Metallation of Isatin (2,3-Indolinedione). X-Ray Structure and Solution Behavior of Bis(Isatinato)Mercury(II)

The first X-ray structure of an isatin (2,3-indolinedione, isaH) metal complex, bis(isatinato)memury(II) (C(16)H(8)N(2)O(4)Hg) (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) (*)0.5CH(3)OH (3). (1) crystallizes in the monoclinic system, space group P2(1)/ a with a = 7.299(1) A, b = 8.192(1) A, c = 11.601(1) A , beta = 105.82(1) degrees , V = 667.4 A(3), Z = 2, D(calc) = 2.452 g cm(-3), MoKalpha radiation(lambda = 0.71073 A), mu = 115.5 cm(-1), F(000) = 460, 21(1) degrees 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 A from the two planes of the isa ligands (tau Hg-N1-C2-O2= -16 degrees ). The Hg-N bond length is 2.015 A. Nopi-aryl-memury(ll)-pi-aryl stacking interaction was observed either in the solid state or in the solution state. The IR, electronic, and (1)H and (13)CNMR spectral data of (1) and (3) suggest binding of the memury to the heterocyclic nitrogen, in agreement with the crystal structure determination of (1).