The reaction of W 6 Br 12 with CuBr sealed in an evacuated silica tube at the temperature gradient 925/915 K and annealing at 625/300 K yields a mixture of orthorhombic α-Cu 2 [W 6 Br 14 ] and cubic b-Cu 2 [W 6 Br 14 ] in the low temperature zone. α-Cu 2 [W 6 Br 14 ] crystallizes in the space group Pbca (no. 61), a = 15.126 A Ê , b = 9.887 A Ê , c = 15.954 A Ê , Z = 4, oP88, and b-Cu 2 [W 6 Br 14 ] crystallizes in the space group Pn3 (no. 201), a = 13.391 A Ê , Z = 4, cP88. The crystal structures are built up by [(W 6 Br i 8 )Br a 6 ] 2± cluster anions and Cu + cations. The cluster anions show only in the peripheral shells small deviation from m3m symmetry (d(W±W) = 2.630 A Ê ; d(W±Br i ) = 2.618 A Ê ; d(W±Br a ) = 2.614 A Ê ). The anions are arranged in a slightly compressed bcc pattern (α) and ccp (b) pattern, respectively. The Cu + cations are trigonal-planar coordinated by Br a ligands with d(Cu±Br) = 2.377 A Ê (α) and 2.378 A Ê (b). The cubic b-modification is diamagnetic with an unexpected large susceptibility (v mol = ±884 × 10 ±6 cm 3 mol ±1 ) and have a band gap of 2.8 eV. It decomposes under dynamic vacuum in two steps at 795 K und 1040 K.