Showing papers by "Alexander J. Blake published in 1993"

Polynuclear nickel(II) complexes of N4O2- and N4S2-compartmental macrocycles: the structures of a Ni4O4 cubane cluster and the binuclear nickel(II) complex of a benzenethiolate macrocycle

Abstract: The tetranuclear cluster [{Ni2(L1)(MeCO2)}2]2+(L1= the dianion of the condensation product of 1,3-diaminopropane and 2,6-diformyl-4-methylphenol) shows a distorted Ni4O4cubane structure consisting of octahedral nickel(II) centre; the structure of the dithiolate analogue [Ni2(L2)](PF6)2·2dmf (L2= the dianion of the condensation product of 1,3- diaminopropane and 2,6-diformyl-4-methylbenzenethiol;dmf = dimethylformamide)shows square-planar coordination at nickel(II).

Structural isomerism in silver thioether macrocyclic chemistry: the synthesis, redox properties and crystal structures of [Agn([15]aneS5)n][PF6]n′[Ag2([15]aneS5)2][BPh4]2 and [Ag([15]aneS5)][B(C6F5)4]([15]aneS5= 1,4,7,10,13-pentathiacyclopentadecane)

Abstract: Reaction of AgNO3 with 1 molar equivalent of [15]aneS5(1,4,7,10,13-pentathiacyclopentadecane) in refluxing MeOH–water gives a colourless solution. Addition of excess of counter ion [PF6–, BPh4– or B(C6F5)4–] affords the colourless complexes [Agn([15]aneS5)n][PF6]n′[Ag2([15]aneS5)2][BPh4]2 and [Ag([15]aneS5)][B(C6F5)4] respectively in high yield. Single-crystal X-ray structural studies on these systems have revealed different cation stereochemistries as the counter ion is altered. Thus, [Agn([15]aneS5)n][PF6]n crystallises in the orthorhombic space group lba2 with a= 25.713(3), b= 25.749(3), c= 11.6989(19)A and Z= 16. The two independent infinite chains of cations in the structure are antiparallel. The stereochemistry at Ag1 is severely distorted octahedral through an [S4+ S2] donor set, Ag(1)⋯ S(1) 3.219(5), Ag(1)–S(4) 2.659(5), Ag(1)–S(7) 2.651(6), Ag(1)⋯ S(10) 3.075(7), Ag(1)–S(13) 2.564(6)A, with one thioether donor from an adjacent [Ag([15]aneS5)]+ fragment asymmetrically bridging two metal centres, Ag(1)–S(1B) 2.742(5)A. A similar geometry is observed at the second Ag ion, Ag(2)⋯ S(1′) 3.263(5), Ag(2)–S(4′) 2.605(5), Ag(2)⋯ S(7′) 2.964(8), Ag(2)–S(10′) 2.713(7), Ag(2)–S(13′) 2.637(6), Ag(2)–S(1D) 2.714(5)A. The complex [Ag2([15]aneS5)2][BPh4]2 crystallises in the triclinic space group P with a= 11.462(3), b= 11.895(3), c= 27.019(10)A, α= 78.503(18), β= 84.729(13), γ= 67.118(18)°, and Z= 2. The structure of the [Ag2([15]aneS5)2]2+ cation shows an unusual binuclear stereochemistry with [4 + 1] thioether donation to one silver(I) centre, Ag(2)–S(7′) 2.558(4), Ag(2)–S(10′) 2.623(5), Ag(2)–S(13′) 2.716(5), Ag(2)–S(1) 2.486(3), Ag(2)⋯ S(1′) 3.131(3)A, and [3 + 1] thioether donation to the other, Ag(1)–S(7) 2.529(3), Ag(1)–S(10) 2.608(4), Ag(1)–S(1′) 2.537(3), Ag(1)⋯ S(1) 2.907(3)A. Thus, one S-donor [S(1) and S(1′)] of each macrocycle bridges asymmetrically between the two metal centres. The complex [Ag([15]aneS5)][B(C6F5)4] crystallises in the triclinic space group P with a= 12.476(5), b= 13.658(7), c= 15.608(6)A, α= 108.300(22), β= 108.467(17), γ= 100.518(21)° and Z= 2. The structure contains discrete mononuclear [Ag([15]aneS5)]+ cations and [B(C6F5)4]– anions. The geometry at Ag1 is asymmetric with all five thioether donors of the macrocycle interacting with the metal centre: Ag–S(1) 2.4712(19), Ag ⋯ S(4) 2.7262(20), Ag–S(7) 2.6847(21), Ag–S(10) 2.5621(19), Ag ⋯ S(13) 2.8813(19)A. In MeCN solution [Ag([15]aneS5)]+ shows a chemically reversible AgI–AgII redox couple at E½= 0.76 V and a quasi-reversible AgI–Ago couple at –0.37 V vs. ferrocene–ferrocenium. The intensely coloured d9 silver(II) oxidation product has been observed by X- and Q-band ESR spectroscopy and the oxidation of AgI to AgII monitored spectroelectrochemically.

Synthesis, molecular and crystal structures of arene derivatives of [Ru6C(CO)17]

Abstract: The complexes [Ru6C(CO)14(η6-C6H4Me2-1,3)]1, [Ru6C(CO)14(η6-C6H3Et3-1,3,5)]2 and [Ru6C(CO)14(µ3-η2:η2:η2-C16H16)]3 have been prepared from the reaction of [Ru3(CO)12] and the appropriate arene. The molecular and crystal structures of the three derivatives have been established by single-crystal X-ray diffraction studies. Complexes 1 and 2 carry the arene fragment bound in a terminal fashion. Crystalline 1 contains two independent molecules showing different rotameric conformations of the xylene ligands. The [2.2]paracyclophane complex 3 provides the first example of a mono(arene) derivative of [Ru6C(CO)17] to contain the µ3-η2:η2:η2-bonding mode. The molecular organization in the crystal structures of 1, 2 and 3 was also determined.

New synthetic routes to [M3(CO)9(µ3-η2:η2:η2-C6H6)](M = Ru or Os)

Abstract: A new, more convenient route to the benzene cluster [Ru3(CO)9(µ3-η2:η2:η2-C6H6)] directly from [Ru3(CO)12] has been established. Triruthenium dodecacarbonyl, [Ru3(CO)12], undergoes reaction with Me3NO–CH2Cl2 in the presence of cyclohexa-1,3-diene to give the clusters [Ru3H(CO)9(C6H7)] and [Ru3(CO)9(µ3-η2:η2:η2-C6H6)] in moderate yield. Triosmium dodecacarbonyl does not react similarly, but from the reaction of [Os3(CO)10(MeCN)2] with cyclohexa-1,3-diene a key intermediate compound [Os3(CO)10(η4-C6H8)] has been isolated and the solid-state structure of its acetonitrile solvate established by single crystal X-ray diffraction analysis at 150 K. The structure is monoclinic, space group P21/n, with a= 8.932(8), b= 17.387(13), c= 14.833(15)A, β= 105.69(6)° and Z= 4. The three osmium atoms form a regular triangle with a mean Os–Os distance of 2.877(12)A. Two osmium atoms, Os(1) and Os(2), are co-ordinated to four carbonyl ligands and one, Os(3), co-ordinates to two carbonyl ligands. All carbonyl ligands are terminal and approximately linear. The cyclohexadiene ligand is η4 co-ordinated to Os(3)via the 1,3-diene moiety, donating four electrons in total. On thermolysis, this compound is converted to [Os3H(CO)9(C6H7)] and then eventually to [Os3(CO)9(µ3-η2:η2:η2-C6H6)] by established means.

Synthesis, structure and electrochemistry of [Pt([10]aneS3)2][PF6]2 ([10]aneS3 = 1,4,7-trithiacyclodecane)

Abstract: The orange complex [Pt([10]aneS3)2][PF6]2([10]aneS3= 1,4,7-trithiacyclodecane) is centrosymmetric with primary S4 co-ordination, Pt–S(5) 2.297(4), Pt-S(8) 2.309(4), A, with long-range interactions to the two remaining S-donors, Pt ⋯ S(1) 3.233(4)A; [Pt([10]aneS3)2]2+ shows a broad two-electron oxidation centred at E½=+0.35 V (vs. ferrocene–ferrocenium) assigned to a PtII–PtIV couple.

Synthesis, structure and electrochemistry of [Pd([9]aneNS2)2]-[BF4]2([9]aneNS2= 1,4-dithia-7-azacyclononane)

Abstract: The centrosymmetric purple-blue complex [Pd([9]aneNS2)2][BF4]2([9]aneNS2= 1,4-dithia-7-azacyclononane) shows a primary N2S2 co-ordination, Pd–N(1) 2.081(9), Pd–S(7) 2.322(3)A, with longrange interactions to the two remaining S donors, Pd ⋯ S(4) 3.011(3)A; [Pd([9]aneNS2)2]2+ shows two one-electron oxidations at 1E½=+0.43 V and 2E½=+0.84 V vs. ferrocene–ferrocenium assigned to PdIII–PdIII and PdIII–PdIV couples respectively.

Synthesis of binuclear platinum metal N4O2-compartmental complexes: the structures of the protonated metal-free macrocycle [LH4](PF6)2·MeNO2 and of [Pd2(L)](BF4)2·2MeNO2

Abstract: Reaction of [LH4](PF6)2, formed by condensation of 1,3-diaminopropane and 2,6-diformyl-4-methylphenol in the presence of HBr followed by addition of NH4PF6, with platinum metal salts in the presence of base affords [M2(L)]2+(M = Pd, Pt) and [M2Cl4(L)](M = Rh); the structure of [LH4](PF6)2·MeNO2 shows a folded conformation incorporating both inter- and intra-molecular π–π interactions between phenyl rings; in contrast, the structure of [Pd2(L)](BF4)2·2MeNO2 shows the binucleating macrocycle to be planar with intermolecular π-ring stacking

The synthesis and low-temperature single crystal X-ray structure of the charge-transfer complex ([9]aneS3)2(l2)4([9]aneS3= 1,4,7-trithiacyclononane)

Abstract: Reaction of [9]aneS3(1,4,7-trithiacyclononane) and I2 in cold CH2Cl2 results in the formation of 1 :1 and 1 : 2 adducts; the single crystal X-ray structure of the 1 :2 adduct ([9]aneS3)3(I2d2)4 shows an unusual polymeric structure with I2 bridging [9]aneS3 thioether units.

(5R)-7,8:9,10-Di-O-isopropylidene-2,6-dioxa-4-azaspiro[4,5]decan-3-one: a new chiral spirooxazolidin-2-one derived from D-(+)-galactose for use in asymmetric transformations

Abstract: Starting from D-(+)-galactose, the crystalline spirooxazolidin-2-one 2 can be readily prepared in an optically pure state by a nitrene-mediated four-step sequence, and serves to control both aldol and Diels–Alder reactions with high chiral efficiency, being easy to remove after use.

Nickel thioether chemistry: synthesis, structures and electrochemistry of five-co-ordinate nickel(II) complexes of [9]aneS3. Crystal structures of [Ni([9]aneS3)-(dppm)][PF6]2′, [Ni([9]aneS3)(dcpe)][PF6]2·1.25MeCN and [Ni([9]aneS3)(tdpme)][PF6]2{[9]aneS3= 1,4,7-Trithiacyclononane, dppm = Ph2PCH2PPh2′, dcpe =(C6H11)2–PC2H4P(C6H11)2′, tdpme = CH3C(CH2PPh2)3}

Abstract: Reaction of [Ni(L–L)Cl2]{L–L = Ph2PCH2PPh2(dppm), R2PCH2CH2PR2[R = Ph (dppe), C6H11(dcpe) or Me (dmpe)], cis-Ph2PCHCHPPh2(dppv), Ph2PCH2CH2CH2PPh2(dppp) or MeC(CH2PPh2)3(tdpme)} with 1 molar equivalent of 1,4,7-trithiacyclononane([9]aneS3) afforded the complex cations [Ni([9]aneS3)(L–L)]2+. The crystal structures of [Ni([9]aneS3)(dppm)][PF6]2, [Ni([9]aneS3)(dcpe)][PF6]2·;1.25MeCN and [Ni([9]aneS3)(tdpme)][PF6]2 showed five-co-ordinate complexes with distorted square-pyramidal geometries about the nickel(II) centres with the S-donors of [9]aneS3 occupying two basal and the apical position, Ni–Sapical 2.40–2.65 A, Ni–Pbasal 2.17–2.22 A. The complex [Ni([9]aneS3)(dppm)][PF6]2 crystallises in triclinic space group P, a= 10.9748(25), b= 13.9702(20), c= 15.7688(24)A, α= 80.071(7), β= 70.817(8), γ= 76.441(8)°, Dc= 1.374 g cm–3, Z= 2; [Ni([9]aneS3)(dcpe)][PF6]2·;1.25MeCN crystallises in triclinic space group P, a= 12.432(8), b= 13.382(4), c= 15.070(6)A, α= 86.83(2), β= 70.47(2), γ= 77.28(2)°, Dc= 1.445 g cm–3, Z= 2; [Ni([9]aneS3)(tdpme)][PF6]2 crystallises in monoclinic space group Cc, a= 10.7597(16), b= 37.399(5), c= 13.104(3)A, β= 103.746(11)°, Dc= 1.491 g cm–3, Z= 4. Cyclic voltammetry of the complexes [Ni([9]aneS3)(L–L)][PF6]2 in MeCN (0.1 mol dm–3 NBu4PF6) at 293 K at platinum electrodes showed one chemically reversible and one quasi-reversible one-electron reduction at 1E1/2=–0.77 to –1.16 V, 1Ep= 61–92 mV, 2E1/2=–1.31 to –1.93 V vs. ferrocene–ferrocenium. On the basis of ESR and electronic spectroscopy, these reduction products are assigned as pyraidal d9 nickel(I)[Ni([9]aneS3)(L–L)]+ with binding of both P-donors retained, and tetrahedral d10 nickel(0)[Ni([9]aneS3)(L–L)]0 species respectively. The reaction of [Ni([9]aneS3)(L–L)]+ with CO in MeCN is discussed.

Agostic Pd ⋯ H+⋯ NHR2 and apical Pd ⋯ NHR2 interactions: the synthesis and structures of [PdIICl2(H[9]aneN3)]+, the PdII–PdII dimer [(H[9]aneN3)Cl2Pd–PdCl2(H[9]aneN3)]2+, and [Pd(Me3[9]aneN3)(NCMe)2]2+

Abstract: Long-range agostic Pd ⋯ H+⋯ NHR2 interactions are observed in the crystal structure of the protonated form of cis-[PdIICl2([9]aneN3)], while a direct apical Pd ⋯ NHR2 interaction is observed in the purple complex [Pd(Me3[9]aneN3)(NCMe)2](PF6)2.

Conformational studies on [16]aneS4. Structures of α‐ and β‐[16]aneS4 ([16]aneS4 = 1,5,9,13‐tetrathiacyclohexadecane)

Abstract: Three morphologies - acicular (α), lamellar (β) and columnar (γ) - are observed for crystals of [16]aneS 4 (1,5,9,13-tetrathiacyclohexadecane). The absolute structures of the α and β forms have been determined: the molecular structures are essentially the same but the two forms differ in their crystal packing. α-[16]aneS 4 crystallizes in the orthorhombic space group Pbc2 1 while β-[16]aneS 4 crystallizes in the monoclinic space group P2 1

Interconversion of auI/II/III centres in thioether macrocyclic complexes: the synthesis, structures and redox properties of [Au([18]aneS6)]PF6 and [Au2([15]aneS5)2][B(C6F5)4]2

Abstract: The interconversion of mononuclear AuI/II/III centres in thioether macrocyclic complexes is related to the stereochemical properties of the parent AuI species; the structure of [Au([18]aneS6)]+ shows a distorted tetrahedral [2 + 2] coordination at AuI, while the AuI complex of [15]aneS5 is binuclear with AuI ions bridging [15]aneS5 ligands in a macrobicyclic structure

Solvent control of structural type: three different structures from the reaction of a dimeric copper complex with lanthanum nitrate in three different solvents

Abstract: The reaction of a dimeric copper complex, [Cu2L4]1(L = C5H3CINO–, the anion of 6-chloro-2-hydroxypyridine), with hydrated lanthanum nitrate has been studied. The crystalline products are determined by the solvent used. If the reaction is carried out in a mixture of methanol–dichloromethane a compound of stoichiometry [Cu3LaL5(NO3)(OMe)(MeOH)2]·1.5MeOH·0.5Et2O 2 is isolated. If the reaction is carried out in ethanol–dichloromethane a compound of stoichiometry [Cu3LaL8(NO3)(EtOH)]·0.5Et2O 3 is found. If acetonitrile–dichloromethane is used the complex [Cu2La2L8(HL)2(NO3)2]·2HL·2MeCN 4 can be crystallised. All of these compounds have been characterised by X-ray crystallography and the unusual structures are described.

CuII and PdII complexes of 3-hydroxy-1,3-bis(2-thienyl)prop-2-en-1-one

Abstract: The 1:2 complexes formed between Cu II or Pd II and the anion of 3-hydroxy- 1,3-bis(2-thienyl)prop-2-en-1-one [LH: Baxter, Blake, Heath & Stephenson (1990). Acta Cryst. C46, 508-510], bis[(3-hydroxy-kO')-1,3-bis(2-thienyl)prop-2-en-1-onato(1-)-kO]copper(II) and bis-(3-hydroxy-kO')-1,3-bis(2-thienyl)prop-2-en1-onato(1-)-kO]palladium(II), crystallize with the metal ions occupying crystallographic inversion centres and coordinated by approximately square planes of four O atoms. The similarities within the pairs of M-O, C-C and C-O bonds in the chelate rings indicate the latter are behaving as delocalized systems. The mean Cu-O and Pd-O distances are 1.910 (3) and 1.980 (3) A, respectively

[rh([9]anes3)(co)(pph3)]+.pf6-

Abstract: (Carbonyl)(triphenylphosphine-P)(1,4,7-trithiacyclononane-S,S',S'')rhodium hexafluorophosphate, [Rh(C 6 H 12 S 3 )(C 18 H 15 P)(CO)]PF 6 , M r =718.45, orthorhombic, Pnma, a=12.4367 (8), b=12.7190 (6), c=18.0229 (8) A, V=2850.9 A 3 , Z=4, D x =1.674 Mg m -3 , λ(Mo Kα)=0.71073 A, μ=0.968 mm -1 , F(000)=1448, T=298 K, R=0.0498 for 1401 unique observed reflections. The Rh centre is five-coordinate, with the donor atoms conferring a distorted trigonal bipyramidal environment in which the carbonyl group and two of the three thia donors are equatorial and the remaining thia donor and the phosphine are axial

Pyrazolo[1,2-a]1,2,3-triazinium-4-olate

Abstract: The title mesomeric betaine 1 is formed by a novel thermal cyclisation method; its X-ray crystal structure, that of its 3-bromo derivative, and its reactions with acids, bases and electrophiles are reported.

The preparation and characterization of the mixed valence complex dianion [Mn3(CO)6(µ2-NO2)4(µ2-ONO)2]2–

Abstract: Treatment of Mn(Co)5Cl With trimethylamine N-Oxide In CH2Cl2 in the presence of [PPN]NO2[PPN+=(Ph3P)2N+] yields the new dianion [Mn3(CO)6(µ2-NO2)4(µ2-ONO)2]2–, which has been shown to contain a trinuclear Mn3 mixed valence unit linked by both nitro- and nitrito-bridges.

Tetra(n‐butyl)ammonium trifluoromethanesulfonate

Abstract: The title structure comprises two ion pairs in each asymmetric unit. There are no close contacts between any of the ions. Although the structure determination was carried out at reduced temperature there are large vibration amplitudes for some F atoms and disorder in one of the n-butyl chains

Structure of disulfuryl difluoride at 100 K

Abstract: S 2 O 5 F 2 , M r =182.07, tetragonal, P42 1 c, a=7.5214 (5), c=9.2610 (10) A, V=523.9 A 3 , Z=4, D x =2.308 Mg m -3 , λ(Mo Kα)=0.71073 A, μ=0.975 mm -1 , F(000)=360, T=100 K, R=0.024 for 433 unique observed reflections. Molecules of S 2 O 5 F 2 occupy special positions on twofold axes. Principal bond lengths and angles are: S-O 1.6108 (11); S=O 1.3947 (20), 1.4021 (18); S-F 1.5215(16) A; S-O-S 123.44(7); O-S=O 109.82 (8), 104.46 (9); O-S-F 98.34 (7); O=S-F 107.42 (9), 108.16 (10); O=S=O 125.35 (11) o

Regio- and face-selective cycloaddition of benzonitrile oxide and C,N-diphenylnitrone to 6,8-dioxabicyclo[3.2.1]oct-3-ene

Abstract: Benzonitrile oxide, generated by dehydrochlorination of benzohydroximoyl chloride, undergoes regioand face-selective cycloaddition to 6,8-dioxabicyclo[3.2.1]oct-3-ene 5 yielding a 4:1 mixture of 4,5-dihydroisoxazoles 6 and 7. Both products have exo-stereochemistry resulting from approach of the nitrile oxide from the face opposite the methyleneoxy bridge. The structures of the adducts were determined by 1H NMR spectroscopy and, in the case of compound 6, by X-ray crystallography. The corresponding reaction with C,N-diphenylnitrone yielded three of the eight possible isoxazolidines, the major isomer being exo,endo-adduct 16.

Structure of trans‐carbonyl(thiocyanato‐N)bis(triethylphosphine)rhodium(I)

Abstract: The title compound is a four-coordinate Rh I complex in which the metal is ligated by two mutually trans triethylphosphines, a carbonyl and an isothiocyanate group. The molecule lies on a crystallographic twofold axis which passes through the metal, the carbonyl and the isothiocyanate group. Steric factors play a part in determining the coordination mode of the NCS - ligand: in particular, the bulk of the triethylphosphine ligands disfavours linkage through the larger S atom, whose preference for non-linear coordination would also cause steric problems

(Diisopropyldithiocarbamato‐S,S')(1,3‐diphenyl‐1,3‐propanedithionato‐S,S')nickel(II)

Abstract: [Ni(C 7 H 14 NS 2 )(C 15 H 11 S 2 )], M r =490.4, monoclinic, P2 1 , a=11.415 (5), b=11.185 (5), c=9.075 (4) A, β=96.93 (3) o , V=1150 A 3 , Z=2, D x =1.416 Mg m -3 , λ(Mo Kα)=0.71073 A, μ=1.204 mm -1 , F(000)=512, T=298 K, R=0.0537 for 1915 unique observed reflections. The metal atom is in a distorted square-planar coordination; the Ni atom is coplanar with the four S atoms, but successive S-Ni-S angles are 77.49 (8) (within the dithiocarbamate ligand), 87.12 (9), 102.70 (9) (within the 1,3-dithionate ligand) and 92.57 (9) o

Crystal structure of (1,4,7-trithiacyclononane)-(1,2-bis(diphenylphosphino)ethane)nickel(II)bis(tetrafluoroborate), C32H36NiP2S3(BF4)2(H2O)0.4

Abstract: Crystallization in P12 1 /n1 with lattice parameters a = 12.873 (1), b = 39.821 (2), c = 14.1368 (9) A, β = 91.666°, Z = 8; the final R value is 0.072. Geometry at Ni centre is distorted square-based pyramidal, with the basal donor atoms deviating by 0.8A on average from the plane

Structure of carbonylbis(diphenyldithiophosphinato)(triphenylphosphine)ruthenium diethyl ether solvate [Ru(CO)(S2PPh2)2(PPh3)].0.25Et2O

Abstract: Ruthenium is six coordinate; the principal distortion from octahedral geometry at the metal centre arises from the narrow bite angle of the chelating dithio ligand. The Ru-S distances vary by more than 0.11 A; the bond trans to CO [2.5407 (11) A] is significantly longer than that trans to PPh 3 [2.5205 (11) A] and both are much longer than the other two mutually trans Ru-S distances [2.4295 (11), 2.4363 (10) A]. These observations concur with the expected order of decreasing trans influence, CO>PPh 3 Ph 2 PS 2 -

[{(η6‐C6H6)(PMe2Ph)RuCl}2(μ‐Ph2PCH2CH2PPh2)]2+.2PF6−.CH3NO2

Abstract: In the title compound, [μ-ethylenebis(diphenylphosphine]-bis[(η 6 -benzene)chloro(dimethylphenylphosphine)ruthenium(II)] bis(hexafluorophosphate) nitromethane solvate, the cation is crystallographically centrosymmetric about the midpoint of the CH 2 -CH 2 bond. The diphosphine ligand adopts a bridging function between the two Ru II centres

Redox-Structural Correlations in Metal Thioether Macrocyclic Complexes: The Stabilisation of Mononuclear Silver(II) and Gold(II)

Abstract: The complexation of Ag(I) and Au(I) by tri-, tetra-, penta- and hexathia crown thioethers is described. The mismatch between metal ion and ligand co-ordination leads to complexes which often incorporate unusual stereochemical features and therefore show novel redox properties in solution. The stabilisation of mononuclear Ag(II) and Au(II) radical complexes has been investigated spectroelectrochemically using electronic and esr spectroscopy. In particular, the single crystal X-ray structures and redox interconversion of [Au([9]aneS3)2]+/2+/3+ are described.