No abstract

No abstract

No abstract

No abstract

Magnetic susceptibilities have been measured for a series of niobium and tantalum halide compounds containing the MeXIzn+ (n = 2-4) cluster ions. Derivatives of the cluster anions (MsX1z)Ys3-exhibited simple Curie behavior with magnetic moments somewhat less than the spin-only value of 1.73 BM for one unpaired electron. Some derivatives where the MeX123+ cluster units were interlinked through bridging halogen atoms exhibited Curie-Weiss behavior. This was interpreted as evidence for electron delocalization and exchange coupling between cluster units via the bridging atoms. However the compound (Ta&llz)ClB * 6HzO also provided evidence for strong exchange coupling, even though the structure was not thought t o involve such bridging atoms. Large temperature-independent paramagnetic susceptibilities (XTIP) were found for all compounds after special corrections for the diamagnetic atomic core and delocalized metal-metal bonding electron contributions were subtracted from the molar susceptibilities. For the Nb&%"+ and T~& z~+ clusters, respectively, 106xTIp values of ca. 600 and 500 cgsu were derived.