New compounds with a Y2ReB6 type structure

The Ln-Mo-B ternary systems (where Ln is Tm, Yb, Lu) are studied by means i f X-ray analysis. New compounds of the Y2ReB6 structure type (space group P bam) were found: Tm2MoB6 (a = 0.9210(2), b = = 1.1409(1), c = 0.35983(6) nm ), Yb2MoB6 (a = 0.9068(3), b = 1.1394(3), c = 0.3588(1) nm), Lu2MoB6 (a = 0 9031(4), b = 1.1364(3), c = 0.35526(9) nm); the atomic factors of the last structure are refined up to R = 0.068. Lattice parameters for the known bor ide Er2MoB6 are relined: a = 09254(2), b = 1.1449(3), c = 0.36065(6) nm. Th e smoothly decreasing lattice parameters and unit cell volumes in the serie s Ln(2)MoB(6) (Zn is Er, Tm, Yb, Lu) point to the trivalent state of the ra re earth atoms (REM).