Simon R. Drake

Synthesis and X-ray crystal structures of the one-dimensional ribbon chains [MOBut•ButOH]∞ and the cubane species [MOBut]4 (M = K and Rb)

Abstract The series [MOBut·ButOH]∞ (M = K, Rb and Cs) have been prepared by the reaction of M with ButOH in THF. Single-crystal X-ray diffraction studies revealed for M = K or Rb that [MOBut·ButOH]∞ crystallizes from tetrahydrofuran-n-pentane at −20°C in the triclinic space group P 1 , with unit cell dimensions [K, Rb]: a = 9.862(3), 9.886(2) A; b = 9.929(4), 9.914(2) A; c = 6.330(2), 6.640(1) A; β = 90.66(2), 90.46(1)° and Z = 2, as a one-dimensional chain linked by hydrogen-bonding. The strong hydrogen-bonding within the chain O(2)O(7) (2.46, 2.44 A) also results in a near linear O(7)HO(2) angle (167.4, 172.61°) with the hydrogen atom closer to O(7) (1.22, 1.18 A), than O(2) (1.24, 1.27 A). These alcohol adducts may be readily converted into the compounds [MOBut]4 (M = K, Rb and Cs) by sublimation. Single-crystal X-ray diffraction studies reveal for M = K or Rb, that [MOBut]4 crystallizes from toluene at −20°C in the cubic space group P 4 3M; with unit cell dimensions [K, Rb]; a = 8.372(1), 8.514(1) A, and Z = 4, as cubane structures. Within the cubane-like structures the OMO angles are found to deviate only slightly from 90°, with OMO (90.18, 89.11°) and MOM (89.82, 90.89°) for M = K and Rb, respectively. The alcohol adducts undergo an alkoxide ligand exchange process that is rapid on the 1H NMR time scale at room temperature.

Monomeric strontium and barium β-diketonate adducts with polyethers; the X-ray crystal structures of [Sr(Ph2ACAC)2(tetraglyme)] and [Ba(THD)2(tetraglyme)]

Abstract The reaction of the ethanol solvated strontium ethoxide [Sr(OEt)2(EtOH)4]∞ with the β-diketonate thd-H in the presence of tetraglyme in hexane at ambient temperature yields [Sr(thd)2(tetraglyme)] (1); while the analogous reaction of the in situ prepared [Sr(tfa)2]∞ and triglyme produces [Sr(tfa)2(triglyme)] (2). Reaction of [Sr(Ph2acac)2]∞ with tetraglyme yields [Sr(Ph2acac)2(tetraglyme)] (3). The corresponding barium complex [Ba(OEt)2(EtOH)4]∞ also reacts rapidly with thd-H and tetraglyme in hexane to yield the glyme-chelated monomeric complex [Ba(thd)2(tetraglyme)] (4). These complexes are all monomeric and have been characterized by IR, 1H and 13C NMR spectroscopy, microanalysis, mass spectrometry, and in selected cases TGA and DSC. The X-ray structures of [Sr(Ph2acac)2(tetraglyme)] (3) and [Ba(thd)2(tetraglyme)] (4) reveal that they are monomeric with similar nine-coordinate metal centres. The tetraglyme coordinates via all its available oxygen atoms which wrap in a meridional plane and the two β-diketonates are positioned on either side of this plane.

Preparation, crystal and molecular structure of a hydrocarbon soluble, volatile oxo-alkoxide of barium: H4Ba6(µ6-O)(OCH2CH2OCH3)14

Barium granules suspended in toluene react rapidly and exothermically with 2-methoxyethanol to yield a hydrocarbon-soluble, volatile (160 °C, 10–1 Torr; 1 Torr = 133.322 Pa), crystalline oxo-alkoxide H4Ba6(µ6-O)(OCH2CH2OCH3)14 which has been characterized by a single-crystal X-ray study; a central octahedral Ba6(µ6-O) unit is supported by eight µ3-η2-OCH2CH2OCH3, four η2-OCH2CH2OMe and two η1-OCH2CH2OMe groups and intermolecular hydrogen bonds.

The synthesis and characterization of volatile lithium alkoxides, and the single crystal X-ray structure of [LiOCMe2Ph]6

Abstract The lithium alkoxides, [LiOR]n, [R = But (1) and PhMe2C (2)], have been prepared and fully characterized in solution by IR, 1H, 13C and 7Li NMR, and cryoscopy in benzene, which gave a value of n = 6. Single-crystal X-ray diffraction studies on [LiOC Me2Ph]6 (2) at −169°C revealed that this molecule crystallizes in the monoclinic space group P21/n, with unit cell dimensions, a = 12.555(2), b = 12.010(2), c = 16.405(3) A; β = 99.44(1)°, Z = 2, dcalc = 1. 161 g cm−3, as a hexagonal prism. The oxygen and lithium atoms in the hexameric species are arranged into two Li3O3 planes.

Group IIA metal β-diketonate complexes; the crystal structures of [Sr3(tmhd)6(Htmhd)]·C6H5Me·C5H12 and [Ba4(tmhd)8](Htmhd = 2,2,6,6-tetramethylheptane-3,5-dione)

Hydrocarbon-soluble Group IIA metal ethoxides [{M(OEt)2(EtOH)4}n](M = Sr or Ba) react with the β-diketonate 2,2,6,6-tetramethylheptane-3,5-dionate (Htmhd) to yield the volatile complexes [Sr3(tmhd)6(Htmhd)] and [Ba4(tmhd)8] in excellent yield. These materials have been studied by classical spectroscopic techniques, differential scanning calorimetry and thermogravimetric analysis. They have also been characterised by single-crystal X-ray diffraction at 150 K, and shown to exist as a trimer and tetramer respectively, the former also incorporating a neutral Htmhd ligand.

Synthesis and structural characterisation of two novel GdIIIβ-diketonates [Gd4(µ3-OH)4(µ2-H2O)2(H2O)4(hfpd)8]·2C6H6·H2O 1 and [Gd(hfpd)3(Me2CO)(H2O)] 2(hfpd–H = 1,1,1,5,5,5-hexafluoropentane-2,4-dione)

Two novel GdIII–hfpd complexes 1 and 2 have been synthesised from aqueous and non-aqueous media; the crystal structural studies reveal that 1 has a M4O6 bicapped cubane core with the metals having tricapped trigonal prismatic geometry, while 2 is a monomeric adduct with water and acetone in the coordination sphere, with the metal having square antiprismatic geometry.

Group 2/titanium heterometallic alkoxides; their reproducible syntheses and characterization. Crystal structures of the compounds [SrTi4(OEt)18] and [Sr2Ti(OPri)8(PriOH)3] · 2PriOH

Abstract The reactions of either (i) bulk metal in alcohol (EtOH or Pr i OH); or (ii) the preformed metal alkoxides, [ M ( OR ) 2 ( ROH ) x ] n with a stoichiometric amount of Ti(OPr i ) 4 at reflux yielded the novel hydrocarbon soluble molecular aggregates [ MTi 2 ( OEt ) 10 ( EtOH ) 5 ] n [ M = Sr (1) and Ba (2)]; [MTi 4 (OEt) 18 ] [ M = Sr (3) and Ba (4)]; [ M 2 Ti ( OEt ) 8 ( EtOH ) 5 ] n [ M = Sr (5) and Ba (6)]; and [Sr 2 Ti(OPr i ) 8 (Pr i OH) 3 ] · 2Pr i OH (7). All complexes have been characterized by elemental analyses and spectroscopic methods; (3) and (7) have also been characterized by X-ray crystallography. The structure of (3) is based on a “bow-tie” Ti 2 SrTi 2 unit where the strontium is coordinated to two face sharing bioctahedral Ti 2 (OEt) 9 − units, via two “terminal” and two “bridging” ethoxo ligands from each Ti 2 (OEt) 9 − unit. In (7) the Sr 2 Ti unit forms a triangle, bridged by three μ 2 - Pr i O ligands and capped by two μ 3 - Pr i O ligands, and further supported by six terminal Pr i O/Pr i OH ligands.

Insertion reactions of small molecules into group 2 metal alkoxides; structural characterization of [Mg9(μ5−CO3)(O2COMe)8(μ3−OMe)8(MeOH)13] · MeOH · C7H8

Abstract The SO 2 inserted compounds [M(O 2 SOMe) 2 (MeOH) 2 ] ∞ (M = Mg 1; M = Ca 2) were synthesized from the reaction of the corresponding [M(OMe) 2 ] ∞ complexes in methanol, followed by recrystallization from either n -hexane or toluene. The reaction of COS or CS 2 gas with [M(OMe) 2 ] ∞ in methanol, yielded the inserted products [M({OCS}OMe) 2 (MeOH) x ] n ( x = 2, M = Mg 3, x = 3, n = 2, M = Ca 4) and [M(S 2 COMe) 2 (MeOH) x ] n ( x = 6, M = Mg 5; x = 4, M = Ca 6), respectively. The analogous reaction of [M(OMe) 2 ] ∞ (M = Mg, Ca) with CO 2 gas gave the mixed methoxide/methylcarbonato compounds [Mg(O 2 COMe(OMe)(MeOH) 1.5 ] n 7a and [Ca(O 2 COMe)(OMe)(MeOH)] n 8. Recrystallization of 7a from a “wet” hydrocarbon solvent mixture led to the crystalline product [Mg 9 (CO 3 )(O 2 COMe) 8 (OMe) 8 (MeOH) 13 ]·MeOH·C 7 H 8 7b. The corresponding insertion reaction of CO 2 gas with [M(OEt) 2 ] ∞ M = Cg, Ca) gave the mixed ethoxide/ethylcarbonato compounds [M(O 2 COEt)(OEt)(EtOH) 2 ] n (M = Mg 9; M = Ca10). Similarly, the reaction of CO 2 gas with [Mg(OR) 2 ] ∞ (R = Pr i , Bu t ) in the parent alcohol, resulted in the [Mg(O 2 COR)(OR)(ROH)] n compounds (R = Pr i 11; R = Bu t 12). All compounds have been characterized by spectroscopic techniques including NMR ( 1 H and 13 C) and IR spectroscopy, and in selected cases by TGA/DSC. Complex 7b was unambiguously characterized by single crystal X-ray diffraction. It was established that 7b is a nonameric complex comprising of two Mg 4 O 4 cubes, with a remote ninth magnesium atom held in position via two bridging methylcarbonato groups and an unusual μ 5 -carbonate ligand.

Synthesis, structure and characterisation of magnesium and calcium β-diketonate complexes [Ca3(tmhd)6] and [Ca2(tmhd)4(EtOH)2](Htmhd = 2,2,6,6-tetramethylheptane-3,5-dione)

The reaction of the oligomeric Group 2 metal ethoxide complexes [{Mg(OEt)2}n] and [{Ca(OEt)2(EtOH)4}n] with 2 equivalents of 2,2,6,6-tetramethylheptane-3,5-dione (Htmhd) yielded the homoleptic β-diketonate compounds [{M(tmhd)2}n](M = Mg 1 or Ca 2). An intermediate en route to complex 2 is the ethanol-solvated species [Ca2(tmhd)4(EtOH)2]3. The reaction of 1 with triglyme (2,5,8,11-tetraoxadodecane, C8H18O4) yielded the air- and moisture-stable derivative [{[Mg(tmhd)2]2(C8H18O4)}n]4. The calcium complexes 2 and 3 were characterised structurally by X-ray crystallography: 2 is the first structurally characterised homoleptic β-diketonate of calcium and has a novel triangular core, with all the calcium ions six-co-ordinate and held together by tmhd ligands in a wide range of co-ordinating modes; 3 has a dimeric structure with both chelating and bridging tmhd ligands and two terminal ethanol molecules.

The synthesis and X-ray structure characterisation of the volatile complexes [Sr(thd)2{Me(OCH2CH2)3OMe}] and [Sr2(thd)4{Me(OCH2CH2)2OMe}2(µ-H2O)](Hthd = 1,1,1,6,6,6-hexamethylheptane-2,4-dione)

The reaction of [Sr3(thd)6(Hthd)] with one equivalent of triglyme [Me(OCH2CH2)3OMe] has yielded the monomeric species, [Sr(thd)2(triglyme)]1; while with a 2 : 1 mixture of diglyme [Me(OCH2CH2)2OMe] and H2O the dimeric complex, [Sr2(thd)4(diglyme)2(µ-H2O)]2 is obtained; the related [Sr(tfa)2] reacts with one equivalent of hexamethyltriethylenetetramine to yield [Sr(tfa)2(hmteta)]3; complexes 1 and 2 are the first structurally characterised discrete molecular strontium β-diketonates [hmteta = Me2NCH2CH2CH2N(Me)CH2CH2N(Me)CH2CH2NMe2].