coordination compounds Flashcards
moleculare compounds
2 or more simple salt combined together in a fixed proportion by their WEIGHT
DOUBLE SALT
dissociate into ions completely when dissolved in water
e.g: potash alum. karnalite , mohrs salt
complex compounds
it doesn’t dissociate into ions completely when dissolvwd in water
WERNERS THEORY OF CC
- Metals have two types of links (valences) in coordination compounds: primary and secondary
- Negative ions satisfy the primary valances, which are generally ionisable
- Secondary valences cannot be ionised. Neutral molecules or negative ions satisfy these needs. For a metal, the secondary valence is equal to the coordination number and is constant
- Ions/groups coupled to the metal by secondary connections have distinct spatial configurations that correspond to different coordination numbers
Coordination entity
a CMA/i BOUNDED TO A FIXED NO. OF IONS OR MOLECULES
CMA/I
LIGAND
CMA also reffered to as LEWIS ACID
- the atom which has fixed no. of atoms or molecule bounded to it in a definite geometric arrangements
- the ions or molecules bounded to the CMA/i
UNIDENTATE
AND EXAMPLE
WHEN ligand is bounded to CMA/i through **single donor atom **
Cl, H2O, NH3
DIDENTATE
AND EXAMPLE
WHEN ligand is bounded to CMA/i THROUGH two donor atom
en or C2O42-
ethane - 1,2- diammine
POLYDENTATE AND EXAMPLE
WHEN LIGAND is bounded to CMA/i thru more than 2 donor atom
EDTA4-
ethylenediamminetetraacetate
hexadendate
2 N2 and 4O2
CHELATE LIGAND
chelate ring
WHEN di or polydendate ligand uses 2 or more donor atoms to bind to the CMA/I simultaneously
if they form ring
chelate ring = cordination no, - 1
DENTICITY
No, of ligating grp
AMBIDENDATE LIGAND
LIGETES
Ligand which have 2 different donor atom and either one of the 2 ligetes in the complex
e.g: 1. NO2
M<-ON=O or M<-NO2
NITRITO-O AND NITRITO-N
2. SCN
M<-SCN or M<-NCS
THIOCYANATO -S AND THIOCYANATO - N
COORDINATION NO.
THE NO. of ligands directly attached to the CMA/i
find the CN of:
- [PtCl6]^2-
- [Ni(NH3)4]+2
- [Fe(C2O4)3]3-
- [Co(en)3]3+
C2O42- and en are didendate
CN= denditicity * ligands
- 6
- 4
- 6
- 6
ONLY SIGMA BONDS
COORDINATION SPHERE
COUNTER ION
the CMA/ion and the ligand attached to it are enclosed in a square bracket
the ionisable group written outside the brackett
COORDINATION POLYHEDRON
THE spatial arrangement of ligands which are directly bounded to the CMA/i
name the spatial arrangement of the following
- [Ni(Co)4]
- PtCl4
- [Co (NH3)6]
3 most common spatial arrangement
- tetrahedral
- square planar
- octahedral
HOMOLEPTIC AND EXAMPLE
WHEN THE metal is bounded to only one kind of donor grp
[Co(NH3)6]3+
HETEROLEPTIC AND EXAMPLE
COMPLEXES IN WHICH METAL IS bounded to more than one kind of donor grp
[Co(NH3)4Cl2]+
Write the formulas for the following coordination compounds:
(i)Tetraamminediaquacobalt(IlI) chloride
(ii)Potassium tetracyanidonickelate(II)
(iii)Tris(ethanp-1,2-diamine) chromium(III) chloride
(iv)Amminebromidochloridonitrito-N- platinatc(II)
(v)Dichloridobis(ethane-l ,2-diamine) platinum (IV) nitrate
(vi)Iron(III)hexacyanidoferrate(II)
- [Co(NH3)4(H20)]Cl2
- K2[Ni(CN)4]
- [Cr(en)3]Cl3
- [Pt(NH3)BrClNO2]-
- [Pt Cl2(en)2] (NO3)2
- Fe4[Fe(CN)6]3
Write IUPAC names of following co-ordination compounds :
(a) [CO(NH3)6]Cl3
(b) [CO(NH3)Cl]Cl2
(C) K3[Fe(CN)6]
(d) [K3[Fe(C2O4)3]
(e) K2[PdCl4]
(f) [Pt(NH3)2ClNH2CH3]Cl
(a) hexaamminecobalt (III) chloride
(b) pentaamminechloridocobalt (III) chloride
(c) potassium hexacyanoferrate (III)
(d) potassium trioxalatoferrate (III)
(e) potassium tetrachloridoplatinum (II)
(f) diamminechlorido (methylamine) platinum(II) chloride.
Using IUPAC norms, write the formulae for the following :
(a) tetrahydroxozincate(II)
(b) hexaammineplatinum (TV)
(c) potassiumtetrachloridopalladate(II)
(d) tetrabromidocuprate (II)
(e) hexaaminecobalt(III) sulphate
(f) potassiumtetracyanonicklate (II)
(g) potassiumtrioxalatochromate(III)
(h) pentaamminenitrito-O-cobalt(III)
(i) diamminedichloridoplatinum(II)
(j) pentaamminenitrito-N-cobalt (III).
(a) [Zn(OH)4]2-
(b) [Pt(NH3)6]4+
(c) K2[PdCl4]
(d) [Cu(Br)4]2-
(e) [CO(NH3)6]2 (SO4)3
(f) K2[Ni(CN)4]
(g) K3 [Cr(OX)3]
(h) [CO(NH3)5ONO]2+
(i) [Pt(NH3)2Cl2]
(j) [CO(NH3)5NO2]2+.
Using IUPAC norms write the systematic names of the following:
(i) [Co(NH3)6]CI3,
(ii)[Pt(NH3)2CI (NH2CH3)] Cl
(iii) [Ti(H20)6]3+
(iv) [Co(NH3)4Cl(N02)]CI
(v)|Mn(H20)6]2+
(vi)[NiCl4]2-
(vii)[Ni(NH3)6]CI2
(viii)[Co(en)3]3+
(ix) [Ni(CO)4]
(i) Hexaammine cobalt (III) chloride.
(ii) Diammine chlorido (methylamine) platinum (II) chloride.
(iii) Hexaaquatitanium (III) ion.
(iv) Tetraammine chlorido nitrito-N-cobalt (IV) chloride.
(v)Hexaaquamanganese (II) ion.
(vi)Tetrachloridonickelate (II) ion.
(vii)Hexaammine nickel (II) chloride.
(viii)Tris (ethane -1,2-diamine) cobalt (III) ion.
(ix) Tetra carbonyl nickel (0).
Linkage isomerism And EXAMPLE
- ARISES IN coordination compound containing AMBIDENTATE LIGAND
[Co(NH3)5 (NO2)]Cl2
obtained in red form when nitrite ligand is bound thru OXYGEN
obtained in yellow form when nitrite ligand is bound thru NITROGEN
COORDINATION isomerism and EXAMPLE
- ARISES due to interchange of cationic and anionic entities of different metal ions
[Co(NH3)6] [Co(CN)6 ]
ITS COORDINATION ISOMERISM: [Cr(NH3)6] [Co(CN)6]
oxi no. is same: co3+ and cr3+
IONISATION ISOMERISM AND EXAMPLE
- arises when counter ion is itself a potential ligand
- and displace the ligand which can then become counter ion
[Co(NH3)5(SO4)]Br and its ionisation isomerism:
[Co (NH3)5 Br]SO4
SOLVATE ISOMERISM AND EXAMPLE
AKA HYDRATE ISOMERISM
- water is involved as a solvent
- similar to IONISATION isomerism
- it differ by whether or not a solvent molecule is directly bonded to the metal ion or merely present as free solvent molecules in the crystal lattice
[Cr(H20)6]Cl3 - VIOLET
and its solvate isomer[Cr (H2O)5Cl]Cl2. H2O- grey green
limitation of werners theory
It could not explain
* the inability of all elements to form coordination compounds.
* the directional properties of bonds in various coordination compounds.
* the colour, the magnetic and optical properties shown by coordination compounds.
How many geometrical isomers are possible in . the following coordination entities?
(i) [Cr(C2O4)3]3- (ii) [CoCl3(NH3)3]
(i) [Cr(C2O4)3]3- => No geometrical isomers
(ii) [Co(NH3)3 Cl3] => Two geometrical isomers are possible (fac and mer) in this coordination entity.
Indicate the types of isomerism exhibited by the following complexes
(i)K[Cr(H2O)2(C2O4)2]
(ii)[CO(en)3]Cl3
(iii)[CO(NH3)5(NO2)(NO3)2], .
(iv)[Pt(NH3)(H2O)Cl2]
- a. geometrical isomerism of cis and trans
b. optical isomerism of cis - optical isomerism
- ionisation and linkage
- geometric
why is geometrical isomerism for tetrahedral complexes not possible
bcz the relative positions of unidentate ligands with CMA are the same with respect to each other
enantiomer
[Co(en)3]3+
[PtCl2(en)2]2+
non superimposable image
optically active
limitations of VALENCE BOND THEORY
- involve no. of assumptions
- no quantitative interpretation of magnetic data
- no explanation about colour exhibited by coordination compounds
- it doesnt explain about the thermodynamic or kinetic stabilities of CC
- no exact prediction btwn tetrahedral and square planar structures of 4 cordinate complexes
- doesnt distinguish btwn weak and strong ligand
sp3d2
- weak ligand
- outer orbital
- high spin
- presence of unpaired electron
- paramagnetic
- OCTAHEDRAL
d2sp3
- strong
- low spin
- diamagnetic
- inner orbital
- OCTAHEDRAL
- No unpaired e-
sp3
- tetrahedral
- outer orbital complex
- high spin
- paramagnetic
dsp2
- square planar
- low spin
- diamagnetic
- inner orbital complex
SPECTROCHEMICAL SERIES
I BRought Some CoLourful Sweets From Office COntaining H2O. Nisha EDiTs Nine ENglish Cyan COupons
weak ligand:
1. I
2. Br
3. SCN
4. Cl
5. S
6. F
7. OH
8. C2O42-
9. H2O
strong ligands
1. NCS
2. EDTA4-
3. NH3
4. en
5. CN
6. CO
CRYSTAL FIELD SPLITTING
Thus, the repulsions in octahedral coordination compound yield two energy levels:
t2g– set of three orbitals (dxy, dyz and dxz) with lower energy
eg – set of two orbitals (dx2-y2 and dz2) with higher energy
This splitting of degenerate level in the presence of ligand is known as crystal field splitting.
IN OCTAHEDRAL COMPLEX WHAT DOES DEGENERATE ORBITALS SPLIT INTO?
t2g– set of three orbitals (dxy, dyz and dxz) with lower energy
eg – set of two orbitals (dx2-y2 and dz2) with higher energy
WHY does CRYSTAL SPLITTITNG OCCUR IN OCTAHEDRAL CC
😎repulsion between the electrons in d orbitals and ligand electrons.
This repulsion is experienced more in the case of** dx2-y2 and dz2 orbitals as they point towards the axes along the direction of the ligand.
Hence, they have higher energy than average energy in the spherical crystal field.
On the other hand, dxy, dyz, and dxz **orbitals experience lower repulsions as they are directed between the axes.
Hence, these three orbitals have* less energy *than the average energy in the spherical crystal field.
WHAT does CFS depend on
field produced by ligand
and
charge on metal ion
how would u determine where the fourth e- entering the eg or pair with t2g e-
relative magnitude of cfs delta0
and
pairing energy
pairing energy: energy required for e- pairing in single orbital
if relative magnitude of CFS< PAIRING ENERGY
4TH e- enters eg
ligands are weak
form high spin complex
config: t23g eg1
if relative magnitude of CFS > PAIRING ENERGY
4th e- occupy t2g
config: t2g4 eg0
strong field ligands
low spin complexes
d4 to d7
treatment of LEAD POISONING
EDTA
CIS PLATIN
PT
INHIBIT growth of tumours
wilkinson catalyst
rhodium complex
bonding in carbonyl complex
- synergic bonding provides stability
- metal carbon bond contain both pi and sigma character
- M-C sigma bond is formed by donation of lone pair of e- on CO into a vacant orbital of metal
- M-C pi bond is formed by the donation of a pair of e- from a filled d orbital of metal into vacant antibonding pi orbital of CO
THE LIGAND TO METAL IS WHICH BOND IN METAL CARBONYLS
σ
THE METAL TO LIGAND IS WHICH BOND IN METAL CARBONYLS
π
