Rational Design and Synthesis of a New Organometallic Ligand, 1-Ferrocenyl-3-(5-bromopyridyl)-prop-3-enol-1-one and Its Heteronuclear Coordination Polymer, {Cu[1-ferrocenyl- 3-(5-bromopyridyl)prop-1,3-dionate] 2 } n Chengeto Gwengo, Ratnasabapathy Iyer, and Muthukrishna Raja* Department of Chemistry, Claflin University, Orangeburg, South Carolina 29115, United States * S Supporting Information ABSTRACT: A new bifunctional organometallic ligand was synthesized, by reacting ferroceneacyl anion with ethyl-5- bromonicotinic acid, isolated, and characterized as 1- ferrocenyl-3-(5-bromopyridyl)-prop-3-enol-1-one (HL 1 ). This new ligand reacts with Cu(II) salt to yield a new two- dimensional (2D) heteronuclear (Fe-Cu) coordination polymer of type [Cu(L 1 ) 2 ] n. Single crystal X-ray diffraction analysis of both the ligand and the coordination polymer is provided in this report. ■ INTRODUCTION Crystal engineering of porous materials such as zeolites, coordination polymers, and metal-organic frameworks (MOFs) is a contemporary area of research 1 with potential uses in areas such as gas storage, 2 ion exchange, 3 catalysis, 4 conductivity, 5 drug delivery, 6 magnetism, 7 spin-transition, and nonlinear optics. 8 Since the early 1990s, research interest in this field is driven not only by the desire to synthesize aesthetically attractive and functionally accessible molecular helicates, strings, rings, boxes, and grids 9-17 but also to establish structurally complex coordination polymers similar to that of biopolymers such as proteins. 18 In most of the coordination network polymers, ions of a single metal, usually labeled as nodes, are bonded to two or more multidentate organic ligands that also serve as spacers. 19 Coordination polymers with one type of metal center are relatively abundant, as evident from the number of reports in the literature. Recent emphasis on coordination polymers has been to introduce a second or even a third metal center in order to produce multifunctional materials. 20-23 While most of the heterometallic coordination polymers consist of naked metal ions bridged by organic ligands, 24-28 structures in which a metal is part of the linker, as an organometallic ligand, are much rarer. 29-38 Incorporat- ing organometallic ligands in the design and synthesis of coor- dination polymers is still at a very early stage. For example, Sweigart and co-workers have used an “organometalloligand”, [(η 6 -ben- zoquinone)Mn(CO) 3 ] - , to synthesize various bimetallic coordina- tion polymers and coined the term “metal-organometallic frameworks (MOMFs)” to identify them. 39,40 An organometallic sandwich complex of iron, [(η 5 -Cp)Fe(η 6 -1,4-benzenedicarbox- ylate)] - , has been used to synthesize a series of 3D MOMFs containing Co(II) and Ni(II) ion. 41 Apart from these examples, most of the organometallic ligands used in coordination polymer synthesis are based on commercially available ferrocenecarboxylic acid. 33,34,42,43 Integrating organometallic moieties as parts of multidentate ligands will be useful not only in constructing ligands with specific shapes but also in designing coordination polymers with interesting optical and electrochemical properties. 44,45 Ligands such as acetylacetonate anion, pyridine, bipyridine, and their functionalized analogues are used extensively in the preparation of both classical coordination complexes and coordination polymers. 24,46 Similarly, ferrocene, other metal- locenes, and their derivatives are generally viewed as corner- stones of contemporary organometallic chemistry. 47 With these basic facts in mind, we initiated a study to synthesize simple ligands 48-50 comprising a pyridine ring with a labile group, a metallocene, and a β-diketonate moiety and explore their reaction chemistry in the design and synthesis of heteronuclear coordination polymers and metal organometallic networks. Herein, we report the synthesis of a new organometallic ligand, 1-ferrocenyl-3-(5-bromopyridyl)-prop-3-enol-1-one, HL 1 , and its reaction with Cu(II) salt to form a new heteronuclear coordination polymer with Fe 0 -Cu II ions. The coordination chemistry of this new organometallic ligand, with both transition and lanthanide metals, will enable us to design and synthesize various heteronuclear coordination polymers. Postsynthetic modification of metal organic frameworks is an emerging branch in the study of MOFs. 51 The “C-Br” in our new class of ligands Received: November 4, 2011 Revised: December 2, 2011 Published: December 7, 2011 Communication pubs.acs.org/crystal © 2011 American Chemical Society 49 dx.doi.org/10.1021/cg2014573 | Cryst. Growth Des. 2012, 12, 49-53