Controlled copper-mediated chlorination of phenol rings under mild conditions.
The very unusual case of copper-mediated chlorination of phenol rings under mild conditions at room temperature is reported. Reaction of the ligand 1,7-bis(2-hydroxyphenyl)-2,6-diaza-4-hydroxylheptane (H3L1) with CuCl2 in acetonitrile leads to either the formation of a tetranuclear copper(II) complex [Cu4(HL3)2(mu-Cl)2Cl2](CH3CN) (1) or a linear trinuclear complex [Cu3(HL1)2Cl2(CH3CN)2](CH3CN)2 (2), depending on the reaction conditions. Both compounds have been fully characterized, including the determination of their 3D structures by X-ray diffraction. The unprecedented tetranuclear compound 1 is constituted of a dichlorido-bridged dimer of di-mu-phenoxido-dinuclear species, whereas the trinuclear complex 2 presents a linear array of copper(II) ions, held together through di-mu-phenoxido bridges of the central and external ions. The magnetic susceptibility of the two compounds was investigated, revealing either very strong (J<-500 cm-1) or strong (J value around -370(1) cm-1) antiferromagnetic dominant interactions among the CuII ions for 1 and 2, respectively. The tetranuclear complex 1 is obtained, under dry conditions, through the in situ formation of ligand HL3 (H3L3=1,7-bis(2-hydroxy-5-chlorophenyl)-2,6-diaza-4-hydroxylheptane) by oxidative chlorination of (HL1)2-. In the presence of traces of water, 1 is partially hydroxylated at the ortho position of one of the phenyl rings. The use of trimethylorthoformate as the dehydrating agent prevents the formation of hydroxylated ligands. Several partly chlorinated/hydroxylated products (identified as H3L2) have also been obtained through slight variations of the synthetic procedures (presence or absence of water and/or triethylamine in the reaction mixtures). These partially chlorinated and/or hydroxylated coordination species are mutually isomorphous to either 1 or 2. Several "modified" ligands have been isolated and characterized by 1H NMR and MS, after reaction with sodium sulfide of the complexes formed.
Song
Yu-Fei
YF
Gorlaeus Laboratories, Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands.
van Albada
Gerard A
GA
Tang
Jinkui
J
Mutikainen
Ilpo
I
Turpeinen
Urho
U
Massera
Chiara
C
Roubeau
Olivier
O
Costa
José Sanchez
JS
Gamez
Patrick
P
Reedijk
Jan
J
D002713:Chlorine / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D008280:Magnetics; D013058:Mass Spectrometry; D015394:Molecular Structure; D010636:Phenols / Q000737:chemistry*; D014867:Water / Q000737:chemistry; D014961:X-Ray Diffraction
D008024:Ligands; D010636:Phenols; D014867:Water; D002713:Chlorine; D003300:Copper