Highly Oriented Poly ( di - n - alkylsilylene ) Films on Oriented PTFE Substrates
نویسنده
چکیده
The present results show that indeed the structural data allow us to decide which vanadium centers must be considered formally as + 5 and which as + 4, at least with respect to the limit of strong localization. In fact, if the V3 and V3a centers were to be considered as vanadium(Iv), or as intermediates between vanadium(rv) and vanadium(v), they would be involved in several strong p o x 0 bridges, thus providing a complete change in the exchange pattern. In particular, they would be expected to be involved in strong antiferromagnetic exchange interactions with the V1 and Vla centers, which would then have their spins coupled, contrary to observation. The successful calculation of the magnetic susceptibility confirms that bis pox0 bridges are very effective in transmitting antiferromagnetic exchange interactions between oxovanadium(1v) moieties. The variability of the exchange interactions between vanadium centers and the possibility of fixing the ratio of vanadium(1v) and vanadium(v) centers in the cluster enables us in principle to tune and/or design the topology and as a consequence the magnetic properties of polyoxovanadates (IV/V) through the template effect.I4'
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