Reactions of yttrium atoms in hydrocarbon matrices: electron paramagnetic resonance evidence for matrix-isolated YO and Yn(n= 5 or 7)

Abstract

Deposits given by condensing resistively heated yttrium metal into cyclohexane and adamantane matrices under high vacuum and at 77 K on a rotating cryostat have been examined by EPR spectroscopy. The principle paramagnetic products under these conditions are YO in at least two distinct trapping sites and yttrium clusters, Y_n, where n= 5 or 7. Analysis of the yttrium hyperfine interaction for YO indicates that the unpaired electron has 60% metal 5s character with the remainder of the unpaired spin in oxygen, matrix and metal p and 4d orbitals. An yttrium cluster, Y_n, is produced in adamantane that is tumbling freely or pseudorotating above 205 K and has ca. 10% unpaired spin in the Y 5s orbital with the rest pressumed to be in metal 4d orbitals. A different Y cluster is formed in cyclohexane that could be a rigid pentemer or septemer with a trigonal bipyamidal or pentagonal bipyramidal structure. It is tentatively suggested that Y₅ is formed in adamantane and that Y₇ is formed in cyclohexane.