Ira Bloom

Catalytic activation of molecular hydrogen in alkyne hydrogenation reactions by lanthanide metal vapor reaction products

A rotary metal vapor was used in the synthesis of Lu, Er, Nd, Sm, Yb, and La alkyne, diene, and phosphine complexes. A typical catalytic hydrogenation experiment is described. The lanthanide metal vapor product is dissolved in tetrahydrofuran or toluene and placed in a pressure reaction vessel 3-hexyne (or another substrate) is added, the chamber attached to a high vacuum line, cooled to -196/sup 0/C, evacuated, warmed to ambient temperature and hydrogen is added. The solution is stirred magnetically while the pressure in monitored. The reaction products were analyzed by gas chromatography. Rates and products of various systems are listed. This preliminary survey indicates that catalytic reaction chemistry is available to these metals in a wide range of coordination environments. Attempts to characterize these compounds are hampered by their paramagnetic nature and their tendency to polymerize.

Synthesis and crystallographic characterization of a dicyclopentadienylvanadium alkynide complex: (C5H5)2VCCC(CH3)3

Abstract (C 5 H 5 ) 2 VCl reacts with LiCCC(CH 3 ) 3 to form (C 5 H 5 ) 2 VCCC(CH 3 ) 3 which was characterized by spectroscopic, analytical, and crystallographic methods. The complex crystallizes from pentane at 0°C as a monomer in the orthorhombic space group Pnma with four molecules in a unit cell of dimensions a 9.075(3), b 9.807(3), c 16.444(5) A. Full-matrix least-squares refinement based upon 1300 nonzero intensity data converged to a final conventional R factor of 0.060. The molecule has a mean VC 5 H 5 -ring centroid distance of 1.941 A with 146.6° ring centroid-V-ring centroid angle. The vanadium alkynide carbon distance is 2.075(5) A.