SOME REACTIONS OF TETRAKIS (TERT-BUTYLIMIDO) OSMIUM (VIII) - X-RAY CRYSTAL-STRUCTURES OF OS(NBUT)O(O2CBUT)2(NH2BUT)2.BUTCO2H, (BUTN)2OS(MU-NBUT)2OS(NBUT)X2 (X = CL OR I) AND [OS2(NBUT)4(MU-NBUT)2]I3

Reactions of Os(NBu(t))4 with carboxylic acids and halogens have been studied. Acetic and pivalic acids give different oxo carboxylate complexes, the acetate being Os(NBu(t))O(O2CMe-O)(O2CMe-OO')(NH2Bu(t)) 1 and the pivalate Os(NBu(t))O(O2CBu(t)-O)2(NH2Bu(t))2 2. The osmium(vi) compounds (Bu(t)N)2Os(mu-NBu(t))2Os(NBu(t))X2 (X = 1, 3; or Cl, 5) have been obtained by interaction of Os(NBu(t))4 with, respectively, I2 and PPh4I in 1,2-C2H4Cl2; the iodine reaction also produces the paramagnetic mixed-valence diosmium(VI, VII) compound [Os2(NBu(t))4(mu-NBu(t))2]I3 4. The X-ray crystal structures of compounds 2-5 have been determined: 2 is octahedral with trans-NH2Bu(t) and trans-carboxylate groups; 3 and 5 are isomorphous with tetrahedral and trigonal-bipyramidal osmium atoms, the latter having trans-halogens, a linear NBu(t) and two NBu(t) bridging groups. Compound 4 is similar to the dimeric compounds previously described and completes the series [Os(NBu(t))2(mu-NBu(t))]2(0,+,2+.