| Abstract
| - We have prepared tungsten bispyrrolyl (Pyr) or bis-2,5-dimethylpyrrolyl (Me2Pyr) complexes W(NAr)(CHCMe2Ph)(η1-Pyr)2(DME) (1), W(NAr)(CHCMe2Ph)(η1-Me2Pyr)(η5-Me2Pyr) (2), W(NArCl)(CHCMe3)(η1-Pyr)2(DME) (3b), and W(NArCl)(CHCMe3)(η1-Me2Pyr)(η5-Me2Pyr) (4) (Ar = 2,6-diisopropylphenyl,ArCl = 2,6-dichlorophenyl) in excellent yields by treating the appropriate W(NR)(CHCMe2R‘)(OTf)2(DME) species with LiPyr or LiMe2Pyr. Compounds 2 and 4 react with ethylene slowly to yield stablemethylene complexes, W(NAr)(CH2)(η1-Me2Pyr)(η5-Me2Pyr) (5) and W(NArCl)(CH2)(η1-Me2Pyr)(η5-Me2Pyr) (6). In contrast, treatment of what is believed to be a fortuitous 1:1 mixture of 3b and[W(NArCl)(CHCMe3)(η1-Pyr)2][W(NArCl)(CHCMe3)(η1-Pyr)(η5-Pyr)] with ethylene leads to formationof [W(μ-NArCl)(η1-Pyr)2]2 (7) in moderate (54%) yield. Compounds 2 and 4 react with [HNMe2Ph][B(ArF)4] (ArF = 3,5-(CF3)2C6H3) in dichloromethane to yield cationic species that contain one η5-Me2Pyr ligand and one 2,5-dimethylpyrrolenine ligand formed through addition of a proton to C(2) of adimethylpyrrolyl ligand, e.g., [W(NArCl)(CHCMe3)(Me2Pyr){NC4(H3-2,3,4)(Me2-2,5)}]+[B(ArF)4]- (9).X-ray studies were carried out on 1, 2, 6, 7, and 9.
- Tungsten bispyrrolyl (Pyr) or bis-2,5-dimethylpyrrolyl (Me2Pyr) complexes can be prepared readily by treating W(NR)(CHCMe2R‘)(OTf)2(DME) species (R = 2,6-dichlorophenyl or 2,6-diisopropylphenyl) with LiPyr or LiMe2Pyr. Dimethylpyrrolyl species react slowly with ethylene to give isolable stable methylene complexes in good yield or with [HNMe2Ph][B(ArF)4] (ArF = 3,5-(CF3)2C6H3) to yield cationic species that contain a 2,5-dimethylpyrrolenine ligand.
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