Synthesis and controlled hydrolysis of organolanthanide complexes with mono- and dianionic benzimidazole-2-thiolate ligandsElectronic supplementary information (ESI) available: Additional data. CCDC reference numbers 762741-762744, 783261, 762746, 762745, and 762747-762750. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c0dt00129e

Treatment of Cp 3 Er with one equivalent of benzimidazole-2-thiol (H 2 Bzimt) in THF affords the monoanionic HBzimt − complex Cp 2 Er(η 2 -HBzimt)(THF) 2 ( 1 ). Reaction of Cp 3 Yb with two equivalents of H 2 Bzimt gives complex CpYb(η 2 -HBzimt) 2 (THF) ( 2 ) at room temperature. Treatment of Cp 3 Ln with three equivalents of H 2 Bzimt in reflux THF affords the homoleptic Ln(η 2 -HBzimt) 3 (THF) 2 (Ln = Er ( 3 ), Y ( 4 )). Cp 3 Ln reacts with 0.5 equivalents of H 2 Bzimt to afford the dianionic Bzimt 2− complexes [(Cp 2 Ln)(THF)] 2 (μ-Bzimt) (Ln = Yb ( 5 ), Er ( 6 ), Dy ( 7 ), Y ( 8 )) in good yields, in which the Bzimt 2− ligand bridges the two metals in an μ-η 2 :η 2 coordination mode. Interestingly, controlled hydrolysis of complexes Cp 2 Ln(η 2 -HBzimt)(THF) 2 , CpLn(η 2 -HBzimt) 2 (THF) and [(Cp 2 Ln)(THF)] 2 (μ-Bzimt) produces the same tetranuclear complexes [CpLn(μ 3 -OH)(μ-η 1 :η 2 -HBzimt)] 4 (Ln = Yb ( 9 ), Er ( 10 ), Y ( 11 )), indicating that the hydrolysis selectivity greatly depends on the number of coordinated cyclopentadienyl groups. All complexes were characterized by elemental analysis, spectroscopic properties and X-ray single crystal diffraction analysis. A series of novel mono- and dianionic benzimidazole-2-thiolate lanthanide complexes were synthesized by controlled abstraction of the Cp ligands of Cp 3 Ln with benzimidazole-2-thiol. It was also found that hydrolysis of mixed Cp/H x Bzmt (2− x )− ( x = 0, 1) lanthanide complexes is the superior number or charge ligand to be preferably protonated.