Effects of the η5-C5H4iPr Ligand on the Properties Exhibited by Its Tungsten Nitrosyl Complexes

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• 作者：Diana Fabulyak ; Rhett A. Baillie ; Brian O. Patrick ; Peter Legzdins ; Devon C. Rosenfeld
• 刊名：Inorganic Chemistry
• 出版年：2016
• 出版时间：February 15, 2016
• 年：2016
• 卷：55
• 期：4
• 页码：1883-1893
• 全文大小：540K
• ISSN：1520-510X

文摘

Reaction of Na[η⁵-C₅H₄ⁱPr] with W(CO)₆ in refluxing THF for 4 days generates a solution of Na[(η⁵-C₅H₄ⁱPr)W(CO)₃] that when treated with N-methyl-N-nitroso-p-toluenesulfonamide at ambient temperatures affords (η⁵-C₅H₄ⁱPr)W(NO)(CO)₂ (1) that is isolable in good yield as an analytically pure orange oil. Treatment of 1 with an equimolar amount of I₂ in Et₂O at ambient temperatures affords (η⁵-C₅H₄ⁱPr)W(NO)I₂ (2) as a dark brown solid in excellent yield. Sequential treatment at low temperatures of 2 with 0.5 equiv of Mg(CH₂CMe₃)₂ and Mg(CH₂CH═CMe₂)₂ in Et₂O produces the alkyl allyl complex, (η⁵-C₅H₄ⁱPr)W(NO)(CH₂CMe₃)(η³-CH₂CHCMe₂) (3), as a thermally sensitive yellow liquid. Complex 3 may also be synthesized, albeit in low yield, in one vessel at low temperatures by reacting 1 first with 1 equiv of PCl₅ and then with the binary magnesium reagents specified above. Interestingly, similar treatment of 1 in Et₂O with PCl₅ and only 0.5 equiv of Mg(CH₂CH═CMe₂)₂ results in the formation of the unusual complex (η⁵-C₅H₄ⁱPr)W(NO)(PCl₂CMe₂CH═CH₂)Cl₂ (4), which probably is formed via a metathesis reaction of the binary magnesium reagent with (η⁵-C₅H₄ⁱPr)W(NO)(PCl₃)Cl₂. The C–D activation of C₆D₆ by complex 3 has been investigated and compared to that exhibited by its η⁵-C₅Me₅, η⁵-C₅Me₄H, and η⁵-C₅Me₄ⁿPr analogues. Kinetic analyses of the various activations have established that the presence of the η⁵-C₅H₄ⁱPr ligand significantly increases the rate of the reaction, an outcome that can be attributed to a combination of steric and electronic factors. In addition, mechanistic studies have established that in solution 3 loses neopentane under ambient conditions to generate exclusively the 16e η²-diene intermediate complex (η⁵-C₅H₄ⁱPr)W(NO)(η²-CH₂═CMeCH═CH₂), which then effects the subsequent C–D activations. This behavior contrasts with that exhibited by the η⁵-C₅Me₅ analogue of 3 which forms both η²-diene and η²-allene intermediates upon thermolysis. Sixteen-electron (η⁵-C₅H₄ⁱPr)W(NO)(η²-CH₂═CMeCH═CH₂) has been isolated as its 18e PMe₃ adduct. All new organometallic complexes have been characterized by conventional spectroscopic and analytical methods, and the solid-state molecular structures of two of them have been established by single-crystal X-ray crystallographic analyses.