313 Journal of Organometallic Chemistv, 258 (1983) 373-381 Elsevier Sequoia S.A., Lausanne - Printed in The Netherlands zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQ THE P,Se, CAGE MOLECULE AS A LIGAND. CRYSTAL STRUCTURE OF [{N(CH,CH,PPh,),}Ni(P,Se,)]*2~H, MASSIMO DI VAIRA, MAURIZIO PERUZZINI and PIER0 STOPPIONI Dipartimento di Chimica, Universitri di Firenre and Istituto I.S.S.E.C.C., C.N.R., Via J. Nardi, 39, 50132 Firenre (Itab) (Received July 13th, 1983) Summary zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA The structure of the compound [(np,)Ni(P.,Se,)] * 2C,H,, obtained from reaction of the nickel(O) complex (nps)Ni (nps = tris(2-diphenylphosphinoethyl)amine) with tetraphosphorus triselenide, P,Se,, has been determined by X-ray diffraction studies. Crystal data: cubic, space group P2,3, u 17.413(7) A, Z = 4; final R = 0.050. The intact P,Se, entity is coordinated to the metal through the apical phosphorus atom. The small changes occurring in the geometry of the cage molecule upon coordination are analyzed by a comparison with the structure of uncoordinated P,Se,, which has been refined to R = 0.045. Introduction We recently found that the P& and P,Se, cage molecules react with d” metal complexes formed by the tetradentate tripod ligand tris(2-diphenylphosphino- ethyl)amine, np,, yielding compounds of formula [(nps)M(P,X,)] *nC,H, (M = Ni, X = S or Se, n = 2; M = Pd, X = S, n = 0) [l]. An X-ray structural investigation of the compound [(np3)Ni(P,S,)]. 2C,H, showed that the intact P,S, entity is coordi- nated to the metal through its apical P atom [l]. It was of interest to obtain detailed structural information also on the isomorphous Se derivative [l], because the P,Se, molecule had never been used before as a ligand for transition metal complexes. However, this study was prevented for some time by the bad quality of crystals. Suitable crystals were recently obtained for [(npJ)Ni(P,Se,)J. 2C,H,, the structure of which is reported here. In addition, refinement of the structure of the isolated P,Se, molecule, determined several years ago from two-dimensional film data [2], was undertaken in order to allow detailed comparisons between the coordinated and uncoordinated cage molecule. 0022-328X/83/%03.00 8 1983 Ekevier Sequoia S.A.