Thioether Donor Research Articles

Metal-ion complexation in aqueous solutions of 1 - thia-4,7-diazacyclononane-, 1-thia-4,8-diazacyclodecane and 2,5-diazahexane-N,N′-diacetic acid

The stability constants of the macrocyclic 1-thia-4,7-diazacyclononane-and 1-thia-4,8-diazacyclodecane-N,N′-diacetic acid (H2L1 and H2L2) and of the open-chain 2,5-diazahexane-N,N′-diacetic acid (H2L3) with MgII, CaII, SrII, BaII, MnII, CoII, NiII, CuII, ZnII, CdII, PbII and LaIII have been determined in aqueous solution (25 °C, 0.1 mol dm–3 KNO3) by pH potentiometry, and in some cases in combination with visible absorption spectrophotometry. The complexation enthalpies with CuII have been determined by adiabatic calorimetry. The electronic absorption spectra of the complexes of CuII and NiII were also recorded. All metal-ion complexes with H2L1 are stronger than with H2L3, even for the harder metal ions. The presence of the thioether donor particularly enhances covalent bonding with CuII as indicated by a higher heat of complexation, a more favourable entropy change and a stronger ligand-field strength. The change in stability of the complexes upon replacing H2L1 with a five-membered chelate ring between the metal ion and the two tertiary nitrogens, by H2L2 having a six-membered one, is dependent on the metal-ion size. The larger metal ions are destabilised relative to the small metal ions: the metal ion size-based selectivity for this pair of ligands is controlled by the chelate-ring size. Binding of CuII by H2L2 is sterically much more efficient than by H2L1 and is evidenced by a higher heat of complexation and a stronger ligand field.

Enforced coordination of chromium(III) to a thioether donor in an encapsulated complex

The synthesis, structure and preliminary spectroscopic and electrochemical properties of a hexadentate chromium(III) complex of a mixed sulfur–nitrogen containing ligand, with the 3-thia-6,10,13,16,19-pentaazabicyclo[6.6.6]icosane macrobicyclic structure, are reported.

A square-planar NiS4unit with an aliphatic thiolato–thioether donor set: a carbon monoxide dehydrogenase model that binds CO

Ni+–CO was generated by using a newly prepared square-planar nickel compound with an aliphatic thiolato–thioether sulfur ligand, with relevance to the nickel centre of carbon monoxide dehydrogenase.

Synthesis and spectroscopic properties of the encapsulated cobalt(III) complexes derived from the unsymmetrically substituted ligand 5-methyl-5-(4-amino-2-azabutyl)-3,7-dithianonane-1,9-diamine (N4S2)

The cobalt(III) complex of the unsymmetricallysubstitutedligand5-methyl-5-(4-amino-2-azabutyl)-3, 7-dithianonane-1, 9-diamine (NS) has been prepared. The complex reacts with formaldehyde and ammonia, and formaldehyde and nitromethane, to form the encapsulated complexes [(8-methyl-6, 10-dithia-l, 3, 13, 16, 19-pentaaza-bicyclo[6.6.6]icosane)cobalt(III)] perchlorate ([Co(AZANSsar)](ClO)) and [(l-methyl-8-nitro-3, 13-dithia-6, 10, 16, 19-tetraazabicyclo[6.6.6]icosane)cobalt(III)] perchlorate ([Co(NONSsar)](ClO)), respectively. The nitro-substituted encapsulated metal complex is readily reduced to the NH -substituted compound; this substituent is replaced to form, successively, chloro- and proteo-capped complexes. The uncapped and the nitro-capped complexes have been characterized by single-crystal X-ray study: crystals of the former complex are orthorhombic, space group, P222, a = 8.963 (2) A, b = 13.293 (2) A, c = 18.229 (6) A, Z = 4, R = 0.030 (1756 F); crystals of the latter are monoclinic, space group, P2/n, a = 15.669 (6) A, b = 9.620 (2) A, c = 17.772 (2) A, β = 105.26 (2)°, Z = 4, R = 0.040 (3317 F). The octahedral ligand-field parameters 10Dq and B are progressively reduced as the number of thioether donors increases, a result of the increased covalency associated with the thioether coordination. Comparison of the solution circular dichroism for Co(NS) complexes reveals that the net positive rotational strength for the A absolute configuration increases with the number of thioether groups coordinated to the metal.

Transition-metal complexes with sulfur ligands. Part LXXXIV. CH 3 complexes with [NiS] fragments as models for CO dehydrogenase. Synthesis and properties of [Ni(‘MeS 2’) 2] and (NMe 4)[Ni(CH 3)(‘MeS 2’) 2] (‘MeS 2’ −= o-(methylthio)thiophenolate(1−))

Reaction of [Ni(‘MeS 2’) 2] ( 1) (‘MeS 2’ −= o-(methylthio)thiophenolate(1−)) with methyl lithium yields the methyl complex anion [Ni(CH 3)(‘MeS 2’) 2] − which can be isolated as (NMe 4)[Ni(CH 3)(‘MeS 2’) 2] ( 2). The molecular structures of 1 (monoclinic, P2 1/ c, Z=2, a=791.5(5), b=1083.1(8), c=894.1(6) pm, β=92.79(5)°, R/ R w=0.063/0.049) and 2·MeOH (monoclinic, P2 1/c, Z= 4, a=1901.0(12), b=830.3(9), c=1716.1(14) pm, β=113.84(5)°, R/ R w=0.072/0.053) were elucidated by X-ray structure analysis. 1 contains a planar [NiS 4] core, 2·MeOH exhibits a planar [NiS 3C] core, one thioether donor being decoordinated. 1 does not react with CO but 2 undergoes immediate reaction with CO. Monitoring the reaction by IR spectroscopy yields evidence for the intermediate formation of labile Ni-acetyl complexes. Reaction of 2 with protonic acids (HBF 4/Et 2O, HCl/THF) yields CH 4 and 1. Thermolysis of 2 in solid state as well as in acetone solution at room temperature, however, gives C 2H 6, and 1 was identified as one of the resulting nickel species.

Übergangsmetallkomplexe mit Schwefelliganden, LXXXVI. Säure-Base- und Redox-Reaktionen von [Ni(′MeS2′)2] mit H+, PMe3, NO+ und NO. Röntgenstrukturanalyse von [Ni(PMe3)(′MeS2′)2] (′MeS2′ = o-(Methylthio)thiophenolat(1–)) / Transition-Metal Complexes with Sulfur Ligands, LXXXVI. Acid-Base and Redox Reactions of [Ni(′MeS2')2] with H+, PMe3, NO+ and NO. X-Ray Structure Determination of [Ni(PMe3)(′MeS2′)2] (′MeS2′ = o-(methylthio)thiophenolate(1–))

In order to elucidate specific properties of nickel-sulfur complexes, addition and substitution reactions of [Ni(′MeS2′)2] (1) were investigated. 1 is rapidly hydrolyzed by aqueous HCl yielding ′MeS2′–H and Ni(II) ions. 1 coordinates phosphines as coligands, thioether donors decoordinate, however, simultaneously. The monophosphine complex [Ni(PMe3)(′MeS2′ )2] (2) was characterized by X-ray structure determination. It contains a square-planar NiS3P unit and one decoordinated thioether group. Redox reactions of 1 occur with NO+ and NO, yielding the binuclear nitrosyl complexes cis- and trans-[Ni(NO)(′MeS2′)]2 (3) and the disulfide [′MeS2']2•

Thallium macrocyclic chemistry: synthesis and crystal structures of [Tl([18]aneN2S4)]PF6and [Tl([18]aneS6)]PF6([18]aneN2S4= 1,4,10,13-tetrathia-7,16-diazacyclooctadecane, [18]aneS6= 1,4,7,10,13,16-hexathiacyclooctadecane)

Reaction of TIPF6 with 1 molar equivalent of L (L =[18]aneN2S4 or [18]aneS6) in refluxing MeCN followed by addition of diethyl ether affords the 1 : 1 complex [TlL]PF6 in high yield. The complex [Tl([18]aneN2S4)]PF6 crystallises in the triclinic space group P with a= 9.733(6), b= 9.775(6), c= 11.370(8)A, α= 102.68(4), β= 92.35(4), γ= 95.05(5)° and Z= 2. The structure shows the thallium(I) ion occypying the ‘cardle’ formed by the macrocycle and bound via an [N2S2+ S2] donor set, Tl–S(4) 3.1299(13), Tl–S(13) 3.1445(13), Tl–N(7) 2.834(4), Tl–N(16) 2.992(4), Tl ⋯ S(1) 3.4778(15) and Tl ⋯ S(10) 3.4739(14)A. This leaves the top face of the metal centre exposed, except for long-range interactions with two further thioether donor atoms from adjacent [Tl([18]aneN2S4)]+ cations, Tl ⋯ S(1′) 3.643(1)(related by 1 –x, 1 –y, 1 –z), Tl ⋯ S(10″) 3.676(1)A(related by 1 –x, 1 –y, -z), and one F atom of the PF6– counter-ion, Tl ⋯ F(1) 3.326(4)A. The complex [Tl([18]aneS6)]PF6 crystallises in the monoclinic space group P21/c with a= 11.0279(13), b= 18.617(5), c= 10.8568(13)A, β= 96.876(13)° and Z= 4. The structure shows TlI interacting with all six macrocyclic thioether donors; two of those interactions, Tl–S(1) 3.164(5) and Tl–S(13) 3.205(7)A, being considerably shorter than the other four, Tl ⋯ S(4) 3.370(5), Tl ⋯ S(7) 3.315(6), Tl ⋯ S(10) 3.347(7) and Tl ⋯ S(16) 3.356(6)A. There are additional long-range interactions with two further thioether donors from adjacent [Tl([18]aneS6)]+ cations, Tl ⋯ S(7prime;) 3.689(6)(related by –x, 1 –y, 1 –z) and Tl ⋯ S(16″) 3.688(6)A(related by 1 –x, 1 –y, 1 –z). There is also a long-range contact with one F atom of the PF6– counter-ion, Tl ⋯ F(6) 3.052(24)A.

Thioether macrocyclic chemistry: Synthesis of [RhCl([15]aneS 5)] 2+ and [Ru(PPh 3)([15]aneS 5)] 2+. The single crystal X-ray structure of [Ru(PPh 3)([15]aneS 5)](BPh 4) 2 ([15]aneS 5 = 1,4,7,10,13-pentathiacyclopentadecane)

Reaction of RhCl 3 with one molar equivalent of [15]aneS 5 in refluxing MeOH yields a yellow solution containing the complex cation [RhCl([15]aneS 5)] 2+. Addition of excess NH 4PF 6 affords the complex [RhCl([15]aneS 5)](PF 6) 2 as a yellow solid, which can be recrystallized from MeCN. [RhCl([15]aneS 5)] 2+ shows two irreversible reductions at E pc = −0.78 and −1.93 V vs Fc/Fc + at a scan rate of 200 mV s −1. Treatment of [RuCl 2(PPh 3) 3] with one molar equivalent of [15]aneS 5 in refluxing MeOH, followed by addition of excess NH 4PF 6 or NaBPh 4 affords [Ru(PPh 3)([15]aneS 5)]X 2 (X = PF 6 − or BPh 4 −) as a yellow solid, which can be recrystallized from MeCN/diethyl ether. [Ru(PPh 3) ([15]aneS 5)](BPh 4) 2 has been characterized by X-ray crystallography. The structure confirms coordination of all five macrocyclic thioether donors, RuS(1) = 2.3371(15), RuS(4) = 2.3785(12), RuS(7) = 2.4458(10), RuS(10) = 2.3732(15), RuS(13) = 2.3099(10) Å, and the P donor of the PPh 3 ligand, RuP = 2.3679(8) Å, to give an overall distorted octahedral stereochemistry at ruthenium(II).

Übergangsmetallkomplexe mit Schwefelliganden, LXXVI Redox- und Additionsreaktionen von Nickelkomplexen mehrzähniger Thioether-Thiolat-Liganden. Röntgenstrukturanalysen von (NMe4)2[Ni(′S2′)2] und [Ni(′S4 – C3′)(PMe3)] / Transition Metal Complexes with Sulfur Ligands, LXXVI Redox and Addition Reactions of Nickel Complexes with Multidentate Thioether-Thiolato Ligands. X-Ray Structure Determinations of (NMe4)2[Ni(′S2′)2] and [Ni(′S4–C3′)(PMe3)

In order to elucidate specific properties of nickel sulfur complexes, redox and addition-elimination reactions of [Ni(′OS4')]2, [Ni(′NHS4')]2, [Ni(′S5')], [Ni('S4—C5')], and [Ni('S4—C3')] were investigated ('OS4′ 2' = 2,2'-bis(2-mercaptophenylthio)diethylether(2—), 'NHS4'2- = 2,2'-bis(2-mercaptophenylthio)diethylamine(2—), 'S5'2- = 2,2'-bis(2-mercaptophenylthio)diethylsulfide(2—), 'S4-C5'2- = 1,5-bis(2-mercaptophenylthio)pentane(2—), 'S4—C3'2- = 1,3-bis(2-mercaptophenylthio)propane(2—)). Cyclovoltammetry proves the complexes to be redox inactive between —1.4 and +0.8 V vs. NHE. Above +0.8 V the complexes are irreversibly oxidized, below —1,4 V desalkylation takes place and [Ni(′S,′)2]2- is formed. An X-ray structure analysis was carried out of (NMe4)2[Ni(′S2')2], which shows a planar anion with the Ni center in a nearly perfect square planar coordination. Distances and angles are practically identical to those in the [Ni(′S2')2-] monoanion. The complexes coordinate only phosphines as coligands, but thioether donors simultaneously decoordinate and, dependant of reaction temperature, mono- or trisphosphine complexes are formed. [Ni(′S4—C3')(PMe3)] was characterized by X-ray structure analysis and exhibits a square pyramidal coordination geometry.

Quinquedentate Coordination of 6-Methyl-1,11-dithia-4,8-diazacyclotetradecan-6-amine to Cobalt(III). X-Ray Crystal Structure of the [Co(N3S2)(OOCCH3)] (ClO4)2.H2O Complex

The pendant arm macrocycle 6-methyl-1,11-dithia-4,8-diazacyclotetradecan-6-amine (7) can coordinate to cobalt(III) as a quinquedentate N3S2 ligand . Spectroscopy indicated a geometry with the macrocycle folded and the pendant amine and the unidentate donor in cis dispositions for the [Co(7) Cl ]2+ and [Co(7)(OOCCH3)]2+ products isolated. An X-ray crystal structure analysis of [Co(7)(OOCCH3)](ClO4)2.H2O characterized the cis stereochemistry. The complex crystallized in the Pbca space group, a 10.620(9), b 13.926(9), c 32.35(2)Ǻ, and analysis defined a distorted octahedral geometry with the primary and two secondary nitrogen donors occupying an octahedral face with relatively short Co-N bonds [1.937(7)-1.950(7)Ǻ], the acetate ion [Co-O 1.905(6)Ǻ] trans to one of the secondary amine donors and thioether donors [Co-S 2.223(3), 2.227(3)Ǻ] trans to the other nitrogen donors. Significant angle distortions occur around the metal ion. Base hydrolysis of the chloro complex is slow and stereoretentive , with a rate constant of 1.08×103 dm3 mol-1 s-1 at 25°C, 15-fold faster than for the pentaaza analogue.

Model monooxygenase reactivity by binuclear two-coordinate copper(I) complexes extends to new ligand systems containing nitrogen and sulphur donors

The oxygen insertion reaction exhibited by binuclear two-coordinate copper(I) complexes derived from bis-imine Ligands extends to systems containing additional benzimidazole, tertiary amine and thioether donor groups; an inverse correlation has been found between the rate of the reaction and the basicity of the donor group.

Mercury thioether chemistry: The synthesis and X-ray crystal structure of [Hg([15]aneS 5](PF 6) 2

Reaction of mercury sulphate with one molar equivalent of [15]aneS 5 (1,4,7,10,13-pentathiacyclopentadecane) in refluxing methanol/water for 2 h affords a colourless solution containing the complex cation [Hg([15]aneS 5)] 2+. Addition of excess NH 4PF 6 gives a white precipitate which can be recrystallized from acetonitrile/diethyl ether to give [Hg([15]aneS 5)](PF 6) 2 as a white solid. An X-ray crystal structure determination shows the mercury (II) ion and one thioether sulphur-donor occupying a site of m symmetry with the macrocycle disordered over two equally likely conformations, neither of which possesses m symmetry, but which are mirror images of each other. The mercury (II) ion is bound to all five thioether donors of the macrocycle, giving a distorted square-based pyramidal stereochemistry, HgS = 2.491(6), 2.717(6), 2.561(8) Å.

Notes. Geometric effects on the redox properties of complexes [RuX2(R2SO) n (R2S)4-n ] and the implications for oxidation catalysis

The electrochemistry of ruthenium(II) complexes of the type [RuX2(R2SO)n(R2S)4-n](where n= 1–4) have been studied with examples for fourteen of the fifteen possible isomers for this system. Cyclic voltammograms in CH2Cl2 reveal that a plot of E½versus n is linear with a slope of +0.22 V, indicating that each replacement of a sulphoxide ligand with a thioether donor increases the energy of the highest occupied molecular orbital (dπ) by ca. 4.8 kcal (ca. 20.08 kJ). When n= 2 five different structural isomers are possible, all of which have been synthesized. Their E½ values range from + 0.72 to 1.42 V. Ligand-additivity theory provides a consistent rational for interpretation of the results. Catalytic studies are described which reveal that only one structure, all-trans-[RuX2(R2SO)2(R2S)2], is catalytically active for O2 oxidations of alcohol. A discussion of the relationship between structure and redox catalysis is included.

Coordination behavior of the ligand 1,9-bis(3,5-dimethyl-1-pyrazolyl)-3,7-dithianonane (bddn) towards first-row transition metals. X-ray structure of [Cu(bddn)(H 2O)](BF 4) 2

The synthesis and characterization of the ligand 1,9-bis(3,5-dimethyl-1-pyrazolyl)-3,7-dithianonane (bddn) and its coordination compounds, viz. [M(L)(X) 2] where M is Co 2+, Zn 2+; X is Cl −, Br −, NCS −, and [Cu(L)(H 2O)](BF 4) 2 are described. The X-ray structure of [Cu(bddn)(H 2O)](BF 4) 2 has been determined. The compound crystallizes from ethanol in the monoclinic space group P2 1/ c with unit-cell parameters a=18.508(5), b=9.253(3), c=15.743(5) Å, β=107.91(3)°, V=2565.5 Å 3, D calc=1.57 g/cm 3 for Z=4. The structure was refined to R=0.099 and R w=0.116 for 1841 unique reflections with I>σ( I). The copper(II) ion is coordinated by two pyrazole nitrogen donors, two thioether donors and a water molecule in a trigonal bipyramidal environment, with the two pyrazoles in an unusual cis position. The donor atoms at the axial positions area nitrogen and a sulfur, the equatorial plane donors are nitrogen, sulfur and the oxygen atom. From the ligand field spectra, the infrared patterns and the X-ray powder patterns it was concluded that the structures of the cobalt(II)- and zinc(II)-containing compounds are structurally similar to Zn(bddo)(NCS) 2, a previously reported chain like structure with an MN 2N′ 2 chromophore, in which the ligand S atoms do not bind to the metal ion.

Synthesis, structures, and electrochemistry of palladium and platinum macrocyclic complexes of [18]aneN2S4(1,4,10,13-tetrathia-7,16-diazacyclo-octadecane) and Me2[18]aneN2S4(7,16-dimethyl-1,4,10,13-tetrathia-7,16-diazacyclo-octadecane). Single crystal X-ray structures of [Pd(Me2[18]aneN2S4)][PF6]2·Me2CO, [Pd([18]aneN2S4)][BPh4]2, and [Pd2Cl2([18]aneN2S4)][PF6]2·2MeCN

Reaction of PdCl2 with the N2S4 donor macrocycles [18]aneN2S4(1,4,10,13-tetrathia-7,16-diazacyclo-octadecane) and Me2[18]aneN2S4(7,16-dimethyl-1,4,10,13-tetrathia-7,16-diazacyclo-octadecane) affords the 1 : 1 complex cations [Pd([18]aneN2S4)]2+ and [Pd(Me2[18]aneN2S4)]2+ respectively in high yield. The yellow complex [Pd(Me2[18]aneN2S4)][PF6]2·Me2CO crystallises in the orthorhombic space group Pcab, with a= 14.3369(15), b= 17.691 5(7), c= 24.295 2(11)A, and Z= 8. The single crystal X-ray structure of [Pd(Me2[18]aneN2S4)]2+ shows square-planar coordination at PdII with the four thioether donors of the macrocycle bound to the metal centre, Pd–S(1) 2.339 9(22), Pd–S(4) 2.333 1(22), Pd–S(10) 2.326 1(22), and Pd–S(13) 2.323 9(21)A; the two N atoms are non-bonding, Pd ⋯ N(7) 3.744(7) and Pd ⋯ N(16) 3.760(6)A. The green complex [Pd([18]aneN2S4)][BPh4]2 crystallises in the monoclinic space group P21/c, with a= 16.888 8(12), b= 16.553 3(15), c= 18.537 6(12)A, β= 93.144(8)°, and Z= 4. The structure of [Pd([18]aneN2S4)]2+ is markedly different to that of [Pd(Me2[18]aneN2S4)]2+ and shows the PdII ion co-ordinated to an N2S2 donor set in a square-planar configuration, Pd–S(1) 2.311(3), Pd–N(7) 2.123(7), Pd–S(13) 2.357(3), and Pd–N(16) 2.068(7)A; the S(1)–N(16)–S(13) linkage binds meridionally to the metal centre, The two remaining thioether donors interact at long range with the metal centre, Pd ⋯ S(10) 2.954(4) and Pd ⋯ S(4) 3.000(3)A with S(4)–Pd–S(10) 158.94(9)°. The overall stereochemistry at PdII is therefore tetragonally distorted octahedral with a formal [N2S2+ S2] co-ordination sphere. The structural differences between [Pd(Me2[18]aneN2S4)]2+ and [Pd([18]aneN2S4)]2+ are reflected in their spectroscopic and redox properties. Cyclic voltammetry of [Pd(Me2[18]aneN2S4)][PF6]2 in MeCN (0.1 mol dm–3 NBun4PF6 supporting electrolyte) at platinum electrodes shows a chemically reversible one-electron reduction at E1/2=–0.74 V vs. ferrocene–ferrocenium. Controlled potential electrolysis affords a bright yellow paramagnetic species which has been assigned on the basis of coulometry, e.s.r. and u.v.–visible spectroelectrochemistry as a mononuclear d9 PdI species. No oxidative activity is observed for [Pd(Me2[18]aneN2S4)][PF6]2 within the range of the solvent up to +2.0 V. In contrast, cyclic voltammetry of [Pd([18]aneN2S4)][PF6]2 shows a chemically reversible one-electron oxidation at E1/2=+0.57 V vs. ferrocene-ferrocenium (ΔEp= 195 mV at a scan rate of 150 mV s–1). Controlled potential electrolysis affords a bright-red paramagnetic product which is assigned on the basis of coulometry, e.s.r. and u.v.–visible spectroelectrochemistry as a mononuclear d7 PdIII species. Two irreversible reductions are also observed for [Pd([18]aneN2S4)][PF6]2 at Epc=–1.01 and –1.54 V vs. ferrocene–ferrocenium. Reaction of PdCl2 with Me2[18]aneN2S4 or [18]aneN2S4 in a 2 : 1 molar ratio affords the corresponding binuclear complexes [Pd2Cl2(Me2[18]aneN2S4)]2+ and [Pd2Cl2([18]aneN2S4)]2+. The complex [Pd2Cl2([18]aneN2S4)][PF6]2·2MeCN crystallises in the monoclinic space group C2/c, with a= 18.617(13), b= 15.569(11), c= 14.323(14)A, β= 113.59(5)°, and Z= 4. The single crystal X-ray structure of [Pd2Cl2([18]aneN2S4)]2+ shows each PdII bound in a square plane to two S-donors, Pd–S(1) 2.317(4), and Pd–S(7) 2.316(4)A, and to one N-donor, Pd–N(4) 2.049(13)A, of the macrocycle, and a terminal Cl– ligand, Pd–Cl 2.305(4)A. The Cl– ligand is displaced out of the least-squares plane S(1)–N(4)–S(7)–Pd by 0.0712 A due to the steric influence of the central methylene groups bridging the S-donors. The closest non-bonded interaction of 3.406(2)A is between two Pd atoms in adjacent molecules related by a crystallographic two-fold axis. The intramolecular Pd ⋯ Pd distance is 4.196(2)A. The synthesis and structures of the analogous mono- and bi-nuclear PtII complexes [Pt(Me2[18]aneN2S4)]2+, [Pt([18]aneN2S4)]2+, and [Pt2Cl2([18]aneN2S4)]2+ are also discussed.

Magneto-structural correlations and ESR spectra of dinuclear copper(II) complexes of thiophenophane ligands containing thioether donor atoms

Magnetic susceptibility data on powdered samples of the dinuclear complexes (CuCl 2 •L1) 2 and (CuCl 2 •L2) 2 (L1=2,5,8-trithia[9](2,5)thiophenophane; L2=2,5,9,12-tetrathia[13](2,5)thiophenophane) have been collected in the temperature range 5-297 K. The data have been fitted to the Friedberg magnetization expression containing a molecular field correction, and from the fit, values for intradimer exchange, interdimer exchange and g have been obtained. ESR spectra yield values for g ∥ and g ⊥ that give average g values for (CuCl 2 •L1) 2 and (CuCl 2 •L2) 2 . The experimental results are correlated with structural details of the complexes

The remarkable indifference of alkali metal cation binding constants to sidearm thioether and sulfoxide donors in azalariat ethers

The first example of a lariat ether containing a sulfur sidearm donor is reported here along with a comparison of cation binding strengths to Na+ and K+. The binding strength differs remarkably little from analogs completely lacking a sidearm donor group and similar results are observed for the novel sulfoxide analog.

Synthesis of a Cis-N2s2 Donor Macrocycle by Metal-Directed Condensation of Formaldehyde, Nitroethane and a Diaminodithiaalkane - Crystal-Structure of the (6-Methyl-6-Nitro-1,11-Dithia-4,8-Diazacyclotetradecane)-Copper(II) Perchlorate Product

Reaction of (3,7-dithianonane-1,9-diamine)copper(II) ion with nitroethane and formaldehyde in basic methanol gives the macrocyclic complex ion (6-methyl-6-nitro-1,II-dithia-4,8- diazacyclotetradecane )copper(II) in high yield. The complex as the perchlorate salt crystallizes in the monoclinic space group P21/n, a 15.008(5), b 8.606(3), c 17.967(4)Ǻ, β 113.79(2)�. The copper ion lies in a square plane of two nitrogen (average Cu-N 2.02 Ǻ) and two thioether (average Cu-S 2.295 Ǻ) donors, with perchlorate oxygens (Cu-O 2.46 and 2.70 Ǻ) in axial sites. Physical and structural properties of the CuIII complexes of the 14-membered cis-N2S2 macrocycle and the known analogous 14-membered N4-donor macrocycle 6-methyl-6-nitro-1,4,8,11- tetraazacyclotetradecane are compared.

Comparative Calorimetric and 1H N.M.R. Studies of the Interaction of Ag(I) With a Series of Mixed-Donor Macrocycles Incorporating Nitrogen, Oxygen and or Sulfur Donor Atoms

The interaction of silver ion with a range of mixed-donor macrocyclic ligands incorporating nitrogen, oxygen and/or sulfur donors has been investigated. Complementary calorimetric and n.m.r. studies in acetonitrile (and its deuterated derivative) were used to investigate the nature of the equilibria present as the metal/ ligand ratio was varied. In all systems the formation of a 1 : 1 species was observed, with a 1:2 (metal/ ligand ) species also being formed in the presence of excess ligand in the majority of cases. Enthalpies of formation for the various complexes have been determined. Stepwise stability constants for the respective [ AgL ]+ + L ↔ [AgL2]+ equilibria have been estimated from the calorimetric titration data, and the factors promoting the formation of the 1:2 species are discussed. The studies confirm the enhanced affinity of AgI for thioether donors over ether donors.

Metal ion size selectivity of 1-Thia4, 7-diazacyclononane (9-aneN:S), and other tridentate macrocycles. A study by molecular mechanics calculation, structure determination, and formation constant determination of complexes of 9-aneN 2S

Several aspects of the coordination chemistry of the tridentate cyclononane type macrocycles are examined using molecular mechanics calculations, crystallography and formation constant determinations. The molecular mechanics calculations show that small metal ions coordinate best to these ligands, such that metal ions with a covalent radius of 1.25 A fit best into 9-aneS3 and 1.40 Ä fit best into 9-aneN3 (9-aneS3 = 1,4,7-trithiacyclononane, 9-aneN3 = 1,4,7-triazacyclononane). For mixed donor members of the series such as 9-aneN:S (1-thia4,7-diaza- cyclononane) the disparity in M-L bond length between the M-N and M-S bond lengths leads to a much higher strain situation than expected from the strain energies of the 9-aneN3 and 9-aneS3 complexes. This accounts for the order of ligand field strength in complexes of these ligands of 9-aneS 3 > 9-aneN 3 > 9-aneN:S. It is concluded that in the absence of the strain effects encountered in mixed donor ligands containing the thioether donor group, the latter group should always be higher in the spectrochemical series than ligands containing the secondary nitrogen donor. The formation constants of 9-aneN:S with Ni(II), Zn(II), Cd(II), Co(II), Fe(II), and Pb(II) are reported. Comparison of these with the formation constants for the 9-aneN:O and 9-aneN3 complexes shows that the macrocyclic effect (the difference in stability between the complex of the macrocycle and of its open chain analogue) is much higher for small metal ions, and small with large metal ions, in agreement with the molecular mechanics calculations which show that the cyclononane macrocycles coordinate best with small metal ions. The crystal structure of the complex [Cu(9-aneN:S)Br:] is reported: monoclinic, space group P2 1/n, with cell dimensions a = 7.603(1), b = 13.167(2), and c -- 10.873(2) Å, and β = 91.94- (1)°, Z = 4. Final conventional R = 0.061. The un-