Ligand exchange reactions of [Re2(μ-OR)3(CO)6]- (R = H, Me) with sulfur, selenium, phosphorus and nitrogen donor ligands, investigated by electrospray mass spectrometry

Negative-ion electrospray mass spectrometry has been used to investigate the reactions of the dinuclear rhenium aggregates [Re-2(mu-OH)(3)(CO)(6)](-) 1 and [Re-2(mu-OMe)(3)(CO)(6)](-) 2 with a range of thiols, benzeneselenol, and some other sulfur-, phosphorus- and nitrogen-based ligands. Typically up to three of the hydroxo ligands are replaced by simple thiolates, giving the series of species [Re-2(OH)(2)(SR)(CO)(6)](-), [Re-2(OH)(SR)(2)(CO)(6)](-), and [Re-2(SR)(3)(CO)(6)](-). Similarly, reaction of 1 with H2S gives the species [Re-2(mu-SH)(3)(CO)(6)](-), which undergoes an analogous fragmentation process to [Re-2(mu-OH)(3)(CO)(6)](-), at high cone voltages, by loss of H2S and formation of [Re-2(S)(SH)(CO)(6)](-). With ligands which are good chelating agents (such as dithiocarbamates R2NCS2-, and thiosalicylic acid, HSC6H4CO2H) initial substitution of one or two OH groups readily occurs, but on standing the dimer is cleaved giving [Re(S2CNR2)(2)(CO)(3)](-) and [Re(SC6H4CO2)(CO)(3)](-). The different reactivities of the dithiol reagents benzene-1,2- and benzene-1,4-dimethanethiol towards 1 are also described. Complex 1 also reacts with aniline, and with primary (but not secondary) amides RC(O)NH2, giving monosubstituted species [Re-2(OH)(2)(NHPh)(CO)(6)](-) and [Re-2(OH)(2){NHC(O)R}(CO)(6)](-) respectively. The reactions with adenine and thymine, and with the inorganic anions thiocyanate and thiosulfate, are also described.