SYNTHESES AND SPECTRA OF (CO)(2)(NO)CR(ETA(5)-C5H4-R) (R=-C(O)-N-3,-N=C=O,-NH2,-NH-C(O)-O-CH2C6H5 OR -NH-C(O)-NH-(ETA(5)-C5H4)CR(CO)(2)(NO)) AND CRYSTAL-STRUCTURE OF TA(5)-C5H4)-NH-C(O)-NH-(ETA(5)-C5H4)]CR(CO)(2)(NO)

(eta(5)-Isocyanatocyclopentadienyl)dicarbon(5) (hereafter called isocy anatocynichrodene) was prepared from cynichrodenoic acid (2) via the C urtius rearrangement. Hydrolysis of 5 with 20% aqueous potassium hydro xide solution gave dicynichrodenylurea (8) with a 40% and aminocynichr odene (6) with a 30% yield. The structure of 8 was solved by an X-ray diffraction study: space group, 14(1)/a; tetragonal; a = 20.383(4) and c = 18.001(4); Z = 16. Compound 8 adopts a transoid conformation at t he organic imido bridge. The dihedral angle between the two planes of imido-substituted cyclopentadienyl rings is 38.9 degrees. The nitrosyl group in each cynichrodenyl moiety is located at the site towards the corresponding imido nitrogen atom with twist angles of 8.3 degrees an d 9.7 degrees respectively. The chemical shifts of H(2)-H(5) protons a nd C(2)-C(5) carbon atoms of a series of cynichrodene derivatives have been assigned using two-dimensional HetCOR NMR spectroscopy. The assi gned chemical shifts of selected monosubstituted cynichrodene derivati ves were compared with the NMR data of their analogues of ferrocene an d benzene derivatives. For derivatives with electron-donating substitu ents, an analogy was observed between the shielding of C(2,5) and C(3, 4) carbon atoms of cynichrodene derivatives and ferrocene derivatives and ortho- and para-carbon atoms of benzene derivatives. For derivativ es bearing electron-withdrawing substituents, the opposite correlation on the assignments was observed between cynichrodene derivatives and the derivatives of ferrocene and benzene. The electron density distrib ution in the cyclopentadienyl ring is discussed on the basis of C-13 N MR data and that of 8 is compared with the ab-initio calculations.