Summary inorganic chemistry _ v0.05.doc

7/27/2019 Summary inorganic chemistry _ v0.05.doc

http://slidepdf.com/reader/full/summary-inorganic-chemistry-v005doc 1/18

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LO H M

O H LO H M K

z +

=

∏= n K 6β

∑= )log()log( 6 n K β

n z

m

z

n

n

LO H M

ML]][)([

][2

+

+

=β

Summary inorganic chemistry part 1

Paragraph 6.11: Coordination complexes. In a “Coordination complex” a central atom or

ion is coordinated by one or more molecules or ions (ligands) which act as

Lewis bases (donates electrons), forming coordinate bonds with the centralatom or ion which acts as a Lewis acid (accepts electrons). toms in the

ligands that are directly bonded are called donor atoms. line is used to

denote the interaction between an anionic (negati!e ion) ligand and the

acceptor, an arrow is used to show the donation of an electron pair from a

neutral ligand to an acceptor. "he resulting species from a coordinate bond is

called an adduct. Can be indicated by a dot, e.g.# $%&'"$.

eutral complexes are usually sparingly soluble in water, but readily soluble in

organic sol!ents. "he p$ also has an effect, $* can compete for the ligand, and +$ can act

as ligand.

Paragraph 6.12: Stability constants. -etal ions are often

hydrated, -($/+)012* is often written as -2*. 34uilibrium

constants (normally written without $/+1 because that5s the

unity) for each displacement step (e.g. 6 7 depicted on the right

here) can be ta8en together by multiplying them (also see

right), resulting in the o!erall stability constant βn. 9sually

stability constant 6 n decreases with increasing n (more ligands).

$ighly charged ions more negati!e :hyd;< because they

impose more order on water, when highly charged ions form

complexes charge neutrali2ed (and also enthalpy significantly

negati!e) = :>< substantially negati!e.

umber of donor atoms through which ligand

coordinates is called denticity of ligand (mono, didentate etc).

?olydentates = chelate ring (chelate from crab5s claw) with bite

angle @-A. 0 membered ring is stabili2ed Bbonding. ;mall

metal ions fa!or 0 member rings, larger metal ions fa!or member rings. (..) Chelate complexes more fa!orable than

corresponding monodentate complexes (chelate effect). (..)

-acrocyclic ligands# a macrocylce is a cyclic macromolecule or

a macromolecular cyclic portion of a molecule.

O

B

HH

H



Paragraph 19.2: Ground state e- conigurations. -etals are elements that readily lose

electrons to form cations. Dbloc8 metals shown in image below. transition element (E d

bloc8 metal) is an atom that has incomplete dsubshell or forms cations with incomplete

subshells. 3ach group of dbloc8 metals consists of three members and is called a triad, first

and second row metals denoted by “hea!ier”. irst, second and third row correspond

respecti!ely filling %d, Fd, and d orbitals, from which there are howe!er minor de!iations.

-/* and -%* ions of first row metals all ha!e r1%dn.

Paragraph 19.!: Physical properties. -etallic radii show little !ariation across a gi!en

row of dbloc8, the first row metal is has smallest radii, the second and third are similar. "his

last fact is due to the lanthanoid (La (G) H Lu (G7))contraction# the steady decrease in si2e

along the lanthanoid elements. -etals of dbloc8 hard, ductile, malleable, less !olatile then s

bloc8. ll %d metals ha!e !alues of I37 and I3/ larger than those of calcium and all (except

2inc) ha!e ha!e higher !alues of a$<, which ma8e them less reacti!e than calcium. ;ince all

8nown -/* ions of %d metals are smaller than Ca/* lattice and sol!ation energy effects are

more fa!orable for %d metal ions.

Paragraph 19.": #eacti$ity. -etals are moderately reacti!e. +n thermodynamic grounds

metals should liberate $/ from acids, but generally do not either because passi!ation by thin

surface coating of oxide or because they ha!e a dihydrogen o!erpotential, or both. ;il!er,

gold and mercury least reacti!e metals.

Paragraph 19.%: Characteristic properties. Colors are specific for species with other

ground state than d< and d7< and are pale because they5re against the Laporte selection rule#

e transitions only if l J K7. -ore intenser colors originate from charge transfer absorptions

or emissions. 3@?D I"$ ;3C"I+ 70.F.



(..) (paramagnetism). Intercon!ersion between oxidation states characteristic of d

bloc8 metals. pparent oxidation state from molecular or empirical formula may be

misleading, e.g. La%*(I)/(e), sometimes metalmetal bonds or ambiguous oxidation states,

e.g. "i(bpy)%1n (n J <, 7, /).

Paragraph 19.6: &lectroneutrality. ?auling5s electroneutrality principle estimates charge

distribution by assuming charge on single atom only 7 to *7. M

Co

NH3+

NH3+

NH3+

NH3+

+H3N

+H3N

3-

Co

H3N

NH3

NH3

NH3

H3N

H3N

3+

Co

NH3+

NH3+

NH3+

NH3+

NH3+

NH3+

3+

Co

NH31/2+

NH31/2+

NH31/2+

NH31/2+

H3N

H3N

1/2+

1/2+

conventional 100% covalent 100% ionic inbetween

Paragraph 19.': Coordination numbers. Coordination numbers and geometries are often

distorted from regular geometries, because e.g. steric effects. If there5s a small energy

difference between geometries, fluxional beha!iour in solution may be obser!ed.

In the 6epert model the metal lies at the centre of a sphere o!er which the ligands

are free to mo!e. "he ligands are considered to repel each other li8e N;3?O, bot nonbonding

electrons are ignored, and the geometry is thus independent of the ground state e

configuration. Common arrangement in the table on the right, not all are predicted by 6epert

because electronic factors or the inherent constraints of ligands. "ripodal ligands are ligands

containing three arms, each with a donor atom, originating from central atom or group which

also may be donor.

Coordination number 2. 9ncommon, restricted only a few metalions (d7<). Coorindation

number 3. lso uncommon, also in!ol!ing d7<. ;ome pbloc8 ha!e tshaped molecules

because stereochemically acti!e lone pairs, but not seen dbloc8. Coordination number 4.

re !ery common, mostly tetrahedral# d<,7,/,,0,G,P,Q,7<. ;4uare

planar if electronic factors strongly fa!or s4uare planar

arrangement, usually dP. Coordination number 5. "rigonal

bipyramid and s4uare based pyramidal. ;ince small energy

difference often between extremes. Coordination number 6.

lmost always octahedral, but dF and dQ tetragonally distorted# elongated or s4uashed. "his

octahedron trigonal pri!



is called the Rahn"eller effect. lso a small group of d< and d7 trigonal prismatic or distorted

trigonal prismatic en!ironment. Coordination number 7. 3arly second S third row (and also

lanthanoids and actinoids), rcation must be relati!ely large. In reality much distortion from

these structures. Coordination numbers 8, 9 and 10. (..)

Paragraph 19.(: )somerism. (..) (Oead blue boxes).

Ligand

s

Geometr !bridi"atio

n/ linear sp

% trigonal planar sp/

F tetrahedralT sp%

F s4uare planar sp/d

trigonal bipyramidal sp%d

s4uare based pyramidal sp%d

0 octahedral sp%d/

G pentagonal bipyramidal sp%d%

P dodecahedral sp%dF

P s4uare antiprismatic sp%dF

P hexagonal bipyrimidal U

Q tricapped trigonal

prismatic

sp%d



Paragraph 2*.2: $alence bond

theory. Nalence bond theory

(hybridi2ation and o!erlap)#

hybridi2ation schemes can be used to

describe bonding dbloc8 metals. &ut

!alence bond theory is !ery unrealistic

when trying to describe metal

complexes. ;ee third electron

configuration, where electrons are put unpaired in %d shell to achie!e diamagnetism (or high

spin) and Fd shell thus has to be used for hybridi2ation.

Paragraph 2*.!: crystal ield theory.

Ligands are considered points charges and

there are no co!alent metalligand interactions.

3lectrostatic field J crystal field. ;ee fig. /<./,

if spherical approach ligands, all %d orbitals

would be raised. &ut octahedral approach# d2/

and dx/y/ raised more than dy2, dyx and d2x (the

closer the ligand, the greater the raise in

energy, V repulsion). "he separation

energy is oct, because the total energy remains the same, and two and three orbitals are at

the same energy le!el, energy is splitted <.0 and <.F oct. -agnitude of oct is determined by

the strength of the crystal field# oct(strong field) W oct(wea8 field). ith absporption

spectrum ion, e promotion from t/g to eg (the resulting orbitals from splitting the dorbital)

can be seen and oct can thus be estimated. oct determined by identity and oxidation metal

and nature of ligands. oct depends on ligands as follows#

"

L

L

L

L

L

L

n+#

$

%



wea8 field# octX1 IY Z &rY Z ;/Y Z ;CY Z ClY Z +%Y Z %

Y Z Y Z +$Y Z C/+F/Y Z $/+ Z

C;Y Z C$%C Z py (pyridine) Z $% Z en (ethylenediamine) Z bipy (/,/[bipyridine) Z phen

(7,7<phenanthroline) Z +/

Y

Z ??h% Z C

Y

Z C+ strong field# oct\1

;ame donor atoms close together. oct !aries irregularly

across the first row of the dbloc8. or metals, oct

decreases down triad, spectrochemical series of metals

can be made independent of ligands#

wea8 field# octX1 -n(II) Z i(II) Z Co(II) Z e(III) Z Cr(III)

Z Co(III) Z Ou(III) Z -o(III) Z Oh(III) Z ?d(II) Z Ir(III) Z

?t(IN) strong field# oct\1.

o increases with oxidation state.

o decreases within group

or a gi!en dn configuration the crystal field stabili2ation

energy (C;3) is the difference in energy between the d

electrons in an octahedral crystal field and the d electrons if they would be located in a

spherical crystal field.

"his depends on oct and ?. ? is the electronpairing energy, the energy it costs to puttwo electrons from parallel spin to spinpaired. "his energy is comprised of the (loss of)

exchange energy and the coulombic repulsion between the spin paired electrons. 3xchange

energy (see orbital image right)# difference both electrons parallel

spin (more stabile) and re!erse spins.

3lectrons can be put in the two splitted orbitals “low spin” or “high spin”. In low spin

the lowest orbitals gets filled completely first, and in high spin the aufbau principle goes for

all orbitals. "he electrons will fill the orbitals creating the lowest C;3, which is thus#

C;3 J (nlow) ' oct,low * (nhigh) ' oct,high H ?

]#$ere % is t$e & o' aired in omarison #it$ s$eria* 'ie*d+

$ence, or loo8ed upon differently, if oct W ? (strong crystal

field) it costs more energy to put the electron in the high

energy orbital (eg) than paired in the lower t/g orbital, the



complex will thus be low spin. "he other way around# if oct Z ? (wea8 crystal field), it is more

energy efficient to put the electrons in the higher orbital (eg) first, if these are empty.

a$n-e**er distortions. Rahn"eller distortions

originate if electron density is not e4ually

distributed. "he metalligand bond lengths are

stretched if nearby orbitals are filled and !ice !ersa

(see image), leading to a distortion. "his is often the

case in octahedral dF and dQ complexes.

$e a$n-e**er t$eorem states t$at an non-*inear mo*eu*ar sstem in a degenerate

e*etroni state #i** be unstab*e and #i** undergo distortion to 'orm a sstem o' *o#er

smmetr and *o#er energ, t$ereb remo/ing t$e degenera.

etra$edra* rsta* 'ie*d. dxy, dy2, dx2 orbitals nearer to ligands than

d2/ and dx/y/. tet J F^Q'oct, because tet is smaller, tetrahedral

complexes are high spin. lso different colours. In e+FF Rahn

"eller distortions lead to different bond angles.

uare *anar rsta* 'ie*d. Can be deri!ed by remo!ing two trans ligands from an

octahedral configuration. 3.g. from 2axis, d2/ greatly stabili2ed, dy2 and dx2 (also

point partially in 2direction) also stabili2ed, dx/y/ is massi!ely destabili2ed, whereas dxy is

moderately destabili2ed. iClF1/ is tetrahedral, while ?d(II)@F12 and ?t(II)@F12 are both

s4uare planar, because ?d and ?t (/nd and %rd row) cause larger crystal fields.

t$er rsta* 'ie*ds. ;ee image on next page, though only for li8e ligands_

Fe(IV)

O O

O O

125&

12'&

-



+ctahedral Pentagonal bipyramidal S,uare antiprismatic

S,uare planar S,uare pyramidal etrahedral

rigonal bipyramidal

Paragraph 2*.": olecular orbital theory. -olecular orbital theory offers alternati!e for

the crystal field theory. irst ta8e a loo8 at `%./ and pp 7<Q.

Paragraph !.2: Symmetry operations / elements. symmetry operation is an

operation which lea!es it in a configuration that is indistinguishable from its original

configuration. "he operation is carried out with respect to symmetry elements, i.e. points,

lines or planes. "he symmetry operation around an nfold axis is noted by Cn, nfold meaning

that a (%0<^n) rotation leads to the same configuration. If a molecule possesses more than

one axis, the axis with the highest n!alue is called the principal axis. ;ometimes different

order axes coincide (e.g. CF with C/ in s4uare planar).

Oeflection through a plane is denoted with the symbol. If the plane is perpendicular

to a Cn axis, it is labelled h (hori2ontal) and if it coincides with the principal axis it is labeled

http://en.wikipedia.org/wiki/Image:Trigonal_bipyramidal.PNG

http://en.wikipedia.org/wiki/Image:Tetrahedral.PNG

http://en.wikipedia.org/wiki/Image:Square_pyramidal.PNG

http://en.wikipedia.org/wiki/Image:Square_planar.PNG

http://en.wikipedia.org/wiki/Image:Square_antiprismatic.PNG

http://en.wikipedia.org/wiki/Image:Pentagonal_bipyramidal.PNG

http://en.wikipedia.org/wiki/Image:Octahedral.PNG



! (!ertical). ! refers to the plane bisecting the ($+$) bond and !5 refers to the plane in

which the molecule lies. d (dihedral) label is gi!en if the plane bisects an angle between

two Cn axes.

"he center of in!ersion is the point from which you can draw an infinite number of

straight lines such that each line passes through (a) pair(s) of similar points, one on each

side of the centre of symmetry and at e4ual distance from it.

rotation followed by a reflection through a plane perpendicular to that axes, which

is called the improper rotation axis, resulting in the same configuration, is designated with

;n.

ll obects can be operated upon by identity operater 3, which lea!es the molecule

unchanged, all elements are thus at least said to ha!e the symmetry element 3.

Page 1*9: 0 bent triatomic: 2+. ;ymmetry can be used in different ways, a short

example follows.

C2/ C2 / (") / (")7 7 7 7 7/ 7 7 7 7&7 7 7 7 7&/ 7 7 7 7

It is possible to de!elop an -+ picture of the $/+ bonding based upon symmetry information.

"he “C/! character table” is shown abo!e# labels in the first column under the “point group

symbol” tell us the symmetry types of orbitals that are permitted within the specified point

group. point group is a set of symmetry operations forming a mathematical group, for

which at least one point remains fixed under all operations of the group7. "he numbers in the

3 column indicate the degeneracy of each type of orbital, in the C/! point group all orbitals

ha!e a degeneracy of 7, i.e. they are nondegenerate. "he rows of numbers following a gi!en

symmetry label indicate how a particular orbital beha!es when operated by each symmetry

operation# 7 means unchanged, 7 means it changes sign, < means it changes in some other

way. or example# the /s orbital remains unchanged by all symmetry operations (resulting in

only “ones”), and is as defined in the character table gi!en the label a7 (lower case, only in

the table uppercase letters are used).

7 http#^^en.wi8ipedia.org^wi8i -olecularsymmetry?ointgroups



mb

o*

eration *ement am*e

Cn Ootation nfold axis

(%0<^n)

Oeflection ?lane

i Centre

;n Ootation * reflection through a

plane perpendicular to the axis

nfold improper

rotation axis



Paragraph 2*.": olecular orbital theory continued3. -+ theory does consider

co!alent interactions in complexes.

t$eor (based on $ater 4 120 : 6 )

-+ theory compares symmetries to establish a molecular orbital diagram. or example, a

first row metal has %d, Fs and Fp !alence shells. "hose can be di!ided in different

symmetries.

Fs a7g symmetryFp t7u symmetry%dx/y/, %d2 eg symmetry%dxy, %dy2, %dx2 t/g symmetry

It is 8nown that only p orbitals of the ligands interact with the metal.

-ore precise, only the p2 orbitals (if each ligand is gi!en its own axis

set). urthermore, from an examination of how many of these p

orbitals are the same after +h symmetry operations it can be

concluded that the L>+ is a sum of 7g, "7u and 3g symmetries. 0 new

wa!efunctions can thus be deri!ed by mixing the p orbitals.

"o construct the -+ diagram, orbitals of same symmetry are

mixed. +rbitals with another symmetry become nonbondingorbitals. Displayed to the left an image of bonding in ;0. ; only

has s S p orbitals.

-bonding on*. or an octahedral metalligand complex an -+ diagram can thus beconstructed, each ligand beha!es similar to the aforementioned fluor. "he metal has fi!e %d

orbitals (eg and t/g), a Fs orbital (a7g) and three Fp orbitals (t7u). "his leads to the following -+

diagram#



"here is greater o!erlap between the metal s and p orbitals and the ligand p orbitals than

between the metal %d and the ligand p, which leads to more stabili2ation. If there is no Bbonding, the energy le!els between t/g and eg] correspond with oct. +b!iously, if the eg, t7u

and a7g orbitals are filled (which can be done by the electrons supplied by the ligands), the

remaining electrons (from the metal) are di!ided depending on wea8 or strong field, ust as

in the crystal field theory.

Com*ees #it$ ; bonding a*so. ;ometimes B bonding considered for d t/g orbitals (dxy, dx2,

dy2) and ligand d orbitals in the case of phosphine ligands (e.g. ?O% or ?%), but more often

other interactions. I.e. ligand ]orbitals as acceptor orbitals. "here are two types of ligands#

Bdonor and Bacceptor ligands.

a Bdonor ligand donates electrons to metal

centre in an interaction that in!ol!es a filled

ligand orbital and an empty metal orbital.

a Bacceptor ligand accepts electrons from

the metal centre in an interaction that

in!ol!es a filled metal orbital and an empty

ligand orbital.

Bacceptor ligands can stabili2e low oxidation state metal complexes.



;-donor

*igands

;-aetor *igand

Cl, &r, I C+, /, +

hen a metal is bound to a Bdonor ligand, the t/g orbitals will not be split !ery far. hen a

metal is bound to a Bacceptor ligand, the splitting will be much more. ;ee diagrams abo!e.

lso, when the metal is bound to a Bdonor ligand, these orbitals will bring in more

electrons, thus changing “where the metal electrons will go” (mar8ed light greenT the rest is

filled with bonding electrons, in case of donor thus also donated electrons). "he number of

bonding electrons is always the same in the two separate cases respecti!ely, the number of

metal electrons can change# in complexes there are 7/ electrons from the ligand and in B

complexes the and B orbitals from the ligand contribute 7P electrons (0]/ * 0B). "hesecan be considered to fill the orbitals below the “green orbitals” (see picture).

or better, but still 4ualitati!e pictures, see p. 0P boo8. $owe!er, conclusions can be

drawn#

oct decreases in going from only complex to and Bcomplex (compare abo!e

donor picture to picture on pre!ious pageT and bare in mind that eg] stays e4ual).

o or a complex with Bdonor ligands, increased Bdonation (U) stabili2es t/g le!el

and destabili2es t/g], thus decreasing oct.

oct !alues are relati!ely large for Bacceptor ligands, and those complexes are thus

li8ely to be low spin.

o or a complex with Bacceptor ligands, increased Bacceptance stabili2es t/g,

increasing oct.

urthermore, since filling antibonding orbitals is detrimental for complexformation,

octahedral complexes with Baccepting ligands will not be fa!oured by dnW0. n obser!ation



can be made that dbloc8 metals tend to obey the “effecti!e atomic number rule” or the “7P

electron rule”. ;ee also chapter /%# low oxidation state organometallic complex contains B

acceptor ligands and the metal centre tends to ac4uire 7P electrons in its !alence shell (the

“7Pelectron rule”), thus filling the !alance shell. "he 7Peletron rule is useless for higher

oxidation state metals, can be rationali2ed by smaller energy seperations. +ther complexes

than octahedral fall out of the scope of this discussion (see p. G<).

(..T some exceptions for +).

Paragraph 2*.%: 4igand ield theory. on5t go in to mathematics of ligand field theory,

howe!er, ligand field theory is an extension to crystal field theory which is freely

parameteri2ed (as opposed to locali2ed field from point charge). It is also confined to d

orbitals. part from oct it also uses “Oacah” parameters which are obtained from electronic

spectroscopic data.

Paragraph 2*.6: &lectronic spectra. bsorptions arise from transition between electronic

energy le!els#

"ransitions between metalcentred orbitals possessing dcharacter (dd5 transitions).

o ea8er.

o Can be mas8ed due C" transition.

"ransitions between metal and ligandcentred -+s which transfer charge from metal

to ligand or !ice !ersa.

o -ore intense.

o -LC"# metaltoligand charge transfer

o L-C"# ligandtometal charge transfer

is wa!elength, is propagation speed en c is the speed of light, is the

wa!enumber.

bsorptions are relati!ely fast in comparison to molecular !ibrations and rotations (with

which the energy le!els change), hence, the obser!ed absorption fre4uencies !ary. "here isan absorption maximum max (nm), with corresponding max (absorbance), max is used to

describe the particular band. "he molar extinction coefficient (a8a molar absorpti!ity) max#

here max is the molar extinction coefficient, max the maximum absorption (j

max), c the concentration, and l the pathlength (in cm_) of the spectrometer

cell.

c

ν

λ ν ==

1

⋅=c

A!a%!a%ε



ote (without explanation) that#

d7,F,0,Q complexes consist of one absorption.

d/,%,G,P copmlexes consist of three absorptions.

d complexes consist of a series of wea8 but sharp absorptions.

e*etion ru*es.

;pin selection rule# paired^unpaired electrons stays e4ual. ;pin 4uantum number

; doesn5t change (; J <).

Laporte selection rule# +rbital 4uantum number l has to change with 7# l J < (e.g. s=s

and p=f forbidden).

"hese selection rules are strict, but exceptions occur under specific conditions (see p. G7)#

e ia* <ma

;pin forbidden, dd5 Z7Laporte forbidden, ;pin allowed d

d5

77< (centrosymmetrisch),

7< 7<<< (niet

centrosymmetrisch)Charge transfer (fully allowed) 7<<< < <<<

Paragraph 2*.(: agnetic properties. ?aramagnetism arises from

unpaired electrons. 3ach electron has a magnetic moment with one

component associated with spin angular momentum of electron, and a

second component associated with the orbital angular momentum(except when l J < (s)). "he image to the right depicts momenta,

howe!er, this is not realistic, “spins are not real”.

or many dbloc8 complexes the orbital momentum can be ignored, and the magnetic

moment k can be determined from the number of unpaired electrons#

)2()1(2 +=+= nnS S µ

here ; J total spin 4uantum number and n J unpaired electrons (; J n^/).

3ffecti!e magnetic moment, keff , can be obtained from experimentally measured molar

magnetic susceptibility, m. "he keff can be determined from m as follows#

T L

T k m

B

meff χ

µ µ

χ µ ')''*0

32

0

== (for ;.I. units).

8 J &olt2man, m J magnetic susceptibility, " J temperature, L J !agadro number,

k< J !acuum permeability, k& J “&ohr magneton” (see p. GQ).



3.g. a >ouy balance# sample is hung in balance and magnetic field

applied to it, sample mo!es and difference in weight can be read

out, from which magnetic susceptibility, m, can be determined.

:erromagnetism, anti'erromagnetism and 'errimagnetism. If metal

centres are separated by diamagnetic species, they are said to be “magnetically dilute”.

hen paramagnetic species are close together (bul8 metal), or separated by species able to

transmit magnetic interactions (as many dbloc8 oxides, fluorides and chlorides are), the

metal centres can “couple” (interact). "his may gi!e rise to ferromagnetism or

antiferromagnetism.

In a ferromagnetic material, large domains of dipoles

are aligned in the same direction. In anantiferromagnetic material, neighbouring magnetic

dipoles are aligned oppositely. bo!e the Curie

temperature ("c) the thermal energy is sufficient to

o!ercome the alignment. ntiferromagnetism occurs

be*o# the el temperature ("). errimagnetism

occurs when relati!e !alues of momenta are different.

hen a bridging ligand facilitates coupling of

electron spins on adacent metal centres, this

happens by superexchange. "he two metal

centres (in image on the left and right) interact

with two spinpaired electrons in the same orbital of a ligand. ;ince these are spin paired,

and the configuration in the -+ also has to be spinpaired, the result is an antiparallel

coupling of the two metal centres.

Paragraph 2*.9: ligand ield stabili5ation energies 4S&3. L;3 terms are only small

parts of total interaction energy. $owe!er, going to the different dn configurations, it shows

remar8able similarities with other thermodynamic energy trends, such as lattice energies

and hydration enthalpies of metals. De!iation from the dotted line may thus be ta8en as

measures of “thermochemical L;3” !alues. >enerally L;3 !alues are in compliance with

oct !alues measured from electronic spectroscopy.



s can be seen the figure abo!e, d<,,7< complexes should

not fa!our octahedral or tetrahedral configurations.

$owe!er, other factors should be ta8en into account.

3.g. the smaller si2e of tetrahedral complexes results in

higher lattice and sal!ation energies, hence, for example

i/* (dP) does not form tetrahedral complexes in a4ueous

solutions, only in melts or nona4ueous media.

(..T !erhaal o!er “spinels”).

Paragraph 2*.1*: he )r$ing-7illiams series. In a4ueous solutions, water is replaced by

other ligands, and the position of this e4uilibrium will be related to the difference between

the two L;3s, since oct is liganddependent. "he stability constants howe!er show the

following singlehump#

-n(II

)

Z e(II

)

Z Co(II

)

Z i(II

)

Z Cu(II

)

W n(I

I)d d0 dG dP dQ d7<

"his is not in accordance with the L;3 energies (that pea8 at dP), but this can be explained

from the fact that L;3 is not the only contributing factor. Ionic radii should also be ta8en

into account, these ha!e the following trend#

-n(II

)

W e(II

)

W Co(II

)

W i(II

)

Z Cu(II

)

Z n(I

I)d d0 dG dP dQ d7<

(Lattice energy)



"his trend can also be explained by dependency on dn configurations (and not only on the eff

increment leading to a decrease in radius). $owe!er, this trend also doesn5t explain the

stability of copper. Copper is !ery stabile because a dQ complex has a Rahn"eller distortion.

"his also renders the image of a fixed ionic radius useless. ppearantly in this distortions F

stronger bonds compensate for the / wea8er (longer) bonds in such a way to ma8e it more

stabile than i(II).

Paragraph 2*.11: oxidation states in a,ueous solutions. 3< !alues (..T nog le2en_ na

“deel /”).

+o8 nog doen:

Chelaat effect meer uitleg ]2ie %P

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Summary inorganic chemistry _ v0.05.doc