The rhenium(I) dinitrogen complex (PhMe2P)(4)ClRe(N-2) reacts with [Mo-2(S2CNEt2)(6)](OTf)(2) (6) to give the N-2-bridged complex [(PhMe2P)(4)ClRe(mu-N-2) Mo(S2CNEt2)(3)] OTf ([7] OTf). Spectroscopic (v(NN) = 1818 cm(-1)) and structural data [d(NN) = 1.167(6) angstrom] indicate that the bridging N-2 moiety in 7(+) is slightly activated relative to free N-2 or to the mononuclear Re complex. However, the complex is stable with respect to N2 cleavage. The putative products of such a cleavage, the known (Et2NCS2)(3)Mo(N) (5) and the newly prepared [(PhMe2P)(4)ClRe(N)] OTf ([9] OTf), are stable compounds that do not react with each other to give products of nitride coupling. Thus, the failure of 7(+) to interconvert with 5 and 9(+) is due not to the thermodynamic stability of the N N bond but rather to kinetic factors that disfavor N-2 cleavage and nitride coupling. Implications of this result for using polar effects to facilitate N-2 cleavage to nitrides as a strategy for nitrogen fixation are discussed.