148604-06-2Relevant academic research and scientific papers
Coordination and oligomerization of alkynes at mononuclear tungsten aryloxide metal centers
Kriley, Charles E.,Kerschner, Judith L.,Fanwick, Phillip E.,Rothwell, Ian P.
, p. 2051 - 2058 (2008/10/08)
Reduction of either [W(OC6H3Ph2-2,6)2Cl4] (OC6H3Ph2-2,6 = 2,6-diphenylphenoxide) or [W(OC6H3Pri2-2,6)2Cl 4] (OC6H3Pri2-2,6 = 2,6-diisopropylphenoxide) in toluene with sodium amalgam in the presence of alkynes (EtC≡CEt; PhC≡CPh; 4Me-PhC≡CPh-4Me) leads to a series of alkyne (ac) adducts of general formulae [(ArO)2WCl2(ac)] (1) and [(ArO)2W(ac)2] (2). The 13C NMR spectra of 1 and 2 show downfield shifts for the coordinated alkyne carbon atoms. A single crystal X-ray diffraction analysis shows five coordinate [W(OC6H3Ph2-2,6)2Cl 2(C2Et2)] (1a) to adopt a square pyramidal geometry about tungsten with trans aryloxide ligands and an axial 3-hexyne. The solid state structure of [W(OC6H3Ph-2,6)2(C2Et 2)2] (2a) shows a pseudotetrahedral environment about tungsten with the two 3-hexyne ligands arranged parallel with each other. Reaction of the η6-arene complex [W(OC6H3Ph-η6-C6H 5)(OC6H3Ph2-2,6)(dppm)] with 3-hexyne generates the compound [W(OC6H3Ph2-2,6)2(C 4Et4)] (3) which contains a tungstacyclopentatriene ring. This ring is nonplanar both in the solid state and solution (NMR). The bis-cyclometalated compounds [W(OC6H3Ph-C6H4)2(L) 2] (L = PMe2Ph, PMePh2, and py) react with alkynes to form a number of products. From the reaction with 3-hexyne, two new compounds of formula [W(OC6H3PhC6H4)2(C 4Et4)] (4) and [W(OC6H3PhC6H4H4) 2(C6Et6)] (5) were isolated. Structural studies on 4 and 5 show them to contain multiple metallacyclic rings formed by transfer of one of the metalated aryloxide carbon atoms to an α-carbon of an intermediate tungstacyclopenta-2,4-diene complex. Crystal data at -100°C for WCl2O2C42H36 (1a): a = 9.331(2), b = 12.271(2), c = 16.334(3) A?; α = 107.48(1), β = 101.78(2), γ = 95.13(2)°; Z = 2, dcalcd = 1.595 g cm-3 in space group P1; for WO2C48H46 (2a) at 20°C: a = 11.458(1), b = 17.961(4), c = 10.915(2) A?; α = 104.65(1), β = 115.23(1), γ = 92.08(1)°; Z = 2, dcalcd = 1.437 g cm-3 in space group P1; for WO2C48H46 (3) at -114°C: a = 11.086(2), b = 18.400(7), c = 19.453(5) A?; α = 98.96(2), β = 97.14(2), γ = 98.67(2)°; Z = 4, dcalcd = 1.454 g cm-3 in space group P1; for WO2C48H44 (4) at 20°C: a = 10.805(7), b = 11.662(1), c = 17.008(3) A?; α = 80.12(1), β = 84.71(3), γ = 63.07(3)°; Z = 2, dcalcd = 1.476 g cm-3 in space group P1; for WO2C54H54 (5) at 20°C: a = 9.835(2), b = 11.8298(7), c = 19.620(2) A?; α = 104.748(6), β = 98.717(9), γ = 104.478-(8)°; Z = 2, dcalcd = 1.467 g cm-3 in space group P1.
