a Hameed 2018/2019 orasens Coordination Chemistry N i omenclature of Coordination Compounds me ational Union Coordination compounds are named according to the rules suggested by Internation of Pure and Applied Chemistry, IUPAC (1976), These rules are given blow . Tl also the Ir The positive ion (cation) comes frst, followed by the negative ion (anion). This is common order for simple salts diamminesilver(1) chloride, [Ag(NH).]CI Potassium hexacyanoferrate(IIl), Ks[Fe(CN).] . la. Wi he > The inner coordination sphere is enclosed in square brackets in the formula. Within th Coordination sphere, the ligands are named before the metal, but in formulas the metal ion is written first. tetraamminecopper(II) sulfate, [Cu(NHs),]SOx hexaamminecobalt(II1) chloride, [Co(NHs)«]Cls 3- The number of ligands of one kind is given by the following prefixes. If the ligand name includes these prefixes or is complicated, it is set of in parentheses and the second set of. prefixes is used 20 di bis 3 tri tris 4 tetra tetrakis 5 penta pentakis 6 hexa —_hexakis 7 hepta_—_hiptakis 8 octa octakis 9 mona —_nonakis 10 deca —_—_decakis dichlorobis(ethylenediamie)cobalt(II1), [Co(NH3CH;CH,NH,);Ch]” tris(bipyridine)iron(II), [Fe(NHsCs-CsNH,)3]"2018/2019 Dr, Asia Hameed Coordination Chemistry 4 Ligands are named in ; d, not the prefix) alphabetical order (according to the name of the ligan {etraamminedichto; Tocobali(II), [Co(NH)Ch]" amminebromochloro, So methylamineplatinum(I1), [PUNE )BrCl(CH,NH2)]} Anionic ligands chloro, CI bromo, Br sulfato, $0.2 are given an o suffix, Neutral ligands retain their usual name. Coordinated water is called agua and coordinated pana 'Scalled ammine (the double m distingishes NH; from alkyl amines). Methylamine, 7H3NH; 6- To name the central metal atom, the following two cases arise: a- If the coordination sphere of the complex compound has negative charge, the name of the central metal atom ends in ate and the oxidation state of the metal (whether positive, Begative or Zero) is written in roman numerals (0, I, I, Ill... -I, -Il,-III etc) in brackets at the end of the name of the metal atom. Cr......chromate Pd... .palladate Co......cobaltate —_Re......thenate Cu......cuperate Pt.......platinate Na,[CrOF,], sodium tetrafluorooxochromate(IV) K,[Ni(CN)«]. potassium tetracyanonickelate(0) [Co(CO),J, tetracarbonyleobaltate(-1) For some metals, their Latin names are used : Fe......ferrate Pb.......plumbate Ag.....argentate—Au......aurate Sn. stannate K,[Fe(CN),] potassium hexacyanoferrate(II) Na[AgF.] sodium tetrafluoroargentate(|) 21018/2019 Dr. Asia Hameed Coordination Chemistry . sha neutral > IF the coordination sphere of the complex compound has positive charge or is tate (non-ionic), the name of the central metal atom remains as such and the oe net al e met * ‘ rine F.is itten in Roman numerals in bracket at the end of the name o} [Ag(NH,),] diamminesitver(1) INi(CO),)" tetracarbonyinickel(0) 7 For complex compounds which are composed of complex cation and complex anion, the Catton is named first then followed by the anion name [CrQNHs),]°* [Cok] hexaamminechromium(III)-hexafluorocobaltate(II1) [PdQNH,),}* [Pac tetraamminepalladium(11)-tetrachloropalladate(II) & There are many ligands which have two or more different donor atoms in their structure. Such ligands can coordinate to the metal atom through any of their donor atoms and hence are given different names corresponding to the nature of donor atoms linked to the metal atom. Such compounds are called linkage isomers [Co(NH5)s(NO3)]Cl,__ pentaamminenitrocobalt(III) chloride [(Co(NHs)(ONO)]CL, pentaamminenitritocobalt(II1) chloride NOs" ion coordinated to the metal atom through the lone pair of electrons on negatively- charged N atom, while ONO” through the lone pair of electrons on negatively-charged on O atom. SCN’ ion thiocyanato (through $) NCS ion isothiocyanato (through N) 9- To name bridging ligands between two metal ions, the prefix wis used before the name of each of the ligands. . [(NH3),Co(OH)(NH2)Co(NH3),J Octaammine-p-amido-jt-hydroxodicobalt(II1) NH Nay 1 HAN RR 8 nn, C6. ‘Co’ PNR Sy HON" iy 8” Nu Nteed 1018/2019 br. Asia Hamee! Coordination Chemistry {a complex has two similar bridging ligands, -di is used for its name. se OH". 6 (H,0), FeO Re. o.| (SO,). [ Sows? octaaqua-p-di-hydroxodi-iron( Il) sulphate vations in square 10- The prefixes cis- and trans- designate adjacent and opposite geometric locations in sq planar complexes type [MA;B;] [PtCl(NH3):] _ cis-and trans-diamminedichloroplatinum(IL) ss NI cis trans For octahedral complexes of [MA3Bs] type the prefixes fac (facial) and mer (meridional) are used. ol (fac) isomer (mer) isomer 11- For optical isomers, octahedral complexes of [M(AA)s] type, the prefixes d (dextro) and | (levo) are used. [Co(en);]** d and | tris(ethylenediamine)cobalt(III) ‘mirror plane deform &br. Asia Hameed 1018/2019 Coordination Chemistry Coordination Numbers i ns which are Coordination number can be defined as the number of the lone pairs of electro bonded directly with the metal ion. factors. The overall shape of a coordination compound is the product of several interacting fi a Some factors involved in determining the struc:ures of coordination complexes ine following: 1- The number of bonds, Because bond formation is usually considered exothermic, more bonds should make for a more stable molecule. 2- VSEPR arguments, as used in the simpler ceses of the main group elements. 3- Occupancy of d orbitals. Example of how the number of d electrons may affect the geometry (square-planar versus tetrahedral). 4- Steric interference by large ligands crowding each other around the central metal 5- Crystal packing effects. These include the eifects resulting from the sizes of ions and the overall shape of coordination complexes. Coordination Number 2 Coordination number 2 is rare The dest known example is [Ag(NH;),]", the diamminesilver(1) ion. The silver 1+ ion is d'° (a filled, spherical subshell), so the only electrons to be considered in the VSEPR treatment are those forming the bonds with the ammonia ligands, and the structure is linear as expected for two bonding positions. Other examples are also d'’ and linear [CuCl], [Hg(CN)2] and [Au(CN),J. Coordination Number 3 Coordination number 3 also is more likely with d'° ions, with a trigonal-planar structure being the most common. Three-coordinate Au(I) and Cu(l) complexes that are known include [Au(PPh;)]° and [Au(PPh;).Cl. Most three coordinate complexes seern to have a low coordination number because of ligand crowding, =2018/2019 r. Asia Hameed Coordination Chemistry Or. Asia H Gq ' 3) ¢ O . CSC “MOC KO © ge awry ast Coordination Number 4 Tetrahedral and square-planar structures are two common structures with four ligands. Crowding around small ions of high positive charge prevents higher coordination numbers for ions such as Mn(VII) and Cr(V1), and large ligands can prevent higher coordination for other ions. Many d” or d' complexes have tetrahedral structures, such as MnO,’ , CrO.”, [Ni(CO),], and [Cu(py),]’ . with a few d°, such as MnCl”. Square-planar geometry is also possible for four-coordinate species, with the same geometric requirements imposed by octahedral geometry (both require 90° angles between ligands). Pd(I1) and Pi(II) complexes are square-planer, as are the d* complexes [AgFs]', [RhCI(PPhs)s] , [Ni(CN),]* and [NiCl(PMes)2]. Fond On C.,./ NW Z| ‘Ni om fC oe gi Ox ‘ > O or, MnO NCO), (cupy,*2018/2019 Coordination Chemistry H3N cl cl cl NO NO 7 Pt Pd ZN HAN No a Coordination Number 5 onal bipyramid, and the The structures possible for coordination number 5 are the fe smd and the square Square pyramid. The energy difference between the trigonal Le arene pyramid is very small, In fact, many molecules with five ligan Pratl behavior. For between these two or can switch easily from one to the other in example, Fe(CO); and PFs. al site. There [VO(acac),] is a square pyramid, with the doubly bonded oxygen a ee in liquid is also evidence that [Cu(NHs)s]”* exists as a square pyramidal s ammonia. 2296 2391 tcuciyp bsecr> Coordination Number 6 he most common coordination number. The most common structure is octahedral. If a ar ‘i 1rge enough to allow six ligands to fit around it and the d electron a faa shape results from VSEPR arguments. Such compounds exist for octahedral metals with d’ to d’” configurations. 8 are ignored, an all the transition2018/2019 Coordination Chemistry Oras aces) Examples of octahedral complexes include tris(ethylenediamine)cobalt(III, [Co(en)s]"* and hexanitritocobaltate(III) [Co(NO>)}* toten)?* {Co(N0,)? For complexes that are not regular octahedral, several types of distortion are possible. The | | first is elongation, leaving four short bonds in a square-planar arrangement together with two longer bonds above and below the plane. Second is the reverse , a compression with two short bonds at the top and bottom and four longer bonds in the plane. Elongated Compressed Coordination Number 7 Three structures are possible for seven-coordinate complexes, the pentagonal bipyramid capped trigonal prism and capped octahedron. , Although seven-coordination is not common, all three shapes are found ex the differences apparently resulting from different counterions and the Steric r¢ ligands (especially chelating ligands). Perimentally, with equirements of the Examples include the following: en - Pentagonal bipyramids; [NiF;}” and [NbFr} in both of which the seventh fluoride ca fa 5 I, caps rectangular face ofa trigonal prism; and [W(CO).BN], @ mono capped octahedron PS a | — ee ,abe a Dr. Asia Hameed 2018/2019 Coordination chemistry Coordination Number § such Although the cube has Cight-coordinated geometry, it exists only in simple SS a8 CSCI. The square antiprism and dodecahedron are common in transition a on and there are Many eight-coordinate complexes. Because the central ion must be ao inane © accommodate eight ligands Cight-coordination is rare among the first row transitio its, and Solid state examples include Na;ZrgFs), which has square antiprisms of ae aa with (Zr(acac),), a regular dodecahedron, [AmCI(H,O)" is a trigonal prism of water ‘ane chloride caps on the trigonal faces, ZsFs Higher Coordination Numbers There are few structures known with coordination numbers larger than 8. Discrete nine- dinate structures are known for complexes such as [Ln(H0) "ny for the hydride coord MHy}” (where M = Te or Re). These structures (Capped square-antiprism) are ae eee a ligand to each of the rectangular faces ofa trigonal priv on1.1 Learning Outcomes After studying this module, student will be able f° Define Crystal field stabilization ener | Describe d electronic configuration ‘and Calculation of the cree Octahedral complex. Describe d electronic configuration and Calculation of the Cee Tetrahedral complex. i Describe d electronic configuration and Calculation of the CFSE in Square planar complex. 1.2 Subject Introduction approach the central metal electron and the d orbital approaches the CMI by and approaches @ In transition metal complex when ligand ion_the repulsion creates between the ligand electrons of central metal atom or ion. This ligand two ways: along the axis or between the axis. When this lig eeetral metal atom then orbital splits into two different energy Sets Cs and tag The gap between this eg and tas is called energy £8? OF crystal field stabilization energy. ays Iyer Gear pitting of 5 d DEGENERATE ORBITAL Figure 1: Splitting in d-orbital Page 4 of 24vigand geiterence between the energy of the electron configuration 1° pond energy of the electronic configuration in the isotropic field 1s as crystal field stabilization energy. CFSE for different transition metal complexes are calculated by given formula’ CFSE. AE = Enigana tetd~ E isotropic eld In this module, we will discuss about the Crystal field stabilization energy. Here, we will have calculated CFSE for different metal complex like- octahedral, tetrahedral and square planar complexes. Also, we will have calculated the CFSE for weak field and strong field ligand. We will discuss about high spin and low spin complexes. 1.3.1 Calculation of the CFSE in Octahedral complexes In octahedral complexes the ligands approach metal ions along the axis. Therefore, the energies of dyy, dex and dyz are lower than those of diz-s2 and di orbitals. The diy, dex and dy, orbitals of lower energy are called tag orbitals and dx-y2 and dz orbitals of higher energy are called ¢, orbitals 0 ey det “ou, i Berycenter, _ 4.CFSE Era 6 ‘ 4 Ba ; ‘ro stig ete conten Figure 2: (a) Metal complex (b) splitting in Octahedral complex Page 5 of 24second Year jeld BY between eg and ta, is called Coppatie re ‘o’ stan octahedral complex Presented as Ao or Dq, where The energy of each 3/5 above their energy three lower energy orbi in a spherical field. sed b: of the two high energies orbital eg is increased’ OY ‘ the in a spherical; field, where the energy of each oe tal tag is decreased by 2/5 or 0.4 below their en The total energy increase is equal to the total decrease, therefore (2) X [3/5 Ao] = (3) x [2/5 Ao] Or the eg level lie +0.6d0 or 3/5 Ao above the average level and the t2e level lie -0.4o or -2/5 Ao below the ‘center of gravity,’ or ‘barycenter’ so that the total increase in energy of ‘e,’ electrons is equal to the total decrease in energy of ‘tz-’electron.or the average of eg and tz, is known as barycenter. The value of barycenter is Zero because the average of eg and t2g sets CFSE value is zero. Energy below and above the barycenter has must be same. Which is explain by that the factor to be multiplied to number of electrons in. eg OF tg. We calculate CFSE are -0.4 As for tz electron and +0.6 Ao for e electron in octahedral complex. Overall energy: 3 x (-0.4 Ao) = -1.2A0 2x (+0.6 Ao) = +1.2A0 ‘The overall average is calculated zero. ‘The gap in d-orbitals depend upon the ligand nature. This gap is high in case of strong field ligand and small for weak field ligand. In case of strong filed ligand more electronic repulsion creates thus more splitting occur in d-orbital.so splitting of d-orbital or the value of CFSE will depend on the ligand field strength. Ligand field strength is show in following order: CO > CN: > NO» > NHs> H20 > F-> OH-> Cs Br > ‘trong field ligand (SFL) Weak feta ligand (WEL) Page 6 of 24Weak Field Ligand Strong Field Ligand -orbital splitting for weak field or strong field ligand Figure 3: Splitting in Octahedral complex for WFL and SFL Example: - 1) Calculation of Crystal filed stabilization energy for d7 electronic configuration in case of weak field ligand The splitting of d- orbital and electronic configuration for both isotropic and ligand field are given below: og a dx2-y? dz? . 40.605 [ I 2 CFSE 7 . 0.45 sd DEGENERATE ORBITAL “th ht dy Ge aes orbital splitting for weak field ligand in ? electronic configuration Figure 4: d-orbital splitting for WFLSecond Year isotropic hea) = (7 x : + 2P) =2P ‘lral ligand field ig E ligand fj nd fe) = eal = 18 % -2/5 Ao) + (2. x 3/5 Ao) + 2P = -4/5 Ao +2P Evipand feta isotropic field ~(-4/5 Ao +2) — 2p --4/5 do 2) electronic o The Cal Raines of Crystal filed stabilization energy for a” 8 tee ot in case of Strong field ligand Plitting of d- orbital and electronic configuration for both ‘sotropic and ligand field are given below: 5S d DEGENERATE ORBITAL d-orbital splitting for Strong field ligand in d” electronic configuration Figure 5: d-orbital splitting for SFL ‘The energy of isotropic field is (E isotropic eta) = (7 XO + 2P) =2P The energy of octahedral ligand field is (E tigana sets) = (6X -2/5 Ao) + (1.x 3/5 Ao) + 3P = -9/5 Ao +3P CFSE = Eigana seta~ E isotropic tela = (-9/5 Ao +3P) - 2P -9/5 ho +P We can also calculate the crystal field stabilization energy in octahedral complex for weak field ligand by given formula:Second Year 7 i Transition Elements, Chemi-energetic CFSE = 0.6 Ao xatbx(-0 Where Ao= CFSE ae A = number of electrons present in e, number of electrons present in tg whe! ‘ n electron pairing occurs then pairing energy will be added. Table 1- ‘able 1-CFSE value of Metal ion in different electronic configuration in Octahedral complex for WFL Electronic | —— configuration n[Spin(a) | Spin | Magnetic {no. of muttipli | nature unpair city ed (2s+1) electro n) Paramagn‘ Paramagnetic Pararagnetic Paramagnetic Paramagnetic Paramagnetic Paramagnetic Pararagnetic Paramagnetic, Diamagnetic d rule a @ & a t a t ae wr a aur 2 ae wu a ain [wT 2 ae nin [tw 1 CFSE [oct) (WFL) (A0 P) low spin Complex) ~it does not folow Hund rule 1.3.2 Calculation of the CFSE in Tetrahedral complexes In tetrahedral complex ligands approach between the axes where t2 set of orbitals feel more 4, orbitals. Therefore, in tetrahedral complexes, dx2_ya lower energy than dxy, dzx and dyz orbitals.E N t R G y ay. yes Gey, 22, de? — tHe, dz? & orbital spliting in Tetrahedral complex Figure 7: Crystal field splitting in Tetrahedral complex In tetrahedral complex the splitting pattern is reverse of the splitting pattern of octahedral complexes. {Note the lack of a g in the subscripts (tz, e) because tetrahedral complex does not have a center of symmetry.) ‘The energy difference between the two sets of d-orbitals is called crystal field stabilization energy (CFSE) or crystal field splitting energy. It is represented by a symbol At, where ‘’ stands for tetrahedral complex. ‘The energy of each of the two low energy orbitals e is decreased by 3/5 above their energy in a spherical field, while the energy of each of the three high energies orbital t2 is increased by 2/5 below their energy in a spherical field. Tetrahedral splitting is always less than octahedral splitting because in tetrahedral complex 4 ligand approaches through space in between the axis so feel less repulsion, So due to less splitting Hund’s rule is followed in tetrahedral complex. ‘The difference of energy between two energy levels is At(At= Electron don't pair due to this small gap between two energy tetrahedral complexes have a high spin configuration. 4/940) sets. So Now we calculate the crystal field stabilization energy in tetrahedral complex, ‘The calculation formula is: Module 2.06PM xat dx (0.40) Where At= CFSE &* number of electrons present in ¢ b= number of electrons present in ta Finda itals in filled in ¢ orbitals it clectronic configuration the electron is filled i both conditios 7 strong field or weak field ligand. Pigure6.1: electron distribution in complexes in which metal ion possess d? and a? electronic configuration So, the crystal field stabilization energy in tetrahedral and d? configuration is calculated by gi complex for di iven formula: CPSE (@) = -0.6 dtxa+bx(0.4 At) 0.6 Atx1+0x (0.4 at) = -0.6 At The CFSE value is same for both Strong field and weak field ligand, CFSE (d2) = -0.6 At xatbx(0.g At) 0.6 Atx2+0x (0.4 ar) =-1.2at The CFSE value is same for both strong fi# In d8 & d* electronic configuration if the CFSE value for strong field ligand is higher than pairing energy then electron pairing occurs a orbital. But in weak field ligand pairing not occurs because of CFS! value for WPL is less then pairing energy- Q0O 1 wm & # xt SA Je ane Figure 8.2: eledtron distribution in complexes in which metal ion poggess d° electronic configuration in strong field ligand (SFL) and Weak field ligand (WFL) CFSE (4°) SFL = -0.6 At x a + b x (0.4 At) =-0.6 At x 3 + 0 x (0.4 At) 1.8 At Total CFSE value of complex= -1.8 At + P Here pairing energy also added when electron pairing occurs. The value of pairing energy is differing for different metal ion. 0.6 Atxa + b x (0.4 At) CFSE (49) WFL = =-0.6 At x 2 +1 x (0.4 At) =-1.2 At + 0.4 at = -0.8 At Total CFSE value of complex=Second Vor" Second Year 8 d¢ electronic Figure8.3: electron distribution in complexes in which metal ion pot ‘configuration in strong field ligand (SFL) and Weak field ligand (WFL) CFSE (d*) SFL = -0.6 atx a+ bx (0.4 At) =-0.6 At x 4 +0.x (0.4 At) =-2.4 at Total CFSE value of complex= -2.4 At | 2P CFSE (d') WFL = -0.6 Atx a + bx (0.4 At) “1.2. at + 0.8 At =-0.6 Atx 2 + 2x (0.4 At) =-0.4 at Total CFSE value of complex= -0.4 At + In d5, do & d7 electronic configuration 5%, 6", and 7° electron is filled in tz orbital 000, 000 », e6.4: electron distribution in complexes in which metal ion possess 45, d® and d? ae electronic configuration Page 14 of 241 Transitinn Blase? Chemistry Paper II Transition Elements, Chemi-energetics, PP! CFSE (49) = -0.6 Axa +b x (0.4) 0.6 xX 4 +1 x (0.4 A) = -2.4 A+ 0.4 ds = 20, Total CFSE value of complex= -24, + 2P CFSE (d5) = -0.6 Axa +b x (0.4 A) =-0.6 Ae x 4+ 2 x (0.4 Ay) = -2.4 e+ 0.8 Oe =-1.6a Total CFSE value of complex= -1.64: + 2P CFSE (”) = -0.6 A: xa +b x (0.4 di) =-0.6 Ac x 4 +3 x (0.4 Ay) = -2.4 Ort 1.2 de = 12h Total CFSE value of complex= -1.2: + 2P The CFSE value is same for both strong field and weak field ligand. & In d8, a? & d}® electronic configuration 8%, 9%, and 10% electron is filled in t orbital. Figures.s: electron distribution in complexes in which metal on possess d* d and d10 ‘electronic configuration CFSE (d8) = -0.6 Ai xa + b x (0.4 A) =-0.6 Ax 4 +4 x (0.4 Ay) = -2.4 Ait 1.6 A = -0.8 A Total CFSE value of complex= -0.84; + 3P CFSE (d°) = -0.6 Aix a + bx (0.4 A) Page 18 of 24Theminter second Year, kum Paper II Transition Elements, Chemi nergetics, Phase Equilib’ 0.6 Ax 4 4 S104 A) = 2.4.4 2a = 0.4, Total CFSE value of complex= 0.40, + 4P, CFSE (= 0.6 x04 bx (0.4.9 =0.6AXx4 +6 x (0.4 Ay =0 2.4 d+ 2.4 dy Total CI E value of complex= 0 For tetrahedral complex electron pairing energy value is alway mote CFSE value, Therefore, in case of tetrahedral complex always bea weak field ligand electronic distribution. This is the main reason in tetrahedral geometry low spin complex are not found than The electron distribution and CFSE value for Weak and strong field ligand for tetrahedral complex is given below in table: ne (no. of unpaired electron) ‘Table 3: - d electron distribution and CFSE in tetrahedral complexes for weak field ligand S Electronic [e | t [Spin] | Spin [Magnetic | CFSE configuratio mnultiplic | nature value p y | (2s+1) } Wa T - T 12 (2 Paramagnetic |-0.60] | Je Ti zfs PParamagnetic [1 | e 7 Tt a [3a PParamagnetic [0880] | # a Paramagnetic | Oabo | 7 le ~ TT Mt 5 5/2 6 - Paramagnetic | 0 | Paramagnetic | O.6ho C te wt (/iit 4 2 5 A went 77 F wh [tit 3 32 a . | Paramagnetic | “1.20 oe nn [att [2 1 3 Paramagnetic | 0.80 e wn [war fr fia [2 Paramagnetic | 0.400 ae wi [wun jo fo 7 Diamagnetic | Page 16 of 24psc. Chemistry Paper nsit delectr il ‘on distribution and CFSE in tetrahedral comptes ligand Magnetic Electronic configuration Spin) | Spin nature TParamagnetic ——paramagnete TParamagnetic T | Paramagnetic TT Paramagnetic Trt wtt Paramagnetic Faramagnete wT | multiplicity (2s+1) cts + paramagiete [0 =| ee “1.280 7.880 wat ] Diamagnetic _Lcomplexes The crystal field splitti splitting diagea try can be from octahedral diagram lagram for square planar geometry Or Figure 9: Square planar complex derived If two Trans ligands in an octahedral MLs complex (based on Z axis) are moved away from the metal ion, then the resulting complex is said to be tetragonally distorted and such distortion favored because of a John teller effect. ‘The removal of two ligands stabilizes the orbitals having z component (ie., dz?, dex, and dyz). While the “non z ° orbitals will be raised in energy. As a result, eg set of orbitals split into two level, an upper level big (dx?) and a lower aig (dz), and tg set is split into bag(dr) higher in energy and double degenerate idvz, dzx) lower in energy. As a result, low spin complexes with d electrons occupying the low energy dy, dyz, and dx: orbitals while the high energy d,2,? orbitals remain unoccupied, Examples; - [Ni (CN)s]*, [Ptcl:|*ete. Page 18 of 24Second Year Octahedral gq square Planar Figure 10: Crystal field splitting in octahedral complex ML6 and square planar complex MLA [where M=Cos, Ni2+ Cu2+] ‘The splitting diagram for square planar complex is more complex than for octahedral ad tetrahedral complex. CFSE value for square planar complex is related to Ao: Asp=1.74 do ‘That means CFSE value for square planar is 1.74 multiple of octahedral CFSE value. Page 19 of 24