Question

Spectral data for two nickel complexes. a) [Ni(H2O)6]2+ absorption bands occur approximately at 3000 cm−, 12,500 cm− and 25,000 cm− b) [Ni(NH3)6]2+ absorption bands occur approximately at 8000 cm−, 17,000 cm− and 27,500 cm−

Using the appropriate Tanabe-Sugano perform the following for both complexes:

a) For both complexes assign all bands to their electronic transitions (write them above each peak)

b) For both complexes calculate the value of ∆oct, does your results agree with the spectrochemical series prediction that ammonia is a weaker field ligand than water

Answer 1

The 3 transitions are. Bola ['No' (NH3) 6.]2+ & INI (140)72, has Ni ai +2 oxidation state with de syslim ( using a 8 Tanabe sugabo diagram) Electronic Configuration Ni 2+ = [H I 30 The 3 transitions are. Azq -> 9 Tag (P) 4 Ang "Hg (F) Azg *Tig (P) ay for Watei complex . for anmune complex 4A2g Tag = 3000 cmt 9 Ang +479 (A) = 8000cm7 Ang → CF) = 12500 cmt 4 Avant 4 Ang > 4 tia () = 1 Houd cm 7 482g = 9779 () = 25000 cm 4 Aining 747,9 () = 27500 cm? by The energy gap between Tag Tag = 40 So for [Ni (H20) 6727 - 70 = 3000 cm? TNI (A143) 672+ = 40 = 8000 cm. in the spectrochemical Series NH3 is strong field ligand than Nale , so the extent of splitting will be more to so will be more. this is in accordance wilū Ao oblained above. 12 CM с u

1т, TS 50 • ............... .... ... . E/B 30 1 1G 20 на эр 101 o 10 30 40 20 ДІВ