title: Cationic and Neutral Cp*M(NO)(κ2-Ph2PCH2CH2PPh2) Complexes of Molybdenum and Tungsten: Lewis-Acid-Induced Intramolecular C-H Activation.
abstract: Treatment of CH2Cl2solutions of Cp*M(NO)Cl2(Cp* = η5-C5(CH3)5; M = Mo, W) first with 2 equiv of AgSbF6in the presence of PhCN and then with 1 equiv of Ph2PCH2CH2PPh2affords the yellow-orange salts [Cp*M(NO)(PhCN)(κ2-Ph2PCH2CH2PPh2)](SbF6)2in good yields (M = Mo, W). Reduction of [Cp*M(NO)(PhCN)(κ2-Ph2PCH2CH2PPh2)](SbF6)2with 2 equiv of Cp2Co in C6H6at 80 °C produces the corresponding 18e neutral compounds, Cp*M(NO)(κ2-Ph2PCH2CH2PPh2) which have been isolated as analytically pure orange-red solids. The addition of 1 equiv of the Lewis acid, Sc(OTf)3, to solutions of Cp*M(NO)(κ2-Ph2PCH2CH2PPh2) at room temperature results in the immediate formation of thermally stable Cp*M(NO→Sc(OTf)3)(H)(κ3-(C6H4)PhPCH2CH2PPh2) complexes in which one of the phenyl substituents of the Ph2PCH2CH2PPh2ligands has undergone intramolecular orthometalation. In a similar manner, addition of BF3produces the analogous Cp*M(NO→BF3)(H)(κ3-(C6H4)PhPCH2CH2PPh2) complexes. In contrast, B(C6F5)3forms the 1:1 Lewis acid-base adducts, Cp*M(NO→B(C6F5)3)(κ2-Ph2PCH2CH2PPh2) in CH2Cl2at room temperature. Upon warming to 80 °C, Cp*Mo(NO→B(C6F5)3)(κ2-Ph2PCH2CH2PPh2) converts cleanly to the orthometalated product Cp*Mo(NO→B(C6F5)3)(H)(κ3-(C6H4)PhPCH2CH2PPh2), but Cp*W(NO→B(C6F5)3)(κ2-Ph2PCH2CH2PPh2) generates a mixture of products whose identities remain to be ascertained. Attempts to extend this chemistry to include related Ph2PCH2PPh2compounds have had only limited success. All new complexes have been characterized by conventional spectroscopic and analytical methods, and the solid-state molecular structures of most of them have been established by single-crystal X-ray crystallographic analyses.
authors.affiliation: Department of Chemistry, The University of British Columbia , Vancouver, British Columbia, Canada V6T 1Z1.
authors.forename: Rex C
authors.identifier: http://orcid.org/0000-0002-3693-1697
authors.initials: RC
authors.lastname: Handford
authors.affiliation: Department of Chemistry, The University of British Columbia , Vancouver, British Columbia, Canada V6T 1Z1.
authors.forename: Russell J
authors.initials: RJ
authors.lastname: Wakeham
authors.affiliation: Department of Chemistry, The University of British Columbia , Vancouver, British Columbia, Canada V6T 1Z1.
authors.forename: Brian O
authors.initials: BO
authors.lastname: Patrick
authors.affiliation: Department of Chemistry, The University of British Columbia , Vancouver, British Columbia, Canada V6T 1Z1.
authors.forename: Peter
authors.identifier: http://orcid.org/0000-0002-3914-3768
authors.initials: P
authors.lastname: Legzdins