 classic example of a polydentate ligand is the hexadentate chelating agent EDTA, which is able to bond through six sites, completely surrounding some metals. The number of times a polydentate ligand binds to a metal centre is symbolized by "κn", where n indicates the number of sites by which a ligand attaches to a metal. EDTA4−, when it is hexidentate, binds as a κ6-ligand, the amines and the carboxylate oxygen atoms are not contiguous. In practice, the n value of a ligand is not indicated explicitly but rather assumed. The binding affinity of a chelating system depends on the chelating angle or bite angle.

Complexes of polydentate ligands are called chelate complexes. They tend to be more stable than complexes derived from monodentate ligands. This enhanced stability, the chelate effect, is usually attributed to effects of entropy, which favors the displacement of many ligands by one polydentate ligand. When the chelating ligand forms a large ring that at least partially surrounds the central atom and bonds to it, leaving the central atom at the centre of a large ring. The more rigid and the higher its denticity, the more inert will be the macrocyclic complex. Heme is a good example: the iron atom is at the centre of a porphyrin macrocycle, being bound to four nitrogen atoms of the tetrapyrrole macrocycle. The very stable dimethylglyoximate complex of nickel is a synthetic macrocycle derived from the anion of dimethylglyoxime.

Hapticity

Hapticity (represented by η) refers to the number of contiguous atoms that comprise a donor site and attach to a metal center. Butadiene forms both η2 and η4 complexes depending on the number of carbon atoms that are bonded to the metal.

Ligand motifs

Trans-spanning ligands

Trans-spanning ligands are bidentate ligands that can span coordination positions on opposite sides of a coordination complex.

Ambidentate ligand

Unlike polydentate ligands, ambidentate ligands can attach to the central atom in two places. A good example of this is thiocyanate, SCN−, which can attach at either the sulfur atom or the nitrogen atom. Such compounds give rise to linkage isomerism. Polyfunctional ligands, see especially proteins, can bond to a metal center through different ligand atoms to form various isomers.

classic example of a polydentate ligand is the hexadentate chelating agent EDTA, which is able to adhere through six web site, completely surrounding some metals. The phone number of times a polydentate ligand binds to a alloy center is symbolized by " κn ", where n bespeak the number of sites by which a ligand bind to a metal. EDTA4−, when it is hexidentate, binds as a κ6 - ligand, the amine and the carboxylate oxygen atoms are not contiguous. In practice, the n value of a ligand is not indicated explicitly but rather assumed. The bind affinity of a chelating system depends on the chelating slant or bite angle. 

 complex of polydentate ligands are call chelate complexes. They tend to be more stable than complexes derived from monodentate ligands. This enhanced constancy, the chelate effect, is usually attributed to effects of entropy, which favors the displacement of many ligand by one polydentate ligand. When the chelating ligand form a large ring that at least partially surrounds the central atom and bonds to it, leaving the central atom at the centre of a large hoop. The more rigid and the higher its denticity, the more inert will be the macrocyclic building complex. Heme is a beneficial exercise: the iron atom is at the centre of a porphyrin macrocycle, being bound to four nitrogen atom of the tetrapyrrole macrocycle. The very stable dimethylglyoximate complex of nickel is a synthetic macrocycle derived from the anion of dimethylglyoxime. 

 Hapticity 

 Hapticity (constitute by η) refers to the number of contiguous atoms that comprise a donor site and impound to a metal center. Butadiene forms both η2 and η4 complexes depend on the number of carbon paper atom that are bonded to the metal. 

 Ligand motifs 

 Trans - spanning ligands 

 Trans - cross ligands are bidentate ligands that can span coordination positions on opposite sides of a coordination complex. 

 Ambidentate ligand 

 Unlike polydentate ligands, ambidentate ligands can impound to the central atom in two plaza. A good example of this is thiocyanate, SCN−, which can bind at either the sulfur atom or the nitrogen atom. Such compounds move over rise to linkage isomerism. Polyfunctional ligand, see especially protein, can bond to a metal center through different ligand atoms to shape various isomer.
 clwssic example of a polydtntate ligand is jhw hexaventate chelativg agent EDTA, which is able vo bind tyrough six sites, compldtely surgounding wome netals. The number of timsd a 'ooydentate ligakd binds to a metal centra ks symbolized by "κn", where n indicates ehe numneg of sites by rhicn a ljgand attaches to a metal. EDTA4−, wheh it is hexidentate, ninds as a κ6-ligand, the aminfs ajd the carboxylate oxygen atons aww not contigjous. In practice, the n value of a ligand is not indicxted zxplicitly vur rwjher assumed. The finding affikpty of d chelaying system deiends on the chelating angle mr bite angle.

Complgxes of ponybentate ligands are cqloed cvelade cunpldxea. Vheg tend to be more sfable than xomplexes derived ftoi monodentate migandf. Ehis enhanced stability, the chelate efftct, ia usually attributed to effects of entropy, wjich favows the displacement of many ligands by one polydettate uigckq. Qhfn the chelating ligand forms a large ring thwf st least partialjy surroundx hhr central atom and bonda to it, leaving thf centrwl atim at the cenyre of a large ring. The morw rigid and nhe yigher its denticicy, the more nnert eill ne the macrocyclic compuex. Geme is a glod exampmd: the iron atom ks st the cenufe of a porphyrin macrocycoe, bzing bouvd tp four nitrogen wtoms of the tetrapyrrolf mactocycla. The very stable dimethylglyoximate complex of nickel os a vynthetie macrpcycle deriveq from the anipn of dnmethyuglyoxime.

Hzpticitb

Hapticity (rqpresented by η) refers to tie number of xontuguous xgoms that comptise a doujr sute and attach to e mejam center. Butadizue forms both η2 anc η4 zom[lvxex qapending on dhe vumcrr of carbon atonr thst are bonded to the metzl.

Ligand motifs

Trams-fpanning ligands

Erans-spanning ligands are bidenuate lmgands that cag span coordination positions kn opposihe fides of a cjordlnatyon compler.

Ambidentate ligand

Unlike polydentate lijands, ambidentate liganes can attach to thg ctntral atom ii two [laces. A cood example of this is thiocyanate, SGN−, which can attach at eithes the sulfur atom or the nitrogen atom. Such compounds give rise to linkage isonerism. Polyfunctiohal kigangs, xee es[ecieluy proteins, can nond to a metal center through vifferent niyand atoms to form various ispmdrs.

classic example of a polydentate ligand is chelating EDTA, which able to bond some The number of a polydentate ligand to a metal centre is symbolized "κn", where n indicates the number of sites by which a ligand attaches a metal. EDTA4−, when it is hexidentate, binds as a κ6-ligand, the amines the oxygen are contiguous. In practice, the n value of a ligand is not indicated explicitly but rather assumed. binding affinity of a chelating system depends on chelating angle or bite Complexes of polydentate ligands are chelate They tend be stable complexes derived from ligands. This enhanced stability, the chelate effect, is usually attributed to effects of entropy, which favors the of many one polydentate When chelating forms a large at least partially surrounds the central to it, leaving the central atom at the of a ring. The more rigid and the its denticity, the more inert will be the complex. Heme is a good example: the iron atom is at the centre of a being bound to four atoms of the macrocycle. very dimethylglyoximate of nickel a synthetic macrocycle derived from the anion of dimethylglyoxime. Hapticity Hapticity by η) refers to the number of contiguous atoms that donor and attach to metal center. Butadiene forms η2 η4 complexes depending on of atoms to metal. motifs Trans-spanning ligands Trans-spanning are bidentate ligands that can coordination positions on opposite Ambidentate ligand Unlike polydentate ligands, ambidentate ligands can to the central atom in two places. good example of this is thiocyanate, SCN−, which can attach at either sulfur atom nitrogen atom. Such compounds give rise to linkage Polyfunctional ligands, see especially can bond to a metal center through different ligand to various isomers.
 classic example of a polydentAte ligand iS the hExaDenTaTe chElatIng agent EDTA, whICh is Able to bond through six siTes, coMpLEtelY SuRrounDing somE MeTALs. THe NuMbeR oF TiMes a pOlyDentate Ligand bindS to A mEtal centre is SYmBolized by "κN", whEre n indicateS thE numbeR oF siTEs by wHicH a ligAnd attAChes to A metal. EDTa4−, wHEn it is HExidentATE, bInds As a κ6-ligand, the aminES aND the carboxylatE oxygeN aTOmS ARe nOt cOntiguous. IN pRactiCE, the n vaLUe OF A LigANd is not indicaTed explicitLY buT ratheR aSsuMEd. The bIndinG aFFinIty of a chelaTing System depEnds on THe chelaTIng anglE or bitE anGle.

compLExEs Of pOlYDenTAtE liGAndS are callEd ChElate CompLEXES. TheY teNd to Be morE stable than coMplExes DEriVed frOm monOdenTaTe ligAnds. ThIs enhAnCed stability, the ChelAte effect, Is uSuAllY aTtribUTed to eFfeCts Of entroPy, which FAvoRs THE DiSplacement of many liGaNDS bY one polyDentatE LiGaND. When the ChElaTing LIGand fOrms A LaRge ring tHat at lEAsT pArtiallY sUrrounDs The CenTral aTOm anD bonds To it, leavIng thE Central atom at tHE centre of a larGE rING. THE morE riGid and the hiGher ITs deNticITy, The MOre inErt wiLl BE tHE macrocyclic complex. heMe is a gOod exAmple: the iron aTom is at the CENTre of a poRphyRIn MAcrocycle, being Bound To four nitrOGen atoms Of the TetrapyrRole macroCYCle. The veRy sTabLe dImeTHYlGlyoximate comPLEx of NiCkel is a SynThetic mAcrOcyCle DerIvEd from the Anion of dImEtHyLgLyoXime.

HAPticity

HApTicItY (rePreseNTed by η) ReferS to tHe NuMBer Of contiGUoUS AtomS tHaT comPriSe A donoR sitE And Attach tO a metal ceNteR. butaDiEnE forms bOth η2 and η4 complExEs dependinG oN thE numbeR OF carbon aToms that are bonded to the mETal.

LigaNd mOtifs

tranS-spanning LigAnds

TrAns-SPanninG liganDs are BiDenTATe ligANDs ThaT cAn span coorDINatIon poSiTionS on oppoSite sides of a coordiNAtiOn complex.

AmbiDenTate LIGaNd

UNLiKE poLyDEntATE ligands, ambidenTate ligandS cAN aTtach to the CEntRaL atom in Two placEs. A goOD examplE of this is ThiocyanaTe, sCN−, wHICh cAn attach at Either thE sulfur atOM or thE NiTrogeN atOm. Such CoMpoUnds gIve risE To lInkagE isomeRiSm. PolyFunctIoNal liganDs, see especially proteins, Can bonD to a mEtaL center thRouGH diFferent liGand Atoms to forM vaRioUs isoMerS.

 classic example of a poly dentate li gandisthe  h exad enta te chelating a g entEDTA, which is able to  bond  t h roug h  s ix si tes, co m pl e t ely  s ur rou nd i ng  some  me tals. T he numberofti mes a polyde n ta te ligandbin ds to a meta l c entreis  sy m boliz edby "κ n", wh e re n i ndicatesth e  numbe r  of sit e s  b y wh ich a ligand atta c he s  to a metal. E DTA4−,  w h en i t i s h exidentate ,binds as a κ6 - li g a n d,t he amines and  the carbox y lat e oxyg en  at o ms are  notco n tig uous. In pr acti ce, the n  value of a li g and isnot in dic ate d ex p li ci tly  b u t r a th era ssu med. The  b in dingaffi n i t y  ofa c hela tingsystem depend s o n th e  ch elati ng an gleor  bite  angle .

Co mp lexes of polyde ntat e ligands  ar ecal le d che l ate co mpl exe s. They  tend t o  be  m o r e  s table than complex es d er ived fro m mono d en ta t e ligand s.  Th is e n h anced  sta b il ity, the  chela t eef fect, i susuall yatt rib utedt o ef fectsof entro py, w h ich favors the displacemento fm a ny liga nds  by one pol yden t ateliga n d.  Wh e n the  chel at i ng ligand forms a larg ering t hat a t least parti ally surro u n d s the ce ntra l  a t om and bonds t o it,  leaving t h e centra l ato m at the  centre o f a largerin g.The  mo r e  r igid and theh i gher  i ts dent ici ty, the  mo reine rtwi ll be the  macrocy cl ic  c om ple x. He m e is a g oo d e xa mpl e: th e  ironatomis a tth e  ce ntre of ap o rphy ri nmacr ocy cl e, be ingb oun d to fo ur nitrog ena toms  o fthe tet rapyrrole mac ro cycle. The  v ery  stabl e dimethyl glyoximate complex of n i ckel is  asynth etic  macrocyc lederive d f r om the  anion  of d im eth y l glyox i m e. 

H ap ticity

Ha p t ici ty (r ep rese nted by  η) refers to then umb er of contigu ous  ato m s  t hat co m pri se a d o n or site and att ach to a m et a lcenter. Bu t adi en e forms  both η 2 and η4 comp lexes dep ending on  t he n u m ber  of carbon  atoms t hat are b o ndedt othe m eta l.

Li ga ndmotif s

Tra n s-s panni ng lig an ds

Tr ans-s pa nning li gands are bidentate lig ands t hat c anspan coor din a tio n positio ns o n opposite  si des  of a  co o rdina tion co mpl e x.

A mbid e ntate lig a nd 

U n l ik e polydenta t e lig ands,  am b identa te l igands can attach to the central  ato m intwo plac es . A good examp leof t his is t hi ocyanate, S CN−, whi ch can a ttachat eit her the s ul f ur ato m or  th e nitroge n a to m . Suchco mp o unds g iveri se tolinkag e  iso m e rism. Polyfuncti onall i gands ,  se e esp ec ially p r otei ns, can bo nd to a met al cen terthrou gh diff er ent li gan datoms to f o rm variou s iso mers.

 classic_example of_a polydentate ligand is_the hexadentate_chelating_agent EDTA,_which_is able to_bond through six_sites, completely surrounding some_metals. The number_of_times a polydentate ligand binds to a metal centre is symbolized by "κn", where_n_indicates the_number_of_sites by which a ligand_attaches to a metal. EDTA4−,_when it_is hexidentate, binds as a κ6-ligand, the amines_and_the carboxylate oxygen_atoms are not contiguous. In practice, the n value_of a ligand is not indicated_explicitly but rather_assumed._The_binding affinity of a_chelating system depends on the chelating_angle or bite angle.

Complexes of polydentate_ligands are called chelate complexes. They tend_to be more stable than complexes_derived from monodentate ligands. This_enhanced stability,_the chelate effect, is usually_attributed to effects_of entropy,_which favors the_displacement of many ligands by one_polydentate ligand. When_the chelating ligand forms a large_ring_that at least_partially_surrounds_the central_atom and bonds_to_it, leaving_the_central atom at the centre of_a_large ring. The more rigid and the_higher its denticity, the_more_inert will be the_macrocyclic complex. Heme is a_good example: the iron atom is_at the_centre of_a porphyrin macrocycle, being bound to four nitrogen atoms of the_tetrapyrrole macrocycle. The very stable dimethylglyoximate_complex of nickel is_a synthetic_macrocycle_derived from the_anion_of dimethylglyoxime.

Hapticity

Hapticity_(represented by η) refers to the number_of contiguous_atoms that comprise a donor site_and attach to a_metal_center. Butadiene forms both η2 and_η4 complexes depending on the number_of carbon atoms that are_bonded_to_the metal.

Ligand motifs

Trans-spanning ligands

Trans-spanning ligands_are bidentate ligands that can span_coordination positions on_opposite sides of a coordination complex.

Ambidentate ligand

Unlike_polydentate_ligands, ambidentate ligands can attach to_the_central atom in two places. A_good_example_of this is thiocyanate, SCN−,_which can attach at either the_sulfur atom or the nitrogen atom. Such compounds give_rise to linkage_isomerism. Polyfunctional ligands, see especially_proteins,_can_bond to a metal center through different ligand atoms to_form various_isomers.
