eg Energy35 Tetrahedral Field t2 2 5 Energy 35 Thehigherenergysetoforbitalsislabeledast an thelowe r z 2 x 2 y 2 islabeled aseThecrystalfieldsplittinginthetetrahedralfieldisintrinsicallysmall ID: 387762
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Crystal Field Splitting in an Octahedral Field eg Energy3/5 Tetrahedral Field t2 2 / 5 Energy 3/5 Thehigherenergysetoforbitals()islabeledast an thelowe r z 2 x 2- y 2 ) islabeled aseThecrystalfieldsplittinginthetetrahedralfieldisintrinsicallysmallerthanintheoctahedral For purposes be t = 4 / 9 o [Ti(Ha The single electron in the torbitals absorb energy in the form of light and gets excited to the eorbitals. In case of [Ti(H 520 nm(243 kJ/mol) Factors Affecting the Magnitude of 1.Higher oxidation states of the metal atom correspond to larger 2. In groups, heavier analogues have larger For hexaammine complexes [M 22870 1 (C) = 22 , 870 cm- 1 o ) 34,100 cm-141,200 cm-1 greatly. Tetrahedral complexes MLthan octahedral ones ML= 10,200 cm II(NH3)4]2+4. Nature of the ligands. For[Co III incm -1 :13100(F );20760(H O);22870(NH ) [Co L 6 ] , : 13 , 100 20 , 760 2 22 , 870 3 ) For [CrIII6], in cm-1: 15,060 (F-); 17,400 (H2O); 26,600 (CN-) Distribution of Electrons in an Octahedral Complex d 1 d 2 d 3 Strong fieldWeak fieldStrong fieldWeak fieldStrong fieldWeak field d 1 d 2 d 3 Net energy decrease is called crystal field stabilization energy (CFSE) For d 1 ,CFSE = 1 × = o d , o , CFSE = 2 ×0.4 = , CFSE = 3 ×0.4 = o o Distribution of Electrons in an Octahedral Complex Therearetwopossibilitiesformetalionshavingelectronicconfiguration.Dependingonthenatureoftheligandsandthemetaltheycouldbe u.e.Forthesystem,CFSE= g 3×0.4 ) ( 1×0.6 ) =0.6 o forlow-spin,4×0.4= 5 6 7 1 u.e. 5 u.e. 0 u.e.4 u.e. 1 u.e.3 u.e. Distribution of Electrons in an Octahedral Complex d 1 t 2g 1 e g 0 o t 2g 1 e g 0 o Low-spin o t 2g e g o d2t2g2eg0ot2g2eg0od3t2g3eg0ot2g3eg0o d 4 3 1 4 0 d 4 t2g 3 eg 1 ot2g 4 eg 0 od5t2g3eg2ot2g5eg0od6t 2g 4e g 2 o t 2g 6e g 0 o 2g g o 2g g o d7t2g5eg2ot2g6eg1od8t2g6eg2ot2g6eg2o d 9 t 6 3 t 6 3 d 9 t 2g 6 eg 3 0 . 6 o t 2g 6 eg 3 0 . 6 od10t2g6eg4ot2g6eg4o When to Expect Tetrahedral Geometry Ifligandsarelarge;soastoavoidligand - ligandrepulsion large; ligand In case of metal ions with zero CFSE ( ( d0 ) , FeCl 4 - ( d5, h.s. ) , ZnCl 4 2- ( d10 ) 4 ( ) 4 ( ) 4 ( ) In case of metal ions with small CFSE (, h.s.) 0.8 vs 1.2