Syntheses, characterizations, and reactivities of new 1,4,7-trimethyl-l,4,7-triazacyclononane (Me3tacn) molybdenum and tungsten complexes

Abstract

The reported complexes of [(Me3tacn)M0(CO)3] (Me3tacn = 1,4,7-trimethyl-1,4,7-triazacyclononane; M = W, 1a; Mo, 1b), [(Me3tacn)MII(CO)3I](PF6) (M = W, 2a; Mo, 2b), [(Me3tacn)MVOCl2](PF6) (M = W, 3a; Mo, 3b), and [(Me3tacn)MVIO3]·4H2O (M = W, 4a; Mo, 4b) were synthesized as tungsten and molybdenum precursors according to the works by Wieghardt [20,21,24]. Reaction of 2a with sodium dialkyl dithiocarbamate afforded complexes [(Me3tacn)WII(CO)2(S2CNR2)]I (R = Me, 5a; iPr, 6a). Similar reaction using 2b gave rise to the isolations of complexes [(Me3tacn)MoII(CO)2(S2CNR2)](PF6) (R = Me, 5b; iPr, 6b; nPr, 7). Hydrolysis of 3b in acetonitrile gave a dimeric molybdenum complex [{(Me3tacn)MoVO(OH)}2(μ-O)](PF6)2·2MeCN (8). Treatment of 4b with sodium diisopropyl dithiocarbamate in the presence of HPF6 yielded [(Me3tacn)MoVIO2S] (9), while the similar reaction with S8 powder yielded the oxotetrasulfido complex [(Me3tacn)MoIVO(S4)] (10). All complexes are well characterized by electronic, infrared, and NMR spectroscopies, and the solid-state structures of 1a/b, 2a, 3b, 4a/b, 5a/b, 6a/b, and 7–10 have been also established by single-crystal X-ray diffraction. The electrochemical properties of these molybdenum and tungsten complexes were also investigated in the paper.