The synthesis and structure of the alkaline earth metal organic compounds [M(OAr)2(thf)n][M = Ca, n= 3 (1) or 0; M = Ba, n= 4] and [{Ca(NR2)(µNR2)(thf)}2], and the X-ray structure of (1)(Ar = C6H2But2-2,6-Me-4; R = SiMe3; thf - OC4H8)

Abstract

Treatment of highly reactive, pyrophoric calcium or barium (obtained by co-condensation of the appropriate metal vapour and toluene) in tetrahydrofuran with (i) ArOH (Ca more reactive than Ba) affords the phenoxide [M(OAr)₂(thf)_n][M = Ca and n= 3 (1), or n= 0 after heating at 80°C and 10^–2 Torr; M = Ba, n= 4], or (ii) R₂NH (for M = Ca) yields [{Ca(NR₂)(µ-NR₂)(thf)}₂][also obtained from (1)+ 2LiNR₂ in n-C₆H₁₄; Ar = C₆H₂Bu^t₂-2,6-Me-4; R = SiMe₃)]; the X-ray structure of crystalline (1) shows a distorted trigonal bipyramidal Ca environment with the thf ligands in apical sites.