STRUCTURE OF ([(ETA(5)-C5H5)(2)ZR(MU-P(C6H5))](2))([(THF)(3)LI](2)(MU-CL)) AND ITS IMPLICATIONS FOR THE NATURE OF DILITHIUM DINITROGEN COMPLEX

X-ray structure of the complex salt {[Cp(2)Zr(mu-PPh)](2)}{[(THF)(3)Li](2)(mu-Cl)}, 1, as well as its EPR spectrum and magnetic susceptibility have been investigated. The results indicate that the anionic part of the complex is the mixed valence [Zr(III)Zr(IV)] monoanion. From the comparison of the complex 1 and dinitrogen complex {[Cp(2)-Zr(mu-PPh)](2)}{[(THF)(3)Li](2)(mu-N-2)}, 2, published elsewhere it follows that the anions of both the complexes are identical and therefore the cation of 2 has also a unit charge. it is concluded that the cation {[(THF)(3)Li](2)(mu-N-2)}(+) can be regarded as a complex of N-2 with the pair (Li...Li)(+) or that of N-2(-) stabilized by two Li+ cations. Theoretical grounds for the existence of such complex ion are discussed.