Affiliations: Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716
Note: [] Dedicated to Professor Max Herberhold on the occasion of his 60th birthday.
Note: [] Current address: Science Department, St. Mary’s College, P.O.Box 159, St. Mary’s, KS 66536
Abstract: From adventitious sources, single-crystal samples of the first aromatically substituted cyclopentaarsines, cyclo(C6H5As)5 and cyclo(p-CH3C6H4As)5, have been obtained and crystallographically characterized. In both cases, the structures are those expected of cyclopentane isolobal analogues, i.e., an essentially zero dihedral plane of four atoms with a fifth atom residing in a sharply angled flap plane. The flap angle is about 10° smaller for the phenyl- and p-tolyl-substituted rings than for two previously reported alkyl-substituted rings, but is 15–20° larger than the six-membered phenyl- and p- tplyl-substituted systems. For cyclo(PhAs)5: monoclinic, P21/n, a = 9.770(2)Å, b = 10.385(2)Å, c = 27.941(6)Å, β = 91.85(2)°, V = 2833.5(10)Å3, Z = 4, d(calcd) = 1.782 g cm−3, R(F) = 7.82%. For cyclo(p-TolAs)5: monoclinic, P 21/c, a = 10.785(2)Å, b = 8.798(1)Å, c = 35.872(7)Å, β = 92.52(2)°, V = 3400.4(11)Å3, Z = 4, d(calcd) = 1.820 g cm−3 R(F) = 5.13%.
