Structural diversity in the borohydrido lanthanides series: First isolation and X-ray crystal structure of ionic [formula omitted

Abstract

The reaction of Sm ( BH 4 ) 3 ( THF ) 3 with a half equivalent of KCp ∗ ′ ( Cp ∗ ′ = C 5 Me 4 n Pr ) affords a compound comprising one Cp ∗ ′ ligand and three THF molecules per two Sm atoms, [ Cp ∗ ′ Sm 2 ( BH 4 ) 5 ( THF ) 3 ] , according to analytical data. Crystals of penta-THF adduct 1, showing the same 1H NMR spectrum except for the quantity of THF, could be isolated from a solution of half-samarocene Cp ∗ ′ Sm ( BH 4 ) 2 ( THF ) ( 2). X-ray structure determination of 1 revealed an ionic compound [ Sm ( BH 4 ) 2 ( THF ) 5 ] + [ Cp ∗ ′ Sm ( BH 4 ) 3 ] - with two discrete mononuclear Sm polyhedrons. The expected neutral samarocene Cp 2 ∗ ′ Sm ( BH 4 ) ( THF ) ( 3) could be obtained from the reaction of Sm ( BH 4 ) 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 BH 4 - ligands in 1 and 3 exhibit an η 3 - H 3 BH bonding mode.