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Keywords:

  • Redox transmetallation;
  • Lanthanoids;
  • Dimethyltin reagents;
  • Organo­tin(IV);
  • Pyrazolate;
  • Rare-earth elements

Abstract

Reaction of SnMe2Cl2 with [Li(Ph2pz)] (Ph2pz = 3,5-diphenylpyrazolate) in diethyl ether in a 1:2 ratio afforded the new transmetallation reagent [SnMe2(Ph2pz)2]. Treatment of [SnMe2(Ph2pz)2] with Ln metals in either 1,2-dimethoxyethane (dme) or tetrahydrofuran (thf) provided a new route to the divalent [Ln(Ph2pz)2(dme)2] (Ln = Sm, Eu, Yb) and the trivalent [La(Ph2pz)3(dme)2] and [Yb(Ph2pz)3(thf)2] complexes in comparable yields to those from alternative methods. These reactions enabled isolation of the highly reactive [Sm(Ph2pz)2(dme)2] complex in good yield, in addition to the new cis isomer of [Eu(Ph2pz)2(dme)2], thereby establishing a rare case of geometric isomerism in lanthanoid chemistry. 1H and 119Sn NMR spectral studies and EDAX measurements were performed on the reaction mixture and/or residue to identify the tin-containing products and suggest formation of SnMe4, Sn2Me6, tin metal and two other SnMe3 species, which plausibly result from decomposition of unstable “SnMe2”. Treatment of [Yb(Ph2pz)2(dme)2] with [SnMe2(Ph2pz)2] or [Tl(Ph2pz)] resulted in the isolation of [Yb(Ph2pz)3(thf)2]·2C6D6 and [Yb(Ph2pz)3(dme)]·0.5dme complexes, the structures of which have eight-coordinate Yb atoms and contrast nine-coordination observed for previous [Ln(Ph2pz)3(thf or dme)n] complexes.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)