N7 AND C8 COORDINATED PURINE COMPLEXES OF [(NH3)5OSIII] - CRYSTAL-STRUCTURES OF 7-[9MEHYP(NH3)5OS]CL3.H2O AND 8-[1,3,7ME3XAN(NH3)5OS]CL3.2H2O

Pentammineosmium(III) coordinates to both the N7 and C8 positions of purine rings. The compound 7[SIC] [9MeHyp(NH3)5Os]Cl3.H2O Crystallizes in the orthorhombic space group Pnma (No. 62) with the unit cell parameters: a = 11.542(2), b = 6.9841(8), c = 21.960(3) angstrom and Z = 4. The compound 8-[1,3,7Me3Xan(NH3)5O[SIC] Cl3.2H2O crystallizes in the monoclinic space group P2(1)/c (No. 14) with the unit cell parameters: a = 7.1228[SIC] b = 14.613(l), c = 19.667(1) angstrom, beta = 91.782(9)-degrees and Z = 4. The Os-C bond in the latter structure is 2.039(9) angstrom and the imidazolylidine ligand exerts a slight trans influence seen in the lengthening of the Os-N(ax) distance (2.172(8) angstrom) by about 0.05 angstrom relative to the average of the equatorial Os-N(eq) value of 2.123(8) angstrom. The spectroscopic, electrochemical and structural properties of these and additional N-bound purine complexes are compared with those of similar N7 and C8 ruthenium(III) species.