Question

20.38 (a) The values of Emer for the most intense absorptions in the electronic spectra of CoCl4]- and (Co(OH).]2+ differ by a factor of about 100. Comment on this observation and state which complex you expect to exhibit the larger value of max- (b) In the electronic absorption spectrum of a solution containing V(OH))"+, two bands are observed at 17200 and 25 600 cm . No absorption for the A2, Tję(F) transition is observed. Suggest a reason for this, and assign the two observed absorptions. (c) Red crystalline (NiCl (PPh CH Ph), is diamagnetic. On heating to 387 K for 2 hours, a blue-green form of the complex is obtained, which has a magnetic moment of 3.1818 at 295 K. Suggest an explanation for these 20.40

Answer 1

[co clu]? [Colom), [colly] is more intense ---tar pink intense blue colour Rearon of Intensity 1) Raporte selection Rule the tounsitim occurs between studerd opposite paisy le géow are allowed. stop, prod, dof allowed. 14.0=41 lapurte allased Te touchedral splittey dd-orbital hence transition occur - Somad Intensity E-molar Extinction coefficient - more the intensity more will be ualue ch le' hence [co (cly)] has more E' value as compared to [Co (OH2)772 sarep-ed miny -

③ [V(H20)] +3 shows blue calous two adsorption bands are observed 3 Tag € 3tig at 17200 cal both are observed in visible Region the transition 1. Zaagt stig corrosponds to excitation of both electrons and requires high energy, and thus corrosponding to this transition is of low intensity and does not expertama experimentally observed. c) Nicla (epha Cha Ph2 ] exist in two forms Paramagnetic diamagnetic Blue gree complia Red crystalline this complex exust in two froms tetrahedral and octan square planer square feanan form tetrahedral (panamagnetic) (damagnetic) on heating complex at 387 K Reaction goer in tetrahedral direction hence complex becomes para magnetic