Steric and Electronic Factors Affecting the Conformation of Bimetallic Cu I Complexes: Effect of the Aliphatic Spacer of Tetracoordinating Schiff-Base Ligands

A family of six homoleptic [Cu (L )] (ClO ) and six heteroleptic [Cu (L )(PPh ) ] (ClO ) bimetallic complexes, in which L are bis-Schiff base ligands with alkyl spacers of variable length (n=2-7 -CH -), were prepared to evaluate the role of the spacer on the formation of helicates or mesocates. In t...

Full description

Saved in:
Bibliographic Details
Published in:Chemistry : a European journal 2018-09, Vol.24 (52), p.13839-13849
Main Authors: Díaz, Daniel E, Llanos, Leonel, Arce, Pablo, Lorca, Romina, Guerrero, Juan, Costamagna, Juan, Aravena, Daniel, Ferraudi, Guillermo, Oliver, Allen, Lappin, A Graham, Lemus, Luis
Format: Article
Language:English
Subjects:
Chemistry
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:A family of six homoleptic [Cu (L )] (ClO ) and six heteroleptic [Cu (L )(PPh ) ] (ClO ) bimetallic complexes, in which L are bis-Schiff base ligands with alkyl spacers of variable length (n=2-7 -CH -), were prepared to evaluate the role of the spacer on the formation of helicates or mesocates. In the homoleptic series, spectroscopic and theoretical studies indicate that preferences for a conformation are based on energetic parameters, mainly, the establishment of noncovalent interactions. The odd-even nature of the spacers preconditions the superposition of the aromatic rings to allow the juxtaposition necessary for noncovalent interactions, whereas the increase of the length reduces the strength of such interactions. Consequently, complexes with even-spacers of short length were identified as helicates in solution, [Cu (L )] (n=2, 4). Complexes [Cu (L )] (n=3-7) dissociate in solution to produce the monometallic complexes in equilibrium, [Cu (L )] . The stability of the bimetallic species is discussed in terms of their conformations. The set of heteroleptic complexes was prepared to evaluate the reach of the "odd-even rule" in the solid, which is based on the "zig-zag" arrangements of the spacers. Based on crystallographic information, "S-" and "C"-type conformations of L are related to even and odd spacers, respectively. This trend is considered in addition to other factors to explain preferences for either a mesocate or helicate conformation in the homoleptic series.
ISSN:0947-6539
1521-3765
DOI:10.1002/chem.201802290