Question

oct Original Color (M2+ H20) Complex Color (M2+/ Ligand) de calidad superior de haute qualité CI- Complex ion Formula Effect of H20 Cu2+ Complex ions: [Cucl.]2- changed BLUE ZEHIO NH3 dark en BLUE SCN- green Ni2+ Complex ions: CI- NH3 GREEN Ligand Effect of OH- green BLUE no change. bue I (NH) no change. Changed to (percip). cloudy/lignt bowe dariple ese (Haiche, no change. no change BLUE line neon [Cursen) i no change. Shangcaute changed to peras) Ligand cloudy out GREEN Green [NiCl no change. no change. crkve [N°(NH24 no change. Changes cloudy light/whitebuie (percipo GREEN purple fu (H₂NCH 2 no change. no change. I parpic CH2CH₃NH2) GREEN SCN- Green [Ni(san), 12. no change. changed to percpp Ligand Co2+ Complex ions: ORANGE-Yellow Orange- al 72- no change. no change. yellow ORANGE-Yellow green gross SSLCoche) i no change. changed with brown LC (NH30 same cola w/ (percipo) en Cu (H2WCH,CH, no change. changed to dark orange. ORANGE-Yellow dark changed to SCN- orange-yell. [CO (SON) I changed orange-yellon, percep.) en CH- NH3 ORANGE-Yellow crange CH He changed che

Answer 1

Answer: List of the ligands in order of decreasing bonding strength-

en (ethylenediamine) > NH3 > Cl^-> SCN^-

The color of complex ion depends on the bonding strength of metal and ligand. Strong complex will exhibit color of lower wavelength and weak complex will show color of high wavelength.

Strength of the ligand is mainly depends on its bond strength wheteher it is forming sigma bond or pi bond with central metal ion.

In th above list, ethylenediamine (en) forms stronger bond than ammonia (NH₃). While among NH₃ and Cl^-, NH₃ is strong sigma donor than Cl^- which makes NH₃ more strong than Cl^-.

In Cl^- and SCN^-, both forms weak bond with metal ion. Still Chloride ion forms stronger bond with metal ion than SCN^-, because of the soft center S atom in SCN^- which makes weaker sigma bond with metal ion.