Raymond J. Batchelor

The syntheses, 77Se CP-MAS solid state NMR spectra and crystal structures of adducts of the selenium coronand, 1,5,9,13-tetraselenacyclohexadecane, with copper(I) trifluoromethanesulfonate and mercury(II) cyanide

The preparation, characterization, X-ray crystal structures and 77Se CP-MAS solid state NMR spectra of adducts of 1,5,9,13-tetraselenacyclohexadecane with copper(I)trifluoromethansesulfonate and mercury(II)cyanide are reported. Crystal data: [(Cu(Se(CH2)3)4)][SO3CF3] (1); orthorhombic; space group B2212; a = 8.947 (2); b = 15.184(2); c = 15.918(2) A; V = 2162.2 A3; Z = 4; FW = 696.77; ϱc = 2.140 g cm−3; λ = 0.71069 A; R(F) = 0.044 for 622 data (I ⪖ 2.5σ(I)). (Hg(CN)2)3)4) (2); monoclinic; space group P21/c; a = 5.822(1); b = 12.457(2); c = 14.074(2) A; β = 99.07(1)°; V = 1008.1 A3; Z = 2; FW = 736.79; ϱc = 2.427 g cm−3; λ = 0.71069 A; R(F) = 0.038 for 1153 data (I ⪖ 2.5σ(I)). 1 displays orientational disorder of the SO3CF3− anion and correlated disorder of the complex cation. The refinement was stabilized using soft restraints. The cation is a three-dimensional polymeric complex with pseudo-tetrahedral coordination about copper to four distinct ligands. 2 consists of linear Hg(CN)2 molecules which interact weakly with four selenium atoms from different ligands to give a tetragonally distorted octahedral arrangement.

Synthesis of sulfur analogues of methyl and allyl kojibiosides and methyl isomaltoside and conformational analysis of the kojibiosides

Abstract The synthesis of methyl and allyl 5′-thio-α-D-kojibiosides and methyl 5′-thio-α-D-isomaltoside is described. The phenylselenoglycoside and trichloroacetimidate of 2,3,4,6-tetra- O -acetyl-5-thioglucose have been employed as glycosyl donors to glycosylate glucopyranosyl acceptors with 2-OH and 6-OH positions free. The disaccharides thus obtained are potential glucosidase inhibitors. The conformational preferences of allyl 5′-thiokojibioside ( 34 ) were studied by comparison of experimental NOE curves with the theoretical counterparts for the corresponding methyl glycoside 25 , derived from a Boltzmann-averaged grid search using the program PIMM91. Very good agreement of experimental NOE curves derived from selective NOE measurments with the theoretical curves is found. The data are consistent with the population of a global minimum structure (Φ=−43, Ψ=−39 degrees) to the extent of 90%, and a second local minimum (Φ=−36, Ψ=−173 degrees) to the extent of 6%. An X-ray crystal structure of 34 at 190 K (R=4.2%) indicates a conformation (Φ=−46, Ψ=−23 degrees) that is similar to that of the global minimum.

Using HgX2 units (X = Cl, Cn) to increase structural and magnetic dimensionality in conjunction with (2,2'-bipyridyl)copper(II) building blocks

Abstract A series of complexes containing (bipy)nCuCl2 units (bipy=2,2′-bipyridyl; n=1,2) and linear, neutral Hg(CN)2 or HgCl2 building blocks have been synthesized and structurally characterized. Generally, the Lewis acidic HgX2 moieties accept chloride ligands from the copper(II) center, in some cases increasing the structural and magnetic dimensionality of the system as a result. [Cu(bipy)2(μ-Cl)2Hg(CN)2] (1) is a molecular complex in which the chloride ligands bridge the copper(II) and mercury(II) centers. [Cu(bipy)2Hg2Cl6]2 (2) contains two copper(II) centers connected by an [Hg4Cl12]4− bridge, that was generated by chloride migration from the harder copper(II) to the softer, highly Lewis acidic HgCl2 group. N-cyano coordination from Hg(CN)2 in {[Cu(bipy)Hg(CN)2Cl2]2Hg(CN)2} (3) generates a “Chinese-kite” type Cu2Hg2 rectangular cluster. The clusters are connected to form a 1D chain by Hg(CN)2 groups, that accept bridging chloride ligands from adjoining clusters. The crystallization of (bipy)CuCl2/Hg(CN)2-containing complexes from aqueous NH4OH yields 1D {[Cu(bipy)(OH)(Cl)]2Hg(CN)2}·2H2O (4) which is composed of [(bipy)Cu(OH)(Cl)]2 units bridged by Hg(CN)2 moieties. The variable temperature magnetic susceptibility of 3 can be fitted to the theoretical expression for a 1D antiferromagnetic chain of S=1/2 centers with alternating interaction pathways (J=−0.92 cm−1, α=0.17, g=2.26). For 4, μeff increases with decreasing temperature to a maximum and then decreases; fitting with the Bleaney–Bowers model for copper(II) dimers with weak antiferromagnetic interdimer interactions yielded J=56.3 cm−1, zJ′=−0.06 cm−1 and g=2.23. Complexes 3 and 4 are examples of coordination polymers with the rarely used Hg(CN)2 building block.

Conformational preferences in glycosylamines. implications for the exo-anomeric effect.

The conformational preferences about the C-N bond in N-(4-methoxyphenyl)-2,3,4,6-tetra-O-acetyl-alpha (1) and beta-D-glucopyranosylamine (2), in the solid state and in solution, have been investigated. The crystal structure of the axially substituted alpha anomer (1) indicates a conformational preference about the C-1-N bond in which nN-->sigma*C-O exo-anomeric interactions may be expressed, although this conformational preference is not displayed in solution. The solution conformation relieves steric interactions that result from expression of the exo-anomeric effect in the solid-state conformation. The conformational preference in the equatorially substituted beta anomer (2) both in solution and in the solid state is similar and permits expression of nN-->sigma*C-O exo-anomeric interactions. The structural data for 1 and 2 indicate significant differences in O-5-C-1-N-1 bond angles but insignificant differences in each of the O-5-C-1 or C-1-N-1 bond lengths. The J(C-1-H-1 coupling constants in 1 and 2 indicate a greater coupling constant for the alpha anomer that is consistent with a dominant nO-->sigma*C-H orbital interaction in the beta anomer that weakens the C-1-H-1 bond.

Selenium coronands. A novel conformational pair

The synthesis and characterization of the novel selenium coronands, 1,3,7,9-tetraselenacyclododecane 1a, 1,3,7,9,13,15-hexaselenacyclooctadecane 2a, the corresponding β-gem-dimethyl derivatives 1b, 2b, and 1,5,9,13-tetraselenacyclohexadecane 3, and 1,5,9,13,17,21-hexaselenacyclotetracosane 4 are described. X-ray crystallographic analysis of 1a reveals three independent molecules that exist in two distinct conformations, one molecule having approximate two-fold symmetry together with two molecules (of similar conformation) each having crystallographic symmetry. The conformations are denoted as [3333] or [66]. Whereas one resembles that of cyclododecane and tetrathia-12-crown-4 with respect to torsion angles, the other resembles that of tetraoxa-12-crown-4. The solid state CP-MAS 77Se and 13C nmr spectra are interpreted in light of the crystallographic information. Crystal structure: formula Se4C8H16; fw = 428.05; monoclinic, P21/c; Z = 8; a = 15.823(2) A, b = 5.534(1) A, c = 27.962(5) A, β = 92.26(1)°; V =...

Preparation and characterization of two chiral Au(CN)2-based coordination polymers containing (1R,2R)-N,N′-dimethylcyclohexanediamine

Two chiral heterometallic coordination polymers have been prepared using enantiopure 1R,2R-(N,N′)-bismethylcyclohexanediamine (Me2cydm) as an ancillary ligand along with copper(II) cations and KAu(CN)2. The resultant polymers, Cu(Me2cydm)[Au(CN)2]2 (1) and Cu(Me2cydm)Au(CN)2(ClO4) (2), crystallize in the chiral space groups P21 and C2221, respectively. Polymer 1 consists of 1D zig-zag chains of copper atoms bridged by [Au(CN)2]− groups with pendant [Au(CN)2]− units holding the 1D chains through Au–Au interactions of 3.2799(13) A, generating an overall 2D array. Polymer 2 has both [Au(CN)2]− and ClO4− anions bridging Cu(II) centres in a 2D (4,4) corrugated net motif. Both polymers exhibit weak antiferromagnetic interactions down to 1.8 K with no ordering behaviour. Despite the weak forces holding the 2D sheets in place, the polymers did not exhibit any porosity or vapochromic behaviour, indicating that the structural networks are surprisingly rigid.

A paramagnetic Cu(I)/Cu(II)/Zn(II) coordination polymer with multiple CN-binding modes and its solid-state NMR characterization

A Cu(I)/Cu(II)/Zn(II) mixed-valent [Cu(en)2][Zn(NC)4(CuCN)2] polymer, which has a 2-D layer structure with six structurally inequivalent cyanides in four distinct bonding modes, has been prepared; structurally informative 13C and 15N MAS NMR spectra of this paramagnetic system are readily observable.

Cationic rhenium allyl complex [Cp∗Re(η3-C3H5)(CO)2][BF4] and its acetonitrile derivatives [Cp∗Re(η3-C3H5)(CO)(NCMe)][BF4] and [Cp∗Re(η3-C3H5)(NCMe)2][BF4]. Products of reactions with borohydride, methoxide and trimethylphosphine, and the X-ray crystal structure of the bis-ethylamine complex [endo-Cp∗Re(η3-C3H5)(NH2Et)2]ReO4].solv

Abstract By replacing one or both of the CO groups in [ Cp ∗ Re (η 3 - C 3 H 5 )( CO ) 2 ][ BF 4 ] (1) by MeCN to give [ Cp ∗ Re (η 3 - C 3 H 5 )( CO )( NCMe )][ BF 4 ] (3) or [ Cp ∗ Re (η 3 - C 3 H 5 )( NCMe ) 2 ][ BF 4 ] (4), it was anticipated that the MeCN groups would be labile and would promote ligand substitutior reactions, leading to a variety of new rhenium η3-allyl half-sandwich derivatives. Instead, MeCN is found to be difficult to substitute, and nucleophiles often result in products that arise from attack at either the MeCN or allyl ligands. Complex 1 reacted with NaBH4 to give the propene complex Cp ∗ Re (η 3 - CH 2 CHCH 3 )( CO ) 2 (2), with NaOMe to give the methoxycarbonyl complex Cp ∗ (η 3 - C 3 H 5 )( CO )( COOMe ) (6) and the 3-methoxypropene complex Cp ∗ Re (η 2 - CH 2 CHCH 2 OMe )( CO ) 2 (5), and with PMe3 to give [ Cp ∗ Re (η 2 - CH 2 CHCH 2 PMe 3 )( CO ) 2 ][ BF 4 ] (7). Complex 3 gave the ethylamine complex [ Cp ∗ C 3 H 5 ( CO )( NH 2 Et )][ BF 4 ] (8) when reacted with NaBH4, [ Cp ∗ Re (η 2 - CH 2 CHCH 2 PMe 3 )( CO )( NCMe )][ BF 4 ] (9) with PMe3, and Cp ∗ Re (η- 3 - C 3 H 5 )( CO )( NHCOMe ) (10) with NaOH. Complex 4 similarly yielded the bis-ethylamine complex [ Cp ∗ Re (η 3 - C 3 H 5 )( NH 2 Et ) in2 ][ BF 4 ] (11) when reacted with NaBH4, but with PMe3 ligand substitution occurred, resulting in [ Cp ∗ Re (η 3 - C 3 H 5 )( NCMe )( PMe 3 )][ BF 4 (12). Treating 12 with NaBH4, or 11 wiht PMe3, yielded the ethylamine complex [ Cp ∗ Re (η 3 - C 3 H 5 )( PMe 3 )( NH 2 Et )][ BF 4 ] (13). The X-ray crystal structure of [endo- Cp ∗ Re (η 3 - C 3 H 5 )( NH 2 Et ) 2 ][ ReO 4 ]. solv has been determined. This compound crystallizes in the space group Pnma with a = 8.6554(8) A , b = 11.729(2) A , c = 26.928(3) A , V = 2733.7 A 3 , and Z = 4 . The structure was refined to RF = 0.028 for 1444 data (I0 ⩾ 2.5 σ(I0), 2θmax = 46°) and 158 variables. The cation has a crystallographic mirror plane that relates the two EtNH2 ligands and bisects the endo-η3-allyl and Cp∗ ligands. Selected distances and angles are ReN = 2.228(7) A , ReC (6) = 2.177(9) A (allyl terminal carbon), ReC (7) = 2.090(13) A (allyl central carbon), NC (4) = 1.470(10) A , ReNC (4) = 125.2(6) A , and C (6)- C (7)- C (6) = 114.1(13) A

Synthesis, structure and dynamics of endo- and exo-isomers of η3-allyl(η5-pentamethylcyclopentadienyl)dicarbonylrhenium tetrafluoroborate, [(η5-C5Me5)Re(CO)2(η3-C3H5)][BF4]

Abstract The cationic η 3 -allyl complex [Cp ★ Re(CO) 2 (η 3 -C 3 H 5 )][BF 4 ] ( 1 ) has been synthesized from the propene complex Cp ★ Re(CO) 2 (η 2 -C 3 H 6 ) ( 2 ) by reaction with [Ph 3 C][BF 4 ]. The 1 H NMR spectrum of 1 in CD 2 Cl 2 exhibits individual sets of methyl and allyl resonances corresponding to endo and exo isomers in an approximate ratio endo:exo = 6.4:1. The resonances that are identified with each isomer were determined by application of the nuclear Overhauser effect. Magnetization transfer results show that endo—exo interconversion occurs with no scrambling of syn and anti protons, consistent with a pseudorotation mechanism but not a η 3 -η 1 -η 3 mechanism. The crystal structure of 1 has been determined. The analysis gave a model in which both endo and exo isomers are present in an approximate ratio endo:exo = 4:6. Crystals of 1 are orthorhombic, space group Pcab with a = 12.3142(12), b = 12.8148(18), c = 21.767(3) A, V = 3434.9 A 3 , Z = 8. The structure was refined to R F = 0.027 and R WF = 0.038 using 1480 observed intensities in the range 4 l = 2 n ); 4 l = 2 n + 1) collected on an Enraf Nonius CAD-4F diffractometer with graphite monochromatized Mo- K α radiation.

Dinuclear Iron, Cobalt and Uranium Complexes of New Diamidoether Ligands

A series of new diamidoether ligands of the form {[RN(SiMe2)]2O}2- (R = 2,4,6-Me3Ph, 2,6-iPr2Ph, 3,5-(CF3)2Ph), termed [RNON]2-, were prepared via dilithiation of the precursors H2[RNON], which were synthesized from the reaction of O(SiMe2Cl)2 with the appropriate lithium amide. Reaction of the previously reported Li2[tBuNON] with FeX3 (X=C1, Br) yields dinuclear halide-bridged iron(III) complexes that show an unusual quantum spin-admixed magnetic state. Complexes of iron(III) with the aryl-NON ligands, however, form rare lithium “ate” structures. {[RNON]Co}2 complexes (R=tBu, 2,4,6-Me3Ph) are dinuclear with amido bridges and Co-Co bonds. Each Co(II) centre is roughly trigonal monopyramidal. The analogous reactions with UO2C12(THF)3 give dark red powders. For R=tBu, {UO2[tBuNON]}2 complexes are formed that may have structures similar to {[RNON]Co}2.