Polymeric d-MgCl 2 nanoribbons Michele Vittadello a , Philip E. Stallworth b , Faisal M. Alamgir c , Sophia Suarez c , Sabina Abbrent c , Charles M. Drain d , Vito Di Noto e, * , Steve G. Greenbaum c a Department of Materials Science and Engineering, Rutgers University, 607 Taylor Road, Piscataway, NJ 08854-8065, USA b Division of Science, City College of NY, CUNY Convent Avenue and 138th Street, New York, NY 10031, USA c Physics Department, Hunter College of CUNY, 695 Park Avenue, New York, NY 10021, USA d Chemistry Department, Hunter College of CUNY, 695 Park Avenue, New York, NY 10021, USA e Department of Chemical Sciences, University of Padua, Via Loredan 4, I-35135 Padua, Italy Received 13 January 2006; accepted 30 January 2006 Available online 23 March 2006 Abstract d-MgCl 2 has relevant applications in the field of electrochemical energy storage and Ziegler–Natta catalysis. Here, we clarify the short-range structural peculiarities that make the disordered phase d-MgCl 2 extremely chemically active relative to the higher lattice energy phases, a-MgCl 2 and b-MgCl 2 . X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS) and nuclear magnetic resonance (NMR) results are included. These findings, demonstrate the existence of [MgCl 2 ] n nanoribbons and active nanosurfaces in d-MgCl 2 and provide new insight about the nature of the bonding in the allotropic forms of MgCl 2 . Ó 2006 Elsevier B.V. All rights reserved. Keywords: MgCl 2 ; X-ray diffraction; X-ray absorption spectroscopy; Solid state NMR 1. Introduction Compared to the large degree of attention given to lith- ium-ion systems for electrochemical energy storage appli- cations, relatively little interest has been devoted to magnesium ion-conducting polymer electrolytes [1]. In spite of the potential advantages envisaged as performance, cost and safety, the preparation of magnesium polymer electrolytes has been considered very difficult due to the high lattice energy of magnesium salts [2,3]. However, elec- trolytic complexes based on polyethylene glycol and d-MgCl 2 have been proposed [4] not only for usage in mag- nesium batteries but also for potentiometric pH sensors [5]. The d-MgCl 2 phase is well known as a unique support for the active titanium halide center in the Ziegler–Natta catal- ysis [6] and is characterized by high crystallographic disor- der [4]. The aim of the current study is the understanding of the structure–property relationship of d-MgCl 2 at the nano-scale to target energy storage and catalytic applica- tions of this material. Previous X-ray and FT-IR studies of crystalline MgCl 2 B x adducts (B = Lewis Base like ethyl formate, ethyl acetate, ethyl p-methoxybenzoate, ethanol, etc.) have pro- vided evidence for MgCl 2 polymeric chains [7–11]. These studies suggest that d-MgCl 2 , which can be obtained by the complete elimination of B from the adducts (x ! 0), is the disordered array of a large number of covalent [MgCl 2 ] n polymeric chains [8–12]. The hypothesis of exis- tence of [MgCl 2 ] n polymeric chains certainly claims further experimental evidence. In spite of that, such indications of covalency in d-MgCl 2 are in line with the fact that the crys- tal (a-form or b-form) requires an analysis beyond the Born–Mayer rigid ionic picture [13]. The first-order version of this model does not account for the relatively large num- ber of reported ‘covalent’ effects in this and other suppos- edly ionic systems [14]. In order to explain these and similar observations an extended ionic model was proposed 0020-1693/$ - see front matter Ó 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.ica.2006.01.044 * Corresponding author. Tel.: +39 049 827 5229; fax: +39 049 827 5161. E-mail address: vito.dinoto@unipd.it (V. Di Noto). www.elsevier.com/locate/ica Inorganica Chimica Acta 359 (2006) 2513–2518