Complexes of yttrium, thulium, and lutetium tetrahydridoborates with tetraphenylphosphonium tetrahydridoborate (Ph4P)[M(BH4)(4)] (M = Y, Tm, Lu): Crystal structure of (Ph4P)[Tm(BH4)(4)]

The exchange reaction of NaM(BH4)(4) . nDME (M = Y, Tm, Lu; n = 3, 4; DME = 1,2-dimethoxyethane) with tetraphenylphosphonium tetrahydridoborate yields the salts (Ph4P)[M(BH4)(4)]. The compounds were studied by IR spectroscopy ; the crystal structure of (Ph4P[Tm(BH4)(4)] (1) was determined by X-ray cr ystallography. Compound 1 is tetragonal, a = 14.344(2) Angstrom, c = 13.517 (3) Angstrom, V = 2781.1(8) Angstrom (3), Z = 4, space group I4(1)/a. Cryst als of 1 are composed of (Ph4P)(+) cations and [Tm(BH4)(4)](-) anions held together by Coulomb interaction. Tm and P atoms occupy special fourfold pos itions in different axes 4 in space group I4(1)/a. The Tm atom is bound to a tetrahedral array of four B atoms of BH4- anions (Tm-B, 2.46(1) Angstrom) presented to the central atom by three hydrogen atoms (eta (3) coordinatio n mode; Tm-H-av, 2.32(8) Angstrom). The fourth H atom of a boron hydride te trahedron is located roughly in the extension of the Tm-B line (the TmBH(1b ) angle is 176(8)degrees). In the (Ph4P)(+) cations, the P-C bonds, 1.791(6 ) Angstrom, and angles at the P atom, 108 degrees -110(5)degrees, have stan dard values.