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Aggregation of [Cu ${{\bf }{{{\bf II}\hfill \atop \bf 4\hfill}}}$ ] Building Blocks into [ Cu${{\bf }{{{\bf II}\hfill \atop \bf 8\hfill}}}$ ] Clusters or a [ Cu${{\bf }{{{\bf II}\hfill \atop \bf 4\hfill}}}$ ] ∞ Chain through Subtle Chemical Control
Author(s) -
Aromí Guillem,
Ribas Joan,
Gamez Patrick,
Roubeau Olivier,
Kooijman Huub,
Spek Anthony L.,
Teat Simon,
MacLean Elizabeth,
StoeckliEvans Helen,
Reedijk Jan
Publication year - 2004
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200400671
Subject(s) - deprotonation , chemistry , crystallography , ligand (biochemistry) , dimer , cluster (spacecraft) , metal , stoichiometry , stereochemistry , ion , organic chemistry , biochemistry , receptor , computer science , programming language
Abstract Coordination complexes of the ligand H 3 L [1,3‐bis(3‐oxo‐3‐phenylpropionyl)‐2‐hydroxy‐5‐methylbenzene] with Cu II are reported. Clusters showing various nuclearities or modes of supramolecular organization have been prepared by slightly changing the reaction conditions and have been crystallographically characterized. The reaction of H 3 L with one equivalent of Cu(OAc) 2 in DMF yields the dinuclear complex [Cu 2 (HL) 2 (dmf) 2 ] ( 1 ). Reaction in MeOH of H 3 L with an increased amount of metal, in the form of Cu(NO 3 ) 2 , and excess strong base ( n Bu 4 NOH) affords the cluster [Cu 8 (L) 2 (OMe) 8 (NO 3 ) 2 ] ( 2 ). Complex 2 is a dimer of two linear [Cu 4 ] arrays bridged by methoxide ligands, where the polynucleating ligand is fully deprotonated. The [Cu 4 ] 2 clusters are linked to each other by NO 3 − bridges to form one‐dimensional coordination polymers. The link between [Cu 8 ] units and their relative spatial positioning can be modified by changing the anion of the Cu II salt, as demonstrated by the synthesis of the cluster polymers [Cu 8 (L) 2 (OMe) 8 Cl 2 ] ( 3 ) and [Cu 8 (L)(OMe) 7.86 Br 2.14 ] ( 4 ), where only NO 3 − has been replaced by Cl − or Br − , respectively. Similarly, when ClO 4 − is used, compound [Cu 8 (L) 2 (OMe) 8 (ClO 4 ) 2 (MeOH) 4 ] ( 5 ) can be isolated. It contains independent [Cu 8 ] units. A slight change in the stoichiometry of the reaction leading to 2 affords the related complex catena ‐[Cu 4 (L)(OMe) 3 (NO 3 ) 2 (H 2 O) 0.36 ] ( 6 ). This polymer contains essentially the same [Cu 4 ] moiety as 2 , albeit organized in a completely different arrangement. Each [Cu 4 ] unit in 6 is linked by OMe − ligands to two such equivalent groups to form an infinite chain. Magnetic susceptibility measurements reveal weak antiferromagnetic exchange between Cu II centers in 1 ( J = −0.73 cm −1 ) and strong antiferromagnetic coupling within [Cu 4 ] chains in 2 , 5 , and 6 (most negative J values of −113.8 and −177.3 cm −1 for 2 and 6 , respectively).