The preparation and crystal structures of dicarbonylcyclopentadienylnitrosylchromium and dicarbonylfluorenylnitrosylchromium

Abstract

The X-ray-crystal structures of both (η 5-C 5H 5)Cr(CO) 2(NO) (I) and (η 5-C 13H 9)Cr(CO) 2(NO) (II, η 5-C 13H 9 = η 5-9H-fluorenyl) are described. I crystallizes in the monoclinic space group P2 1/ n with lattice constants a 10.998(4), b 7.066(3), c 11.940(4) Å, β 116.37(4)°, and ϱ calc 1.63 g cm −3 for Z = 4. II belongs to the orthorhombic space group Pnma with a 6.463(4), b 15.512(6), c 12.916(6) Å, and ϱ calc 1.55 g cm −3 for Z = 4. Least-squares refinement gave final conventional R values of 0.037 based on 1081 independent observed reflections for I, and 0.042 with 630 reflections for II. The carbonyl and nitrosyl groups are disordered in I, but the nitrosyl ligand in II occupies a position “ trans” to the electron-rich C(9) of the fluorenyl system. Photolysis of II in liquid olefins (L) or acetyleness leads to substituted derivatives of the type (η 5-C 13H 9)Cr(CO)(NO)L (L = cyclooctene, cycloocta-1,5-diene, norbornene, norbornadiene, phenylacetylene).