Inorganic–organic hybrid metal complexes: 24-membered hexaazamacrocyclic dinuclear nickel complexes hybridized with CdBr 2 4 Deyuan Kong, Xiang Ouyang, Joseph Reibenspies, Abraham Clearfield, Arthur E. Martell * Department of Chemistry, Texas A&M University, P.O. Box 300012, College Station, TX 77842-30012, USA Received 1 July 2002; accepted 27 July 2002 Abstract The24-memberedmacrocyclicmononuclearcadmiumcomplexreactswithNiðClO 4 Þ 2 insolutionandunexpecteddinuclearnickel complexwasobtainedwith ½CdBr 4  2 ascounterions.Inthehomodinuclearnickelcomplex,twodifferentcoordinationenvironmental entities were observed. One of these is a five-coordinated dinuclear species, the other is a six-coordinated dinuclear species ½Nið1AÞ 2 C 26 H 40 N 6 O 2 ðH 2 OÞ 2 .In ½Nið1AÞ 2 C 26 H 40 N 6 O 2 ðH 2 OÞ 2 , nickel ion is coordinated to three nitrogen atoms, one phenolic oxygenfromthemacrocyclicligand,andwithoneexogenouswatermoleculetocompleteanoctahedron.In ½Nið1BÞ 2 C 26 H 40 N 6 O 2 , eachnickelionisfive-coordinatedwithoutsolventinteraction. ½CdBr 4  2 anionsarelocatedinthelatticeandserveashybridbridgesto connecttwodifferentmoleculesandformtwolayerarraysalongthecaxis.Thewholemoleculeisdescribedasanionpairwithatwo- dimensionalhydrogenbondingnetwork.TheaveragebondlengthsofNi–NandNi–O(phenolicoxygen)are2.083,2.028  A. Ó 2002ElsevierScienceB.V.Allrightsreserved. Keywords: Macrocyclic; Dinuclear nickel complex; Inorganic; Hybrid; Crystal structure 1. Introduction Metal complexes with macrocyclic ligands have been of interest in the past decade. Ligands derived from the condensation of 2,6-diformyl-4-phenol with a diamine, have been studied extensively in view of their signifi- cance as biomimetric catalysts in the process of oxy- genation[1].Recentdiscoveriesofdinuclearcoresatthe active sites of some metalloproteins have evoked more interest in the investigation of multimetallic systems [2]. Dinucleatingmacrocyclicligandsarecapableofbinding two metal ions in close proximity have received con- siderable attention [3]. Martell and coworkers [4] re- ported the synthesis of a serial of 24- to 30-membered macrocycles containing diphenolic heads and variable side chains, such as BDBPH, BTBP [5], BDOD [6], BTBD [7] and HDTP [8]. Different catalytic properties of related metal complexes have been explored [9]. In this research on synthesis of the heterodinuclear com- plexes, new dinuclear nickel complexes with ligand BDBPH have been investigated and structurally char- acterized. 2. Results and discussion Figs.1and2showtheORTEPstructureofthefive- coordinated and six-coordinated homodinuclear nickel complexes, respectively. Fig. 3 gives the cell packing diagram of the whole molecule. A summary of crystal- lographic results is given in Table 1. Selected bond lengthsandbondanglesaregiveninTable2.Tablesof atomic coordinates and thermal displacement parame- ters are contained in the Supporting materials. As shown in Scheme 1, the heterodinuclear Cd–Ni macrocyclic complexes were expected to form in a Inorganic Chemistry Communications 5 (2002) 873–878 www.elsevier.com/locate/inoche * Corresponding author. Tel.: +1-979-845-5055; fax: +1-979-845- 4719. E-mail address: martell@mail.chem.tamu.edu (A.E. Martell). 1387-7003/02/$ - see front matter Ó 2002 Elsevier Science B.V. All rights reserved. PII:S1387-7003(02)00569-5