Download - Coordination Compounds I.ppt

7/23/2019 Coordination Compounds I.ppt

1/58

Transition MetalTransition Metal

Complexes IComplexes IThe structures, nomenclatureThe structures, nomenclature

and isomers of coordinationand isomers of coordinationcompoundscompounds


2/58

Coordination CompoundsCoordination Compounds

Any compound containing a metalAny compound containing a metal

atom or ion with one or more ligandsatom or ion with one or more ligands

is called ais called a coordination compoundcoordination compoundoror

complex. The ligands donatecomplex. The ligands donate

electrons to the metal via coordinateelectrons to the metal via coordinate

covalent bonds.covalent bonds.


3/58


The structures of these compounds wasThe structures of these compounds was

not always evident. Ions or moleculesnot always evident. Ions or molecules

might be directly bonded to the metal, ormight be directly bonded to the metal, or

serve as a counter ion for an ionic salt.serve as a counter ion for an ionic salt.

[Mn(![Mn(!""##$$% &% &'' sulfate ion issulfate ion is outer sphereouter sphere

[Mn(![Mn(!""## &&''%%..!!"" sulfate ion is sulfate ion is innerinnerspheresphere


4/58

CoordinationCoordination

CompoundsCompounds)arly chemists approached transition)arly chemists approached transition

metal complexes using the concept ofmetal complexes using the concept of

*valences+ adapted from main group*valences+ adapted from main group

metals. Metals with a - charge, such asmetals. Metals with a - charge, such asiron(III# or cobalt(III# were believed toiron(III# or cobalt(III# were believed to

only mae three bonds.only mae three bonds.

A compound such as [/o(0!A compound such as [/o(0!--##$$%/l%/l--waswas

thought to have three /o1/l bonds, withthought to have three /o1/l bonds, with

no way to explain the bonding of ammoniano way to explain the bonding of ammonia

in the compound.in the compound.


5/58


ne approach by 2lomstrand proposedne approach by 2lomstrand proposed

chains of lined ammonia molecules,chains of lined ammonia molecules,

with the nitrogens having 3ve bondswith the nitrogens having 3ve bonds

and connecting a chloride to the metal.and connecting a chloride to the metal.

Alfred 4erner proposed that theAlfred 4erner proposed that the

ammonia molecules could bondammonia molecules could bond

strongly and directly to the metal, withstrongly and directly to the metal, withchlorides either directly bonded, orchlorides either directly bonded, or

loosely bonded and ionic in solution.loosely bonded and ionic in solution.


6/58



7/58


5orgensen supported5orgensen supported

2lomstrand6s approach, and 4erner,2lomstrand6s approach, and 4erner,

in order to support his theory,in order to support his theory,

synthesi7ed new compounds andsynthesi7ed new compounds and

studied their isomers. )ventually, instudied their isomers. )ventually, in

89:;, 4erner prevailed and proved89:;, 4erner prevailed and proved

the octahedral geometry ofthe octahedral geometry ofcoordination compounds.coordination compounds.


8/58


Alfred 4erner (8uare planar and octahedral

shapes.shapes.


9/58

Possible Structures for 6-Possible Structures for 6-

Coordinate CobaltCoordinate Cobalt


10/58




11/58




12/58

Proposed Structures forProposed Structures for

6-Coordinate Cobalt6-Coordinate Cobalt


13/58

Structure of CompoundsStructure of Compounds

/omposition/omposition ? ions? ions ModernModern

formulationformulation

@t/l@t/l""..

'0!'0!-- - - [@t(0![@t(0!--##''%%""

"/l"/l11

@t/l@t/l""..-0!-0!-- " " [@t/l(0![@t/l(0!--##--%%/l/l11

@t/l@t/l"".."0!"0!-- : : [@t/l[@t/l""(0!(0!--##""%%

(" forms#(" forms#


14/58


15/58

Nomenclature ofNomenclature of


There is a separate system for namingThere is a separate system for naming

coordination compoundscoordination compounds

pre3x indicating ligand name metal pre3x indicating ligand name metal

(oxidation ?(oxidation ?? of ligands? of ligands in roman in roman numerals#numerals#

oror

* * ** * * * * * * * * * * * (charge of * * * (charge ofcomplex#complex#


16/58



8. If ionic, the positive ion is named8. If ionic, the positive ion is named

3rst, then the negative ion.3rst, then the negative ion.

". The inner coordination sphere is". The inner coordination sphere is

indicated by s>uare bracets. In theindicated by s>uare bracets. In the

formula, the metal is written 3rst,formula, the metal is written 3rst,

followed by the ligands. In naming,followed by the ligands. In naming,the ligands are named 3rst, then thethe ligands are named 3rst, then the

metal.metal.


17/58



-.-. @re3xes@re3xes If the ligand itself contains a pre3x If the ligand itself contains a pre3x

in its name (ex. dimethyl amine#, then thein its name (ex. dimethyl amine#, then the

pre3x to indicate the number of ligandspre3x to indicate the number of ligands

changes, and the ligand name is placed inchanges, and the ligand name is placed in

parenthesis.parenthesis.

"" didioror bisbis pentapentaoror pentakispentakis


18/58



'. Bigands are listed in alphabetical order'. Bigands are listed in alphabetical order

(ignoring any pre3xes#. Most ligands have(ignoring any pre3xes#. Most ligands have

special names, with all negatively chargedspecial names, with all negatively charged

ligands ending in the letter*ligands ending in the letter*oo+.+.Most neutral ligands retain their usualMost neutral ligands retain their usual

names, with the following commonnames, with the following common

exceptionsexceptions

0!0!-- ammineammine !!"" aquaaqua // carbonylcarbonyl


19/58

Names of CommonNames of Common

LigandsLigands CormulaCormula 0ame0ame

2r2r11 bromobromo

//--"1"1 carbonatocarbonato

/l/l11 chlorochloro/0/011 cyanocyano

!!11hydridohydrido

!!11 hydroxohydroxo"1"1oxooxo


20/58

Linkage IsomerismLinkage Isomerism

CormulaCormula 0ame0ame

00""11 nitritonitrito(via #(via #

00""11

nitronitro (via 0#(via 0#


21/58

Linkage IsomersLinkage Isomers

Binage isomersBinage isomersinvolve ligands thatinvolve ligands that

may bond via diDerentmay bond via diDerent

sites. In this example,sites. In this example,

nitro bonds vianitro bonds via

nitrogennitrogen

((00""11#, and nitrito#, and nitrito

bonds via an oxygenbonds via an oxygen

(0(0""11#. The#. The

compounds havecompounds havediDerent propertiesdiDerent properties

and colors.and colors.


22/58

Poldentate LigandsPoldentate Ligands

CormulaCormula 0ame0ame

0!0!""/!/!""/!/!""0!0!"" ethylenediamineethylenediamine

(en)(en)

2oth amines of theligand can attach

at the metalforming a ring.


23/58

Poldentate LigandsPoldentate Ligands

ethylenediaminetetraacetateethylenediaminetetraacetate

(EDTA)(EDTA) )=TA is a hexadentateligand.


24/58

!"T#!"T#

)=TA can wrap)=TA can wrap

around a metal ionaround a metal ion

to coordinate at $to coordinate at $

(octahedral# sites.(octahedral# sites.Bigands that bindBigands that bind

to more than oneto more than one

site are calledsite are called

chelating agents.chelating agents.


25/58


Coordination CompoundsCoordination Compounds.. There are two systems for indicating theThere are two systems for indicating the

oxidation number of the metal. The moreoxidation number of the metal. The more

commonly used system indicates the oxidationcommonly used system indicates the oxidation

number in Eoman numerals in parentheses afternumber in Eoman numerals in parentheses after

the name of the metal.the name of the metal.

The other system puts the charge of theThe other system puts the charge of the

coordination complex in Arabic numbers incoordination complex in Arabic numbers in

parentheses after the metal.parentheses after the metal.

[/r(![/r(!""##/l%/l%""is pentaa>uachlorochromium(III#is pentaa>uachlorochromium(III#

oror, pentaa>uachlorochromium("#., pentaa>uachlorochromium("#.


26/58



$. Fsing either system, if the transition metal$. Fsing either system, if the transition metal

complex is negative in charge, the name ofcomplex is negative in charge, the name of

the metal ends inthe metal ends in ateate..

Cor example, [@t(0!Cor example, [@t(0!--##""/l/l''%%"1"1

is namedis nameddiamminetetrachloroplatinate(II#.diamminetetrachloroplatinate(II#.

Cor metals with Batin names, the negativelyCor metals with Batin names, the negatively

charge complex usescharge complex uses

ferrate (for Ce#ferrate (for Ce# argentate (for Ag#argentate (for Ag#plumbate (for @b#plumbate (for @b# stannate (for &n#stannate (for &n#

aurate (for Au#aurate (for Au# cuprate (for /u#cuprate (for /u#


27/58



;. The complete name of the complex must;. The complete name of the complex must

also indicate the presence of geometricalso indicate the presence of geometric

isomers. @re3xes such asisomers. @re3xes such as ciscis,, transtrans,, mermer,,

andandfacfacare used to indicate the relativeare used to indicate the relativepositions of similar ligands.positions of similar ligands.

In addition, stereoisomers are alsoIn addition, stereoisomers are also

possible with tetrahedral and octahedralpossible with tetrahedral and octahedral

geometries, and optical isomers aregeometries, and optical isomers areindicated with the pre3xes G andindicated with the pre3xes G andHH..


28/58




29/58

IsomerismIsomerism


30/58

StereoisomerismStereoisomerism

&tereoisomers have the same&tereoisomers have the same

connectivities but diDerent spatialconnectivities but diDerent spatial

arrangements.arrangements.

InIn geometric isomersgeometric isomers, the ligands have, the ligands havediDerent spatial arrangements aboutdiDerent spatial arrangements about

the metal ion.the metal ion.

ptical isomersptical isomersare compounds withare compounds withnon1superimposable mirror images.non1superimposable mirror images.


31/58

$eometric Isomerism$eometric Isomerism

Jeometric isomers diDer in the geometricJeometric isomers diDer in the geometricarrangement of the ligands around thearrangement of the ligands around the

central metal.central metal.

/ommon examples are s>uare planar/ommon examples are s>uare planar

complexes such as [@t(0!complexes such as [@t(0!--##""/l/l""%.%.


32/58

$eometric Isomerism$eometric Isomerism

In octahedral complexes, the pre3xesIn octahedral complexes, the pre3xesciscisandand transtransare used for complexes ofare used for complexes of

the form [MKthe form [MK''LL""%%


33/58

%cta&edral Complexes%cta&edral Complexes

Cor complexes with the formulaCor complexes with the formula

[MK[MK--LL--%, there are two spatial%, there are two spatial

arrangements of the ligands.arrangements of the ligands.


34/58

%cta&edral Complexes%cta&edral Complexes

facfacstands for facial, andstands for facial, and mermerstands for meridian.stands for meridian.


35/58

C&iralitC&iralit

2oth four1coordinate and six1coordinate2oth four1coordinate and six1coordinate

complexes exhibit chirality. /hiralcomplexes exhibit chirality. /hiral

molecules have either no symmetrymolecules have either no symmetry

elements (other than identity#, or only aelements (other than identity#, or only a//nnaxis.axis.

Tetrahedral complexes can be chiral inTetrahedral complexes can be chiral in

the same way that organic compoundsthe same way that organic compounds

are they may have four diDerent ligands.are they may have four diDerent ligands.They may also have unsymmetricalThey may also have unsymmetrical

chelating ligands.chelating ligands.


36/58

C&iralitC&iralit

&>uare1planar&>uare1planar

complexescomplexes

can also becan also be

chiral, aschiral, as

seen in theseseen in these

compounds ofcompounds of

platinum(II#platinum(II#andand

palladium(II#.palladium(II#.


37/58

%ptical Isomers%ptical Isomers

ctahedral complexes containingctahedral complexes containing

polydentate ligands can form opticalpolydentate ligands can form optical

isomers. /omplexes with threeisomers. /omplexes with three

rings, such as [/o(en#rings, such as [/o(en#--%%-,-,, can be, can beviewed lie a propeller with threeviewed lie a propeller with three

blades. The structure can be eitherblades. The structure can be either

left or right handed, with non1left or right handed, with non1superimposable mirror images.superimposable mirror images.


38/58

%ptical%ptical

IsomersIsomersThe upper

isomer is righthanded, and the

lower one is lefthanded.

i l


39/58

%ptical%ptical

IsomersIsomers

% i l


40/58

%ptical%ptical

IsomersIsomers

% i l


41/58

%ptical%ptical

IsomersIsomers

i l% i l


42/58

%ptical%ptical

IsomersIsomers

% i l% i l


43/58

%ptical%ptical

IsomersIsomers


44/58


The right1The right1

handed isomerhanded isomer

re>uires goingre>uires going

clocwise to getclocwise to getfrom the upperfrom the upper

triangle to thetriangle to the

lower one. Thelower one. The

pre3x for thispre3x for thisisomer is G.isomer is G.


45/58


The left1handedThe left1handed

isomer re>uiresisomer re>uires

goinggoing

counterclocwisecounterclocwiseto get from theto get from the

upper triangle toupper triangle to

the lower one. Thethe lower one. The

pre3x for thispre3x for thisisomer isisomer isHH..


46/58


ctahedral complexes with twoctahedral complexes with two

chelating ligands and two non1chelating ligands and two non1

chelating ligands can also bechelating ligands can also be

optically active.optically active.


47/58

IsomersIsomers

/o(III# and ethylenediamine react to/o(III# and ethylenediamine react to

form several products.form several products.

ciscis[/o/l[/o/l""(en#(en#""%% is violet, and theis violet, and the

trans isomer is green. The reactiontrans isomer is green. The reactionalso forms a yellow product,also forms a yellow product,

[/o(en#[/o(en#--%%--. =etermine the number. =etermine the number

of isomers of each of the products.of isomers of each of the products.Babel any enantiomers with theBabel any enantiomers with the

proper pre3x (G orproper pre3x (G orHH#.#.


48/58

Isomer ProblemIsomer Problem

The yellow product is [/o(en#The yellow product is [/o(en#--%%,-,-..

It exists as an enantiomeric pair.It exists as an enantiomeric pair.


49/58

Isomer ProblemIsomer Problem

The violet product consists of a pair ofThe violet product consists of a pair of

optical isomers. The green product is notoptical isomers. The green product is not

optically active, as it has a mirror plane.optically active, as it has a mirror plane.

C C di iC C di ti


50/58

Common CoordinationCommon Coordination

Numbers ' StructuresNumbers ' Structures

( #) i( t #) ti


51/58

(actors #)ecting(actors #)ecting

Coordination NumberCoordination Number

8. The si7e of the central atom or ion.8. The si7e of the central atom or ion.

". &teric interactions between buly". &teric interactions between buly

ligands such as @(/ligands such as @(/$$!!##--..

-. The electronic structure of the metal-. The electronic structure of the metal

atom or ion. If the oxidation number isatom or ion. If the oxidation number is

high, the metal can accept morehigh, the metal can accept more

electrons from the (Bewis base#electrons from the (Bewis base#ligands. Metals with manyligands. Metals with many ddelectronselectrons

will have lower coordination numbers.will have lower coordination numbers.


52/58

Coordination NumbersCoordination Numbers

/oordination numbers of 8, " and/oordination numbers of 8, " and

- are relatively rare. /oordination- are relatively rare. /oordination

number ' leads to two commonnumber ' leads to two common

structures tetrahedral or s>uarestructures tetrahedral or s>uareplanar geometry. &>uare planarplanar geometry. &>uare planar

structures are most commonly seenstructures are most commonly seen

with dwith d


53/58

* Coordinate Complexes* Coordinate Complexes

coordinate complexes with coordinate complexes with

monodentate ligands are oftenmonodentate ligands are often

highly uxional, so that axial andhighly uxional, so that axial and

e>uatorial positions interchange.e>uatorial positions interchange.nce such method of interchange ofnce such method of interchange of

these positions is via athese positions is via a!erry!erry

pseudorotationpseudorotation..


54/58

+err Pseudorotation+err Pseudorotation

#

#

#

#

#

#


55/58

* Coordinate Complexes* Coordinate Complexes

A planarA planar

polydentatepolydentate

ligand, such as aligand, such as a

porphyrin, mayporphyrin, mayresult in s>uareresult in s>uare

pyramidalpyramidal

structures, when astructures, when a

3fth ligand is3fth ligand isadded, such as inadded, such as in

myoglobin.myoglobin.


56/58

6-Coordinate Complexes6-Coordinate Complexes

$1coordinate$1coordinate

complexes arecomplexes are

usually octahedral.usually octahedral.

&ometimes&ometimesdistortion fromdistortion from

octahedraloctahedral

geometry occurs ifgeometry occurs if

a bidentate liganda bidentate ligandhas a smallhas a small bitebite

angleangle..


57/58

6-Coordinate Complexes6-Coordinate Complexes

In extremeIn extreme

cases, thecases, the

*staggered+*staggered+

con3guration ofcon3guration ofthe octahedronthe octahedron

can be distortedcan be distorted

into a trigonalinto a trigonalprism.prism.


58/58

,- Coordinate Complexes,- Coordinate Complexes

These areThese aremoremorecommon forcommon forff1bloc1blocelements,elements,

and includeand includepentagonalpentagonalbipyramids,bipyramids,cappedcappedoctahedronsoctahedrons

and cappedand cappedtrigonaltrigonalprisms.prisms.

Download - Coordination Compounds I.ppt

Top Related