title: Structural Studies of Cesium, Lithium/Cesium, and Sodium/Cesium Bis(trimethylsilyl)amide (HMDS) Complexes.
abstract: Reacting cesium fluoride with an equimolar n-hexane solution of lithium bis(trimethylsilyl)amide (LiHMDS) allows the isolation of CsHMDS (1) in 80% yield (after sublimation). This preparative route to 1 negates the need for pyrophoric Cs metal or organocesium reagents in its synthesis. If a 2:1 LiHMDS:CsF ratio is employed, the heterobimetallic polymer [LiCs(HMDS)2]∞ 2 was isolated (57% yield). By combining equimolar quantities of NaHMDS and CsHMDS in hexane/toluene [toluene·NaCs(HMDS)]∞ 3 was isolated (62% yield). Attempts to prepare the corresponding potassium-cesium amide failed and instead yielded the known monometallic polymer [toluene·Cs(HMDS)]∞ 4. With the aim of expanding the structural diversity of Cs(HMDS) species, 1 was reacted with several different Lewis basic donor molecules of varying denticity, namely, (R,R)-N,N,N',N'-tetramethylcyclohexane-1,2-diamine [(R,R)-TMCDA] and N,N,N',N'-tetramethylethylenediamine (TMEDA), N,N,N',N″,N″-pentamethyldiethylenetriamine (PMDETA), tris[2-(dimethylamino)ethyl]amine (Me6-TREN) and tris[2-(2-methoxyethoxy)ethyl]amine (TMEEA). These reactions yielded dimeric [donor·NaCs(HMDS)2]2 5-7 [where donor is (R,R)-TMCDA, TMEDA and PMDETA respectively], the tetranuclear "open"-dimer [{Me6-TREN·Cs(HMDS)}2{Cs(HMDS)}2] 8 and the monomeric [TMEEA·Cs(HMDS)] 9. Complexes 2, 3, and 5-9 were characterized by X-ray crystallography and in solution by multinuclear NMR spectroscopy.
authors.affiliation: WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde , Glasgow, G1 1XL, United Kingdom.
authors.forename: Ana I
authors.initials: AI
authors.lastname: Ojeda-Amador
authors.affiliation: WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde , Glasgow, G1 1XL, United Kingdom.
authors.forename: Antonio J
authors.initials: AJ
authors.lastname: Martínez-Martínez
authors.affiliation: WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde , Glasgow, G1 1XL, United Kingdom.
authors.forename: Alan R
authors.initials: AR
authors.lastname: Kennedy
authors.affiliation: WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde , Glasgow, G1 1XL, United Kingdom.
authors.forename: Charles T
authors.initials: CT
authors.lastname: O'Hara