Synthesis, characterization, crystal and molecular structure of diphenyloxophosphinoethylenediamines Bahattin Gu ¨mgu ¨m a , Osman Akba a, * , Feyyaz Durap a , Leyla Tatar Yıldırım b,1 , Dinc ¸er U ¨ lku ¨ b,1 , Saim O ¨ zkar c a Department of Chemistry, Dicle University, 21280 Diyarbakir, Turkey b Department of Engineering Physics, Hacettepe University, Beytepe, 06800 Ankara, Turkey c Department of Chemistry, Middle East Technical University, 06531 Ankara, Turkey Received 4 April 2006; accepted 17 May 2006 Available online 13 June 2006 Abstract Bis-, tris- and tetrakis(diphenyloxophosphino)ethylenediamine compounds can be synthesized starting with ethylenediamine and chlorodiphenylphosphine. Bis(diphenylphosphino)ethylenediamine and tris(diphenylphosphino)ethylenediamine are formed as interme- diates and can be oxidized to the respective phosphine oxides by oxygen dissolved in the reaction solution, while tetrakis(diph- enylphosphino)ethylenediamine is less liable to oxidation and its oxidation requires a stronger oxidizing agent such as hydrogen peroxide. All the three phosphine oxides and tetrakis(diphenylphosphino)ethylenediamine can be isolated as analytically pure solid mate- rials and are fully characterized by elemental analysis, MS and NMR spectroscopies. The crystal and molecular structure of tris(diph- enylphosphino)ethylenediamine was elucidated by single crystal X-ray diffraction analysis. Ó 2006 Elsevier Ltd. All rights reserved. Keywords: Aminophosphine; Chlorodiphenylphosphine; Crystal structure; (Diphenylphosphino)ethylenediamines; Hydrogen bonding; NMR 1. Introduction Aminophosphines possessing P–N bonds have attracted considerable interest in recent years because of their versa- tile coordination chemistry [1] and their potential useful- ness in catalytic applications [2]. Although they posses two potential donor atoms, their coordination compounds involve almost exclusively the metal–phosphorus bond [3]. The coordination through phosphorus is attributed to the low basicity of the amine nitrogen because of the P–N p interaction between the phosphorus d p and nitrogen p p orbitals [4]. Even the aminophosphine oxide derivatives coordinate transition metals through the oxygen atom, as the phosphorus atom has already complete valency [5]. Although poorly exploited in catalysis, with respect to the tertiary phosphines and phosphites, phosphorus(V) derivatives are effective in several catalytic reactions [6]. Phosphine oxide derivatives are potential herbicidal, anti- microbial and neuroactive reagents [7] and can be used in some organic transformations such as formation of a-substituted phosphonates [8] and alkenes [9]. Bis(phos- phines) derived from the ethylenediamine backbone have been used as ligand forming complexes which are active catalysts in many organic syntheses [2c,2e,10]. Usually, the amino phosphine oxide derivatives are generated by oxidation of the respective parent aminophoshine with a suitable oxidizing agent such as paraformaldehyde [11]. Here we report the direct synthesis of bis-, tris- and tetra- kis(diphenyloxophosphino)ethylenediamine from the reac- tion of ethylenediamine and diphenylchlorophosphine in the presence of oxygen. The compounds were isolated from the reaction solution and fully characterized by elemental analysis, IR and NMR spectroscopies. Furthermore, we 0277-5387/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.poly.2006.05.035 * Corresponding author. Tel.: +90 412 248 8550/3186; fax: +90 412 248 8039. E-mail address: oakba@dicle.edu.tr (O. Akba). 1 Authors responsible for the X-ray crystal-structure analysis. www.elsevier.com/locate/poly Polyhedron 25 (2006) 3133–3137