Structural diversity in the borohydrido lanthanides series:: First isolation and X-ray crystal structure of ionic [Sm(BH4)2(THF)5]+[Cp′Sm(BH4)3]-

The reaction of Sm(BH4)(3) (THF)(3) with a half equivalent of KCp*' (Cp*' = (C5Me4Pr)-Pr-n) affords a compound comprising one Cp*' ligand and three THF molecules per two Sm atoms, [Cp*'Sm-2(BH4)(5)(THF)(3)], according to analytical data. Crystals of penta-THF adduct 1, showing the same H-1 NMR spectrum except for the quantity of THF, could be isolated from a solution of half-samarocene Cp*'Sm(BH4)(2)(THF) (2). X-ray structure determination of 1 revealed an ionic compound [Sm(BH4)(2)(THF)(5)](+)[Cp*'Sm(BH4)(3)](-) with two discrete mononuclear Sm polyhedrons. The expected neutral samarocene Cp-2*'Sm(BH4)(THF)(3) could be obtained from the reaction of Sm (BH4)(3) (THF)(3) with two equivalents of KCp*'. X-ray structure analysis showed that 3 is a monomeric complex bearing a terminal borohydride ligand. All BH4- ligands in 1 and 3 exhibit an eta(3)-H3BH bonding mode. (c) 2007 Elsevier B.V. All rights reserved.