The first X-ray structure of an isatin (2,3-indolinedione, isaH) metal complex,
bis(isatinato)memury(II) (C16H8N2O4Hg)
(1), was determined. (1) was obtained from the reaction of
isaH with mercury(II) acetate in methanol. Analogously, treatment of sodium saccharinate and
mercury(II) acetate in methanol yielded Hg(saccharinato)2•0.5CH3OH
(3). (1) crystallizes in the
monoclinic system, space group P21/a with a = 7.299(1) Å, b
= 8.192(1) Å, c
= 11.601(1) Å , β = 105.82(1)°, V = 667.4 Å3, Z = 2, Dcalc = 2.452 g cm−3, MoKα radiation(λ = 0.71073 Å), μ = 115.5 cm-1, F(000) = 460, 21(1) °C. The structure was refined on the basis of 2023 observed reflections
to R= 0.044. The two deprotonated, non coplanar isa ligands are trans to each other in a head to
tail orientation and bound to the Hg through the nitrogen in a linear N-Hg-N arrangement. The Hg
atom is at the center of symmetry of the complex and displaced by 0.62 Å from the two planes of the
isa ligands (τ Hg-N1-C2-O2= -16°). The Hg-N bond length is 2.015 Å. Noπ-aryl-memury(ll)-π-aryl stacking interaction was observed either in the solid state or in the solution state. The IR, electronic,
and H1
and C13NMR spectral data of (1) and (3) suggest binding of the memury to the heterocyclic
nitrogen, in agreement with the crystal structure determination of (1).
Theoretical Study and X-ray Determination of Bianthrones: Long C−C Bond Length and Preferred Gauche Conformation