z_eff across series at same n lowers their energy

Answer 96

Absence of ligand field effects 4f shielded from external charge by 5s/5p

Answer 97

Lanth chem dominated by ionic interactions, 1/r relationship Seen in water exchange mech for Ln³⁺, 1st half undergo Id 2nd half undergoes Ia This is because contraction causes ideal coord number to switch from 9 to 8 by Gd (sterics)

Answer 98

Chem of 4d similar to 5d instead of 3d 5d has similar radii to 4d, both form high oxn states Similar structures and orbital energies (found from LMCT)

Answer 99

Causes alternation effect down main group in IEs This has knock-on effect for stability of group 15 pentachlorides, P/SbCl₅ stable and As/BiCl₅ unstable due to the TM and lanthanide contraction in term

Answer 100

Formed due to e- deficiency and facilitates e- sharing

Answer 101

Set of rules for predicting structures of borane cluster compounds Can be applied to many other clusters

Answer 102

Skeletal e- pair = [total VE - 2xB-H subunit]/2 where the total VE = (# of B * 3) + (# of H * 1)

Answer 103

n vertices = closo n-1 vertices = nido n-2 verticies = arachno n-3 verticies = hypho

Answer 104

1) Determine VE 2) Subtract 2 for each B-H subunit 3) Divide by 2 to get # of SEP 4) SEP = n+1, so then find n and the structure via how many boron atoms 5) n B is closo, n-1 B is nido, n-2 B is arachno, n-3 hypho e.g. if SEP = 8 and it is B₅H₁₁ then n=7 and the structure is n-2 so arachno

Answer 105

A fragment can be replaced by another if: * same # of fronteir orbitals, and they have same symm and similar energies * Fronteir orbitals filled with same # of e- e.g. BH isolobal in C,Sn,Pb, means that the equivalent can be synthesised starting from B

Answer 106

Must be an e- deficient cluster Condition is: SEC < 2x # of bonds

Answer 107

O forms diverse range of compounds Almost always O^2- and brings out high oxn states as small size and favourable formation enthalpy (only F- better) Structures of them shows trends in radii, orbital overlap, e-e- repulsion, etc

Answer 108

Dominated by covalency/orbital overlap

Answer 109

* B forms B₂O₃ * C/N oxides dominated by C=O/N=O * OF₂ is example when has a +1 oxn state * XeO₃ has trig bipyrimidal structure, cant make others as more accessible IEs

Answer 110

More extended structures with E-O bonds, pi bonds derease in strength faster than sigma as p-orbitals more sensitive to distance E.g. CO₂ molecular but SiO₂ has extended cristobalite

Answer 111

SnO/PbO - layered structure, the cation charge density is polarisable by O^2- ns orbitals interact with O 2p which interacts with metal np, hybridisation drives structural dist to form a stereochem lone pair

Answer 112

Group 1 oxides - antifluorite, M in all Td holes of ccp array of O^2- Cs₂O is the exception - large and polarisable so layered oct structure, anti-CdCl₂

Answer 113

Rocksalt - M in all Oh holes of ccp O^2- array

Answer 114

Metallic to Mott-Hubbard insulating as 3d contracts across the series

Answer 115

15% Schottky defects (anion and cation) gives short Ti-Ti distances extended Ti orbitals capable of Ti-Ti bonding (Nb equivalent will have more M-M bonding)

Answer 116

Partial oxn to Ni(III) when heated Ni_1-xO has e- hopping doesnt form d9 config with high e-e- repulsion

Answer 117

Driving force early and late in series Is M-M bonding vs reducing repulsion

Answer 118

ZnO and BeO has ccp zinc blende / hcp wurtzite Small cations so Td rather than Oh coord

Answer 119

Most TM adopt Oh rutile structure (TiO₂) VO₂ rutile at high T but undergoes Pierl's distortion at lower T, then becomes banmd gap insulator as e- localised in V-V bonds NbO₂ same as VO₂ but stronger M-M so always distorted MoO₂ distorts but still conducts, d² so 1e- in M-M bond and 1 to conduct

Answer 120

Higher oxn state more stable down group RuO₄ and OsO₄ stable, but FeO₄ unstable CrO₃ high oxidising, WO₃ not oxidising

Answer 121

Mostly Ln₂O₃ as +3 oxn state dominates lanthanides LnO not as common - Ln(III) O^2- e-, v good conductor as e- is mobile in 5d conduction band Not case for EuO/YbO - exchange energy keep e- localised on metal CeO₂ is rare Ln(IV), fluorite

Answer 122

A₃O₄ Normal - ccp O^2- with A(III) in 1/2 Oh holes and A(II) in Td holes Inverse - A(II) Oh and 1/2 A(III) Td, which max LFS. Occurs when A(III) has 0 LFSE, for example Fe(III)

Answer 123

Fe₃O₄ metallic as Fe(II) and Fe(III) belong to edge-sharing octahedra, so H_AB good and small FC barrier to ET (as t2g to t2g) Co₃O₄ normal spinel (LFSE), poor conductor as eg-eg ET

Inorganic Concepts Flashcards

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