Structure–Solubility Relationship of 1,4‐Dioxane Complexes of Di(hydrocarbyl)magnesium

Abstract

Systematic variation of the 1,4-dioxane (dx) concentration during the precipitation of sparingly soluble [MgBr 2 (dx) 2 ] from ethereal Grignard solutions of RMgBr has allowed the structural investigation of crystallized [R 2 Mg(dx) n ] (n = 1, 1.5, 2, and 3), which form during this dioxane method, depending on the bulkiness of R. The numbering of the complexes explored in this study is based on the number n of dioxane molecules per magnesium atom, followed by the substituent R; an apostrophe denotes coordination polymers. The following derivatives were studied by X-ray crystal-structure determination and NMR spectroscopy :(1.5-oTol), and [(Me 3 Si-CC) 2 Mg(dx) 1.5 ] 1 (1.5'-C 2 SiMe 3 ); n = 2: [tBu 2 Mg(dx) 2 ] (2-tBu) and [oTol 2 Mg(dx) 2 ] (2-oTol); n = 3: [Ph 2 Mg(dx) 3 ] (3-Ph). In the structure types 1', 1.5, and 2, the magnesium atom exhibits the coordination number 4, whereas pentacoordinate metal atoms are observed in types 3 and 1.5'. The structure type 2' is realized for [(Ph-C C) 2 Mg(dx) 2 ] 1 (2'-C 2 Ph), [MgCl 2 (dx) 2 ] 1 (2'-Cl), and [MgBr 2 (dx) 2 ] 1 (2'-Br) with hexacoordinate metal atoms. The solubility of the dioxane adducts in common organic solvents strongly depends on the degree of aggregation with the solubility decreasing from molecular to strand to layer structures.[a] Dr.Scheme 2. Dioxane method to shift the Schlenk equilibrium of organylmagnesium halides toward soluble [R 2 Mg(dx) n ] and insoluble [MgX 2 (dx) 2 ] 1 by substitution of the Lewis base L (e.g., diethyl ether or thf) by 1,4-dioxane (dx).Scheme 3. Structural diversity of hitherto known 1,4-dioxane adducts of diorganylmagnesium complexes authenticated by X-ray crystal-structure determinations.

Exploring the Synthesis and Coordination Chemistry of Pentafluorophenylcopper: Organocopper Polyanions and Coordination Networks

“…1,4-dioxane is added to drive precipitation of MgX2. (dioxane)2 (an insoluble 2D coordination polymer), 36 at which point the major signal from the solution phase by 19 F NMR spectroscopy is consistent with that of [Cu(C6F5)]4(dioxane)x (x ≥ 2) (which we show by 19 F and 19 F DOSY NMR spectroscopy experiments is the likely form in the presence of excess dioxane, vide infra) (Fig. S1, Table S1).…”

“…1-diox has an extended structure composed of dioxane molecules bridging between [CuC 6 F 5 ] 4 tetramers, with a formula of [CuC 6 F 5 ] 4 (dioxane) (Figures , S5 and S6). Similar coordination polymers of other organometallic compounds with 1,4-dioxane are also known, while [CuC 6 F 5 ] 4 units have been previously linked together by η 2 -π interactions in binary stacks of [CuC 6 F 5 ] 4 (naphthalene) . Oxygen donors typically bind weakly to “soft” Cu­(I) centers, and structural examples of ethers coordinating to Cu­(I) are restricted to Cu-alkynyl clusters including [Cu 10 (hfac) 6 (CCtBu) 4 (Et 2 O)] (hfac = 1,1,1,5,5,5-hexafluoropentan-2,4-dione), and [Cu 16 (CCCCTrip) 16 (THF) 4 ] (Trip = 2,4,6-triisopropylphenyl) .…”

“…However, due to the competing interaction of THF, which has a similar donating ability to 1,4-dioxane, incomplete removal of MgX2 occurs under these conditions. 36 The 19 F NMR spectrum of the mixture shows little change after the addition of 1,4-dioxane, i.e. retaining the [Cu(C6F5)2]cuprate ion.…”

16-Electron Nickel(0)-Olefin Complexes in Low-Temperature C(sp2)–C(sp3) Kumada Cross-Couplings

“…We decided to prepare [(CH 3 ) 2 Mg­(TMEDA)] ( 12 ), following the previous work by Kaschube, Pörschke, Wilke, and Westerhausen. , In order to forge the Ni–C bond, complex 12 was reacted with Ni­(C 2 H 4 ) 3 , which was prepared in situ by gently bubbling ethylene into a solution of 8 in Et 2 O (Scheme ). After the mixture was filtered through a cold frit (−20 °C), a yellow powder was isolated, which corresponds to complex 13.…”

Chemistry of alkaline earth metals: It is not all ionic and definitely not boring!

“…Low coordination numbers can in general be achieved with bulky ligands, as exemplified in a study on dithiolenes [33]. Coordination number 5 has been realized for instance in some 1,4-dioxane complexes of di(hydrocarbyl)magnesium compounds, depending on the size of the organic group [34], as well as with the help of capping N-donor ligands, i.e. with amide ligands [35].…”