Extreme N≡N bond elongation and facile N-atom functionalization reactions within two structurally versatile new families of group 4 bimetallic Side-on-Bridged dimitrogen complexes for zirconium and hafnium

Chemical reduction of(r vertical bar 5-C5Me4R)M[N(R-1)C(X)N(R-1)ICL2 (M = Zr or Hf, X = NMe2 or Me, R = H or Me, R' = i -Pr, Et) with 3 equiv of potassium graphite (KC8) in tetrahydrofuran (THF) provides modest isolated yields of the corresponding side-on-bridged dinitrogen complexes, {(y vertical bar 5-C5Me4R)M[N(R')C(X)N(R')]}(2)(/ly vertical bar-2-N-2) (1-6). Single-crystal X-ray analyses of these compounds provide d (N-N) bond length values of 1.518(2), 1.581(4), 1.600(6), 1.611(4), 1.630(4), and 1.635(5) angstrom for 1-6, respectively, that correlate with an increasing fold angle of the M2N2 core for an increase in d (N-N). Compounds 1-6 all undergo hydrosilylation and hydrogenation with PhSiH3 and H-2 to provide the corresponding N-functionalized products, 7 and 8, resulting from single addition of these reagents at 25 degrees C. Compounds 5 and 6 reacted with ethylbromide at 25 degrees C to provide the N-alkylated products 9a and 9b, respectively, while reaction of 5 with 1 equiv of Br-2 provided a near quantitative yield of the diazene dibromide 10 which was obtained as a minor co-product in the N-alkylation of S.