Schiff base derivatives of lanthanons

Bifunctional tridentate Schiff bases such as, $$\begin{gathered} HOC_6 H_4 C(CH_3 ) : NCH_2 CH_2 OH, \hfill \\ HOC_6 H_4 C(CH_3 ) : NCH_2 CH_2 (OH)CH_3 , \hfill \\ HOC_6 H_4 C(H) : NCH_2 CH_2 OH \hfill \\ \end{gathered} $$ and HOC₆H₄C(H)∶NCH₂CH(OH)CH₃ react with La(III), Pr(III) and Nd(III) isopropoxides to 1∶1 and 2∶3 derivatives of the type,Ln(O?i-C₃H₇)(OC₆H₄CR]∶NR′O) andLn ₂(OC₆H₄CR]∶ NR′O)₃ where,Ln=La(III), Pr(III) or Nd(III); R=CH₃ or H and R′=CH₂?CH₂ or CH₂CHCH₃] in dry benzene. The labile nature of the isopropoxy groups in the 1∶1 derivatives has been shown by exchange reactions with an excess oft-butyl alcohol leading to the formation ofLn(O?t-C₄H₉)(OC₆H₄CR]∶NR′O); (where R=CH₃ and R′=CH₂CHCH₃) type derivatives in almost quantitative yield. The IR spectra of the resulting derivatives have been recorded in the range of 4000–400 cm^?1, ν C=N frequency bands appear at ≈ 1620 cm^?1 and almost no change has been noted in their positions on complexation. Some new peaks are, however, observed in the range of 700–600 cm^?1 and these may be ascribed to the ring deformation coupled with both theLn?O stretching and C?CH₃ stretching modes.