Water-soluble organometallic complexes. Synthesis of water-soluble derivatives of cyclopentadienyl ligands

The syntheses and crystal structures of three new water-soluble substituted cyclopentadienyl ligands are reported. The syntheses are based on a method reported by Streitwieser et al., who showed that N,N-dimethylaminopyridine (DMAP) substituted for CI in hexachlorocyclopentadiene. Reported herein are analogous reactions with pyridine. The three ligands are 1,2,3-trichloro-4,5-bis(pyridinium)cyclo chloride (6); 1,2-dichloro-3,4,5-tris(pyridinium)cyclo dichloride (7); and 1,3-dichloro2,4,5-tris(pyridinium)cyclopentadienyl dichloride (8): These ligands are water-soluble, easily synthesized, and unlike many other water-soluble ligands (phosphines in particular) they are easily purified. The products from the analogous reactions with 4-picoline and 2,6-lutidine were not water soluble. The crystal structures of 6, 7, and 8 were determined. Crystals of 6 are monoclinic, space group P2(1)/c, with a = 7.437(3) Angstrom, b = 18.768(2) Angstrom, c = 16.234(2) Angstrom, beta = 95.77(2)degrees, V = 2254(2) Angstrom(3), Z = 4, and R = 0.037 for 2222 reflections. Crystals of 7 are monoclinic, space group P2(1)/n, with a = 8.442(2) Angstrom, b = 25.526(5) Angstrom, c = 10.562(3), beta = 93.83(2)degrees, V = 2271(2) Angstrom(3), Z = 4, and R = 0.036 for 2998 reflections. Crystals of complex 8 are orthorhombic, space group P2(1)2(1)2(1), with a = 8.688(2) Angstrom, b = 15.354(3) Angstrom, c = 16.861(4), V = 2249(2) Angstrom(3), Z = 4, and R = 0.112 for 1135 reflections.