Structures of Z-(nitrostilbene)chromium tricarbonyl complexes: The effect of metal coordination on the nonplanarity of the stilbene system

Abstract

The structures of the nitrostilbene complexes Z-(4-R−C6H4−CH=CH−C6H4-4′-NO2)Cr(CO)3 (R=Me2N,1; H,2; F3C,3), are reported. The copounds were prepared as part of a study of the synthesis of organometallic complexes with potential nonlinear optics applications. For Z-(4-Me2N−C6H4−CH=CH−C6H4-4′-NO2)Cr(CO)3,1, triclinic, $$P\bar 1$$ ,a=7.214 (3) A,b=7.340 (3) A,c=17.238 (9)A, α=88.23 (5)°, β=88.76 (4)°, γ=87.66 (3) °,Z=2. For Z-(C6H5−CH=CH−C6H4-4′-NO2)Cr(CO)3,2, monoclinic, P21/C,a=12.255 (3) A,b=9.415 (1) A,c=13.579 (4) A, β=105.60 (2)°,Z=4. For Z-(4-F3C−C6H4−CH=CH−C6H4-4′-NO2)Cr(CO)3,3, triclinic, $$P\bar 1$$ ,a=7.094 (2) A,b=8.057 (5) A,c=17.295 (9) A, α=87.95 (5)° β=85.94 (4)°, γ=64.24 (5)°,Z=2. The structural data show that the Z isomers exhibit bond lengths and angles similar to those observed in the E isomers, but the stilbene fragment is considerably more nonplanar. As a consequence, these molecules are unlikely to behave as NLO materials.