Connecting Main-Group Metals (Al, Ga, In) and Tungsten(0) Carbonyls via the N 2 S 2 Metallo-Ligand Strategy

摘要

Tetradentate N 2 S 2 ligands (such as bismercaptoethanediazacycloheptane in this study) have seen extensive use in combination with transition metals. Well-oriented N 2 S 2 binding sites are ideal for d 8 transition metals with square planar preferences, especially Ni II , but also as a square pyramidal base for those metals with pentacoordinate preferences, such as [V≡O] 2+ , [Fe(NO)] 2+ , and [Co(NO)] 2+ . Further reactivity at the thiolate sulfurs generates diverse bi, tri, and tetra/heterometallic compounds. Few N 2 S 2 ligands have been explored to investigate the possibility of binding to main group metals, especially group III (M III ) metals, and their utility as synthons for main group/transition metal bimetallic complexes. To open up this area of chemistry, we synthesized three new five-coordinate main group XMN 2 S 2 complexes with methyl as the fifth binding ligand for M = Al, and chloride for M = Ga and In. The seven-membered diazacycle, dach, was engaged as a rigid stabilized connector between the terminal thiolate sulfurs. The pentacoordinate XMN 2 S 2 complexes were characterized by 1 H-NMR, 13 C-NMR, + ESI-Mass spectra, and X-ray diffraction. Their stabilities and reactivities were probed by adding Ni II sources and W(CO) 5 (THF). The former replaces the main group metals in all cases in the N 2 S 2 coordination environment, demonstrating the weak coordinate bonds of M III –N/S. The reaction of XMN 2 S 2 (XM = ClGa III or ClIn III ) with the labile ligand W(0) complex W(CO) 5 (THF) resulted in Ga/In–W bimetallic complexes with a thiolate S-bridge. The synthesis of XMN 2 S 2 complexes provide examples of M III –S coordination, especially Al–S, which is relatively rare. The bimetallic Ga/In–S–W complex formation indicates that the nucleophilic ability of sulfur is retained in M III –S–R, resulting in the ability of main group M III –N 2 S 2 complexes to serve as metalloligands.