Crystal structure of a compound featuring caffeine bound at C8 to ruthenium (III)

The structure of a novel ruthenium purine compound, trans-chloro-8-caffeinechlorotriamminruthenium(III) chloride monohydrate, has been determined using single-crystal x-ray techniques. This compound crystallizes in space group Pbca (D152h) with cell dimensions a equal to 11.341 (3)A, b equal to 11.606 (5) A, c equal to 26.673 (7) A, Z equals to 8. The observed and calculated densities are 1.79 plus or minus 0.01 and 1.781 g/cm3, respectively. The structure has been refined using full-matrix least-squares methods to R equal to 0.059 based on 1314 independent observed reflections. The coordination geometry at the ruthenium atom is distorted octahedral. The carbon-ruthenium bond length is 2.03 (1) A. The chloride-ruthenium bond lengths are 2.350 (4) A and 2.427 (3) A for the cis and trans forms respectively suggesting a strong trans-influence due to the caffeine.