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Dalton Transactions

Spacer length dependent architectural diversity in bis-dipyrrin copper(II) complexes

Authors: Rajendra Prasad Paitandi; Roop Shikha Singh; Sujay Mukhopadhyay; Ashish Kumar; Shankar Pandey

Publication Date: -0001-11-30  Article ASAP

A series of copper(II) complexes (1-9 and 3') derived from bis-dipyrrin ligands (L1-L9 and L3′) with diverse spacer lengths [-(CH2)n-] have been described. Structural diversity in these complexes have been explicitly established by spectral and structural studies on these and a closely related nickel(II) complex (3ʺ). All the ligands and complexes have been thoroughly characterized by spectroscopic studies (ESI-MS, IR, 1H, 13C NMR, UV/vis) and structures of 2, 3', 3ʺ, 6, 8 and 9 determined by X-ray single crystal analyses. It has been unambiguously established that ligands with n < 6 gave heteroleptic binuclear (1-5), while those with n > 7 yielded homoleptic mononuclear (69) bis-dipyrrinato complexes. Spectral and structural studies revealed distorted square planer (1-5) and distorted tetrahedral geometry (69) about the copper(II) centre in these complexes which has further been evidenced by EPR and electrochemical studies. Structural differences based on odd and even number of methylene spacers in these complexes has been supported by DFT studies. A line between syn and anti conformations for the complexes has been drawn on the basis of limiting spacer length.  Read more