The dangers of using KBr, KI and CaI2 as mulling agents during the preparation of infrared discs of complexes

• Published in: Transition metal chemistry (Weinheim) 2002-04, Vol.27 (3), p.337
• Main Authors: Mostafa, Mohsen M, El-shazly, Rafaat M, Rakha, Tawfik H, Abdel-rahman, Mohamed H
• Format: Article
• Language: English
• ISSN: 0340-4285; 1572-901X
• DOI: 10.1023/A:1014830319501

Tribochemical reactions of KBr, KI and CaI^sub 2^ with [Cu(L)Cl^sub 2^(EtOH)^sub 3/2^(H^sub 2^O)]1/2H^sub 2^O (L = formylhydrazine) give novel Cu^sup I^ and Cu^sup II^ complexes, which have been characterized by elemental analyses, spectral (i.r., u.v.-vis., ^sup 1^H-n.m.r.) and magnetic measurements. The i.r. spectra indicate that (L) behaves in a monodentate manner, coordinating via the azomethine nitrogen (C-N) group in the Cu^sup II^ complexes, but behaving as a bidentate ligand, via the carbonyl oxygen and NH^sub 2^ groups in the Cu^sup I^ complexes. KI and CaI^sub 2^ react with [Cu(L)Cl^sub 2^(EtOH)^sub 3/2^(H^sub 2^O)]-1/2H^sub 2^O in the solid state, accompanied by a colour change, substitution of the chloride by iodide ions, and reduction of Cu^sup II^ to Cu^sup I^ to give complexes with formulae [Cu(L)I(EtOH)^sub 1/2^] and [Cu^sub 1.7^(L)I^sub 1.7^(EtOH)^sub 1/2^]. On the other hand, the tribochemical reaction of KBr with [Cu(L)Cl^sub 2^(EtOH)^sub 3/2^(H^sub 2^O)]1/2H^sub 2^O is accompanied by a colour change; substitution of the chloride by bromide ions, but without reduction of Cu^sup II^ and yields a complex of formula [Cu(L)^sub 2^Br^sub 2^(EtOH)(H^sub 2^O)]1/2EtOH. The spectral and magnetic results suggest a distorted octahedral geometry for the Cu^sup II^ complexes while a tetrahedral geometry around the Cu^sup I^ ion. The non-stoichiometric structure of [Cu^sub 1.7^(L)I^sub 1.7^(EtOH)^sub 1/2^] is discussed.[PUBLICATION ABSTRACT]