DALTON FULL PAPER J. Chem. Soc., Dalton Trans., 1998, Pages 279–284 279 Synthesis and characterisation of thioether crown hydrazones, and palladium(II) and platinum(II) complexes of 6-(2,4- dinitrophenylhydrazono)-1,4,8,11-tetrathiacyclotetradecane Liam R. Sutton, Alexander J. Blake, Wan-Sheung Li and Martin Schröder * Department of Chemistry, The University of Nottingham, University Park, Nottingham, UK NG7 2RD Reaction of the functionalised thioether crowns [14]aneS4-6-one (1,4,8,11-tetrathiacyclotetradecan-6-one, L1) and [10]aneS3-9-one (1,4,7-trithiacyclodecan-9-one, L2) with 2,4-dinitrophenylhydrazine in a protic solvent under acidic catalysis afforded the corresponding hydrazones L3 and L4, respectively, in high yield.Reaction of [14]aneS4-6-one with p-nitrophenylhydrazine under similar conditions affords the hydrazone L5. Reaction of L3 with [Pd(MeCN)4][BF4]2 in MeCN yielded the complex [Pd(L3)][BF4]2, while reaction of this ligand with [Pt(EtCN)4][CF3SO3]2 in MeCN afforded [Pt(L3)][CF3SO3]2. The single-crystal structures of L3–L5 and of [Pd(L3)][BF4]2 have been determined. In all cases, p–p stacking is observed, the free macrocycles crystallising as polymeric arrays of face-sharing hydrazone moieties.In [Pd(L3)]21, p–p interactions alternate with face sharing between planar [PdS4]21 units constructing a one-dimensional polymeric array. The hydrazone function forces distortions of the respective macrocyclic rings and imparts chirality to the [Pd(L3)]21 cation.The potential of these molecules as building blocks for macrocyclic liquid crystals and extended supramolecular arrays is discussed, as is the need to consider steric factors in rationalising the reactivity of keto-functionalised thioether crowns. Homoleptic sulfur-donor macrocycles bearing extended functionality are still rare and have only recently been applied to the synthesis of mesogenic materials, both as free macrocycles and as binding agents for the late transition-metal ions.1 The common feature of such materials is that the macrocycle bears a number of lengthy organic substituents which generate the anisotropy necessary to induce liquid-crystalline behaviour.2 Since derivatisation of a thioether crown must necessarily occur on the carbon backbone, work has been undertaken to build in precursor functionality which can be used subsequently for extended derivatisation.Macrocyclic thioether crowns have now been synthesized with hydroxyl,3 methine,4 hydroxymethyl 5 and ketone 6 functionalities. Most examples of further derivatisation have focused on hydroxyl derivatives.1,5,7 To date our own work in this area has concentrated on esterification of [14]- and [16]-aneS4-diols.1 Keto-functionalised thioether crowns, first synthesized independently by Setzer and Kellogg and their co-workers,6a,b have been treated with hydrazine by Kellogg and co-workers 8 to yield both inter- and intra-molecular azines, demonstrating that these carbonyl groups readily undergo sterically innocuous condensations.However, attempted Wittig and Grignard additions to these ketones were unsuccessful, the reason proposed being that they have a high tendency to enolise due to the sulfur atoms situated b to the carbonyl group.8 The tetradentate thioether crown [14]aneS4 (1,4,8,11-tetrathiacyclotetradecane) co-ordinates to an extensive range of metal atoms, most commonly as a platform for a square-planar S4 donor set.9 The d8 palladium(II) cation usually adopts square-planar co-ordination and this is observed in its complexes with both the parent ligand 10 and with several functionalised derivatives 11 where the hydrocarbon links form the sides of a shallow bowl with the PdS4 square as its base.We report herein the synthesis of phenylhydrazono derivatives of [14]- aneS4-6-one (1,4,8,11-tetrathiacyclotetradecan-6-one, L1) and [10]aneS3-9-one (1,4,7-trithiacyclodecan-9-one, L2) and complexes with PdII and PtII.Results and Discussion The ligands were synthesized from the appropriate ketonic starting material via condensation with aryl-substituted hydrazines to generate resonance-stabilised functionalised macrocycles incorporating an sp2-hybridised carbon atom. Interdependence of the conformation of each macrocycle and the nature of its substituent is evident by comparison of the single-crystal structures of the parent ketones, L1 and L2, their hydrazones L3–L5, and [Pd(L3)]21.Synthesis of L1 and L2 The ketones used for further derivatisation, L1 and L2, were prepared by literature methods developed primarily by Kellogg and co-workers 6a and by Setzer et al.6b Crystal structure determinations 6c,12 reveal that L1 and L2 adopt exodentate conformations similar to those exhibited by their unsubstituted parent macrocycles with little distortion due to the presence of the carbonyl oxygen. Synthesis and structural description of L3–L5 Compounds L3 and L4 were synthesized by the condensation 13 of 2,4-dinitrophenylhydrazine with L1 and L2 respectively (Scheme 1).The hydrazine was suspended in EtOH, then protonated by the careful addition of concentrated H2SO4, to yield a bright yellow solution. This was then added to a colourless solution of the ketone in boiling EtOH, generating instant orange cloudiness in the mixture. Cooling to room temperature afforded almost quantitative yields of hydrazone.Analogously, L5 was synthesized from L1 and p-nitrophenylhydrazine using glacial acetic acid to dissolve the hydrazine in EtOH. Crystallisation at 218 8C yielded a mixture of product and excess of hydrazinium salt. Recrystallisation from EtOH afforded a 63% yield of yellow hydrazone L5. Selected bond lengths and angles are listed in Table 1. Features of note are the hydrogen bonds in compounds L3 and L4 between the hydrazone protons and an oxygen atom of the nitro groups in the ortho positions of the phenyl groups. Furthermore, the solid-state conformations of the macrocyclic core change significantly on condensation with the hydrazones.The crystal structure of L3 [Fig. 1(a)] reveals a marked distortion of the macrocycle by comparison with the structure of L1, which displays a quite regular [3434] conformation.6a The280 J. Chem. Soc., Dalton Trans., 1998, Pages 279–284 irregular [2435] conformation adopted by the macrocycle in L3 is, we propose, the result of a minimisation of steric interaction between the hydrazone proton H(16) and S(1) (Table 2).The packing diagram (Fig. 2) illustrates the p–p stacking in the structure.15 Interplanar separations are 3.383 and 3.407 Å (cf. 3.354 Å in graphite),16 offset such that the centroid–centroid separations between phenyl rings are both 3.905 Å (Table 3). Fig. 3 shows the structure of a single molecule of compound L4. The hydrazone proton again induces a solid-state conformational change in the macrocycle relative to its parent ketone which has a [2323] conformation.12 Significantly, the structure of L4 shows 8 out of 10 torsion angles less than 908 (Table 2) thus reducing direct contact between H(12) and S(1) and reflecting severe distortions within the ring.Interaction between the p systems of the molecules allows them to stack as arrays of interlocking L shapes (Fig. 4), with interplanar distances of 3.270 and 3.359 Å.Scheme 1 Synthesis of hydrazones S S S S O S S O S L1 L2 H2NNH NO2 R Hot EtOH/Acid S S S S N L3: R = NO2 L5: R = H HN R NO2 S S S N HN R NO2 L4: R = NO2 Fig. 1 Structures of compounds L3 (a) and L5 (b) A similar disruption of the ring conformation occurs in compound L5, which shows a [23225] conformation [Fig. 1(b)], showing that the NH ? ? ?O2N hydrogen bond present in L3 and L4 is not the key factor in determining the conformation of the macrocycle. Rather, conjugation in the hydrazone forces the NH hydrogen to occupy the position occupied by S(1) in the ketonic macrocycles.By comparison, the structure of an azine-bridged (]] N]N]] ) dimer of [13]aneS2O2 (1,4-dioxa-7,11- dithiacyclotridecane) obtained by Kellogg and co-workers 8 displays little distortion of the rings from the expected structure of [13]aneS2O2-6-one, highlighting the importance of the hydrazone proton. The p–p stacking motif observed in L4 is repeated in L5, with interplanar separations of 3.360 and 3.507 Å.Fig. 2 Packing of compound L3. Hydrogen atoms omitted for clarity Fig. 3 Structure of compound L4 Fig. 4 Packing of compound L4. Hydrogen atoms omitted for clarityJ. Chem. Soc., Dalton Trans., 1998, Pages 279–284 281 In the stacking of compounds L3–L5, large lateral offsets of neighbouring phenyl rings occur. This is due in part to the extended p systems of the phenyl ring, nitro groups and the hydrazone function. The view of the packing in L5 in Fig. 5, perpendicular to the aromatic plane, shows the close aligning of phenyl rings in adjacent hydrazones. Synthesis of complexes of PdII and PtII The complex [Pd(L3)][BF4]2 was synthesized by the addition of a solution of [Pd(MeCN)4][BF4]2 in MeCN to an orange mixture of MeCN and the partially soluble L3. The mixture immediately cleared and darkened slightly, the yellow product being crystallised by layering with Et2O. Crystals of composition [Pd(L3)][BF4]2?1.5MeCN were analysed by X-ray crystallography and the structure of the Fig. 5 Packing of compound L5. Hydrogen atoms omitted for clarity Table 1 Selected bond lengths (Å) and angles (8) L3 C(13)]N(15) N(15)]N(16) C(12)]C(13)]C(14) N(15)]C(13)]C(12) N(15)]C(13)]C(14) C(13)]N(15)]N(16) 1.289(6) 1.380(6) 118.4(5) 115.6(3) 126.0(5) 116.3(4) N(16)]C(17) O(22A) ? ? ? H(16) C(17)]N(16)]N(15) N(16)]C(17)]C(18) N(16)]C(17)]C(22) 1.347(7) 1.98 120.0(4) 120.3(5) 123.6(5) L4 C(9)]N(11) N(11)]N(12) C(8)]C(9)]C(10) N(11)]C(9)]C(8) N(11)]C(9)]C(10) C(9)]N(11)]N(12) 1.266(7) 1.392(5) 115.1(5) 114.2(5) 130.3(5) 119.3(5) N(12)]C(13) O(18A) ? ? ? H(12) C(13)]N(12)]N(11) N(12)]C(13)]C(14) N(12)]C(13)]C(18) 1.351(7) 2.01 117.8(5) 120.0(5) 124.6(6) L5 C(13)]N(15) N(15)]N(16) C(14)]C(13)]C(12) N(15)]C(13)]C(12) N(15)]C(13)]C(14) C(13)]N(15)]N(16) 1.298(7) 1.375(6) 117.8(4) 114.1(5) 127.6(5) 117.2(4) N(16)]C(17) N(15)]N(16)]C(17) N(16)]C(17)]C(18) N(16)]C(17)]C(22) 1.382(7) 118.4(5) 121.8(5) 118.3(5) [Pd(L3)][BF4]2?1.5MeCN Pd]S(1) Pd]S(4) Pd]S(8) Pd]S(11) S(1)]Pd]S(4) S(8)]Pd]S(4) S(8)]Pd]S(11) S(1)]Pd]S(11) C(14)]C(13)]C(12) 2.295(4) 2.301(3) 2.294(4) 2.308(4) 87.9(2) 87.7(2) 87.8(2) 96.6(2) 120.8(13) C(13)]N(15) N(15)]N(16) N(16)]C(17) O(22A) ? ? ? H(16) N(15)]C(13)]C(12) N(15)]C(13)]C(14) N(15)]N(16)]C(17) C(18)]C(17)]N(16) C(22)]C(17)]N(16) 1.29(2) 1.27(2) 1.41(3) 1.96 116.7(14) 123(2) 119(2) 119(2) 122(2) cation is shown in Fig. 6. Disorder modelling of the cation, both anions and both solvate molecules was required to refine the structure, an important factor in the cation being rotation of 1808 about the C(13)]N(15) bond.The minor parts of the disorder are omitted for clarity. The Pd]S distances are similar to those in [Pd([14]aneS4)][PF6]2,10 with the sp2 hybridisation of C(13) leading to an increase in the S(11)]Pd]S(1) angle to 96.6(2)8 but with the other three angles lying in the narrow range 87.7(2)–87.9(2)8. Fig. 6 Structure of the cation in [Pd(L3)][BF4]2?1.5MeCN. Minor parts of disorder and most hydrogens omitted for clarity Table 2 Diagnostic torsion angles for compounds L1–L5 Compound S]C]C]X Angles a/8 L1 L3 L5 L2 L4 211.2(3) b 273.7(6) 250.7(7) 220.7, 219.5 c 246.6(8) 25.8(3) b 2104.5(5) 133.7(4) 137.9, 136.2 c 123.1(5) S(1)]C(2)]C(3)]S(4) C(2)]C(3)]S(4)]C(5) C(3)]S(4)]C(5)]C(6) S(4)]C(5)]C(6)]C(7) C(5)]C(6)]C(7)]S(8) C(6)]C(7)]S(8)]C(9) C(7)]S(8)]C(9)]C(10) S(8)]C(9)]C(10)]S(11) C(9)]C(10)]S(11)]C(12) C(10)]S(11)]C(12)]C(13) S(11)]C(12)]C(13)]C(14) C(12)]C(13)]C(14)]S(1) C(13)]C(14)]S(1)]C(2) C(14)]S(1)]C(2)]C(3) L3 160.9(3) 176.0(4) 70.4(5) 69.0(6) 2164.2(4) 77.3(4) 72.8(5) 2179.4(3) 102.7(4) 2140.4(4) 75.7(5) 106.2(5) 264.1(4) 273.4(4) L5 2167.3(3) 285.5(5) 74.7(5) 50.7(6) 172.4(4) 65.1(5) 72.6(5) 2174(3) 170.4(4) 279.8(5) 253.8(6) 137.9(4) 245.3(5) 2178.7(4) S(1)]C(2)]C(3)]S(4) C(2)]C(3)]S(4)]C(5) C(3)]S(4)]C(5)]C(6) S(4)]C(5)]C(6)]S(7) C(5)]C(6)]S(7)]C(8) C(6)]S(7)]C(8)]C(9) S(7)]C(8)]C(9)]C(10) C(8)]C(9)]C(10)]S(1) C(9)]C(10)]S(1)]C(2) C(10)]S(1)]C(2)]C(3) L4 158.6(3) 266.1(5) 283.5(5) 67.3(6) 72.6(6) 282.2(5) 263.9(6) 141.7(4) 242.1(5) 263.5(5) a X = O or N.b Ref. 6(c). c Taken from the Cambridge Structural Database. 12,14 Table 3 Phenyl ring separations in compounds L3–L5 and [Pd(L3)]- [BF4]2?1.5MeCN L3 L4 L5 [Pd(L3)]21 Centroid–centroid distance a/Å 3.905, 3.905 3.602, 3.700 4.262, 4.519 3.683, — Interplanar separation b/Å 3.383, 3.407 3.270, 3.359 3.360, 3.507 3.270, — a Distance between dummy atoms placed at geometric centroids of adjacent phenyl ring carbon atoms.b Perpendicular distance from dummy atom to mean plane of adjacent phenyl ring carbon atoms.282 J. Chem. Soc., Dalton Trans., 1998, Pages 279–284 Fig. 7 Linear polymeric array of cations in [Pd(L3)][BF4]2?1.5MeCN. Minor parts of disorder omitted for clarity. Phenyl centroid separation (– – – –) = 3.683 Å; S(4) ? ? ? S(4) 3.341 Å Compound L3 co-ordinates to PdII to produce a flattened cup-like structure, resulting in chirality since the hydrazone at the rim of the cup can point either clockwise or anticlockwise, generating distinct enantiomers.The sp2 linkage is rigid and the macrocycle is denied flexibility by the co-ordinated metal atom. In constructing linear polymers of cations (Fig. 7), the dicationic heads are held in close proximity with a shortest contact between neighbouring S(4) atoms of 3.341 Å.The tetrafluoroborate anions appear to exert considerable influence on the arrangement of the cations, with F atoms in close proximity to Pd, S(8) and S(11) and certain H atoms (Fig. 8). The aromatic groups show an interplanar separation of 3.270 Å. The linear polymers, formed from predominantly identical enantiomers, lie side by side to form sheets, with alternate sheets constructed from the alternate enantiomer to produce a racemic crystal. The complex [Pt(L3)][CF3SO3]2 was synthesized using a similar method to that for [Pd(L3)][BF4]2 but using [Pt(EtCN)4]- [CF3SO3]2 as starting material.The yellow suspension of L3 in MeCN cleared only slightly on addition of the [Pt(EtCN)4]- [CF3SO3]2 but no colour change was observed in this case. The cloudiness is presumably due to some hydrolysed platinum(II) starting material, which is relatively moisture-sensitive. The reaction mixture was filtered and the filtrate evaporated, then taken up in a small amount of MeCN and precipitated by layering with Et2O.Satisfactory characterisation data were obtained for all compounds using NMR, IR and mass spectrometry and elemental analysis. Conclusion Thioether crown ketones may be condensed with nitrophenylhydrazines to give new amphiphilic ligands for late transition metals. These ligands may be used in complex-forming reactions with PdII and PtII. The crystal structures highlight extensive p–p interaction while in the new palladium(II) complex sheets of parallel chains of chiral amphiphiles are formed.Furthermore, the crystal structures suggest an additional explanation for the failure of many reactions involving keto- Fig. 8 Influence of BF4 2 on cation packing in [Pd(L3)][BF4]2? 1.5MeCN functionalised thioether crowns. The marked distortion of the macrocycles due to a remote hydrogen atom implies that the steric interaction between the ring and the added substituent is critical. In our hands, attempted acid-catalysed imine formation using anilines in benzene under azeotropic distillation conditions resulted in C]S bond cleavage and decomposition, presumably via b-proton elimination.17a Comba et al.17b have recently investigated thermal C]S bond cleavage and ring contraction in 6-chloro- and 6,13-dichloro-[14]aneS4. We speculate that the thioether crown hydrazones exhibit intermediate stability compared with crown thioethers bearing small substituents like oxygen and CH2 and hypothetical examples bearing sterically demanding aromatic imines.The forcing conditions required to synthesize the imines thus cause decomposition. We also conclude that the failure of certain functionalisations of thioether crown ketones has a steric basis. We are currently attempting to extend the chains attached to the macrocycles using both covalent and non-covalent bonding so increasing the anisotropy of the products. Of particular interest is the nitro–iodo interaction between nitro- and iodobenzenes recently reviewed by Desiraju.18 These approaches should in due course lead to both thermotropic and lyotropic liquid crystals and extended arrays.Experimental Spectra were recorded on a Bruker DPX 300 (1H and 13C NMR) and a Perkin-Elmer 1600 spectrometer (FTIR, samples in KBr discs). Melting points were measured using a Gallenkamp apparatus and are uncorrected. Elemental analytical data were obtained by the Microanalytical Service (Perkin-Elmer 240B analyser) at the University of Nottingham and EI (electron impact) mass spectra were measured using a VG Autospec VG7070E spectrometer.Electrospray mass spectra were obtained by the EPSRC National Mass Spectrometry Service at the University of Swansea. The compounds [14]aneS4-6-one (L1), [10]aneS3-9-one (L2), [Pd(MeCN)4][BF4]2 and [Pt(EtCN)4][CF3SO3]2 were prepared according to literature methods.6,19 All starting materials, including anhydrous dimethylformamide, were obtained from Aldrich or Lancaster Synthesis and used without further purification.Syntheses 1,4,8,11-Tetrathiacyclotetradecane-6-one 2,4-dinitrophenylhydrazone (L3) and 1,4,7-trithiacyclodecane-9-one 2,4-dinitrophenylhydrazone (L4). 2,4-Dinitrophenylhydrazine (50 mg, 0.25 mmol) was suspended in EtOH (5 cm3) in an Erlenmeyer flask (25 cm3). To the stirred solution were added five drops of concentrated H2SO4 yielding a yellow solution. In another Erlenmeyer flask (25 cm3) compound L1 (42 mg, 0.15 mmol) or L2 (31 mg, 0.15 mmol) was dissolved in boiling EtOH (5 cm3) and stirred; the hydrazine solution was added to this colourless solution giving an orange suspension which on cooling to 4 8C yielded a yellow microcrystalline solid and an orange super-J.Chem. Soc., Dalton Trans., 1998, Pages 279–284 283 Table 4 Crystallographic data summarya Empirical formula M Colour, habit Crystal size/mm Crystal system Space group a/Å b/Å c/Å a/8 b/8 g/8 U/Å3 Z Dc/g cm23 T/K m/mm21 F(000) 2q Range/8 Independent reflections Observed reflections [|Fo| > 4s(|Fo|)] Absorption correction method Maximum, minimum transmission Decay correction (%) Number of parameters Weighting scheme a, b b Final R1 (wR2) c Maximum D/s Largest difference peak, hole/e Å23 L3 C16H22N4O4S4 462.62 Yellow plate 0.65 × 0.37 × 0.04 Monoclinic P21/c 7.7711(19) 19.458(9) 13.480(4) — 93.63(3) — 2034.3(10) 4 1.511 150 0.498 968 5–50 4402 2463 y Scans 0.880, 0.803 Random ±2 253 0, 6.41 0.0688 (0.1171) 0.001 0.38, 20.40 L4 C13H16N4O4S3 388.48 Yellow needle 0.35 × 0.10 × 0.06 Monoclinic P21/c 7.249(4) 10.786(4) 21.330(9) — 96.66(4) — 1656.5(10) 4 1.558 150 0.474 808 5–45 2148 1265 None — Random ±8.5 218 0.22, 0 0.0556 (0.1213) 0.001 0.30, 20.31 L5 C16H23N3O2S4 417.6 Yellow plate 0.47 × 0.22 × 0.12 Triclinic P1� 5.6363(11) 8.7733(15) 19.833(4) 93.28(2) 93.55(2) 105.54(2) 940.3(3) 2 1.475 150 0.521 440 5–45 2462 1866 None — 10 227 0.064, 2.54 0.0557 (0.0842) <0.001 0.34, 20.52 [Pd(L3)][BF4]2?1.5MeCN C19H26.5B2F8N5.5O4PdS4 804.22 Yellow column 0.33 × 0.20 × 0.19 Triclinic P1� 10.181(2) 12.569(3) 13.985(3) 96.16(2) 107.81(2) 96.02(2) 1676.1(4) 2 1.594 210 0.881 806 5–45 4402 3257 Numerical 0.898, 0.838 38.6 381 0.13, 39.0 0.1071 (0.1439) 0.009 1.68, 21.83 a Details in common: Stoë Stadi-4 four-circle diffractometer, Oxford Cryosystems open-flow cryostat,21 graphite-monochromated Mo-Ka radiation (l = 0.710 73 Å); w–q scans; refinement based on F 2.b In w21 = s2(Fo 2) 1 (aP)2 1 bP, where P = (Fo 2 1 2Fc 2)/3. c Defined in ref. 20. natant. The solid was separated by suction filtration, washed with cold EtOH (2 × 5 cm3) and dried in vacuo. Crystals of L3 suitable for X-ray diffraction were grown by diffusion of Et2O vapour into a CH2Cl2 solution at 4 8C. Compound L4 was crystallised by slow evaporation of a CH2Cl2 solution at room temperature. Compound L3: yield 64 mg (93%) (Found: C, 41.9; H, 4.8; N, 11.7.C16H22N4O4S4 requires C, 41.5; H, 4.8; N, 12.1%); m.p. 130 8C (decomp.); n& max/cm21 3311m, 1615vs, 1590s, and 1510s; dH(CDCl3) 9.16 [1 H, s, C(NO2)CHC(NO2)], 8.35 (1 H, m, aryl), 7.97 (1 H, m, aryl), 3.75 (2 H, s, Z-CH2C]] NNH), 3.63 (2 H, s, E-CH2C]] NNH), 3.05–2.90 (8 H, m, SCH2CH2S), 2.75 (4 H, m, CH2CH2CH2) and 1.95 (2 H, qnt, CH2CH2CH2); dC[CDCl3, H connectivity confirmed by DEPT (distortionless enhancement of polarisation transfer) 90 and DEPT 135] 151.72 (C]] N), 144.80, 138.71 and 130.24 (aryl CN), 129.95, 123.30 and 116.63 (aryl CH), 39.79 (Z-CH2C]] NNH) and 33.86, 33.65, 32.59, 32.24, 31.03, 30.70, 29.93 and 29.27 (other CH2); m/z (EI) 460 (M1 2 2 H) and 391 (M1 2 71).Compound L4: yield 50 mg (87%) (Found: C, 39.7; H, 4.3; N, 14.0. C13H16N4O4S3 requires C, 40.2; H, 4.15; N, 14.4%); m.p. 168 8C (decomp.); n& max/cm21 3157m, 3087w, 2914w, 2852w, 1613vs, 1590s, 1530m, 1513s and 1499s; dH(CDCl3) 9.15 [1 H, s, C(NO2)CHC(NO2)], 8.33 (1 H, m, aryl), 7.95 (1H, m, aryl), 3.75 (2 H, s, Z-CH2C]] NNH), 3.50 (2 H, s, E-CH2C]] NNH) and 3.24–2.83 (8 H, m, SCH2CH2S); dC(CDCl3, H connectivity con- firmed by DEPT 90 and DEPT 135) 151.38 (C]] N), 144.86, 138.59 and 130.42 (aryl CN), 129.77, 123.34 and 116.55 (aryl CH), 41.68, 35.12, 35.00, 34.16, 33.43 and 31.02 (CH2); m/z (EI) 327 (M1 2 71). 1,4,8,11-Tetrathiacyclotetradecane-6-one 4-nitrophenylhydrazone (L5). In a round-bottomed flask (25 cm3) equipped with a magnetic stirrer bar and a reflux condenser, compound L1 (50 mg, 0.18 mmol) was suspended in EtOH (5 cm3) and refluxed to give a colourless solution.In a second flask (25 cm3), p-nitrophenylhydrazine (50 mg, 0.33 mmol) was suspended in EtOH (5 cm3) and treated with glacial acetic acid (four drops). On heating, a dark brown solution formed which was mixed with the refluxing ketone solution. The mixture was refluxed for 1 h, then stoppered and stored at 218 8C for 18 h.The resulting precipitate was isolated by suction filtration and recrystallised from EtOH to yield a yellow powder. Crystals suitable for X-ray diffraction were grown by slow evaporation of a solution of L5 in CHCl3. Compound L5: yield 47 mg, 0.11 mmol (63%) (Found: C, 46.1; H, 5.7; N, 10.3. C16H23N3O2S4 requires C, 46.0; H, 5.6; N, 10.1%); m.p. 141–143 8C (decomp.); n& max/cm21 3273m, 2920m, 1595vs, 1523s, 1498s, 1481s, 1425w, 1324vs, 1264vs, 1110vs and 1080s; dH(CDCl3) 9.37 (1 H, s, NH), 8.18 (2 H, m) and 7.10 (2 H, m, aryl), 3.69 (2 H, s) and 3.50 (2 H, s, CH2C]] N), 2.98–2.86 (8 H, m, SCH2CH2S), 2.75–2.67 (4 H, m, CH2CH2CH2) and 1.90 (2 H, m, CH2CH2CH2); dC(CDCl3) 149.64 (C]] N), 142.83 and 140.68 (aryl CN), 125.99 and 112.11 (aryl CH), 40.39, 33.32, 32.69, 32.38, 32.06, 30.72, 30.38, 29.64 and 29.40 (CH2); m/z (EI) 417 (M1).[Pd(L3)][BF4]2. A Schlenk tube (50 cm3) was charged with compound L3 (20 mg, 0.04 mmol) and a magnetic stirrer bar and pump-filled with N2.A solution of [Pd(MeCN)4][BF4]2 (19 mg, 0.04 mmol) in degassed MeCN (10 cm3) was added via cannula, which was washed through with degassed MeCN (5 cm3). The yellow solution became orange as all of the hydrazone dissolved. The solution was stirred for 1 h but no further change was observed. The MeCN solution was then layered with diethyl ether (30 cm3) and left to stand for 24 h. Orange crystals formed which immediately became powder on suction filtration.[Pd(L3)][BF4]2?0.5MeCN: yield 28 mg, 0.038 mmol (94%) (Found: C, 26.5; H, 3.3; N, 7.9. C16H22B2F8N4O4PdS4? 0.5MeCN requires C, 26.8; H, 3.1; N, 8.25%); n& max/cm21 3432m, 2923w, 2211vs, 1615s, 1596s, 1503m, 1427w, 1340s and 1084s; dH(CD3CN) 11.12 (1 H, s, NH), 8.99 (1 H, m, CNCHCN), 8.44 (1 H, m) and 7.95 (1 H, m, CNCHCHCN), 4.43–4.37 (4 H, m,284 J. Chem. Soc., Dalton Trans., 1998, Pages 279–284 CH2C]] N) and 3.93–2.90 (16 H, m, other SCH2) (CH2CH2CH2 coincident with solvent peaks at 2.20–1.90); dC(CD3CN4.99, 141.33 and 132.78 (aryl CN), 131.35, 123.74 and 118.20 (aryl CH), 43.26, 42.61, 42.35, 39.18, 38.78, 36.14 (2 C), 32.25, 26.26 (CH2) (CH at 118.20 coincident with CD3CN, detected using DEPT 90 and 135; C]] N not detected but possibly coincident with one of the aryl CN peaks; H connectivity confirmed using DEPT); m/z (positive-ion electrospray, MeOH, 80 V) 567 (M1 2 2 BF4, 100%).Crystals suitable for X-ray analysis were grown by diffusion of Et2O vapour into an MeCN solution of the complex. They were found to be of composition [Pd(L3)][BF4]2?1.5MeCN.[Pt(L3)][CF3SO3]2. To a stirred suspension of L3 (11 mg, 0.024 mmol) in MeCN (5 cm3) in a round-bottomed flask (25 cm3) was added a solution of [Pt(EtCN)4][CF3SO3]2 (17 mg, 0.024 mmol) in MeCN (5 cm3). The flask was stoppered and the mixture stirred for 24 h at room temperature. After this time a faintly cloudy yellow solution had formed which was filtered by gravity.The filtrate was evaporated, the residue taken up in MeCN (2 cm3) and precipitated by layering with Et2O and storing at 4 8C for 16 h. A yellow powder was isolated by suction filtration, washed with Et2O (2 × 5 cm3) and dried in air. [Pt(L3)][CF3SO3]2: yield 17 mg, 0.018 mmol (75%) (Found: C, 25.3; H, 2.9; N, 6.0; Pt, 19.0. C18H22F6N4O10PtS6?Et2O requires C, 25.7; H, 3.1; N, 5.4; Pt, 18.9%); m.p. 155–160 8C (decomp.); n& max/cm21 3454m, 3295w, 2983w, 2926w, 1519s, 1596m, 1502s, 1421w, 1343vs, 1316m, 1261vs, 1165s, 1097w, 1030s, 638s and 518w; dH(CD3CN) 11.16 (1 H, s, NH), 9.00, 8.44, 7.97 (each 1 H, m, aryl), 4.63–4.40 (3 H, m), 3.96–2.85 (m, 13 H, SCH2) and 2.12 (H2O, conceals CH2CH2CH2); dC(CD3CN) 144.99, 141.39, 140.53, 132.60 (C]] N and aryl CN), 131.40, 123.80, 120.01 (aryl CH), 43.42, 43.17, 42.27, 41.23, 38.95, 38.47, 36.61, 32.75, 26.12 (other CH); m/z (positive-ion electrospray, MeCN) 958 (M1 1 2 H) and 657 (M1 2 2 CF3SO3 2 2 H) (both peak sets agree closely with theoretical distributions).Crystallography Table 4 summarises the crystal data, data collection, structuresolution and refinement parameters for ligands L3–L5 and the complex [Pd(L3)][BF4]2?1.5MeCN. All structures were solved using direct methods and all non-hydrogen atoms except for those in disordered groups were refined anisotropically. Hydrogen atoms were placed in calculated positions and refined using a riding model.The asymmetric unit of the complex was found to contain two MeCN sites, one of which was half-occupied: disorder of the full-occupancy MeCN was successfully modelled by an approximately equal distribution of two orientations. Disorder in one BF4 2 was modelled using two-fold rotation about the B(1)]F(1) vector, whilst the other was modelled as two tetrahedra with a common centre at B(2). Disorder in the cation was modelled by a 1808 rotation about the C(13)]N(15) vector with a 65 : 35 random distribution.The symmetry of the unit cell imparts the racemic nature of the crystal. The phenyl ring was restrained to be flat to within 0.02 Å with C]C distances of 1.40(2) Å. Structure solution and least-squares refinement for all crystals was carried out using Dell Dimension 133 MHz Pentium personal computers running SHELXTL PC software 20 except for the structure solution for L4 which was performed using SHELXS 86.22 CCDC reference number 186/773. Acknowledgements We thank the EPSRC for support and the EPSRC National Mass Spectrometry Service at the University of Swansea for electrospray mass spectra. We also thank Professors R.M. Kellogg and P. Comba for details of unpublished results. References 1 A. J. Blake, D. W. Bruce, I. A. Fallis, S. Parsons and M. Schröder, J. Chem. Soc., Chem. Commun., 1994, 2471; A. J. Blake, D. W. Bruce, I. A. Fallis, S. Parsons, H. Richtzenhain, S. A. Ross and M. Schröder, Philos.Trans. R. Soc. London, Ser. A, 1996, 354, 395. 2 F. Vögtle in Supramolecular Chemistry, Wiley, Chichester, 1991, pp. 231–290. 3 V. B. Pett, G. H. Leggett, T. H. Cooper, P. R. Reed, D. Situmeang, L. A. Ochrymowycz and D. B. Rorabacher, Inorg. 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