On the metal-rich lanthanum nitridoborate nitride La-5(B2N4)N-2

La-5(B2N4)N-2 was synthesized by solid state reactions in fused tantalum co ntainers from Li-3(BN2), LaCl3, Li3N and La at 950 degrees C. The crystal s tructure refinement on a needle-shaped single-crystal yielded the monoclini c space group C2/m, the lattice parameters a = 1259.5(2), b = 368.53(4), c = 909.4(2) pm, beta = 106.03(2)degrees, and R values of R1 = 0.041, wR2 = 0 .066 for all independent reflections. The new compound La-5(B2N4)N-2 introd uces the member with x = 2 to the formula type RE3+x(B2N4)N-x (RE = rare ea rth, x = 0, 1). The structure contains the nitridoborate ion B2N48- that is isoelectronic with the oxalate ion and N3-. Corresponding with (La3+)(5)(B 2N4)(8-)(N3-)(2)(e(-)) one additional electron is present.