Synthesis and problematic crystal structures of [Al(CH3CN)6][MCl6]3(CH3CN)3 (M=Ta, Nb or Sb)

Compounds of formula [Al(CH₃CN)₆][MCl₆]₃(CH₃CN)₃ (M=Ta (1); Nb (2); Sb (3)) have been synthesized from the reactions of MCl₅ and AlCl₃ in acetonitrile and characterized by X-ray crystallography. Complex 1 crystallizes in the tetragonal space group P4/mbm with a = B = 10.408(2), C = 7.670(3) Å, V = 830.9(4) ų and Z = 2/3. Complex 2 crystallizes in the tetragonal space group P4/mnc with a = B = 330(a), C = 15.320(3) ų V = 1634.8(4) ų and Z = 4/3. Complex 3 also crystallizes in the tetragonal space group P4/mnc with a = B = 10.313(1), C = 15.238(2) Å, V = 1621.0(1) ų and Z = 4/3. The non-integer Z values for complexes 1–3 result unusual problems of disorder and/or twinning in these crystal structures due to their high symmetry. The M---Cl distances range from 2.329(3) Å in the Ta complex to 2.355(1) Å in the Sb complex, while the Al---N distances are similar in all three complexes, ranging from 1.92(1) to 1.97(1) Å, respectively. Complexes 1–3 are the first structurally characterized complexes that contain a (hexaacetonitrile)aluminum(III) cation.     

Synthesis and characterization of SrCu2(O2CR)3(bdmap)3 and Bi2(O2CCH3)4(bdmap)2(H2O) (R = CH3, CF3; bdmap = 1,3-bis(dimethylamino)-2-propanolato)

New mixed metal complexes SrCu₂(O₂CR)₃(bdmap)₃ (R = CF₃ (1a), CH₃ (1b)) and a new dinuclear bismuth complex Bi₂(O₂CCH₃)₄(bdmap)₂(H₂O) (2) have been synthesized. Their crystal structures have been determined by single-crystal X-ray diffraction analyses. Thermal decomposition behaviors of these complexes have been examined by TGA and X-ray powder diffraction analyses. While compound 1a decomposes to SrF₂ and CuO at about 380°C, compound 1b decomposes to the corresponding oxides above 800°C. Compound 2 decomposes cleanly to Bi₂O₃ at 330°C. The magnetism of 1a was examined by the measurement of susceptibility from 5–300 K. Theoretical fitting for the susceptibility data revealed that 1a is an antiferromagnetically coupled system with g = 2.012(7), −2J = 34.0(8) cm⁻¹. Crystal data for 1a: C₂₇H₅₁N₆O₉F₉Cu₂Sr/THF, monoclinic space group P2₁/m, A = 10.708(6), B = 15.20(1), C = 15.404(7) Å, β = 107.94(4)°, V = 2386(2) ų, Z = 2; for 1b: C₂₇H₆₀N₆O₉Cu₂Sr/THF, orthorhombic space group Pbcn, A = 19.164(9), B = 26.829(8), C = 17.240(9) Å, V = 8864(5) ų, Z = 8; for 2: C₂₂H₄₈O₁₁N₄Bi₂, monoclinic space group P2₁/c, A = 17.614(9), B = 10.741(3), C = 18.910(7) Å, β = 109.99(3)°, V = 3362(2) ų, Z = 4.     

Dinuclear silver(I) complexes of 24-membered bibracchial tetraimine Schiff base macrocycles derived from 2,5-diformylthiophene

The cyclocondensation of 2,5-diformylthiophene and the amines N,N-bis-(2-aminoethyl)-2-phenylethylamine, N,N-bis-(2aminoethyl)-t-butyl-amine and N,N-bis-(2-aminoethyl)-t-butyl-amine in the presence of silver(I) salts yields homodinuclear bibracchial tetraimine Schiff base macrocyclic complexes. The structures of two such complexes are also reported. The complex Ag₂L⁴(NO₃)(PF₆) (2) crystallises in the triclinic space group , No. 2) and has unit-cell dimensions a = 12.834(6), B = 13.183(6), C = 14.588(7) Å, = 64.86(4), β = 79.77(4), γ = 69.44(3)° with Z = 2; there is a monodentate and singly bridging nitrate anion present and the Ag---Ag separation is 4.161 Å. The complex Ag₂L⁴(CH₃CN)₂(BF₄)₂·CH₃CN (9) crystallises in the triclinic space group , No. 2) and has unit-cell dimensions a = 9.297(4), B = 12.985(3), C = 21.770(5) Å, = 91.570(10), β = 92.33(3), γ = 97.92(3) ° with Z = 2; there is a strongly bonded acetonitrile molecule coordinated to each silver atom and the Ag---Ag separation is 4.920 Å.     

The ReH6[P(C6H5)3]2 ion as a ligand: complexes with M(CO)3 fragments (M = Cr, Mo, W)

The reactions of [(H₅C₆)₃P]₂ReH₆⁻ with (CH₃CN)₃Cr(CO)₃, (diglyme)Mo(CO)₃ or (C₃H₇CN)₃W(CO)₃ led to the formation of [(H₅C₆)₃P]₂ReH₆M(CO)₃⁻ (M = Cr, Mo, W) complexes. These have been characterized by IR and NMR spectroscopies, as well as elemental analyses. A single crystal X-ray diffraction study has also been carried out for the M = Cr complex as a K(18-crown-6)⁺ salt. The complex crystallizes as a THF monosolvate in the monoclinic space group P2₁/n with a = 22.323(6), B = 9.523(2), C = 27.502(5) Å, β = 104.98(2)⁰ and V = 5648 ų for Z = 4. The Re---Cr separation is 2.5745(12) Å, and the two phosphine ligands are oriented unsymmetrically. Although the hydride ligands were not found, the presence of three bridging hydrides and a dodecahedral coordination geometry about rhenium could be inferred. Low temperature ¹H and ³¹P NMR spectroscopic studies did not reveal the low symmetry of the solid state structure.     

Correlation of structure and emission in solid state copper(I) complexes; [Cu4I4(CH3CN)2(L)2], L = aniline derivative

Four complexes of the type [Cu₄I₄(CH₃CN)₂(L)₂], L = aniline derivative: Cu₄I₄(CH₃CN)₂(2,6-dimethylaniline)₂ (I), triclinic, , a = 12.449(3), B = 14.108(6), C = 10.606(4) Å, = 73.46(3), β = 95.00(2), γ = 73.42(3)°, V = 1682.3(10) ų; Cu₄I₄(CH₃CN)₂(o-ethylaniline)₂ (II), triclinic,

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, V = 1734.0(8) ų; Cu₄I₄(CH₃CN)₂(6-ethyl-o-toluidine)₂ (III), orthorhombic, Pnam, a = 14.976(6), b = 21.187(6), C = 12.545(2) Å, V = 3980.7(2) ų; Cu₄I₄(CH₃CN)₂(p-anisidine)₂ (IV), monoclinic, A2/a, A = 20.032(10), B = 7.863(1), C = 18.715(9) Å, β = 101.56(4)°, V = 2888.0(2) ų; were examined by single crystal X-ray diffraction. Complexes I and II have no internal symmetry elements, III has an internal mirror and IV has a two-fold axis. Ab initio calculations based on the atomic positional parameters of complexes containing the three types of symmetry elements reveal HOMO orbitals to be dominated by the p orbitals of the iodine atoms whereas the LUMO orbitals contain major contributions from copper based p orbitals.     

Studies of the oxovanadium(IV)—oxalate system: syntheses and crystal structures of binuclear (Ph4P)2[(VO)2(H2O)2(C2O4)3]·4H2O and of the one-dimensional chain material, (Ph4P)[VOCl(C2O4)]

The hydrothermal reactions of (Ph₄P)[VO₂Cl₂] and H₂C₂O₄ at 150 and 125°C yield (Ph₄P)₂[V₂O₂(H₂O)₂(C₂O₄)₃]·4H₂O (1) and (Ph₄P)[VOCl(C₂O₄)] (2), respectively. The structure of the molecular anion of 1 consists of a binuclear unit of oxovanadium(IV) octahedra bridged by a bisbidentate oxalate group. The VO₆ coordination geometry at each vanadium site is defined by a terminal oxo group, an aquo ligand, and four oxygen donors — two from the bisbidentate bridging oxalate and two from the terminal bidentate oxalate. The structure of 2 consists of discrete Ph₄P⁺ cations occupying regions between [VOCl(C₂O₄)]⁻_∞ spiral chains. The structure of the one-dimensional anionic chain exhibits V(IV) octahedra bridged by bisbidentate oxalate groups. Crystal data: 1·4H₂O, monoclinic P2₁/n, A = 12.694(3), B = 12.531(3), C = 17.17(3) Å, β = 106.32(2)°, V = 2621.3(13) ų, Z = 2, D_calc = 1.501 g cm⁻³, structure solution and refinement converged at a conventional residual of 0.0518; 2, tetragonal P4₃, A = 12.145(2), C = 15.991(3) Å, V = 2358.7(12) ų, Z = 4, R = 0.0452.     

Crystal growth in aqueous hydrofluoric acid and (HF)x · pyridine solutions: syntheses and crystal structures of [Ni(H2O)6][MF6] (M = Ti, Zr, Hf) and Ni3(py)12F6 · 7H2O

The syntheses and structures of [Ni(H₂O)₆]²⁺[MF₆]²⁻ (M = Ti,Zr,Hf) and Ni₃(py)₁₂F₆·7H₂O are reported. The former three compounds are isostructural, crystallizing in the trigonal space group (No. 148) with Z = 3. The lattice parameters are a = 9.489(4), C = 9.764(7) Å, with V = 761(1) ų for Ti; a = 9.727(2), C = 10.051(3) Å, with V = 823.6(6) ų for Zr; and a = 9.724(3), C = 10.028(4)Å, with V = 821.2(8)ų for Hf. The structures consist of discrete [Ni(H₂O)₆]²⁺ and [MF₆]²⁻ octahedra joined by O---HF hydrogen bond Large single crystals were grown in an aqueous hydrofluoric acid solution. Ni₃(py)₁₂F₆·7H₂O crystallizes in the monoclinic space group I2/a (No. 15) with Z = 4. The lattice parameters are a = 16.117(4), B = 8.529(3), C = 46.220(7) Å, β = 92.46(2)°, and V = 6348(5) ų. The structure consists of discrete Ni(py)₄F₂ octahedra linked through H---O---HF and H---O---HO hydrogen bonding interactions. Single c were grown from a (HF)_x·pyridine/pyridine/water solution.     

The coordination chemistry of cationic main group clusters: syntheses and structures of [Fe3(Se2)2(CO)10] and [Fe4(Se2)3(CO)12]

The reactions of the polysulfur and selenium cationic clusters S₈²⁺ and Se₈²⁺ with various iron carbonyls were investigated. Several new chalcogen containing iron carbonyl cluster cations were isolated, depending on the nature of the counteranion. In the presence of SbF₆⁻ as a counterion, the cluster [Fe₃(E₂)₂(CO)₁₀] [SbF₆]₂·SO₂ (E = S, Se) could be isolated from the reaction of E₈²⁺ and excess iron carbonyl. The cluster is a picnic-basket shaped molecule of two iron centers linked by two Se₂ groups, with the whole fragment capped by an Fe(CO)₄ group. Crystallographic data for C₁₀O₁₂Fe₃Se₄Sb₂F₁₂S (I): space group monoclinic P2₁/c, A = 11.810(9), b = 24.023(6), c = 10.853(7) Å, β = 107.15(5)°, V = 2942(3) ų, Z = 4, R = 0.0426, R_w = 0.0503. When Sb₂F₁₁⁻ is present as the counterion, or Se₄[Sb₂F₁₁]₂ is used as the cluster cation source, a different cluster can be isolated, which has the formula [Fe₄(Se₂)₃(CO)₁₂] [SbF₆]₂·3SO₂. The dication contains two Fe₂Se₂ fragments bridged by an Se₂ group. Crystallographic data for C₁₂O₁₈Fe₄Se₆Sb₂F₁₂S₃ (III): space group triclinic , b = 18.400(9), C = 10.253(4) Å, = 93.10(4), β = 103.74(3), γ = 93.98(3)°, V = 1995(1) ų, Z = 2, R = 0.0328, R_w = 0.0325. The CO stretches in the IR spectrum all show a large shift to higher wavenumbers, suggesting almost no τ backbonding from the metals. This also correlates with the observed bond distances. All the compounds are extremely sensitive to air and water, and readily lose SO₂ when removed from the solvent. Thus all the crystals were handled at −100°C. The clusters seem to be either insoluble or unstable in all solvents investigated.     

The synthesis, fluctionality and structural characterization of ReMo3H4(CO)12

The reaction of ReH₉²⁻ with Mo(diglyme)(CO)₃ leads to the formation of the mixed metal cluster trianion, ReMo₃H₄(CO)₁₂³⁻. This species has been characterized analytically, spectroscopically and through X-ray diffraction analysis. A pseudo-tetrahedral arrangement of M(CO)₃ fragments is adopted, such that each set of three carbonyl ligands eclipses the adjacent three tetrahedral edges, an apparent result of the location of the hydride ligands on the tetrahedral faces. Variable temperature NMR studies revealed a fluctional process for some of the carbonyl ligands, but not for the hydrides. Crystal data for [Me₄N]₃[ReMo₃H₄(CO)₁₂]·THF; space group P2₁/n, a = 12.157(2), B = 21.480(4), C = 15.964(3) Å, β = 98.26(1)°, Z = 4, R = 0.067 and R_w = 0.076.     

Convenient preparation of [CuX(PCy3)2](X = Br, I, SCN, N3) complexes. X-ray crystal structure of [Cu(N3)(PCy3)2] (Cy = cyclo-C6H11)

The labile cations [Cu(F-BF₃)(PCy₃)₂] and [Cu(OTf)(PCy₃)₂] are versatile precursors for the formation of [Cu(X)(PCy₃)₂] (X = Br, I, SCN, N₃) complexes by metathesis with NaX. The azide [Cu(N₃)(PCy₃)₂] is triclinic, space group , a = 9.755(4), B = 22.78(1), C = 9.284(6) Å, = 96.76(3), β = 115.36(3), γ = 94.20(5)°, Z = 2.     

On the lability of dimethylsulfoxide (DMSO) coordinated to the [Ru(II)-NO(+)] species: X-ray structures of mer-[RuCl(3)(DMSO)(2)(NO)] and mer-[RuCl(3)(CD(3)CN)(DMSO)(NO)

The syntheses of nitrosyl–dimethylsulfoxide–ruthenium(II) complexes with general formula mer-[RuCl₃(L)(DMSO)(NO)] (L=DMSO or CD₃CN) is reported. The mer-[RuCl₃(DMSO)₂(NO)] (1) complex was obtained from the reaction of [RuCl₃(NO)] with the sulfoxide ligand in acetone. The mer-[RuCl₃(CD₃CN)(DMSO)(NO)] (2) compound was obtained from mer-[RuCl₃(DMSO)₂(NO)] maintained in deuterated acetonitrile. These data suggest a slow kinetic reaction due the low lability of the DMSO ligand coordinated to the {Ru^II–NO⁺} species. The crystal and molecular structures of (1) and (2) have been determined from X-ray studies. Crystal data: for (1), monoclinic, P2₁/c, a=8.8340(2) Å, b=12.0230(3) Å, c=13.7064(4) Å, β=114.546(2)°, Z=4, R1=0.0429; for (2), monoclinic, P21/n, a=10.0180(7) Å, b=9.5070(7) Å, c=13.3340(9) Å, β=102.264(4)°, Z=4, R1=0.0472. The spectroscopic characterization of (1), in solid state (infrared spectrum) and in solution (nuclear magnetic resonance and cyclic voltammetry) is also described.     

Reactions of the haloalcohols HO(CH2)nCl (n = 2, 3) with platinum(II) - alkynyl and -alkyne complexes. X-ray crystal structure of trans-[Pt(Me) {C(OCH2CH2Cl) (CH2Ph)} (PPh3)2] [BF4]

The chloro complexes trans-[Pt(Me)(Cl)(PPh₃)₂], after treatment with AgBF₄, react with 1-alkynes HC---C---R in the presence of NEt₃ to afford the corresponding acetylide derivatives trans-[Pt(Me) (C---C---R) (PPh₃)₂] (R = p-tolyl (1), Ph (2), C(CH₃)₃ (3)). These complexes, with the exception of the t-butylacetylide complex, react with the chloroalcohols HO(CH₂)_nCl (n = 2, 3) in the presence of 1 equiv. of HBF₄ to afford the alkyl(chloroalkoxy)carbene complexes trans-[Pt(Me) {C[O(CH₂)_nCl](CH₂R) } (PPh₃)₂][BF₄] (R = p-tolyl, N = 2 (4), N = 3 (5); R=Ph, N = 2 (6)). A similar reaction of the bis(acetylide) complex trans-[Pt(C---C---Ph)₂(PMe₂Ph)₂] with 2 equiv. HBF₄ and 3-chloro-1-propanol affords trans-[Pt(C---CPh) {C(OCH₂CH₂CH₂Cl)(CH₂Ph) } (PMe₂Ph)₂][BF₄] (7). T alkyl(chloroalkoxy)-carbene complex trans-[Pt(Me) {C(OCH₂CH₂Cl)(CH₂Ph) } (PPh₃)₂][BF₄] (8) is formed by reaction of trans-[Pt(Me)(Cl)(PPh₃)₂], after treatment with AgBF₄ in HOCH₂CH₂Cl, with phenylacetylene in the presence of 1 equiv. of n-BuLi. The reaction of the dimer [Pt(Cl)(μ-Cl)(PMe₂Ph)]₂ with p-tolylacetylene and 3-chloro-1-propanol yields cis-[PtCl₂{C(OCH₂CH₂CH₂Cl)(CH₂C₆H₄-p-Me}(PMe₂Ph)] (9). The X-ray molecular structure of (8) has been determined. It crystallizes in the orthorhombic system, space group Pna2₁, with a = 11.785(2), B = 29.418(4), C = 15.409(3) Å, V = 4889(1) ų and Z = 4. The carbene ligand is perpendicular to the Pt(II) coordination plane; the PtC(carbene) bond distance is 2.01(1) Å and the short C(carbene)-O bond distance of 1.30(1) Å suggests extensive electronic delocalization within the Pt---C(carbene)---O moietry.     

Kinetics and mechanisms of ligand substitution reactions of molybdenum SO2 complexes. Synthesis and X-ray structure of trans-Mo(CO)2 (dmpe) (PPh3) (SO2)

Kinetic results are reported for intramolecular PPh₃ substitution reactions of Mo(CO)₂(η¹-L)(PPh₃)₂(SO₂) to form Mo(CO)₂(η²-L)(PPh₃)(SO₂) (L = DMPE = (Me)₂PC₂H₄P(Me)₂ and dppe=Ph₂PC₂H₄PPh₂) in THF solvent, and for intermolecular SO₂ substitutions in Mo(CO)₃(η²-L)(η²-SO₂) (L = 2,2′-bipyridine, dppe) with phosphorus ligands in CH₂Cl₂ solvent. Activation parameters for intramolecular PPh₃ substitution reactions: ΔH^≠ values are 12.3 kcal/mol for dmpe and 16.7 kcal/mol for dppe; ΔS^≠ values are −30.3 cal/mol K for dmpe and −16.4 cal/mol K for dppe. These results are consistent with an intramolecular associative mechanism. Substitutions of SO₂ in MO(CO)₃(η²-L)(η²-SO₂) complexes proceed by both dissociative and associative mechanisms. The facile associative pathways for the reactions are discussed in terms of the ability of SO₂ to accept a pair of electrons from the metal, with its bonding transformations of η²-SO₂ to η¹-pyramidal SO₂, maintaining a stable 18-e count for the complex in its reaction transition state. The structure of Mo(CO)₂(dmpe)(PPh₃)(SO₂) was determined crystallographically: P2₁/c, A=9.311(1), B = 16.344(2), C = 18.830(2) Å, ß=91.04(1)°, V=2865.1(7) ų, Z=4, R(F)=3.49%.     

The monofunctionalized 1,4,7-triazacyclononane derivatives 1,4,7-triazacyclononane-N-acetate (L) and N-(2-hydroxybenzyl-1,4,7-triazacyclononane (HL) and their complexes with vanadium(IV)/(V). Localized and delocalized electronic structures in compounds containing the mixed valent [OV---O---VO] core

The synthesis of the tetradentate pendant arm macrocycles 1,4,7-triazacyclononane-N-acetate (L¹) and N-(2-hydroxybenzyl)-1,4,7-triazacyclononane (HL²) and their coordination chemistry with vanadium(IV) and (V) are reported. The following mononuclear species have been prepared and characterized by UV-Vis, IR spectroscopy: [L¹V^IVO(NCS)] (1), [L¹VO₂]·H₂O (2), [L²VO(NCS)] (3), [L²VO(NCS)]Cl (4), and [L²VO₂] (5). In addition, the dinuclear, mixed valent complexes [L₂¹V₂O₃]Br (6), [L₂²V₂O₃](ClO₄)·0.5acetone (7), and the homovalent complex [L₂²V₂O₃](ClO₄)₂ (8) have been synthesized. Complexes 2, 3, 6 and 7 have been characterized by single crystal X-ray crystallography. Crystal data: 2, space group P2₁c,a=9.944(4),b=6.701(3),c=18.207(8)Å, β=102.88(3)°, V=1182.7 ų, Z=4, D_calc=1.51 g cm⁻³, R=0.049 based on 4760 reflections; 3, space group Pbca, A=11.003(6), b=14.295(7), C=20.21(1) Å, V=3178.8 ų, Z=8, D_calc=1,50 g cm⁻³, R=0.057 based on 1049 reflections; 6, space Pbcn, a=12.922(3), B=13.852(3), C=12.739(3) Å, V=2280.3 ų, Z=4, D_calc=1,75 g cm⁻³, R=0.047 based on 1172 reflections; 7, space group C2/c, A=23.553(9), B=13.497(5), C=20.951(8) Å, β=90.03(3)°, V=6660.2 ų, Z=8, D_calc=1.49 g cm⁻³, R=0.053 based on 3698 reflections. Complexes 6 and 7 are mixed valent V(IV)/(V) complexes containing the [OV---O---VO]³⁺ core. In the solid state 6 belongs to class III (delocalized) and 7 to class I (localized) according to the Robin and Day classification of mixed valent compounds. A rationale for these differing electronic structures is given.     

Electrochemical synthesis and crystal structure of (3-trimethylsilylpyridine-2-thiolato) copper(I), [Cu4(3-Me3Sipyt)4]

(3-Trimethylsilyl-pyridine-2-thiolato-S,N)copper(I), [Cu(3-Me₃Sipyt)], was obtained by electrochemical oxidation of copper metal in an acetonitrile solution of the neutral ligand. The compound is tetrameric and the four copper atoms are arranged with distorted tetrahedral geometry, each copper atom being trigonally coordinated to one nitrogen and two sulfur atoms of three different ligands. Crystal data: 14₁/a, a=14.608(2), C=19.366(4) Å, V=4133(2), Å, Z=4, D_calc=1.581 g cm⁻³, R=0.0397 for 848 reflections.     

Molecular structures of Fe(II) complexes with mono- and di-protonated ethylenediamine-N,N,N′,N′-tetraacetate (Hedta and H2edta), as determined by X-ray crystal analyses

The molecular structure of the title complexes [Fe(H₂O)₄][Fe(Hedta)(H₂O)]₂ · 4H₂O (I) and [Fe(H[₂edta)(H₂O)] · 2H₂O (II) have been determined by single-crystal X-ray analyses. The crystal data are as follows: I: monoclinic, P2₁/n, A = 11.794(2), B = 15.990(2), C = 9.206(2) Å, β = 90.33(1)°, V = 1736.1(5) ų, Z = 2 and R = 0.030; II: monoclinic, C2/c, A = 11.074(2), B = 9.856(2), C = 14.399(2) Å, β = 95.86(1)°, V = 1563.3(4) ų, Z = 4 and R = 0.025. I is found to be isomorphous with the Mn^II analog reported earlier and to contain a seven-coordinate and approximately pentagonal-bipyramidal (PB) [Fe^II(Hedta)(H₂O]⁻ unit in which Hedta acts as a hexadentate ligand. The [Fe^II(H₂edta)(H₂O)] unit in II has also a seven-coordinate PB structure with the two protonated equatorial glycine arms both remaining coordinated, and thus bears a structural resemblance to the seven-coordinate [Co^II(H₂edta)(H₂O)] reported previously.     

Molecular structures and some properties of tris(2-aminoethyl) amine cobalt(III) complexes with thiocarboxylato-O,S such as 3-mercaptopropionato, 2-mercaptoacetato and their derivatives

Cobalt(III) complexes with a thiolate or thioether ligand, t-[Co(mp)(tren)]⁺ (2), t-[Co(mtp)(tren)]²⁺ (1Me) and t-[Co(mta)(tren)]²⁺ (2Me), (mp = 3-mercaptopropionate, MA = 3-(methylthio)propionate and MTA = 2-(methylthio)acetate) have been prepared in aqueous solutions. The crystal structures of 1, 2, 1Me and 2Me were determined by X-ray diffraction methods. The crystal data are as follows, t-[Co(mp)(tren)]ClO₄ (1CIO₄): monoclinic, P2₁/n, A = 10.877(8), B = 11.570(4), c = 12.173(7) Å, β = 92.20(5)°, V = 1531(1) ų, Z = 4 and R = 0.060; t-[Co(ma)(tren)]Cl·3H₂O (2Cl·3H₂O): monoclinic, P2₁/n, a = 7.7688(8), B = 27.128(2), C = 7.858(1) Å, β = 100.63(1)°, V = 1627.7(3) ų, Z = 4 and R = 0.066; (+)₄₆₅^CD-t-[Co(mtp)(tren)](ClO₄)₂ ((+)₄₆₅^CD-1Me(ClO₄)₂): orthorhombic, P2₁2₁2₁, A = 10.6610(7), B = 11.746(1), C = 15.555(1) Å, V = 1947.9(3) ų, Z = 4 and R = 0.068; (+)₄₆₅^CD-t-[Co(mta)(tren)](ClO₄)₂ ((+)₄₆₅^CD-2Me(ClO₄)₂): orthorhombic, P2₁2₁2₁, a = 10.564(1), B = 11.375(1), C = 15.434(2) Å, V = 1854.7(4) ų, Z = 4 and R = 0.047. All central Co(III) atoms have approximately octahedral geometry, coordinated by four N, one O, and one S atoms. All of the complexes are only isomer, of which the sulfur atom in the didentate-O,S ligands are located at the trans position to the tertiary amine nitrogen atom of tren. 1 and 1Me contain six-membered chelate ring, and 2 and 2Me do five-membered chelate ring in the didentate ligand. The chirality of the asymmetric sulfur donor atom in (+)₄₆₅^CD-1Me is the S configuration and that in (+)₄₆₅^CD-2Me is the R one. The ¹H NMR, ¹³C NMR and electronic absorption spectral behaviors and electrochemical properties of the present complexes are discussed in relation to their stereochemistries.     

Crown ether mediated cadmium halide dimers and polymers

The reactions of cadmium halides with the 15-membered macrocyclic crown ethers, 15-crown-5 and benzo-15-crown-5, have been carried out and six new complexes have been isolated and structurally characterized. Metal to ligand stoichiometries of 1:1, 2:1, 3:1 and 3:2 have been observed with a variety of different formulations. Examples of charge separated ion pairs ([(NH₄)(benzo-15-crown-5)₂]₂[Cd₂I₆]), halogen bridged monomers, dimers or polymers ([Cd(15-crown-5)(OHMe)(μ-Br)CdBr₃], [Cd(15-crown-5)(μ-Br)₂CdBr(μ-Br)]₂(isolated from the same reaction mixture) and [(CdCl₂)₂CdCl₂(15-crown-5)]_n), and hydrogen bonded finite chains or polymers ([(Cd(OH₂)₂(15-crown-5)][CdI₃(OH₂)]₂·2(15-crown-5)·2CH₃CN and [CdI₂(OH₂)₂(THF)]·benzo-15-crown-5) have been isolated. Three different types of 15-crown-5 coordination modes have been observed in these complexes. In-cavity coordination resulting in pentagonal bipyramidal geometries about Cd²⁺ was observed in [(CdCl₂)₂CdCl₂(15-crown-5)]_n, [Cd(15-crown-5)(OHMe)(μ-Br)CdBr₃], and [Cd(OH₂)₂(15-crown-5)][CdI₃(OH₂)]₂·2(15-crown-5)·2CH₃CN, [Cd(15-crown-5)(μ-Br)₂CdBr(μ-Br)]₂ displays out-of-cavity coordination with one etheric donor distorted into an axial position of a distorted pentagonal bipyramid. The third coordination mode is secondary sphere coordination via hydrogen bonding which is observed for [Cd(OH₂)₂(15-crown-5)][CdI₃(OH₂)]₂·2(15-crown-5)·2CH₃CN. The good fit of Cd²⁺ within the cavity of 15-crown-5 results in shorter bonding contacts and a more narrow distribution in Cd---O values (2.273(7)-2.344(6) Å) than observed for cadmium halide complexes of 18-crown-6 (Cd---O = 2.69(1)–2.81(1) Å).     

Copper(II) complexes with (2-hydroxybenzyl-2-pyridylmethyl)amine–Hbpa: syntheses, characterization and crystal structures of the ligand and [Cu(II)(Hbpa)2](ClO4)2·2H2O

Copper(II) complexes were synthesized and characterized by means of elemental analysis, IR and visible spectroscopies, EPR and electrochemistry, as well as X-ray structure crystallography. The group consists of discrete mononuclear units with the general formula [Cu(II)(Hbpa)₂](A)₂·nH₂O, where Hbpa=(2-hydroxybenzyl-2-pyridylmethyl)amine and A=ClO₄ ⁻, n=2 (1), CH₃COO⁻, n=3 (2), NO₃ ⁻, n=2 (3) and SO₄ ²⁻, n=3 (4). The structures of the ligand Hbpa and complex 1 have been determined by X-ray crystallography. Complexes 1–4 have had their UV–Vis spectra measured in both MeCN and DMF. It was observed that the compounds interact with basic solvents, such that molecules coordinate to the metal in axial positions in which phenol oxygen atoms are coordinated in the protonated forms. The values were all less than 1000 M⁻¹ cm⁻¹. EPR measurements on powdered samples of 1–3 gave g/A values between 105 and 135 cm⁻¹, typical for square planar coordination environments. Complex 4·3H₂O exhibits a behaviour typical for tetrahedral coordination. The electrochemical behaviour for complexes 1 and 2 was studied showing irreversible redox waves for both compounds.     

Dirhodium(II) tetrakis[N,N-dimethyl-2-pyrrolidone-5(S)-carboxamide]. Structural effects on enantioselection in metal carbene transformations

The preparation and structural characterization of dirhodium(II) tetrakis[N,N-dimethyl-2-pyrrolidone-5(S)-carb- oxamide], Rh₂(5S-DMAP)₄, a new sterically-demanding catalyst for enantioselective metal carbene transformations, is described. The pyrrolidone ligands are arrayed around the dirhodium(II) core with two oxygen and two nitrogen donor atoms, each oriented cis, bound to each octahedral rhodium. The crystal structure of this compound has been determined to be that of Rh₂(5S-DMAP)₄(CH₃CN)₂·CH₃CN·6H₂O: space group P2₁2₁2₁ with cell constants a= 12.685(4), b=15.050(3), c=24.035(4) Å; V=4588.5(1.9) ų, Z=4, R=0.0316, Rh---Rh DISTANCE =2 4538(5) Å. Decreased activity for diazodecomposition catalyzed by Rh₂(5S-DMAP)₄ is observed, and enantiocontrol for cyclopropanation and carbon-hydrogen insertion is lower than expected by analogy to the corresponding di- rhodium(II) tetrakis[methyl 2-pyrrolidone-5(S)-carboxylate], Rh₂(5S-MEPY)₄ Electronic stabilization of the in- termediate metal carbene is absent in reactions catalyzed by Rh₂(5S-DMAP)₄.