Two atropisomers of tricarbonyl[η6-7-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 to the C-6 aromatic ring of the molecule; the existence of atropisomers resulting from the non-equivalence of both faces of the C6 aromatic ring is a consequence of the 3-chloro-2-methylphenyl ring being nearly perpendicular to the mean plane of the 2,4-dibora-1,3-diazanaphthalene ring. The orientation of the Cr(CO)(3) tripod relative to the C-6 aromatic ring is such that it is nearly eclipsed in one isomer (2.4 degrees rotation from being eclipsed with C-N, C-Cl and C-H) and slightly twisted (16.2 degrees) from an eclipsed conformation in the other.