Heterocyclic Thionates as a New Class of Bridging Ligands in Oxo-Centered Triangular Cyclopentadienylchromium(III) Complexes

The interactions of the benzothiazolate complex, CpCr(CO)2(SCSN(C6H4)) (2), and the tetrazole thiolate complex, CpCr(CO)3((eta)1-SCN4Ph) (3), with controlled amounts of Me3OBF4 and (MeO)2SO2, respectively, produced the corresponding (mu)3-oxo trinuclear thionate-bridged complexes, [Cp3Cr3((mu)2-OH)((mu)3-O)((mu)2-(eta)^2-SCSN(C6H4))2](5)BF4 (45%) and [Cp3Cr3((mu)2-OH)((mu)3-O)((mu)2-(eta)^2-SCN4Ph)2](9)(MeOSO3) (53%), together with their respective free dimethylated thiolate ligands, [MeSCSNMe(C6H4)](4)BF4 and (Me2SCN4Ph)(8)MeOSO3. The reaction of 3 with Me3OBF4 resulted in the isolation of a binuclear complex, [Cp2Cr2((mu)-OH)((mu)-(eat)^2-SCN4Ph)2](7)BF4 (43%), and (8)BF4 (27%). The reaction of the thiopyridine complex, CpCr(CO)2(SPy) (4), with I2 also produced a similar (mu)3-oxo complex 10 (31%), together with CpCrI2(THF) (11) and the disulfide (SPy)2. Similar reactions with 2 and 3 and I2 yielded species 5 and 7, together with 11 and disulfides derived from their respective ligands. Cyclic voltammograms recorded in solutions of 5 and 9 indicated that the compounds could be reduced and oxidized at very similar potentials. An EPR spectrum characteristic of a compound with axial symmetry was obtained for 9 at 7 K. Single-crystal X-ray diffraction analyses confirmed that species 7 is dinuclear, whereas 5 and 9 are structural trinuclear analogues, each containing a (mu)3-oxo central core.