No abstract

With the introduction of new

The addition of (p-bromo- or (p-iodophenyl)lithium to 6,6-dimethylfulvene results in the formation of the anionic cyclopentadienyl (Cp) ligands LiCpC(CH3)2C6H4Br (1) and LiCpC(CH3)2C6H4I (2), respectively. Reaction of 4 equiv of ligand 1 or 2 with 1 equiv [Cp*RuCl]4 yields ruthenocenes Cp*RuCpC(CH3)2C6H4Br (3) and Cp*RuCpC(CH3)2C6H4I (4) in high yield. Cp*RuCpC(CH3)2C6H4Br undergoes bromo−lithium exchange with BuLi, and the resulting lithiate can be trapped with Ph2BOMe to give the neutral boron-containing ruthenocene Cp*RuCpC(CH3)2C6H4BPh2Py (5) or with BPh3 to give the anionic borate-containing ruthenocene Cp*RuCpC(CH3)2C6H4BPh3Li, which can be isolated either base-free (6), as a diethyl etherate (6a), or as a tetrahydrofuranate (6b). All new compounds have been characterized in solution by NMR spectroscopy. An X-ray structure analysis of 3 indicates that the neutral ruthenocene adopts a slightly bent, eclipsed structure with the phenyl group directed away from the metal center. An X-ray structure analysis of 6b indicates that the anionic ruthenocene adopts a slightly bent, partially staggered conformation with the borate directed away from the metal center. The staggered conformation appears to be due to the intermolecular interactions within the crystal packing and not intramolecular interactions between sterically-demanding Cp ligands.

The effect of strain on the surface magnetism of the manganite La0.7Sr0.3MnO3 has been studied as a function of temperature, using magnetic force microscopy. The non- uniform strain distribution in the film leads to a two-phase coexistence between ferromagnetic and non-ferromagnetic phases. This leads to a reduction of the surface curie temperature and the formation of ferromagnetic islands. Methods of controlling this behavior in order to fabricate arrays of magnetic nanodots are discussed.