摘要:

946 J.C.S. DaltonComplexes of Pyridine-2-thiol With Some Transition Metals tBy I. Philip Evans "* and Geoffrey Wilkinson. Inorganic Chemistry Laboratories, Imperial College of Scienceand Technology, London SW7 2AYPyridine-2-thiol (LH) complexes of iron(!!). cobalt(ii), nickel(ii), copper(ii), copper(!), rhodium(ii), and palladiurn-(11) have been prepared and characterised by infrared and electronic spectroscopy and by magnetic susceptibilitymeasurements. With the exception of PdL,( LH) all the complexes have unidentate pyridine-2-thio1, most ofthem showing an N-H stretching frequency confirming other evidence that the donor atom is sulphur.THE first metal complex of pyridine-2-thiol (LH) ,RuL,(PPh,),, was formulated as a chelate, despite theshort bite of the ligand, and this structure was con-firmed by X-ray diffraction.2 A similar iridium com-plex containing bidentate pyridine-2-thiolato-groups hasalso been prepared3In extending studies of the complexing by this ligandwe were encouraged by interest * in the complexing ofthiolated nucleosides such as 6-thioguanosiiie (I) whichhas NH and sulphur in the 1 and 6 positions.A brief note has recently a~peared,~ where, using6-mercaptopurine blocked at the 9-position by a benzylS S 0substituent to simulate a riboside, a palladium complexwas prepared and shown to involve bonding at the sulphurNo reprints available.$ Present addvess: Research School of Chemistry, AustralianNational University, Box 4, P.O., Canberra A.C.T., Australia2605.1 J.D. Gilbert, D.Rose, and G. Wilkinson, J . Claem. SOC. ( A ) ,1970,- 2 7 65.2 S. R. Fletcher and A. C. Skapski, J.C.S. Dalton, 1972, 635.3 C. K. Brown, D. Georgiou, and G. Wilkinson, J.C.S. Dalton,1973, 929.and the N(7) donor atoms. Since pyridine-2-thiolexists as the tautomer,6 it is best named as a thione, (11) ;it provides thus a model for the sulphur and N(1)donor atoms in (I). Pyridine-2-thiol (it is more con-venient to call it this) has three potential bonding forms,since co-ordination can occur either through the sulphuror nitrogen donor atoms or through both as in (111).As this work was being completed, the reaction of theligand with some metal ions was de~cribed,~ but there isonly a small overlap with the cobalt(I1) and nickel(I1)complexes as will be noted later.RESULTSIron(11) .-Iron(n) halides react readily with pyridine-2-thiol in anhydrous media (an ethanol-2,2-dimethoxy-propane mixture) to yield complexes of stoicheiometryFeX,(LH), (X = C1, Br).The complexes are paramag-netic and have values of PeR, 5.03 and 4-92 B.M. respec-tively (297 K) , consistent with tetrahedral co-ordination ,8although distortion in octahedral iron(I1) complexes canlower the magnetic moment sufficiently to cause somedoubt if assignment is made on this basis alone.gThe electronic spectrum exhibits a broad, split, band4 S. J . Lippard, personal communication.5 H. I. Heitner, S. J. Lippard, and H. R. Sunshine, J . A~ner.6 R. A. Jouls and A. R. Katritzky, J . Chem. SOC., 1958, 3610.B.P. Kennedy and A. B. P. Lever, Canad. J . Chem., 1972,8 B. N. Figgis and J. Lewis, Prop. Inovg. Chem., 1964, 6, 176.9 W. Hieber and J . G. Floss, 2. ajzorg. Chem.., 1957, 291, 314.Chem. SOC., 1972, 94, 8936.50, 3488947at 4.90 and 5.62 k K (X = C1, Br) which can be assignedto the 5T,t-5E transition of a tetrahedral iron(I1) species.A similar transition occurs at 4.65 and 5.78 k K in the[Fe(NCS)J2- anion lo (Table 1).At 77 K the Mossbauer spectrum is a doublet, ofisomer shift 0.87 mm s-l and quadrupole splitting 3.48mm s-l (relative to metallic iron). This is in the regionexpected for tetrahedral iron(I1) with sulphur 1igands.llIn addition there is a small, somewhat broad, peak with anUsing the temperature dependence of the quadrupolesplitting the degree of distortion, A , in the e levels canbe obtained in a manner similar to that for FeC1,2-.l2,l3A is ca.735 cm-l, and this large distortion is probably dueto the large bulk of the ligand; it is comparable with thedistortions in thioacetamide and thiourea complexes ofiron(@ .I1The i.r. spectrum (4000-200 cm-l) gives little informa-tion as to the bonding, as the various ring modes which, -~ A B L E 1Far-i.r. data Electronic reflectance spectra.Selected i.r.,* far-i.r., f and electronic reflectance spectra for pyridine-2-thiol complexesA 7 - 71.r. data $.. - --A.- _I_____ - _ _ ~ ,--Complex v(K-H)FeCl,(LH) 3162FeBr,(LH), 3150CoCI,(LH) 3150CoBr,(LH), 3145CoI,(LII) 2 d 3140NiCl,(LH), 3160NiBr,(LH), 3150NiI,(LH), d 3140NiCl,(LH) 3160NiBr,( LH), 3065NiI,(LIT\, 313031303140a3090a3170a31763175I , v(c:s) v(N-X)1126 311, 281m1118 242,226m1125 303, 2871111120 230br, s1115 210, 191s1132 298vs.260s1130 233vs1119 193s. l681n1138, 1187 Not co-ord.1118 Not co-ord.1130 2511111118,3125 aa a1125 Not co-ord.a1123b1120bv(M-S)223m220mbb226s236mb218s2181x1a8l81n242111242111243m328s362, 333s262, 243s278s340s243mOthers C264m255VW156, 90m205, 811, 225w28l1n, 144s272, 242wBand4-90, 5.624.90, 5-624.90, 5-8813.89, 15.62, 16.675-32, 7.27, 7.9413.90, 16-875.13, 5.99, 7.2520.41, 22.73(8.33) 9.30 (10.53)14.3022.7315.62(7-69) 8.77, 9-80(12.90) 14.2921.205.40(6.94) 7.9412.58, 13.7020.836.06, 8.3310.31137021.748.8420.008.8420.83211, 205111219m, 211w206, 93, 56m2 6 5 ~219n1297, 275, 206m 11.43Xssig iiinen t51',<-5E6 T#E4 Ti( F ) t 4 A4T1 (P) t 4 A, T 1 ( F ) t 4 A ,4T1(++4A4T1(F)+-4A ,Charge transferTz9f3A 293Tl,t3A 291'19 ( P ) f3A 20lEgt3A 2g3T2g-+3A 293 T l , t 3 A 29TIg ( P ) +3A tl* Nujol mulls, KBr plates, in cni-l.Q Not observed.b Obscured. c s, Strong; m, medium; IV, weak; br, broad; v, very. Measured down t o 20 crn-l.t 450-200 cm-l, Polythcne plates; Vaseline mulls. $ 4-25 kK. 5 Ring breathing mode990 f 6 cn1-l. Thioamide bands,l4>l5 not assigned.isomer shift of 0.29 mm s-l. On raising the temperatureto 300 K this splits into a well resolved doublet of isomershift 0-39 mm s-l and quadrupole splitting 0.51 mm s-l.On re-cooling to 77 K a spectrum identical with thctoriginal is obtained, and this remains essentially un--changed down to 4.2 K.The 300 K spectrum was un-clianged when the complex was set aside in air for a week,and the additional doublet is most likely to be due to somephase change caused by the initial cooling to 77 K. Inthe spectra at 77 and 4.2 K there is a very weak mag-netically split component, probably due to an impurity.are diagnostic proved difficult to assign with any cer-tainty (Table 1). However the presence of an N-Hstretch in both chloride and bromide strongly suggestssulphur co-ordination, with the ligand in the thioneform.In the far-i.r.region, ligand vibrations can be easilyidentified by their lack of sensitivity toward changes ofhalogen, and the bands at 442 and 358 cm-l (X = Cl),and 437 and 356 cm-l (X = Br) are assigned to ligandmodes, or modes of predominantly ligand character.The two M-X stretching bands are consistent with alo D. Forster nncl D. M. L. Gocdgame, J . Claem. SOC., 1965, 268.l1 T. Eirchall and M. F. Morris, Canad. J . CiTzewz., 1978, 50, 211.l2 T. C. Gibb md N. N. Greenwood, J . Chem. Snc., 1965, 6989.l3 P. R. Edwards. C. E. Johnson, and R. 3. P. Williams, J .l4 C. N. R. Rao and R. Venkataraghavan, Spectvochinz. Ada,l5 C. N. R. Rao, R. Venkataraghavan, and T. R. Kasturi,1962, 18, 541.Canad. J . Chem., 1964, 42, 36.Chein. Plzys., 1967, 4'7, 2074948 J.C.S. Daltontetrahedral MX,(LH), system (Table 1) and the band at223 cm-l (X = C1) is in the region expected for an Fe-Sstretching mode .16The compounds decompose slowly during severalmonths even under dry oxygen-free conditions. Theyare immediately solvolysed by water and are insolublein non-polar solvents such as dichloromethane, benzene,and petroleum. They dissolve in solvents of high co-ordinating ability such as dimethyl sulphoxide, wherethere is evidence for some dissociation (A = cn. 50 Q-lmol-l cm-2).No complexes of the type FeX,(LH), could be obtainedeven using ligand to metal ratios >6 : 1. The non-existence of the 4 : 1 species when compared with thewell known FeX,(~yridine)~, is probably due to thesize difference of the ligands, rather than to electronicfactors.CobaZt(II).-The complexes CoX2(LH), (X = C1, Br, I)were prepared from ethanolic solutions of the ligand andthe corresponding metal halide.No dehydrating agentwas necessary, and no difference was observed in thecomplexes if anhydrous salts were used instead ofhydrated salts. Kennedy and Lever have reported thepreparation of these complexes and we are in broadagreement with the spectral data they report.The electronic spectra obtained differ slightly in bandpositions from those reported, but this is most probablydue to the difference between transmission and diffusereflectance spectra, which is significant, especially below5 kK.In the far i.r.region both Co-I stretches can beassigned at 210 and 191 cm-l, corresponding to theCo-C1 stretches in CoCl,(LH), at 303 and 287 cm-l.NickeZ(Ir).-With a 2 : 1 ratio of ligand to metal thecomplexes NiX,(LH), (X = C1, Br, I) were obtainedwhereas a 4 : 1 or 6 : 1 ratio gave the compounds Nix,-(LH), (X = C1, Br, I). Intermediate ratios such as2-5 : 1 or 3 : 1 inevitably led to mixtures of products andit is probable that the yellow and green mixtures re-ported by Lever 7 in some of his preparations are due toformation of complexes intermediate in compositionbetween NiX,(LH), and NiX,(LH),.The series NiX,(LH), are green (X = C1, Br) or brown(X = I) and their susceptibilities of 3.37 (X = Cl), 3.36(X = Br), and 3.43 B.M. (X = I) are not definitive as tooctahedral 71s.tetrahedral co-ordination.The electronic spectra are probably more in agreementwith an octahedral co-ordination around the nickel butin the absence of E values it is difficult to be certain;oscillator strengths and band intensities are not neces-sarily related in reflectance spectra and thus correlationof band intensities is not possible.Comparison of the far-i.r. spectra allows of completeassignment of the halogen modes, the two bands forX = Cl, I being consistent with a tetrahedral NiX,(LH),system rather than the alternative LH bridged octa-hedral system; this would be expected to show only oneNi-X stretch.The data obtained are not definitive of the co-ordinationtype and it would certainly be unwise to use transmissionor reflectance electronic spectra as the deciding factor.With a 4 : 1 ratio of ligand to metal, complexes ofstoicheiometry NiX,(LH), (X = C1, Br, I) were obtained.With X = C1 the complex was mustard yellow andhad peg = 3.16 B.M.(294.5 K) typical of octahedralnickel. The electronic spectrum was consistent withthis, showing the expected three spin-allowed bandsat 8-33 (3T2,p+3A29), 13.70 (T1,t3A*), and 21.74k K [3T1g(P)+-3A2g]. A band a t 10.31 kK is tentativelyassigned to the spin-disallowed l E , t 3 A Q transition,which is frequently observed.The occurrence of only a single v(Ni-C1) a t 242 cm-l inthe far i.r. region indicates a trans-octahedral structurefor the complex.The compounds NiX,(LH), (X = Br, I) are red-brownand dark green respectively, and show very differentmagnetic and spectral properties to NiCl,(LH),. Bothcomplexes are diamagnetic indicating a spin-singletground term characteristic of square NiII.The com-plexes are soluble in solvents such as pyridine or di-methyl sulphoxide giving conductivities at 1 0 - 3 ~ of ca.60-80 !X1 mol-l cm-, apart for X = Br in pyridine,which gave a conductivity of (10 !2 mol-l ern-,. Forthe species which give conducting solutions the cations[Ni( LH),( p ~ ) ~ ] , + or [Ni( LH),( Me2S0),l2+ are presumablyformed.The electronic spectra of the complexes have the~ A G + - ~ A ~ , transition at 20.00 (X = Br) and 20.83 kK(X = I) but the lower-energy band commonly seen inNiS: systems l7 is absent as the band at 8-84 kK inboth compounds is probably too low to be assigned tothis.A sharp band at 6.04 kK (X = Br) and 6.02 kK(X = I) is almost certainly vibrational in origin, prob-ably an overtone of the v(C-H) at ca. 3.0 k ~ .Consistent with the above interpretation the com-plexes NiX,(LH), (X = Br, I) show no bands attribut-able to either v(Ni-Br) or v(Ni-I) in the far infraredregion (450-200 crn-l).Nickel is the only metal investigated which gives both2 : 1 and 4 : 1 complexes. A rationalisation in terms ofligand-field stabilisation energies is possible. Nickel( 11)has the highest negative AH for the transformationtetrahedral+octahedral l8 calculated in terms of LFSE.Since the other parameters involved probably changeuniformly from metal to metal, it is likely that the LFSE'sinvolved do play an important role in the determinationof the stereochemistry involved.Consistent with thisexplanation is the non-existence of Mn2+ complexes withpyridine-2-thio1, no reaction being observed even undervigorous conditions.Co@er(I). Copper( I) chloride and bromide reactreadily as ethanolic suspensions with LH to give com-plexes of stoicheiometry CuCl(LH), and CuBr(LH)2.As expected, the complexes (dl0) are diamagnetic andshow no bands in the electronic spectrum apart from high-16 C . D. Flint and XI. Goodgame, J . Chem. SOC. ( A ) , 1968, 2178.l7 C . K. 101-gensen, J . Inorg. Nuclear Chem., 1962, 24, 1571.18 A. 13. Blake and F. A. Cotton, Inorg. Chem., 1964, 3, 91974 949energy charge-transfer bands.The complexes are doubt-less tetrahedral.lsCuI did not react directly with the ligand but CuI(LH),could be prepared by adding a methanolic solution ofthe pyridine-2-thiol containing potassium iodide to asuspension of copper( 11) sulphate in methanol, in presenceof sulphur dioxide.The complexes are bright orange, due to charge-trans-f er absorption.Silver( I).-- With silver(1) tetrafluoroborate the complexAg(LH),BF, was obtained whereas with AgC10, thecomplex Ag(LH),ClO, was isolated. The i.r. spectrumindicates ionic perchlorate, although there is some slightsplitting of v3; v4 is not observed.PnlZadizmz( 11) and Rhodium(11) .-The interaction ofPdCl, with the ligand in refluxing ethanol led to thecomplex Pd(LH),Cl,,EtOH.The orange complex dis-solved in water and in methanol in which it gave aconducting solution. The conductivity (A = 120 L2-lmol cm ,; c 10-3~) was much lower than that expectedfor a 2 : 1 electrolyte, however, the range in methanolbeing generally 160-220 L2-I mol-I crn-,.,O Analogousbehaviour has been noted for the similar complexPt(I,H),C1,.7 An absorption at 328 cm-l in the far-infrared spectrum may be an indication that there issome degree of Pd-Cl bonding, although it is consideredmore likely to be a mode of primarily metal-ligandcharacter .Displacement of co-ordinated acetate occurs withpalladous acetate, [Pd(CO,Me),],, and the complexPdL,(LH), evidently five-co-ordinate, is obtained.The diamagnetic complex is red, due to charge-transferabsorptions, and is very soluble in chloroform and di-chloromethane.At 35 "C, no lH n.m.r. signal could bedetected in CDCl,, but on cooling to -60 "C some broadresonance was observed from T 2.5 to 3.2. This be-haviour is probably due to a rapid exchange process.Indeed similar behaviour has been noted in the com-plex Pt(I~t,NCS,),(PMePh,),21 and in Pt(SnC1,),3- no tinresonance could be detected.22With the dimeric Rh,(OAc),, no displacement of cc)-ordinatccl acetate was achieved and the adduct Rh,-(OAc),,2LH was obtained. The complex was purple-lirown and had an i.r. spectrum similar to that ofRli,(OAc), with additional bands due to the co-ordinatedpyrictine-2-thiol. Adducts of Rh,(OAc), with manyligands lia\-e been prepared and it has been suggestedthat the colour o f the adduct can be used to distinguishbetween sulpliur and oxygen donor atoms,,, as oxygendonor ligands produced green adducts and sulphurdonor ligands orange or red adducts.There is inorerange in the colour of adducts with nitrogen donorligands so assignment of the donor atom in Rh,(OAc),,-2LH from the c-olour of the adduct is not feasible. Now-ever, the presence of a strong band in the far4.r.spectrum at 375 cm-l, the correct region forv(Rh-S), strongly suggested sulphur bonding of theligands.Attempts to prepare a pyridine-2-thiolato-complexfroin Rh,(OAc), were unsuccessful because the bite ofthe ligand as an anion is insufficient to bridge two metalatoms, which it would be required to do in this case asRh,(OAc), contains a rhodium-rhodium bond.Interaction with Copper( 11) .-Copper( 11) chloride andbromide reacted with pyridine-2-thiol in ethanol to giveyellow species which were diamagnetic and which hadstoicheiometry CuCl( LH) and CuBr,(LH),.I'yridine-2-thiol could reduce CurK to CuI by being oxidised itselfto the disulphide, and the chloride complex is probablya genuine copper(1) species, probably with bridginghalogen atoms. It is difficult to rationalise the bromidecomplex being diamagnetic with its formulation as acopper(I1) complex. The differences in stoicheiometrybetween the copper( I) complexes derived directly fromcopper(1) and those derived from copper(I1) were inde-pendent of the ratio of ligand : metal in the reactions.The different complexes obtained probably reflect thetwo distinct ways by which the complexes are formed.Starting with copper(r), a complex of stoicheiometryCuCl(LH), is not unexpected because of the almost in-evitable preference of copper(1) for a tetrahedral environ-ment. With the complexes derived from copper(II), itmay well be that reduction to copper(1) occurs afterco-ordination of the ligand to the metal, so that thestoicheiometry adopted by the complex reflects more thereaction of a copper(r1) species.Copper@) nitrate, sulphate, acetate, arid perchloratealso gave insoluble yellow species.The sulphate andnitrate had stoicheiometry CuSO,,l BLH and Cu-(NO,),,l+LH and their i.r. spectra indicated co-ordinationof the anions.The sulphate complex had prE = 0-45B.M. and possessed a rather featureless e.s.r. syectruniconsistent with a polymeric structure (g = 2.013). Theacetate reacted to give an extremely insoluble speciescontaining no acetate; it presumably contains ionisedpyridine-2-thiol. It had the stoicheiometry (CuL),,.Because of their insolubility and intractable nature tlieComplexes were not studied further.Although thiourea reduces copper(r1) to copper( I),copper( 11) complexes containing co-ordinated thioureacan be isolated by using copper( 11) perchlorate stabilisedby co-ordination to 1 ,lo-phenanthroline (phen) or 2,2'-bipyridyl (bipy) .24 With Cu(phen),(ClO,), the complexCu(phen),(LH) (ClO,), was isolated by allowing thestabilised species to react with the ligand in ethanol.The complex has a normal magnetic moment for copper-(11) and has an electronic spectrum consistent with afive-co-ordinate species.19 W.E. Hatfield and l i . W-hyman, Tratzsitioti Metal Chewz.,2O W. J . Geary, Co-ordinalion. Chew. Rev., 1971, 7, 81.21 J . 1'. Fackler, jun., J . A. Fetchin, and W. C. Seidel, J . Amev.22 D. R. Eaton, J . Amer. Gheiii. SOC., 1968, 90, 4272.23 S. A. Johnson, H. R. Hunt, and H. M. Neuman, Iizovg.24 A. Montenero and C. Pelizri, I n o ~ g . Chini. -4cta, 1973, 6,1969, 5, 47.Chew., 1963, 2, 960.644. Chem. Soi, 1969, 91, 1217950 J.C.S. DaltonEXPERIMCNTALMicroanalyses by the Microanalytical Laboratory, Im-perial College.1.r. spectra (4000-450 cm-l) were taken on a Perkin-Elmer 457 spectrophotometer; far4.r.spectra (450-200cm-l) on a Perkin-Elmer 325 spectrophotomcter, and(200-20 cn1-l) on a Beckman FS 720 Fourier spectrophoto-meter.Magnetic moments were measured a t room temperatureusing the Evans' modification 25 of the Gouy-Rankinebalance. The balance was calibrated using the compoundHgCo(NCS),.Diffuse reflectance spectra were measured in the region4-25 kK on a Cary 14 R spectrophotometer using a Cary141 1 diffuse reflectance accessory.Dried solvents of reagent grade were used in all reactions,but reactions were not carried out under an inert atmosphereunless specifically stated.Analytical data are collected in Table 2.DichZoi/obis (pyuidine-2-ttzioZ)iron (11) .-Iron (11) dichlorideTABLE 2Analytical dataFound (yo) Required (76) *- Compound C H N C F I XFeCl,(LH) 34.8 2.9 8.2 34.4 2.9 8.0FeBr,(LH), 27.4 2.4 6.4 27.4 2.3 6.4CoCl,(LH) , 34.3 3-0 7.8 34.1 2.8 8.0CoBr,(LH) , 27.7 2.2 6.2 27.2 2.3 6.423-2 1.9 5-5 22.4 1.9 6.234.2 2.6 8.1 34.1 2-8 8-0NiBr,(LH) , 28.0 2.5 6.5 27.2 2-3 6.3Ni I, (LH) 21.9 1.8 8.0 22.4 1.9 6.2NiCl,(LH) , 41.7 3.7 9.9 41.8 3.5 9.RNiBr, (LH), 36.5 3.1 8.6 36.2 3.0 8.4Ni I, (LH) , 32-5 3.0 7.5 31.7 2.(i 7.4CuCl (LH) 42.0 3.6 9.5 41.7 3.5 9.5CuBr(LH), 32.8 3-0 7.2 32.8 2.7 7.7CuI(LH), 29.4 2.4 6.9 29.1 2.4 6.8Cu@hen),(LH)(ClO,), 46-8 2.!1 9.4 47.4 2.9 9-537.7 3.2 8.5 37.6 3.1 8.827.1 2.3 6.2 27.9 2.3 6.6 Ag(LH),ClO,Pd(LH),CI,,EtOH 40.2 3.9 8.9 39.6 3.9 8.4PdL,(L€I) 40.5 3.1 9.8 41-2 3-4 9.0Rh,(OAc),(LH), 33.3 3.6 4.2 32.5 3.3 4-20 I : Found, 31-69;,; Required, 30.87;.COI, (LH) 2 Ni C1, (LH)Ag(LH),BF,tetrahydrate ((1.5 g) was dissolved under nitrogen in amixture of ethanol (30 ml) and 2,2-dimethoxypropane (10ml) which had been degassed with nitrogen.Iron wire(cn. 2 g) was added along with conc. hydrochloric acid (ca.0.2 nil) to provide a reducing system. The flask was sealedand shaken periodically until the solution was colourless.The solution was filtered into a solution of pyridine-2-thiol(0.56 g) in ethanol (15 ml). The yellow powdev whichprecipitated was filtered off under nitrogen, washed withethanol (2 x 10 ml) and diethyl ether (2 x 10 ml), anddried in vacuo over silica gel (0.82 g, 93%).Dibro;izobis(p~i.idine-2-thiol)iron (11) .-This reaction wascarried as that described above, except that the iron(I1)bromide was prepared from an excess of iron wire and 400/,aqueous hydrobromic acid (yield, 0.63 g, 72%).DicAloro-, Dibronao-, and Di-iodo-bis(pyridine-2-thio1)-cobalt(II).-A solution of the halide (2 mmol) in ethanol (10ml) was added to a solution of the ligand (4 mmol) in ethanol(1 5 ml) .The complexes that immediately precipitated werefiltered off, washed with ethanol (2 x 10 ml) and diethyl? 5 11. F. Evans, J . Clieitz. SOC. ( A ) , 1967, 1670.ether (2 x 10 nil), and dried in vacz~o over silica gel. Theyields were essentially quantitative.Dicltloro-, Dibromo-, and Di-iodo-bis(pyridine-2-thiol)-niclzel( 11) .-These compounds were prepared in an analogousway to the cobalt(I1) complexes.The yields were quantita-tive.Dichlorotetrakis(~yvidine-2-thioZ)nickeZ( 11) .-A solution ofnickel(I1) chloride hexahydrate (2 mmol) in ethanol (10 ml)was added to the ligand (8 mniol) in ethanol (20 ml). Theyellow complex which quantitatively precipitated wascollected, washed with ethanol and ether, and dried in vncuoover silica gel.Tetvakis(pyridine-2-thioZ)nickeZ(iI) Dibvomide and Di-iodide.-This reaction was carried out as that for thechloride above, except that the nickel(I1) iodide was formedin situ by mixing equivalent solutions of nickel(I1) chlorideand sodium iodide in ethanol and filtering off the precipi-tated sodium chloride after cooling the solution to -30 "C.The yields of the complexes were ca.80%.Chlorotvis(pyridine-2-thiol)copper(I) and Bronzobis(pyrid-ine-2-thiol)copfier ( I) .-To a suspension of the copper( I)halide (5 nimol) in ethanol (25 ml) was added a solution ofthe ligand (15 mmol for chloride, 10 mmol for bromide) inethanol (30 ml) and the solution was vigorously stirred.The halide dissolved immediately to give an orange solutionand after 25 s the complexes precipitated as bright orangepowders. They were filtered off and washed with ethanoland diethyl ether.I o d o b i s ( ~ y r i d i ~ z e - 2 - t h i o l ) c o ~ ~ e r ( I) .-Sulphur dioxide wasbubbled througli a solution of copper(I1) sulphate pentahyd-rate (0.5 g) in methanol (35 ml) and a solution of pyridine-2-thiol (0.7 g) and sodium iodide (0.7 g) in methanol (35 nil)was added.An orange precipitate formed immediately andthe solution was stirred for a further 10 min to complete thereaction. The orange coinplex was filtered off, washed withethanol and ether, and dried in vacua (0.7 g, 67%).Tetral~is(p~ividine-2-thioZ) silver(1) Tetrafluoroborate.-Silver(1) tetrafluoroborate (0.5 g) in ethanol was addedslowly to a solution of pyridine-2-thiol (0.28 g) in ethanol(1.5 nil) wit11 stirring. An initial precipitate redissolvedand the solution was filtered free from any solid whichremained (an oily deposit often remains a t this stage).When set aside, the solution deposited pale yellow needlesoi the compound. These mere collected, washed with alittle cold ethanol and ether, and dried in vacuo (0.35 g,Bis (pydine- 2-th iol) siluer ( I) Pevchlovate .-Pyridine- 2-thiol(0.32 g) in ethanol (20 inl) was slowly added to a solution ofsilver(1) perchlorate (0.3 g) in ethanol (20 ml).A paleyellow precipitate formed immediately. It was filtered off,washed with ethanol (2 x 10 ml) and ether (2 x 10 ml),and dried iiz uacuo (0.3 g, 50%).Tetv~kis(~yvidine-2-t?~iol)palZadium(11) Dichlovide.-Pal-ladium(I1) chloride (0.5 g) dissolved in the minimum of hotethanol was added to a hot solution (60') of pyridine-2-thiol(0.63 g) in ethanol (15 ml). As the solution was cooled,the orange conzpoz~ntZ precipitated. It was filtered off,washed with ethanol and diethyl ether, and dried in vacuoover silica gel (0-8 g, 71%).Bis( pyridine-2-thiolato) (py~idine-8-thiol)paZlndium(11) .-Yalladous acetate (0.2 g) in hot (60") benzene (30 ml) wasadded to pyridine-2-thiol (0.48 g) in boiling benzene (50 ml) .As the solution was cooled, the red complex precipitated.It was washed with a little benzene and ether and driedin vacuo (0.35 g, 90%).The yields were ca. 75%.4 0 ) 1974 95 1Tetra-~-acetato-bis(pyridine-Z-thioZ)di.t.hodium(II) .- Rhod-iuni(r1) acetate (0.5 g) was dissolved in the minimum of boil-ing methanol and pyridine-2-thiol (0.25 g) in methanol(25 ml) was added. The initial green solution immediatelyturned red on the addition of the ligand and deposited thepurple-brown complex on cooling. It was filtered off, washedwith methanol and ether, and dried in vacuo. More corn-plex could be obtained by reducing the volume of the solu-tion and cooling to -40 "C (0-4 g, 60%).Bis( I, 1 0-phennnthroline) (pyridine-Z-thioZ)copPer(II) Per-26 A. A. Schjlft and R. C. Taylor, J . Ipaorg. Nuclear Chem.,1950. 9. 321.ckZorate.-Bis( 1, 10-phenanthroline)copper(II) perchlorate(0.4 g), dried in vacuo over silica gel, was suspended inethanol (30 ml) and pyridine-2-thiol (0.1 g) in ethanol (15ml) was added. The suspension was stirred for 4 h ; theprecipitated solid was filtered off, washed with ethanol andether, and dried in vacuo to give the green-brown cowzplex(0.2 g, 45%).We thank the S.R.C. for a studentship and JohnsonMatthey Limited for the loan of palladium and rhodium.[3/860 Received, 25th A , 5 d , 1 !I73

ISSN:1477-9226    

DOI:10.1039/DT9740000946

出版商:RSC    

年代:1974

数据来源: RSC