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Abstract:
Black crystals of the isotypic phases LiBa4[Mo2N7] and LiBa4[W2N7]
(monoclinic, P2/n; a = 1552.2(3)/1555.2(4), b = 642.2(1)/644.4(1), c =
1039.9(2)/1042.4(2) pm; beta = 99.23(2)/99.30(3)degrees; Z = 4) were
grown from the melt (Li, Ba3N2, Mo/W; molar ratio 20:5:1; T-max = 1323
K; reaction with N-2, 1 atm, 18 h) by cooling (20 K/h). The crystal
structures contain two independent dimeric units [Mo2N7](9-)/[W2N7](9-)
(staggered conformation; Mo/W-N-Mo/W: 173.6/173.7 degrees and 180
degrees/180 degrees; Mo/W-N-(term): 180(2)-185(1)/181(3)-185(1) pm;
Mo/W-N-(bridge): 195(1)/194(1) pm and 193(1)/194(1) pm).
