Two atropisomers of tricarbonyl[eta(6)-7-chloro-3-(3-chloro-2-methylphenyl)-2,4,8-trimethyl-1,2,3,4-tetrahydro-2,4-dibora-1,3-diazanaphthalene]-chromium(0)

The structures of two atropisomers of the title compound, [Cr(C16H18B2Cl2N2 )(CO)(3)],are reported. For both compounds, the Cr(CO)(3) moiety is bound t o the C-6 aromatic ring of the molecule; the existence of atropisomers resu lting from the non-equivalence of both faces of the C6 aromatic ring is a c onsequence of the 3-chloro-2-methylphenyl ring being nearly perpendicular t o the mean plane of the 2,4-dibora-1,3-diazanaphthalene ring. The orientati on of the Cr(CO)(3) tripod relative to the C-6 aromatic ring is such that i t is nearly eclipsed in one isomer (2.4 degrees rotation from being eclipse d with C-N, C-Cl and C-H) and slightly twisted (16.2 degrees) from an eclip sed conformation in the other.