Syntheses and Structures of New Rare‐Earth Metal Tetracyanidoborates

Six new rare‐earth metal tetracyanidoborates were prepared and characterized by single‐crystal X‐ray diffraction. Crystals of these salts contain co‐crystallized solvent molecules, such as water, acetone, ethanol, or diethyl ether. In [La(EtOH)3(H2O)2{B(CN)4}3] (1), [La(EtOH)(H2O)4{B(CN)4}3]·Et2O (2), and [Y(EtOH)(H2O)4{B(CN)4}3]·EtOH (6) the tetracyanidoborate anions are all or in part bonded to the RE3+ ions, whereas in [Pr(H2O)9][B(CN)4]3·(CH3)2CO (3), [Er(H2O)8][B(CN)4]3·(CH3)2CO (4), and [Lu(EtOH)(H2O)7][B(CN)4]3·EtOH·0.5H2O (5) the [B(CN)4]– anions are not coordinated to the central metal atoms. Only in 1, one of the three crystallographically independent [B(CN)4]– anions acts as a bridging ligand.