Unusual Ring Systems Containing Indium. Synthesis and Structure of the First Mercuraindacycles

The mercuraindacycles bis(μ-1,8-naphthalenediyl)mercury(II)(bis(tetrahydrofuran)chloroindium(III)) (5) and bis(μ-1,8-naphthalenediyl)mercury(II)(bis(tetrahydrofuran)bromoindium(III)) (7) are the products of the reaction of indium(I) halides with 1,8-naphthalenediylbis(mercury(II) halides). Their formation involves a partial transmetalation followed by a spontaneous ring closure. Compounds 5 and 7 have been characterized by 1H, 13C, and 199Hg NMR spectroscopy. The X-ray crystal structures of 5·(InCl3(THF)3) and 7 have been determined. Compound 5 crystallizes as an InCl3(THF)3 adduct in the monoclinic space group P21/c with a = 17.529(2) Å, b = 8.954(1) Å, c = 27.704(1) Å, β = 107.02(1)°, V = 4157.8(7) Å3, and Z = 4. Compound 7 crystallizes in the orthorhombic space group P212121 with a = 8.368(1) Å, b = 15.357(1) Å, c = 19.446(1) Å, V = 2499.0(4) Å3, and Z = 4. In both structures, the eight-membered dimetallacycles adopt a twisted conformation with conspicuously short In··· Hg transannular distances. Finally, the X-ray crystal structure of the diindacycle bis(μ-1,8-naphthalenediyl)bis(bis(tetrahydrofuran)chloroindium(III)) (8) is reported. This compound is isolated as a low-yield side product in the synthesis of 5. Compound 8 crystallizes in the tetragonal space group P4/n with a = 19.492(1) Å, c = 10.432 Å, V = 3963.5(5) Å3, and Z = 4.