Synthesis and X-ray crystal structures of hypervalent arsenic compounds bearing arsenic-iron bonds

A hypervalent arsorane with an As-Fe bond [6: Rf(2)As*FeCp(CO)(2)(Rf:o-C(6)H(4)C(CF(3))(2)O-)] was synthesized by the reaction of the arsoranide anion (4-Et(4)N: Rf(2)As*-Et(4)N(+)) with CpFe(CO)(2)I (5) in the presence of AgBF(4). Diastereomeric arsoranes {7a and 7b: Rf(2)As*Fe*Cp(CO)(PPh(3))} were prepared by irradiation of 6 with a tungsten lamp in the presence of triphenylphosphine. X-ray crystallographic analysis of 6 and 7a showed that the apical As-O bond lengths of these compounds are slightly longer than the equatorial As-C bonds. It is concluded that an electron-donating group at the equatorial position elongates the apical E-O bond by electron donation to the apical oxygens.(C) 2000 John Wiley & Sons, Inc.