Oxidation of germanium(II) azides with HN3:: a convenient route to six-co-ordinate triazidogermanium(IV) compounds

Reaction of GeCl2(C4H8O2) 1 with NaLOEt [L-OEt=(C5H5)Co{P(O)(OEt)(2)}(3)] gave LOEtGeCl 2, which reacts with NaN3 to afford the germanium(II) azide LOEtGeN3 3. A dissociation equilibrium between 3 and the ions [LOEtGe](+) and N-3(-) exists in solution, which is strongly dependent on the solvent polarity. Dissociation into ions is observed in solution for a variety of other four-co-ordinate germanium(II) azides bearing an anionic tridentate ligand. The crystal structures of 2 and 3 revealed a pseudo trigonal-bipyramidal co-ordination geometry around the germanium atom and an unsymmetric bonding of the L-OEt ligand with one long Ge-O-ax and two considerably shorter Ge-O-eq bonds. The structural data are compared with those of other four-co-ordinate germanium(II) chlorides and azides indicating the presence of a polar Ge-X bond (X=Cl or N-3) in 2 and 3. Oxidation of 3 with two equivalents of HN3 gave selectively the six-co-ordinate triazidogermanium(IV) compound LOEtGe(N-3)(3) 4. Similarly, oxidation of the germanium(II) azide Tp'GeN3 5 [Tp'=HB(3,5-Me(2)pz)(3), 3,5-Me(2)pz=3,5-dimethylpyrazol-1-yl] with HN3 affords selectively Tp'Ge(N-3)(3) 6. The crystal structures of 4 and 6 have been determined and are compared with those of other six-co-ordinate germanium(IV) polyazides.