Bromido(η⁵-carboxycyclopentadienyl)dinitrosylchromium(0) and (η⁵-benzoylcyclopentadienyl)bromidodinitrosylchromium(0)

Abstract

In the structures of each of the title compounds, [CrBr(C(6)H(5)O(2))(NO)(2)], (I), and [CrBr(C(12)H(9)O)(NO)(2)], (II), one of the nitrosyl groups is located at a site away from the exocyclic carbonyl C atom of the cyclopentadienyl (Cp) ring, with twist angles of 174.5 (3) and 172.5 (1) degrees. The observed orientation is surprising, since the NO group is expected to be situated trans to an electron-rich C atom in the ring. The organic carbonyl plane is turned away from the Cp ring plane by 5.6 (8) and 15.2 (3) degrees in (I) and (II), respectively. The exocyclic C-C bond in (I) is bent out of the Cp ring plane towards the Cr atom by 2.8 (3) degrees , but is coplanar with the Cp ring in (II); the angle is 0.1 (1) degrees .