Studies in the cycloproparene series: an experimental and theoretical investigation of polar dyes derived from cyclopropa(b)naphthalene

1H-Cyclopropa[b]naphthalene is converted into novel polar olefins 15-19 via reaction of the 1,1-disilyl with anthrone-like ketones. The alkenes so formed are crystalline, polar compounds that range in color from yellow to magenta. Solutions of the 10,10-dimethylanthrylidene 15, the xanthenylidene 16, and N-methylacrydinylidene 18 fluoresce; parent anthrone 19 likely phosphoresces. X-ray crystal structure determinations are reported for 15, 18, and the thioxanthenylidene 17. Theoretical studies using ab initio calculations at the HF/6-31G level have been performed to provide assessments of the structures, charge distributions, and dipole moments of 15-19.