The synthesis and characterization of the complexes Mo[N(R)Ar](3) (R = C(CD3)(2)CH3, Ar = 3,5-C(6)H(3)Me(2)),(mu-N-2){Mo[N(R)Ar](3)}(2), (mu-N-15(2)){Mo[N(R)Ar](3)}(2), NMo[N(R)Ar](3), (NMo)-N-15[N(R)Ar](3), Mo[N(t-Bu)Ph](3), (mu-N-2){Mo-[N(t-Bu)Ph](3)}(2), and NMo[N(t-Bu)Ph](3) are described. Temperature-dependent magnetic susceptibility data indicate a quartet ground state for Mo[N(R)Ar](3). Single-crystal X-ray diffraction studies for Mo[N(R)Ar](3) and NMo[N(t-Bu)Ph](3) are described. Extended X-ray absorption fine structure (EXAFS) structural studies for Mo[N(R)Ar](3), (mu-N-2){Mo[N(R)Ar](3)}(2), and NMo[N(R)Ar](3) are reported. Temperature-dependent kinetic data are given for the unimolecular fragmentation of (mu-N-2){Mo[N(R)Ar](3)}(2) to 2 equiv of NMo[N(R)Ar](3) and for the fragmentation of (mu-N-2){Mo[N(R)Ar](3)}(2) to 2 equiv of (NMo)-N-15[N(R)Ar](3). The temperature dependence of the N-15(2) isotope effect for the latter N-2 cleavage process was fitted to a simple harmonic model, leading to a prediction for the difference in NN stretching frequencies for the two isotopomers. The latter prediction was consistent with the Raman spectroscopic data for (mu-N-2){Mo[N(R)Ar](3)}(2) and (mu-N-15(2)){Mo[N(R)Ar](3)}(2). The Raman spectroscopic data and EXAFS results are both consistent with an NN bond order of approximately 2 in (mu-N-2){Mo[N(R)Ar](3)}(2). Temperature-dependent magnetic susceptibility data consistent with a triplet ground state are given for (mu-N-2){Mo[N(t-Bu)Ph](3)}(2).