By reaction of anhydrous cobalt(ii) chloride with a secondary amine and carbon dioxide in a hydrocarbon solvent, NN-dialkylcarbamato-complexes of cobalt(ii), [Co,(O,CNR,),,] (R = Et or Pri), have been prepared.The crystal and molecular structure of the hexameric violet derivative, [Co6(02CNEt2), ,Ir has been solved by X-ray diffraction methods. The complex is monoclinic, space group C2/c, with a = 18.428( 9), b = 79.189(8), c = 24.654(13) p\, p = 95.90(6)", Z = 8, and R = 0.0639. The six cobalt atoms are joined by bridging carbamato-groups. The main structural feature of the hexameric molecule is that four of the cobalt atoms are five-co-ordinated in a distorted trigonal bipyramidal geometry. The cobalt (11) complexes react with electrophiles with displacement of carbon dioxide.Two preparatiL e procedures are presently available for the synthesis of ?V-V-dialkylcarbamato-complexes of transition elements, of general formula f{M(O,CNR,),j,]: (a) the reaction of dialkylamido-derivatives with carbon dioxide, successfully used for the preparation of titanium(rv),' niobium(v), tantaium(v),' tungsten(~rr),~ and uranium(1v) ' complexes; and ( b ) the reaction of the metal halide with a second amine and carbon dioxide, used in these laboratories for ?he preparation of the lanthanide(ir1) ' s 6 and uranium(rv jderivatives. The second method of preparation does not require the preliminary preparation of the amidocomplex and a3 such has a wider applicability. We are presently engaged in a research project dealing with the preparation of new V&'-dialkylcarbamato-complexes of transition elements N hose corresponding amido-derivatives are unstable or eluslbe. This paper reports the preparation of the first NN-dialk) Icarbamato-compounds of cobalt(I1) and the crystal and molecular structure of one of these.
ExperimentalAll manipulations and reactions involving metal complexes were carried out under an atmosphere of dry nitrogen or carbon dlox.de. infrared spectra were measured with a Perkin-Elmer mode! 283B instrument equipped with a grating monochromator. tlagnetic susceptibilities were measured by the Farada: ii-?.iod using a magnetic balsnce calibrated with CuSO,*5H-Solvents were carefully dried prior to use by conven$:cz.-methods. The anhydrous cobalt(I1) chloride used in t h s *or!. was prepared according to the literature procedure * b> t:eating the hydrated salt Lvith thionyl chloride: however, we found it necessary finally to heat the chloride at about 60 C and lo-' mmHg in order to remove the lattice thionyl chloride contained in the solid.
