Elevated-Temperature Metathesis Syntheses of Structurally Novel Alkali-Metal Tetrakis(3,5-di-tert-butylpyrazolato)lanthanoidate(III) Complexes: Toluene-Coordinated Discrete Bimetallic Complexes and Supramolecular Chains

Glen B. Deacon, Ewan E. Delbridge, David J. Evans, Rita Harika, Peter C. Junk, Brian W. Skelton, Allan H. White

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Abstract

Sodium and potassium tetra-kis(3,5-di-tert-butylpyrazolato)lanthanoidate(III) complexes [M{Ln(tBu2pz)4}] have been prepared by reaction of anhydrous lanthanoid trihalides with alkali metal 3,5-di-tert-butylpyrazolates at 200-300°C, and a 1,2,4,5-tetramethylbenzene flux for M=K. On extraction with toluene (or occasionally directly from the reaction tube) the following complexes were isolated: [Na(PhMe){Ln(tBu2pz)4}] (1Ln; 1Ln= 1Tb, 1Ho, 1Er, 1Yb), [K(PhMe){Ln-(tBu2pz)4}]· 2PhMe (2Ln; 2Ln=2La, 2Sm, 2Tb, 2Ho, 2Yb, 2Lu), [Na{Ln-(tBu2pz) 4}]n (3Ln; 3Ln=3La, 3Tb, 3Ho, 3Er, 3Yb), [K{Ln(tBu 2pz)4}]n (4Ln; 4Ln=4La, 4Nd, 4Sm, 4Tb, 4Ho, 4Er, 4Yb, 4Lu), with the last two classes generally being obtained by loss of toluene from 1Ln or 2Ln, and [Na(tBu2pzH){Ln(tBu 2pz)4}]·PhMe (5Ln; 5Ln=5Nd, 5Er, 5Yb). Extraction with 1,2-dimethoxyethane (DME) after isolation of 2Ho yielded [K(dme){Ho(tBu 2pz)4}] (6Ho). X-ray crystal structures of 1Ln (=1Tb, 1Ho; P21/c), 2Ln (=2La, 2Sm, 2Tb, 2Yb, 2Lu; Pnma), 3,4Ln (=3La, 3La, 4Sm; P21/m), and 5Ln (=5Nd, 5Er, and 5Yb; P1) show each group to be isomorphous regardless of the size of the Ln3+ ion. All complexes contain eight-coordinate {Ln(η2-tBu2pz)4} units. These are further linked to the alkali metal by bridging through two (1,2,5 Ln) or three (3,4Ln) tBu2pz groups which show striking coordination versatility. Sodium is coordinated by an η4-PhMe, a μ-η22-tBu2pz, and a μ-η4(Na):η2 (Ln)-tBu2pz ligand in 1Ln, and by one η1-tBu2pzH and two μ-η 3(Na):η2(Ln) ligands in 5Ln. By contrast, potassium has one η6-PhMe and two μ-η5(K):η 2(Ln) ligands in 2Ln. Classes 3,4Ln form polymeric chains with the alkali metal bonded by two μ-η3(NNC-M):η 2(Ln)-tBu2pz ligands within [MLn(tBu2pz) 4] units which are joined together by η1(C)-tBu 2pz-Na, K linkages.

Original languageEnglish
Pages (from-to)1193-1204
Number of pages12
JournalChemistry - A European Journal
Volume10
Issue number5
DOIs
Publication statusPublished - 5 Mar 2004

Keywords

  • Lanthanoids metathesis
  • Pyrazolates
  • Rare earths
  • Structure elucidation

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