Crown ether complexes of alkaline-earth metal ions. I. Structures of 1,4,7,10-tetraoxacyclododecane (12-crown-4) complexed with calcium, strontium and barium thiocyanates

Wei, Yy.; Tinant, Bernard; Declercq, Jean‐Paul; Meerssche, M. Van; Dale, Johannes

doi:10.1107/s0108270187009090

Cited by 11 publications

(3 citation statements)

References 7 publications

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“…The average Ca–O distances of 2.39, 2.36, 2.38, 2.42, and 2.41 Å in 2 , 3 , 4 , 5 , and 7 , respectively, compare well with those of 2.378–2.501 Å in other calcium diethyl ether adducts, − 2.355–2.502 Å in other calcium thf adducts, − ,,− 2.415–2.507 in other calcium dme adducts, ,,, 2.444–2.514 Å in other calcium diglyme complexes, ,, and 2.380–2.55 Å in other calcium 12-crown-4 adducts. − …”

Section: Resultssupporting

confidence: 58%

Synthesis and Characterization of Calcium N,N-Dimethylaminodiboranates as Possible Chemical Vapor Deposition Precursors

Dunbar

Girolami

2013

Inorg. Chem.

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The reaction of CaBr2 with 2 equiv of sodium N,N-dimethylaminodiboranate, Na(H3BNMe2BH3) in Et2O at 0 °C followed by crystallization and drying in vacuum yields the unsolvated calcium compound Ca(H3BNMe2BH3)2, 1. Before the vacuum drying step, the colorless crystals obtained by crystallization consist of the diethyl ether adduct Ca(H3BNMe2BH3)2(Et2O)2, 2. If the reaction of CaBr2 with 2 equiv of Na(H3BNMe2BH3) is carried out in the more strongly coordinating solvent tetrahydrofuran (thf), the solvate Ca(H3BNMe2BH3)2(thf)2, 3, is obtained. This compound does not desolvate as easily in vacuum as the diethyl ether compound 2. Treating the thf adduct 3 with 1,2-dimethoxyethane (dme), bis(2-methoxyethyl) ether (diglyme), or N,N,N',N'-tetramethylethylenediamine (tmeda) in thf affords the new compounds Ca(H3BNMe2BH3)2(dme), 4, Ca(H3BNMe2BH3)2(diglyme), 5, and Ca(H3BNMe2BH3)2(tmeda), 6, respectively, in greater than 60% yields. Treatment of 3 with 2 equiv of the crown ether 12-crown-4 in thf affords the charge-separated salt [Ca(12-crown-4)2][H3BNMe2BH3]2, 7. Crystal structures of all the Lewis base adducts are described. Compounds 2-6 all possess chelating κ(2)-BH3NMe2BH3-κ(2) groups, in which two hydrogen atoms on each boron center are bound to calcium. Compound 7 is the only ionic compound in the series; the Ca atom is completely encapsulated by two 12-crown-4 rings, and the anions are charge-separated counterions within the unit cell. When heated, the dme, diglyme, and tmeda compounds 4, 5, and 6 melt without decomposition, and can be sublimed readily under reduced pressure (1 Torr) at 90 °C (4) and 120 °C (5, 6). The dme adduct is one of the most volatile calcium compounds known, and is a promising CVD precursor for the growth of calcium-containing thin films.

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Section: Resultssupporting

confidence: 58%

Synthesis and Characterization of Calcium N,N-Dimethylaminodiboranates as Possible Chemical Vapor Deposition Precursors

Dunbar

Girolami

2013

Inorg. Chem.

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“…At the present time we favour the hypothesis (as it agrees with all experimental observations) that in complex II the Ba 2+ ions are bound in a kinetically rather stable 1 : 2 crown ether complex as there is a precedent in the literature for sandwich or half-sandwich structures. 19 Due to the ethylene bridge (C5,C6) in the phenanthroline such a sandwich type coordination is only feasible between two crown ethers stemming from different phenanthrolines that readily explains why only one complex, i.e. I, is seen with 1b.…”

Section: B-d In Presence Of Substoichiometric Amounts Of Ba 2+ Ionsmentioning

confidence: 99%

Effects of multiple ion loading on redox and luminescence properties of ruthenium trisphenanthroline crown ether hybrids

Schmittel¹,

Lin²,

Thiel³

et al. 2006

Dalton Trans.

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Homoleptic and heteroleptic ruthenium trisphenanthrolines were prepared with azacrown ethers attached to the 4,7-positions of the phenanthrolines to maximise the electronic communication between the ruthenium and the crown ethers as complexation sites. Redox and spectral data were processed to explain the non-steady trends in the absorption and emission spectra in the series. Addition of Ba2+ entailed large shifts in the redox potential (up to 370 mV) and in the emission spectra (up to 87 nm). Due to the crowded situation of the azacrown ether units in, this complex showed a non-linear behaviour both in the redox and emission properties upon loading with Ba2+ that is postulated to originate from the intermediate formation of sandwich type complexes.

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“…www.chemeurj.org which is mononuclear with eight-coordinate strontium. [25] The reason for the different structural motifs observed between the mononuclear thiocyanate complexes and the dinuclear or polymeric azide complexes presumably lies in the diminished affinity of the s-block metal for the thiocyanate sulfur (a few examples of S-CN coordinated thiocyanates are known for s-block metals, but they are very rare [13] ). The synthesis of the strontium azide-( [15]crown-5) complex was carried out on a number of occasions and gave the same product (IR evidence), but one sample gave a few clear crystals with a quite different unit cell.…”

Section: Resultsmentioning

confidence: 99%

Synthesis, Structures and DFT Calculations on Alkaline‐Earth Metal Azide‐Crown Ether Complexes

Brown¹,

Davis²,

Dyke³

et al. 2008

Chemistry A European J

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The first examples of azide complexes of calcium, strontium or barium with crown ethers have been prepared and fully characterised, notably [Ba([18]crown-6)(N3)2(MeOH)], [Sr([15]crown-5)(N3)2(H2O)], [Ca([15]crown-5)(N3)2(H2O)] and [Sr([15]crown-5)(N3(NO3)]. Crystal structures reveal the presence of a variety of coordination modes for the azide groups including kappa 1-, mu-1,3- and linkages via H-bonded water molecules, in addition to azide ions. The [Ba([18]crown-6)(N3)2(MeOH)].1/3 MeOH contains dinuclear cations with three mu-1,3-NNN bridges, the first example of this type in main group chemistry. The structures obtained have been compared with molecular structures computed by density functional theory (DFT). This has allowed the effects of the crystal lattice to be investigated. A study of the M--N terminal metal-azide bond length and charge densities on the metal (M) and terminal nitrogen centre (N terminal) in these complexes has allowed the nature of the metal-azide bond to be investigated in each case. As in our earlier work on alkali metal azide-crown ether complexes, the bonding in the alkaline-earth complexes is believed to be predominantly ionic or ion-dipole in character, with the differences in geometries reflecting the balance between maximising the coordination number of the metal centre, and minimising ligand-ligand repulsions.

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Crown ether complexes of alkaline-earth metal ions. I. Structures of 1,4,7,10-tetraoxacyclododecane (12-crown-4) complexed with calcium, strontium and barium thiocyanates

Cited by 11 publications

References 7 publications

Synthesis and Characterization of Calcium N,N-Dimethylaminodiboranates as Possible Chemical Vapor Deposition Precursors

Synthesis and Characterization of Calcium N,N-Dimethylaminodiboranates as Possible Chemical Vapor Deposition Precursors

Effects of multiple ion loading on redox and luminescence properties of ruthenium trisphenanthroline crown ether hybrids

Synthesis, Structures and DFT Calculations on Alkaline‐Earth Metal Azide‐Crown Ether Complexes

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