Synthesis and Structural Characterization of the Dinuclear Beryllium Species [Be2Cl2(μ-Cl)2(PCy3)2]

Due to the toxicity of beryllium compounds, the chemistry of beryllium is far less developed than that of its neighboring elements [1, 2]. As berylliumcontaining materials feature unique properties, most of the corresponding research is done in material sciences [3]. With regard to its toxicity, additional work is focused on the coordination chemistry of Be(II) in aqueous solutions [4, 5]. Thus, tetrahedral fourcoordinate Be species, which result from the coordination of ligands containing main group substituents, are well established [6 – 10]. However, the chemistry of transition metal-beryllium interactions was limited to cluster compounds, particularily to examples consisting of Zr [11, 12]. Based on previous success with the facile formation of “metal-only” Lewis pairs between electron-rich Pt0 complexes and p-block metals, e. g. in the case of [(Cy3P)2Pt–AlCl3] [13] and [(Cy3P)2Pt–GaCl3] [14], we sought to extend this rather unusual bonding pattern to Lewis-base adducts between dand s-block metals. BeCl2 as a strong Lewis acid proved to be a promising starting material, and reaction of [Pt(PCy3)2] with BeCl2 in benzene resulted in the platinum beryllium adduct [(Cy3P)2Pt–BeCl2] (1) comprising an unprecedented, electron precise bond between beryllium and a d-block metal [15]. Recent studies showed that related low-valent palladium complexes also show a propensity to act as metal bases towards metal-coordinate boryl and borylene ligands, and therefore behave similar to their platinum congeners [16 – 19]. In the present paper we report on the reaction of [Pd(PCy3)2] with