Gillian Reid

Mercury thioether chemistry: The synthesis and structure of [Hg([9]aneS3)2](PF6)2 ([9]aneS3 = 1,4,7-trithiacyclononane)

Abstract Reaction of HgSO4 with 2 molar equivalents of [9]aneS3 in refluxing H2O-MeOH (1:1 v/v) for 1 h affords a colourless solution from which the complex [Hg([9]aneS3)2](PF6)2 can be isolated by addition of NH4PF6. [Hg([9]aneS3)2](PF6)2· 1 3 H2O crystallizes in the monoclinic space group I2/a, with a = 11.8667(10), b = 15.1631(23), c = 14.454(4) A, β = 90.224(19)°, V = 2600.7 A3, Dc = 2.18 g cm−3, Z = 4. The single crystal X-ray structure of the complex shows a crystallographically centrosymmetric cation with hexathia coordination at mercury(II), with Hgue5f8S(1) = 2.728(3), Hgue5f8S(4) = 2.638(3) and Hgue5f8S(7) = 2.712(3) A. This structure closely resembles that of the silver(I) analogue, [Ag([9]aneS3)2]+, which also shows hexathia coordination. Cyclic voltammetry of [Hg([9]aneS3)2]2+ shows a chemically reversible reduction at E1/2 = −0.15 V (ΔEP = 80 mV) vs Fc/Fc+ at a scan rate of 90 mV s−1.

Stereochemical and redox properties of palladium complexes of 1,4,10,13-tetrathia-7,16-diazacyclo-octadecane

The square planar S4 donor complex [Pd(L1)]2+(L1= 7,16-dimethyl-1,4,10,13-tetrathia-7,16-diazacyclo-octadecane) shows a reversible PdII/I redox couple at E½–0.74 V vs. Fc/Fc+; in contrast, the complex [Pd(L2)]2+(L2= 1,4,10,13-tetrathia-7,16-diazacyclo-octadecane) shows distorted octahedral N2S2+ S2 co-ordination, and a reversible PdII/III couple at E½+0.57 V vs. Fc/Fc+(ferrocene/ferrocinium).

Mercury thioether chemistry: The synthesis and X-ray crystal structure of [Hg([15]aneS5](PF6)2

Reaction of mercury sulphate with one molar equivalent of [15]aneS5 (1,4,7,10,13-pentathiacyclopentadecane) in refluxing methanol/water for 2 h affords a colourless solution containing the complex cation [Hg([15]aneS5)]2+. Addition of excess NH4PF6 gives a white precipitate which can be recrystallized from acetonitrile/diethyl ether to give [Hg([15]aneS5)](PF6)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, Hgue5f8S = 2.491(6), 2.717(6), 2.561(8) A.

Mercury macrocyclic complexes: The synthesis of [Hg([18]aneN2S4)]2+ and [Hg(Me2[18]aneN2S4)]2+. The single crystal x-ray structure of [Hg([18]aneN2S4)](PF6)2??4/3H2O

Reaction of HgSO 4 with one molar equivalent of L{L = [18]aneN 2 S 4 (1,4,10,13-tetrathia-7,16-diazacyclooctadecane) or Me 2 [18]aneN 2 S 4 (7,16-dimethyl-1,4,10,13-tetrathia-7,16-diazacyclooctadecane)} in refluxing MeOH-H 2 O for 15 min affords a colourless solution containing the complex cation [Hg(L)] 2+ . Addition of excess PF 6 − counterion gives the complex [Hg([18]aneN 2 S 4 )](PF 6 ) 2 ·4/3H 2 O as a cream coloured solid. A single crystal X-ray structure determination shows mercury(II) bound to a severely distorted octahedral arrangement of the six macrocyclic donor atoms, Hgue5f8S = 2.655(5), 2.735(4), 2.751(4), 2.639(5) A, Hgue5f8N = 2.473(11), 2.472(17) A. The cation is in a rac configuration with the two SCH 2 CH 2 NCH 2 CH 2 S linkages bound meridionally to the metal centre.

Platinum metal complexes of mixed thia/oxa ionophores. The synthesis and single-crystal X-ray structures of [Pd([15]aneS2O3)2][PF6]2 and [RuCl(PPh3)([15]aneS2O3)2]PF6•H2O ([15]aneS2O3 = 1,4,7-trioxa-10,13-dithiacyclopentadecane)

The synthesis and characterisation of a series of mixed thia/oxa donor macrocyclic complexes cis-[MCl2([15]aneS2O3)], [M([15]aneS2O3)2]2+(M = Pd or Pt), [MCl2([15]aneS2O3)2]+(M = Rh or Ir), and [RuCl(PPh3)([15]aneS2O3)2]+([15]aneS2O3= 1,4,7-trioxa-10,13-dithiacyclopentadecane) are described. Reaction of MCl2(M = Pd or Pt) with one molar equivalent of [15]aneS2O3 affords the complex cis-[MCl2([15]aneS2O3)]; addition of a second equivalent affords the bis complex cations [M([15]aneS2O3)2]2+. The complex [Pd([15]aneS2O3)2][PF6]2 crystallises in the monoclinic space group P21/c, a= 10.394(4), b= 14.003(4), c= 11.675(5)A, β= 104.22(3), U= 1 647 A3, and Z= 2. The single-crystal X-ray structure shows the PdII occupying a crystallographic inversion centre, with square-planar co-ordination by the [15]aneS2O3 ionophores through the thioether S-donors, Pd–S(1) 2.314 9(10), Pd–S(4) 2.301 7(10)A. The O-donors point away from the PdII to give a relatively flattened complex. Reaction of MCl3·3H2O (M = Rh or Ir) with two molar equivalents of [15]aneS2O3 affords the complex cations [MCl2([15]aneS2O3)2]+. Treatment of [RuCl2(PPh3)3] with two molar equivalents of [15]aneS2O3 gives the complex cation [RuCl(PPh3)([15]aneS2O3)2]+. The complex [RuCl(PPh3)([15]aneS2O3)2]PF6·H2O crystallises in the orthorhombic space group Pbcn, a= 19.252 6(14), b= 25.968(3), c= 18.903 3(23)A, U= 9 451 A3, and Z= 8. The single-crystal X-ray structure shows octahedral co-ordination at RuII with the Cl– and PPh3 ligands mutually trans, Ru–Cl 2.458(3), Ru–P 2.319(3)A. The [15]aneS2O3 ligands are bound exocyclically to RuIIvia four thioether S-donors, Ru–S 2.390(3), 2.394(3), 2.395(3), 2.405(3)A. The O-donors of [15]aneS2O3 are not bound to the metal centre but, unlike the complex [Pd([15]aneS2O3)2]2+, are directed towards the face occupied by the Cl– ligand and away from the sterically bulky PPh3 ligand. The [15]aneS2O3 ligands in [RuCl(PPh3)([15]aneS2O3)2]+ therefore form a cavity at one face of the metal centre in which the co-ordinated Cl– ligand sits.

Transition metal complexes of homoleptic polythia crowns

The binding of transition metal ions to polydentate macrocyclic ligands to give mono-, bi- and poly-nuclear complexes is well known. We have been investigating the complexation of transition metal ions, particularly those of the platinum group metals, by the homoleptic polythia crown ligands 1,4,7,10,13,16-hexathiacyclooctadecane (L1), 1,4,8,11-tetrathiacyclotetradecane (L2) and 1,4,7-trithiacyclononane (L3). These ligands were attractive since they would be expected to bind effectively to the relatively soft second and third row metal ions and lead to the formation of complexes exhibiting unusual stereochemical, electronic and redox properties.

Rhodium thioether chemistry: the synthesis and electrochemistry of [Rh([18]aneS6)]3+ and the ring-opened vinyl thioether complexes [Rh([18]aneS6-H)]2+ and [Rh(Me2[18]aneN2S4-H)]2+ ([18]aneS6 = 1,4,7,10,13,16-hexathiacyclooctadecane, Me2[18]aneN2S4 = 1,10-dimethyl-1,10-diaza-4,7,13,16-tetrathiacyclooctadecane)

Abstract Reaction of [RhCl(C 8 H 14 ) 2 ] 2 with two molar equivalents of [18]aneS 6 in refluxing MeOH/H 2 O with 40% HBF 4 (2 cm 3 ) for 8 h under nitrogen affords the cream coloured precipitate of [Rh([18]aneS 6 )](BF 4 ) 3 . In the absence of acid a bright red solution is generated from which the ring-opened vinyl thioether complex [Rh([18]aneS 6 -H)](PF 6 ) 2 can be isolated upon addition of NH 4 PF 6 . The analogous ring-opened complex [Rh(Me 2 [18]aneN 2 S 4 - H] 2+ can be prepared by treatment of [RhCl(C 8 H 14 ) 2 ] 2 with two molar equivalents of Me 2 [18]aneN 2 S 4 in refluxing MeOH/H 2 O under nitrogen for 3 h, followed by addition of a few drops of NEt 3 and further refluxing. [Rh([18]aneS 6 )](BF 4 ) 3 exhibits two chemically reversible one-electron redox couples at E 1/2 = −0.53 and −0.90 V vs Fc/Fc + , assigned as rhodium(III)/(II) and rhodium(II)/(I) couples, respectively. The golden yellow rhodium(II) complex shows a strong, near axial ESR signal with g 1 = 2.012, g 2 = 2.085 and g 3 = 2.099, similar to that observed for [Rh([9]aneS 3 ) 2 ] 2+ . These reductions have been monitored by in situ electronic spectroscopy using an optically transparent electrode cell, which confirms the chemical reversibility of both processes. [Rh([18]aneS 6 -H)] 2+ shows two ill-defined, irreversible reductions at more cathodic potentials. By contrast, [Rh(Me 2 [18]aneN 2 S 4 -H)] 2+ shows two chemically reversible reductions at E 1/2 = −1.11 and −1.56 V vs Fc/Fc + , corresponding to rhodium(III)/(II) and rhodium(II)/(I) couples, respectively. These reduction products are much less stable than for the ring-closed [18]aneS 6 complexes. A weak, axial ESR signal with g ⊥ = 2.147, g ⊥ = 2.012 and A ⊥ = 21 G has been observed corresponding to the first reduction product of [Rh(Me 2 [18]aneN 2 S 4 -H)] 2+ .

Thioether macrocyclic chemistry: Synthesis of [RhCl([15]aneS5)]2+ and [Ru(PPh3)([15]aneS5)]2+. The single crystal X-ray structure of [Ru(PPh3)([15]aneS5)](BPh4)2 ([15]aneS5 = 1,4,7,10,13-pentathiacyclopentadecane)

Abstract Reaction of RhCl3 with one molar equivalent of [15]aneS5 in refluxing MeOH yields a yellow solution containing the complex cation [RhCl([15]aneS5)]2+. Addition of excess NH4PF6 affords the complex [RhCl([15]aneS5)](PF6)2 as a yellow solid, which can be recrystallized from MeCN. [RhCl([15]aneS5)]2+ shows two irreversible reductions at Epc = −0.78 and −1.93 V vs Fc/Fc+ at a scan rate of 200 mV s−1. Treatment of [RuCl2(PPh3)3] with one molar equivalent of [15]aneS5 in refluxing MeOH, followed by addition of excess NH4PF6 or NaBPh4 affords [Ru(PPh3)([15]aneS5)]X2 (X = PF6− or BPh4−) as a yellow solid, which can be recrystallized from MeCN/diethyl ether. [Ru(PPh3) ([15]aneS5)](BPh4)2 has been characterized by X-ray crystallography. The structure confirms coordination of all five macrocyclic thioether donors, Ruue5f8S(1) = 2.3371(15), Ruue5f8S(4) = 2.3785(12), Ruue5f8S(7) = 2.4458(10), Ruue5f8S(10) = 2.3732(15), Ruue5f8S(13) = 2.3099(10) A, and the P donor of the PPh3 ligand, Ruue5f8P = 2.3679(8) A, to give an overall distorted octahedral stereochemistry at ruthenium(II).

Organometallic macrocyclic complexes: the synthesis, electrochemistry and single crystal X-ray structure of [Fe(C5H5)(L)]+ (L = 1,4,7-trithiacyclononane)

Abstract Reaction of [Fe(C 5 H 5 )I(CO) 2 ] with one molar equivalent of L (L = 1,4,7-trithiacyclononane) affords the complex cation [Fe(C 5 H 5 )(L)] + in high yield. Crystals of [Fe(C 5 H 5 )(L)]BPh 4 are monoclinic, space group P 2 1 / c , with a 15.0461(14), b 10.5866(12), c 19.8032(18) A, β 100.205(9)°, V 3104.48 A 3 , D c 1.327 g cm −3 , Z = 4. The single crystal X-ray structure of the complex shows octahedral Fe II with the carbocyclic and macrocyclic ligands bound facially to the metal centre, Feue5f8S(1) 2.2100(18), Feue5f8S(4) 2.2053(19), Feue5f8S(7) 2.2078(19), Feue5f8S 2.007(12)-2.112(12) A. Two orientations of the C 5 H 5 ring are observed. [Fe(C 5 H 5 )(L)]PF 6 shows a reversible one-electron Fe II/III couple at E 1 2 = +0.44 V vs. Fc/Fc + in CH 3 CN at platinum electrodes. Coulometry confirms that the oxidation is a one-electron process. The Fe III complex has been characterised by ESR and UV-visible spectroscopy.

Platinum metal thioether macrocyclic complexes: synthesis and single crystal X-ray structure of cis-[IrCl2(L)]BPh4 (L = 1,4,8,11-tetrathiacyclotetradecane)

Reaction of IrCl3 with 1,4,8,11-tetrathiacyclotetradecane (L) in refluxing EtOH/H2O gives the complex cation [IrCl2(L)]+. Crystals of [IrCl2(L)]BPh4 are monoclinic, space group P21, with a 12.6927(14), b 12.1361(20), c 14.4912(18) A, β 111.813(13)°, V 2072.4 A3, Dc 1.363 g cm−3, Z = 2. The single crystal X-ray structure of [IrCl2(L)]BPh4 shows a distorted octahedral stereochemistry around IrIII, with mutually cis Cl− ligands, Irue5f8Cl(1) 2.389(5), Irue5f8Cl(2) 2.385(5) A, angle Cl(1)IrCl(2) 91.02(16)°. The tetrathia macrocycle is coordinated to the metal centre via all four S-donors (Irue5f8S(1) 2.277(4). Irue5f8S(4) 2.287(5), Irue5f8S(8) 2.268(4), Irue5f8S(11) 2.343(5) A) with S(1), S(4), and S(8) trans to Cl(2), S(11), and Cl(1) respectively.