The binary cluster [Co@Sn9]4- (1) was extracted directly from ethylenediamine (en) solutions of an intermetallic precursor with nominal composition "K5Co3Sn9", and its reactions with various organometallic reagents were explored. Reaction… Click to show full abstract
The binary cluster [Co@Sn9]4- (1) was extracted directly from ethylenediamine (en) solutions of an intermetallic precursor with nominal composition "K5Co3Sn9", and its reactions with various organometallic reagents were explored. Reaction with Ni(PPh3)2(CO)2 gives [Co@Sn9Ni(CO)]3- (2), a Co-centered closo-Sn9Ni bicapped square antiprism. Analogous reactions with Ni(COD)2, Pt(PPh3)4, and Au(PPh3)Ph led to the isolation of [Co@Sn9Ni(C2H4)]3- (3), [Co@Sn9Pt(PPh3)]3- (4), and [Co@Sn9AuPh]3- (5), respectively. 3 is structurally similar to 2 but significantly distorted from a closo-cluster with one open square face. The coordination of [CoSn9]3- by PtPPh3 (4) or AuPh (5) induces a structural transformation in the CoSn9 core, from a monocapped square antiprism ( C4 v) to a tricapped trigonal prismatic structure ( pseudo- C3 v), with the transition metal fragment capping a triangular face. The four trimetallic anions presented here represent a new family of ternary functionalized Zintl clusters incorporating a d9 transition metal center. All clusters were characterized by single-crystal X-ray diffraction and electrospray ionization mass spectrometry (ESI-MS).
               
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