Harold H. Zeiss

Crystal and molecular structure of cis-diphenylbis-(2,2′-bipyridyl)-chromium(III) iodide

Crystals of the title compound are monoclinic, space group C2/c, with cell dimensions a= 11·034, b= 16·021, c= 16·183 A, β= 103° 31′, Z= 4. The final R for 2227 counter data refined by a block-diagonal least-squares method is 0·054. The organometallic cation, which has the cis-octahedral configuration, possesses a crystallographic two-fold symmetry axis. The chromium–carbon σ bond length [2·087(4)A] is no different from the corresponding length in the cis-[(2-methoxyphenyl)2Cr(bipy)2]+(bipy = 2,2′-bipyridyl) cation. The chromium–nitrogen bonds which are not related by the two-fold symmetry axis have different lengths; those trans to nitrogen [2·087(4)] being shorter than those trans to carbon [2·147 (4)A].

Crystal and molecular structure of bis[(trimethylsilyl)methyl]bis-(2,2′-bipyridyl)chromium(III) iodide

Dark red crystals of the title compound are monoclinic, space group P21/c, with cell dimensions a= 18·139(15), b= 9·611(8), c= 18·919(15)A, β= 104·27(17)°, Z= 4. The structure was solved by direct methods. The final R for 3758 counter data refined by block-diagonal least-squares is 0·057. The cis-octahedral organometallic cation has an approximate two-fold symmetry axis. The CrIII–C(sp3)σ-bond length [2·107(12)A] is the same as that found in two aryl analogues. The Cr–N bond trans to carbon is 2·156(7) while that trans to nitrogen is 2·103(7)A, these differences are discussed in terms of σ- and π-bonding effects.