Showing papers by "Alexander J. Blake published in 2001"
TL;DR: In this article, the design and structure of coordination polymers derived from Ag(I) with N-donor ligands and their role in the investigation of weak non-covalent interactions in the solid state are discussed.
1,085 citations
228 citations
TL;DR: In this paper, three coordination polymers formed between CuI and bpds [bpds ======= bis(4-pyridyl)disulfide] have been prepared and fully characterised, demonstrating rare examples of solvent dependent topological isomerism in tetrahedral polymers.
205 citations
TL;DR: Eight-coordinate metal-ion nodes are linked through 4,4-bipyridine-N,N'-dioxide (L) ligands to form the first examples of eight- and seven-connected coordination networks.
Abstract: Eight-coordinate metal-ion nodes are linked through 4,4-bipyridine-N,N'-dioxide (L) ligands to form the first examples of eight- and seven-connected coordination networks. Thus, whereas [La(L)4 ](CF3 SO3 )3 adopts an eight-connected body-centered hypercubic CsCl-like lattice, [La(L)4 ](BPh4 )(ClO4 )2 shows eight-coordinate, but seven-connected, nodes linked in an unprecedented 417 62 topology.
157 citations
TL;DR: Incorporation of an alkoxide functional group into an N-heterocyclic carbene (NHC) ligand allows the synthesis of the first anionic NHC chelating ligands, which react to give the first neutral, molecular silver-I alkoxide carbene complex, and a copper(I) derivative containing the first nonmacrocyclic, square planar Cu(I), centres.
139 citations
TL;DR: A new N,O-bidentate pro-ligand (HL), [ML2] (M = Cu, Zn) and [CuL2][BF4] have been synthesised; data indicate that the cations are constituted as [Cu2+(L.)(L-)]+ and involve the phenoxyl radical L.
95 citations
TL;DR: A series of complexes of copper(I) halides with either [12]aneS4 (1,4,7,10-tetrathiacyclododecane) or [16]ANES4 as discussed by the authors have been synthesized, characterised and their crystal structures determined.
Abstract: A series of complexes of copper(I) halides with either [12]aneS4 (1,4,7,10-tetrathiacyclododecane) or [16]aneS4 (1,5,9,13-tetrathiacyclohexadecane) have been synthesized, characterised and their crystal structures determined. Discrete molecular entities of formula [CuX([12]aneS4)] (X = Cl, Br or I) were isolated from solutions containing a 1∶1 metal∶ligand stoichiometry. In [CuX([12]aneS4)] (X = Br or I) the copper(I) centres adopt a rare square pyramidal geometry. Located on fourfold axes of symmetry, the copper(I) centres are co-ordinated by one halide ion [Cu–Br 2.4209(11) or Cu–I 2.573(5) A] and four sulfur atoms [2.5386(12) (X = Br) and 2.521(5) A (X = I)]. In contrast, the copper(I) centres in [CuCl([12]aneS4)] adopt the more common tetrahedral co-ordination geometry, which is provided by one chloride ion [Cu–Cl 2.2666(13) A] and three sulfur donors [Cu–S 2.3331(13), 2.3326(13), 2.4720(11) A]. Polymeric materials, [Cu4Br4([12]aneS4)2]∞, [Cu4I4([12]aneS4)]∞ and [Cu2I2([16]aneS4)]∞, were obtained from reactions in which metal∶ ligand stoichiometries of 2∶1 and 4∶1 were used. [Cu4Br4([12]aneS4)2]∞ contains a previously uncharacterised copper(I) halide motif of formula Cu4X4 which is derived from the common Cu4X4 cubane tetramer and the Cu4X4 step-cubane tetramer. These Cu4X4 clusters are linked by [12]aneS4 molecules to generate a two-dimensional framework [Cu–Br 2.410(2)–2.539(2); Cu–S 2.318(3)–2.385(3) A]. In [Cu4I4([12]aneS4)]∞, Cu4I4 cubane tetramers are linked by tetradentate [12]aneS4 molecules to give a two-dimensional sheet structure [Cu–I 2.602(1)–3.021(1); Cu–S 2.285(1)]. In [Cu2I2([16]aneS4)]∞ an infinite three-dimensional co-ordination polymer comprising Cu2I2 rhomboid dimers linked by tetradentate [16]aneS4 molecules is formed [Cu–I 2.5972(9)–2.6702(9); Cu–S 2.292(2)–2.357(2) A]. The Cu2I2 moiety acts as a pseudo-square planar linker while the bridging [16]aneS4 units afford tetrahedral building blocks to give overall a PtS type structure for the polymer.
78 citations
TL;DR: In this paper, a preliminary X-ray study and large 1J(Si-H) coupling constant of 116 Hz suggest that this compound is best described as an unstretched β-agostic (Si−H⋯M) d2 silylamide complex.
Abstract: Reaction of the niobium diphosphine compound [NbCp(NAr)(PMe3)2] (Ar = 2,6-C6H3Pri2) with HSiMe2Cl gives the formally d2 silylamido derivative [NbCp{η3-N(Ar)SiMe2-H}Cl(PMe3)] 6. X-Ray diffraction and NMR studies of this compound show that it has a stretched β-agostic Si–H → Nb interaction. Reaction of the related precursor [NbCp(NAr′)(PMe3)2] (Ar′
= 2,6-C6H3Me2) with HSiMe2Cl gives an isomeric structure [NbCp{η3-N(Ar′)SiMe2-H}(PMe3)(Cl)] 7 differing from 6 in that the phosphine rather than chloride lies trans
to the co-ordinated Si–H bond. A preliminary X-ray study and large 1J(Si–H) coupling constant of 116 Hz suggest that this compound is best described as an unstretched β-agostic (Si–H⋯M) d2 silylamide complex. Reaction of the tantalum diphosphine compound [TaCp(NAr)(PMe3)2] with HSiMe2Cl affords the d0 silylhydride derivative [TaCp(NAr)(H)(SiMe2Cl)(PMe3)] 8 which, according to an X-ray diffraction study and NMR data, has an interligand hypervalent interaction (IHI) between the silyl and hydride ligands. Reactions of 6 and 8 with Me3SiX (X = I, OTf) lead to the corresponding iodido and triflate derivatives [NbCp{η3-N(Ar)SiMe2-H}X(PMe3)]
(X = OTf 11 or I 12) and [TaCp(NAr)(H)(SiMe2X)(PMe3)] (X = OTf 14 or I 15). Reaction of 8 with AgOTf gives [TaCp(NAr)(PMe3)2Cl]OTf 13, the crystal structure of which has been determined. Density functional theory calculations on models of the compounds 6 and 7 showed that the experimental geometries are only correctly reproduced when the phosphine ligands are adequately modelled. The extent of oxidative addition of the Si–H bond to the metal in 6 mainly depends on the basicity of the phosphine ligand. With PH3 in place of PMe3
the calculated structures are better described as silanimine-hydrido derivatives. The formation of isomeric type 6versus7 is determined by an interplay of the steric and electronic effects of the ligand environment.
63 citations
TL;DR: In this article, a 1∶1 ratio of Cd(NO3)2 with dpt in MeCN-CH2Cl2 has been shown to obtain a 1.82 two-dimensional sheet in the solid state.
Abstract: Coordination polymers formed between Cd(NO3)2 or Zn(NO3)2 and 2,4-bis(4-pyridyl)-1,3,5-triazine (dpt) have been synthesized and their single crystal structures determined. Reaction of a 1∶1 ratio of Cd(NO3)2 with dpt in MeCN–CH2Cl2 affords the complex [Cd2(NO3)4(dpt)2(MeCN)]∞ 1 which exists as a doubly interpenetrated 4.82 two-dimensional sheet in the solid state. Each sheet is constructed from nitrate-bridged [Cd(dpt)]4 metallacycles. In sharp contrast the analogous reaction performed using a 2∶1 L∶M ratio affords the discrete molecular complex [Cd(NO3)2(dpt)2(MeCN)] 2 in which both dpt ligands act as terminal donors rather than bridging metal centres. Reaction of Cd(NO3)2 with dpt in EtOH–CH2Cl2 affords a one-dimensional coordination polymer [Cd(NO3)2(dpt)(EtOH)]∞ 3. Zn(NO3)2 reacts with dpt in either a 1∶1 or 2∶1 L∶M ratio to afford the one-dimensional polymer [Zn(NO3)2(dpt)]∞ 4 which can be isolated as two polymorphs 4a and 4b which differ in their nitrate binding modes. The product formed is independent of the L∶M ratio used in the reaction. Only 4a is formed when MeCN–CH2Cl2 is used as reaction solvent whereas both 4a and 4b are formed from either EtOH–CH2Cl2 or iPrOH–CH2Cl2.
55 citations
TL;DR: The tridentate diamido-pyridine ligand adopts a facial coordination mode in the distorted trigonal bipyramidal complexes with the imido ligand occupying an equatorial position, as was established by X-ray diffraction for 3a and 5 as discussed by the authors.
Abstract: Reaction of the lithium amides [(2-C5H4N)C(CH3){CH2N(Li)SiMe3}2]2 (2a) and [(2-C5H4N)C(CH3){CH2N(Li)SiMe2tBu}2]2 (2b) with the imidotransition metal complexes [Ti(NtBu)Cl2(py)3], [Ti(N-2,6-C6H3iPr2)Cl2(py)3], and [Zr(N-2,6-C6H3iPr2)Cl2(thf)2] yielded the five-coordinate imido-titanium and -zirconium complexes [{κ3N-(2-C5H4N)C(CH3)(CH2NSiMe2R)2}Ti(NR‘)(py)] (R = Me, R‘ = tBu: 3a, R= tBu, R‘ = tBu: 3b, R = Me, R‘ = 2,6-C6H3iPr2: 4a, R = Me, R‘ = 2,6-C6H3Me2: 4b) and [{κ3N-(2-C5H4N)C(CH3)(CH2NSiMe3)2}Zr(N-2,6-C6H3iPr2)(py)] (5). The tridentate diamido-pyridine ligand adopts a facial coordination mode in the distorted trigonal bipyramidal complexes with the imido ligand occupying an equatorial position, as was established by X-ray diffraction for 3a and 5. Sublimation of 3a and 4a yielded the pure four-coordinate imidotitanium complexes [{κ3N-(2-C5H4N)C(CH3)(CH2NSiMe3)2}Ti(NR‘)] (R‘ = tBu: 6, 2,6-C6H3iPr2: 7) which were structurally characterized by X-ray crystallography. Reaction of 3a with the Lewis a...
53 citations
TL;DR: Density functional theory calculations indicate the intramolecular Br⋅ⓂⓉⓁH interactions as being responsible for the peculiar structural features of the I-Se-Br groups.
Abstract: Almost linear I-Se-Br groups with d(Se-Br)>d(Se-I) occur in 1⋅2 IBr, the first "T-shaped" Se adduct with IBr, which was synthesized by the oxidative addition of IBr to 1,2-bis(3-methylimidazoline-2-selonyl)ethane (1) in MeCN. Density functional theory calculations indicate the intramolecular Br⋅⋅⋅H interactions as being responsible for the peculiar structural features of the I-Se-Br groups.
TL;DR: The aromatic addition products in this study display more complex dynamic equilibria due to conjugation with the methoxy group; the experimental evidence for this is discussed in detail.
Abstract: Rhodium carboxylate catalyzed aromatic addition reactions of a range of diazoketones bearing methoxy-substituted aryl rings have been explored. While the existence of norcaradiene−cycloheptatriene equilibria in related compounds is well established, the aromatic addition products in this study display more complex dynamic equilibria due to conjugation with the methoxy group; the experimental evidence for this is discussed in detail. In the azulenone products 21−26 derived from p-methoxy-substituted diazoketones 14−16, the diastereomers interconvert via a spiro intermediate 39. A related mechanistic process in the azulenones 43−46 derived from the o-methoxy-substituted diazoketones 17, 18 interconverts regioisomers, explaining the conflicting reports for the regioselectivity of the cyclization of diazoketone 1. With the m-methoxy-substituted diazoketone 19, involvement of the methoxy group through a different pathway results in fragmentation of the azulenone to form the tetralone 47. With the azulenones 21...
TL;DR: In this article, the influence of the anion on structural order was discussed in the context of the reaction of Ag(I) salts with 1,4-dithiane has produced several interesting co-ordination polymers.
Abstract: The reaction of Ag(I) salts with 1,4-dithiane has produced several interesting co-ordination polymers, the structures of which vary significantly with anion. Compounds with metal ∶ ligand ratios of 2 ∶ 3, 1 ∶ 1 and 2 ∶ 1 have been produced and are discussed in the context of the influence of the anion on structural order. The recurrent topological feature of the three 2 ∶ 3 adducts, [{[Ag2(μ2-1,4-dithiane)3][BF4]2}∞, {[Ag2(μ2-1,4-dithiane)3][CF3SO3]2}∞ and {[Ag2(μ2-1,4-dithiane)3][NO3]2}∞], is a {[Ag2(μ2-1,4-dithiane)3]2+}∞ honeycomb sheet of (6,3) topology. The principal differences between these sheets lie in the size and symmetry of the constituent hexagonal units, the packing of the sheets being governed by the anion. For the polymers with [BF4−] and [CF3SO3−] anions, parallel sheets align such that the anions, which complete the four-fold co-ordination of the Ag(I) centres, are located in the hexagonal cavities of adjacent sheets; for the polymers with [NO3−] anions, however, the sheets are perpendicularly interpenetrated. The structures of the three 1 ∶ 1 adducts, {[Ag(μ2-1,4-dithiane)][BF4]}∞, {[Ag(μ2-1,4-dithiane)][SCN]}∞ and {[Ag(μ2-1,4-dithiane)][NO2]}∞, are all based on the same building block, a {[Ag(μ2-1,4-dithiane)]+}∞ chain of alternating metal and organic fragments. They differ, however, in the construction of their extended networks, which are anion dependent. All three anions bridge four-co-ordinate Ag(I) centres to form {[Ag(μ-X)]−}∞ chains which criss-cross the {[Ag(μ2-1,4-dithiane)]+}∞ chains. In the cases where [BF4−] and [SCN−] anions are used, the interlinked chains generate 2-D sheets with (4,4) topology which space fill either by perpendicular two-fold interpenetration to give a 3-D CdSO4 net (for the [BF4−] complex) or by parallel stacking (for the [SCN−] complex). In contrast, when [NO2−] acts as the anion, the interlinked chains give a 3-D diamondoid network. The 2 ∶ 1 polymer, {[Ag2(μ4-1,4-dithiane)][SO4]·H2O}∞, has an unprecedented 3-D architecture in which inorganic pillars brace metal–organic sheets. The metal–organic sheets comprise Ag(I) centres linked by μ2-S, μ2-S′ bridging 1,4-dithiane ligands and the inorganic pillars comprise Ag(I) centres connected by μ1-O (μ1-O is used in this instance to describe an oxygen atom bound to only one silver atom), μ1-O′, μ2-O″-bridging sulfate anions and μ2-O-bridging H2O molecules.
TL;DR: In this paper, a systematic study of two groups of two-dimensional transition metal compounds, Li3−x−y−y□yMxN (M=Co, Ni, Cu, □=Li vacancy) and 2 ternary transition metal nitrides of general formulation AMN2 (A=alkaline earth metal, M=Ti, Zr, Hf), is presented.
TL;DR: In this article, the complexation of the new mixed thia-aza-oxa macrocyclic 5oxa-2,8-dithia (L) containing the 1,10-phenanthroline unit with Ni, PdII, PtII, RhIII and RuII has been investigated.
Abstract: The complexation of the new mixed thia–aza–oxa macrocycle 5-oxa-2,8-dithia[9](2,9)-1,10-phenanthrolinophane (L) containing the 1,10-phenanthroline unit with NiII, PdII, PtII, RhIII and RuII has been investigated. The results have been compared with those obtained with the structurally related ligand 2,5,8-trithia[9](2,9)-1,10-phenanthrolinophane (L′). The most stable conformations of both ligands have been calculated in order to understand their change upon metal complexation and for L good agreement has been found with the conformations observed in the crystal structure of L·½H2O. The single-crystal structures of [Ni(L)Cl]BF4 and [Ru(L)(PPh3)][PF6]2·1//4MeCN reveal a N2S2O coordination sphere about NiII and RuII, with the macrocyclic ligand in a folded conformation and with the sixth coordination site taken up by Cl− or PPh3, respectively. For [Pd(L)][BF4]2 an [N2S2 + O] coordination is observed, with the O-donor interacting weakly with the metal centre at the apical position of a square-based coordination sphere. 13C and 1H NMR spectroscopic studies indicate that the complexes are not fluxional in solution, with the ligand imposing the same coordination sphere as observed in the solid state. 13C NMR spectroscopy has also helped in elucidating the stereochemistry of [Rh(L)Cl2]BF4 for which no suitable crystals could be grown: the two Cl− ligands are mutually trans with the N2S2 donor set of the macrocyclic ligand occupying the equatorial positions of an octahedral coordination sphere and with the O-donor atom left un-coordinated. The redox properties of all the complexes in MeCN have been studied.
TL;DR: 4,4'-Bipyridine N,N'-dioxide (L) acts as a hydrogen-bond acceptor in the compounds to form doubly-interpenetrated framework materials with sixfold topological connectivity.
TL;DR: Better behaved reactions were found between the heavier Group 5 metal complexes [M(NR)Cl(3)(py)(2)] and the dilithium salt Li(2)[N(2)N(py)].
Abstract: Reaction of the vanadium(V) imide [V(NAr)Cl3(THF)] (Ar = 2,6-C6H3iPr2) with the diamino-pyridine derivative MeC(2-C5H4N)(CH2NHSiMe2tBu)2 (abbreviated as H2N‘2Npy) gave modest yields of the vanadium(IV) species [V(NAr)(H3N‘N‘ ‘Npy)Cl2] (1 where H3N‘N‘ ‘Npy = MeC(2- C5H4N)(CH2NH2)(CH2NHSiMe2tBu) in which the original H2N‘2Npy has effectively lost SiMe2tBu (as ClSiMe2tBu) and gained an H atom. Better behaved reactions were found between the heavier Group 5 metal complexes [M(NR)Cl3(py)2] (M = Nb or Ta, R = tBu or Ar) and the dilithium salt Li2[N2Npy] (where H2N2Npy = MeC(2-C5H4N)(CH2NHSiMe3)2), and these yielded the six-coordinate M(V) complexes [M(NR)Cl(N2Npy)(py)] (M = Nb, R = tBu 2; M = Ta, R = tBu 3 or Ar 4). The compounds 2−4 are fluxional in solution and undergo dynamic exchange processes via the corresponding five-coordinate homologues [M(NR)Cl(N2Npy)]. Activation parameters are reported for the complexes 2 and 3. In the case of 2, high vacuum tube sublimation afforded modest quantities of [Nb(NtBu)Cl...
TL;DR: The AB ring system found in the manzamine A and related alkaloids has been prepared from (−)-quinine by a short enantioselective route as discussed by the authors, and the key step in the sequence is a ruthenium-catalysed ring-closing enyne metathesis reaction which delivers a bicyclic diene in good yield.
TL;DR: In this paper, the synthesis and complexation of two heteroditopic lariat azathioether macrocycles incorporating acylurea functionalised pendant arms are described; L1 and L2 are capable of simultaneously binding both the cationic and anionic moieties of a metal salt as confirmed by the structures of [PdCl2(L1), [CuCl(L2)]2CuCl4 and [Ag(NO3)(L2)].
TL;DR: In this paper, the effects of varying starting materials, transition metal stoichiometry, reaction temperature/duration and cooling rate on crystal growth and bulk phase formation of ternary nitridocuprates were examined.
TL;DR: In this paper, the generation and silylation of bridgehead enolates has been accomplished in high enantiomeric excess using a chiral lithium amide base, which is used to generate bridgeheads.
TL;DR: In this article, a structural study of a trisilanol silsesquioxane (also referred to as a silasesquioxANE) was carried out using X-ray crystallography, which revealed the dimeric hydrogen bonded structure of the disilanol ligands.
Abstract: Steric protection of a trisilanol silsesquioxane (also referred to as a silasesquioxane) by one TBDMS group (SiMe2But) generated a new siloxanolate ligand, (c-C5H9)7Si7O9(OH)2(OTBDMS) 1, that allows only restricted access to a co-ordinated metal. Lithiation afforded the stable complex (c-C5H9)7Si7O9(OLi)2(OTBDMS), which has allowed the generation of a samarium adduct [Sm(OC6H3But2-2,6){(c-C5H9)7Si7O9(O)(OLi)(OTBDMS)}2]. A structural study of this samarium adduct revealed two unusual features: an absence of stabilising M–O interactions with the siloxane core, and retention of one apical aryloxide group at the trivalent metal, through which the chemistry of a silica-functionalised Ln3+ ion might be modelled. X-Ray crystallography also revealed the dimeric hydrogen bonded structure of the disilanol ligands. The disilanol ligand 1 may also readily be converted into a dithallium salt, providing a potential precursor for further f-element derivatives of this disilanolate moiety.
TL;DR: Oligo(benzoate) derivatives of cis-and trans-(RO)2[14]aneS4, trans-RO2[16]ANES4 and their corresponding Pd(II) complexes reveal metal-induced mesomorphic behaviour which can be rationalised by conformational locking of the ligand on complexation as discussed by the authors.
TL;DR: In this article, the reaction of silylketenes with thiophenol, mediated by cinchona alkaloid catalysts, proceeds to give α-silylthioester products in good chemical yield and with enantiomeric excess values in the range 79-93%.
TL;DR: Ammonium ylides produced by intramolecular reaction of copper carbenoids tethered to cyclic allylic amines undergo [2,3]-rearrangement to deliver bicyclic amines, finding the CE sub-unit found in the manzamine and ircinal alkaloids.
Abstract: Ammonium ylides produced by intramolecular reaction of copper carbenoids tethered to cyclic allylic amines undergo [2,3]-rearrangement to deliver bicyclic amines. The reaction can be performed using a cyclic N-allylamine in which the diazo group is tethered adjacent to nitrogen, or a vinyl-substituted cyclic amine in which the diazo group is N-tethered to the ring. In the former type of reaction, stereoselective ylide formation and rearrangement usually delivers high levels of diastereocontrol. In the latter case, efficient ‘chirality transfer’ can be accomplished when the reaction is performed using an enantiomerically pure substrate. The reactions have been used to construct pyrrolizidine, indolizidine and quinolizidine systems, and the CE sub-unit found in the manzamine and ircinal alkaloids.
TL;DR: In this article, a cofacial binucleating macropolycycle combining the coordination properties of [9]aneN3 (1,4,7-triazacyclononane) with those of phenol-based compartmental macrocycles is reported together with binuclear CdII and YIII complexes, which show segregated and encapsulated complexation.
TL;DR: In this article, the PF6-anion was converted to tetramethylhexathiaadamantane (hta) in MeOH to give a coordination polymeric material with a rutile-like framework construction.
Abstract: Hydrolysis of the PF6- anion during the reaction of AgPF6 with tetramethylhexathiaadamantane (hta) in MeOH leads to the crystallization of a coordination polymer, {[Ag3(hta)(PO2F2)3]}∞, in which hexanuclear [Ag(PO2F2)]6 cages are linked by tetramethylhexathiaadamantane molecules in a three-dimensional architecture. The unprecedented [Ag(PO2F2)]6 cages act as six-connecting units with approximately octahedral geometry, and the tetramethylhexathiaadamantane molecules form three-connecting units with approximately trigonal planar geometry to give a rare example of a metal-organic material with a rutile-like framework construction.
TL;DR: Oligo(benzoate) derivatives have been synthesized and have been prepared as transesterification products as discussed by the authors, which can be deprotected using aqueous NH3.
Abstract: Oligo(benzoate) derivatives, (R)[9]aneNS2,
of 1,4-dithia-7-azacyclononane [R = OC-C6H4-4-OR′
(1)
[R′ = C3H7
(a) C8H17
(b)], OC-C6H4-4-O2C-C6H4-4-OC8H17
(2), OC-C6H4-4-O2C-C6H4-4-O2C-Z, Z = C6H4-4-OC8H17
(3), C6H3-3,4-(OR′2)2
(4)
[R′ = C4H9
(a), C8H17
(b), C12H25
(c)], C6H2-3,4,5-(OC12H25)3
(5)] have been synthesised. Compound 3 displays monotropic nematic and smectic phases,
while 5 shows an enantiotropic columnar
hexagonal phase (Colh) just above room temperature as
characterised by X-ray scattering experiments. Dilatometry suggests a model
for the packing of molecules of 5
in the mesophase. An alternative route to these compounds has been developed via
the preparation of the protected species 6
[R = OC-C6H4-4-OC(O)OMe],
which can be deprotected using aqueous NH3 to give 7
[R = OC-C6H4-4-OH],
followed by reaction with the appropriate acid chloride or anhydride. Oligo(benzoate)
derivatives, (R)2[9]aneN2S, of 1-thia-4,7-diazacyclononane [R = OC-C6H4-4-OC(O)OMe (8),
OC-C6H4-4-OH (9)
OC-C6H4-4-O2C-C6H4-4-OC8H17
(10), OC-C6H4-4-O2C-C6H2-3,4,5-(OC12H25)3
(11)]
have been prepared as transesterification products.
TL;DR: In this paper, the anti-CdCl2 structure of Ca2N has been investigated in the context of diffraction studies, and it has been shown that the c-axis dimension changes with the synthetic method employed.
Abstract: Ca2N adopts the anti-CdCl2 structure in which two sheets of calcium ions enclose a sheet of N3− ions, with each calcium bonded to three N3− at 2.4500 (3) A and each nitrogen octahedrally coordinated by six calciums. Within one calcium sheet, each metal has three others at 3.2944 (8) A and a further six at 3.6271 (3) A. The distance between two calcium layers with no intervening nitrogen layer is 4.3221 (6) A, and this intervening region contains no observable electron density. Neutron and X-ray powder diffraction studies have shown that the c-axis dimension changes with the synthetic method employed. In the single-crystal, c is significantly lower, reflecting the higher temperature employed in its formation.