Research Article Synthesis and Structural Study of the Bis(ethylenediamine)CdFe(CO) 4 Monomer Marcus Tofanelli, Atta M. Arif, and Richard D. Ernst Department of Chemistry, University of Utah, 315 South 1400 East, Room 2020, Salt Lake City, UT 84112-0850, USA Correspondence should be addressed to Richard D. Ernst; ernst@chem.utah.edu Received 31 December 2013; Accepted 24 February 2014; Published 25 March 2014 Academic Editor: L´ ıgia R. Gomes Copyright © 2014 Marcus Tofanelli et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Te new (en) 2 CdFe(CO) 4 complex has been isolated from the crystallization of [(en)CdFe(CO) 4 ]  from ethylenediamine (en). Te cadmium center bears square-pyramidal coordination, with the iron atom occupying the apical position. Te iron coordination may be described either as trigonal bipyramidal, with the cadmium atom being in an axial position, or as monocapped (by cadmium) tetrahedral. Te Cd-Fe distance was found to be 2.6250(2) ˚ A. Te complex crystallizes in the monoclinic space group 2 1 / with  = 14.4137(3) ˚ A,  = 7.65740(10) ˚ A,  = 14.5465(2) ˚ A, and  = 119.4972(9) ∘ at 150(1) K. 1. Introduction Since the frst reports of CdFe(CO) 4 and various base adducts [1, 2], primarily being of the [L 2 CdFe(CO) 4 ]  type with L representing chelating or nonchelating amine or ether ligands, surprisingly little efort has been expended toward the investigation of their structural natures, including their degrees of association. To date, most of the ligand adduct complexes have been found to be trimeric, as observed for THF, pyridine, and 2,2  -bipyridine [3, 4], though dimeric species have also been isolated (vide infra), as well as more complicated ring systems [5–7]. In the [L 2 CdFe(CO) 4 ]  complexes, oligomerization occurs through the formation of metal-metal bonded rings composed of alternating cadmium and iron atoms. Under the right conditions, additional base coordination can be used to generate monomeric L 3 CdFe(CO) 4 species (Figure 1)[8], which are actually more typical of analogous zinc complexes [2, 8, 9]. For the cad- mium complexes, either the use of special chelating ligands, such as tren (2,2  ,2  -triaminotriethylamine), or crystalliza- tion from strongly coordinating solvents such as pyridine, can be used to favor the isolation of such monomers [8]. As an example of the latter approach, crystallization of [(neocuproin)CdFe(CO) 4 ]  ( = 2, 3) from pyridine has led to the isolation of (py)(neocuproine)CdFe(CO) 4 monomers (neocuproine = 2,9-dimethylphenanthroline) [10]. Herein we report that crystallization of the known [(en)CdFe(CO) 4 ]  complex from en (en = ethylenediamine) leads to the for- mation of (en) 2 CdFe(CO) 4 monomers, which are especially unusual due to the presence of fve-coordinate, square- pyramidal cadmium coordination. 2. Materials and Methods 2.1. Synthesis. All reactions were carried out in Schlenk appa- ratus under a nitrogen atmosphere. All nonmetallic reagents were obtained commercially, and [(NH 3 ) 2 CdFe(CO) 4 ]  was prepared by a published procedure [2]. (en) 2 CdFe(CO) 4 (en = ethylenediamine) was synthesized by adding 20 mL of ethylenediamine to 1 g (3 mmol) of [(NH 3 ) 2 CdFe(CO) 4 ]  while stirring, leading to complete dissolution of the com- pound. In order to form crystals, water was added at room temperature until a small amount of precipitate had formed. Te solution was then heated with stirring to 90 ∘ C until the precipitate was completely redissolved and allowed to cool slowly back to room temperature. Te collected crystals were subsequently subjected to an X-ray difraction study. Anal. Calc. for C 8 H 16 O 4 N 4 CdFe: C, 23.99; H, 4.03; N, 13.99. Found: C, 24.4; H, 4.58; N, 14.1. 2.2. X-Ray Crystallography. Single crystals of the compound were examined under Paratone oil, and a suitable crystal was selected for data collection. It was transferred to a Nonius Hindawi Publishing Corporation Journal of Crystallography Volume 2014, Article ID 217478, 4 pages http://dx.doi.org/10.1155/2014/217478