Studies of Metal-Nitrogen Multiple Bonds. I. Crystal and Molecular Structure of Nitridodichlorotris(Diethylphenylphosphine)Rhenium(V), ReNCl₂[P(C₂H₅)₂C₆H₅]₃

The crystal and molecular structure of nitridodichlorotris(diethylphenylphosphme)rhemum(V), ReNCl₂[P(C₂H₅)₂C₆H₅]₃, has been determined from three-dimensional X-ray data collected by counter methods. The structure has been refined by least-squares techniques down to a final R factor of 5.1% on F. The material crystallizes in space group C_2h⁵-P2_t/c of the monoclinic system, with four molecules in a cell of dimensions a = 18.67, b = 11.51, c = 18.19 A; β = 122° 34’. The individual molecular units are well separated. The inner coordination around Re is octahedral. If the three P atoms and one Cl atom are taken to define an equatorial plane, then N and the other Cl are above and below this plane, respectively. The octahedral configuration is somewhat distorted. Multiple bonding between the Re and N atoms is suggested by several features of the molecular structure: (1) the Re-N distance is 1.778 ± 0.011 A; (2) there is some over-all lengthening of the equatorial distances (Re-Cl = 2.454 ± 0.004 A; Re-P = 2.442 ± 0.004, 2.469 ± 0.005, 2.490 ± 0.005 A); (3) the Re-Cl distance of 2.563 ± 0.004 A trans to N is exceedingly long.