摘要:
J. CHEM. SOC. DALTON TRANS. 1994 3135Palladium( 11) and Platinum( 11) Dihalogeno-complexescontaining the Polyfunctional Phosphine7- Di phenyl phosphi no-2,4-d i met hyl -1.8- napht hyrid ine(dpnapy). Crystal Structure of the Metallocycletrans,trans-[{Pd( p-dpnapy)CI2),].2H2O tSandra Lo Schiavo,*Sa Giovanni De Munno,lb Francesco Nicoloa and Giuseppe Tresoldi aa Dipartimento di Chimica lnorganica, Analitica e Struttura Molecolare, Universita di Messina,Salita Sperone n. 31, 98166 Vill. S. Agata, Messina, ItalyDipartimento di Chimica, Universita della Calabria, 87030 Arcavacata di Rende, Cosenza, ItalyThe co-ordination chemistry of the polyfunctional phosphine 7-diphenylphosphino-2,4-dimethyl-l,8-naphthyridine (dpnapy) with some palladium(1i) and platinum( 11) dihalogeno-complexes has beeninvestigated.It reacts with [Pd(cod)CI,] (cod = cycloocta-1,5-diene) in 1 :1 molar ratio to give themetallocycle trans,trans- [{Pd(p-dpnapy)CI,},] 1, the molecular structure of which was unambiguouslydetermined by an X-ray analysis. The structure consists of two trans-PdCI, moieties linked by twodpnapy molecules in a head-to-tail arrangement. In this way the two palladium atoms and two bridgingdpnapy comprise a quasi-planar twelve-membered ring. Attempts to include a metal ion in the centralcavity of the metallocycle failed. This result has been explained in terms of the geometric constraints ofdpnapy, the structure of which was also determined. When [ Pd( PhCN),CI,] was used as starting palladiumsource the reaction proceeded in a different way.Complexes of general formula [M(dpnapy),CI,](M = Pd 2 or Pt 3) containing two dangling dpnapy-P ligands were obtained from the reaction ofdpnapy with [M(cod)CI,] (M = Pd or Pt), [Pd(PhCN),CI,] and [Pt(dmso),CI,] (dmso = dimethylsulfoxide) when the ligand-to-metal molar ratio was 2 : l . Complexes 2 and 3 have been used asstarting materials for the synthesis of homo- and hetero-metallocycles. Unexpectedly, only homo-metallocycles have been isolated from these reactions, e.g. trans- [Pd(dpnapy),CI,] reacts with[ { R h ( CO ) ,CI},] giving trans, trans - [ { Pd ( p- d pna py ) CI,},] and cis,cis- [ { R h ( CO ) ( p- d pna py ) CI},] theformation of which requires the transfer of a dpnapy ligand from the palladium to the rhodium complex.On the basis of IR and NMR findings, a mechanism is proposed for this and other related reactions.The design and synthesis of polydentate ligands as buildingblocks for linear polymetallic systems are of current interestbecause of the unique chemical and physical properties thatsuch systems can display.' In previous work we reportedthe synthesis and NMR characterization of the polyfunctionalphosphine 7-diphenylphosphino-2,4-dimethyl- 1,8-naphthyri-dine (dpnapy).This compound can be regarded as acombination of the well known binucleating short-bitecompounds 1 ,%naphthyridine and 2-(dipheny1phosphino)-~yridine,~ and is expected to act as the backbone of linear metalarrays as well as of metallocycles which are good precursors oflinear trinuclear metal arrays5The co-ordination chemistry of dpnapy has been studied inrelation to some rhodium(i),' iridium(r),6 and Rh,4f ' com-plexes displaying various geometries ranging from P-mono-dentate, P,N( 1) bridging bidentate and P,N(8),N( 1) binucleat-ing tridentate.Formation of a metallocycle has been observedby using [{Rh(CO),Cl),] as starting material. In this case thet welve-membered metallocycle cis, cis- [ { R h( CO)(p-dpnapy)-CljJ, as confirmed by an X-ray diffraction analysis,' wasobtained. Unfortunately this metallocycle does not possessthe overall assembly to host metal ions in the central cavity.Inclusion of a metal ion in the cavity of a metallocycle requirest Supplementary data available: see Instructions for Authors, J.Chem.SOC., Dalton Trans., 1994, Issue 1, pp. xxiii-xxviii.a trans arrangement of the bridging ligands around the twometal centres. Only in this way, the lone pairs of two 'central'nitrogens can bind an incoming metal ion. As confirmation,the metallocycle [{Rh(C0)(pL-dppy)C1},1 [dppy = 2,6-bis(di-phenylphosphino)pyridine), exhibiting a trans P-Rh-P con-figuration, easily co-ordinates a SnCl' ion in its cavity withformation of Sn-N and Sn-Rh bonds.'In the present paper we report the results of an investig-ation which led to the synthesis of a series of mononuclearpalladium(I1) and platinum(I1) dpnapy complexes. The synthesisand crystal structure of the metallocycle trans,trans-[(Pd(p-dpnapy)C1,),]~2H20 as well as the structure of free dpnapyare also described.ExperimentalGeneral Data.-The compound dpnapy was prepared aspreviously described.' The starting complexes [Pd(cod)Cl,](cod = cycloocta- 1,5-diene), trans-[Pd(PhCN),Cl,], ' [Pt-(cod)Cl,],' ' and cis-[Pt(dmso),Cl,] I' (dmso = dimethyl sulf-oxide) were prepared according to the literature.AII otherchemicals were obtained from commercial sources and used assupplied. None of the compounds reported here is air sensitive,but all reactions were carried out under an atmosphere of drynitrogen. Infrared spectra were recorded on KBr or CsI pelletswith a Perkin-Elmer FT 172OX spectrometer, NMR spectraon a Bruker AMX 300 spectrometer using standard puls3136 J. CHEM. SOC. DALTON TRANS. 1994sequences. Molecular weights were determined with a Knauervapour-pressure osmometer.Elemental analyses were per-formed by Malissa-Reuter Mikroanalytishes Laboratorium,Elbach, Germany, and REDOX snc Laboratorio di Micro-analisi, Cologno Monzese (Milano), Italy.Preparations.-trans,trans-[{Pd(p-dpnapy)CI,},] 1. Pro-cedure (a). Solid dpnapy (0.120 g, 0.350 mmol) was added to adichloromethane solution (50 cm3) of [Pd(cod)Cl,] (0.100 g,0.350 mmol) and the resulting mixture left to stir for ca. 2 h.During this time it changed from yellow to orange, and a smallamount of an unidentified light yellow solid was formed. Thiswas filtered off and then, by addition of diethyl ether (40 cm3) tothe filtrate, complex 1 precipitated as an orange microcrystallinesolid. Yield 0.136 g (75%) (Found: C, 50.25; H, 3.50; C1, 13.30;N, 5.25.C4,H38C14N,P,Pd, requires C, 50.85; H, 3.65; CI,13.65; N, 5.40%). IR (Nujol mull, CsI): v(Pd-C1) 333 cm-'.NMR (room temperature, CD,Cl,): 'H, 6 3.53 (s, 3 H, 2-Me)and 2.53 (s, 3 H, 4-Me); 13C, 6 29.13 (2-Me) and 18.61 (4-Me);31P, 6 21.69.Procedure (b). The complex trans-[Pd(dpnapy),Cl,] 2(0.050 g, 0.058 mmol) was treated with the equivalent amountof trans-[Pd(PhCN),Cl,] (0.022 g, 0.058 mmol) in dichloro-methane (40 cm3). The insoluble 2 dissolved progressivelyupon reaction while the solution became orange. Uponcompletion (ca. 5 min), hexane (40 cm3) was added inducingthe precipitation of complex 1 as orange microcrystals innearly quantitative amount.Procedure (c). Complex 2 (0.050 g, 0.058 mmol) was treatedwith the equivalent amount of [Pd(cod)Cl,] (0.017 g, 0.058mmol) in dichloromethane (40 cm3).Complex 1 was obtainedin high yield by following the procedure used previously.Reaction ofdpnapy with trans-[Pd(PhCN),Cl,] in 1 : 1 molarratio. Solid dpnapy (0.200 g, 0.584 mmol) was added to aCH,Cl, solution (40 cm3) of trans-[Pd(PhCN),Cl,] (0.224 g,0.584 mmol). The resulting mixture was stirred for 10 min andthen left to stand for ca. 24 h. During this time a dark yellowcrystalline solid precipitated. It was filtered off, washed withdiethyl ether and dried under vacuum. Yield 0.176 g (58%)(Found: 50.80; H, 3.60; C1, 13.60; N, 5.35. C,,Hl,C1,N2PPdrequires C, 50.85; H, 3.65; Cl, 13.65; N, 5.40%). IR (Nujol mull,CsI): v(Pd-C1) 342 and 291 cm-'.The low solubility of thecomplex prevents an NMR solution characterization.trans-[Pd(dpnapy),Cl,] 2. Procedure ( a ) . Solid dpnapy(0.200 g, 0.584 mmol) was added to a dichloromethane solution(50 cm3) of trans-[Pd(PhCN),CI,] (0.1 12 g, 0.292 mmol) andthe resulting solution left to stir for 30 min. During this timecompound 2 precipitated as a yellow solid. It was filtered off,washed with diethyl ether and dried. Yield 0.213 g (85%)(Found: C, 60.85; H, 4.35; Cl, 8.15; N, 6.45. C4,H,,C1,N,P2Pdrequires C, 61.3; H, 4.45; C1, 8.20; N, 6.50%). IR (Nujol mull,CsI): v(Pd-Cl) 366 cm-'.Procedure (b). Solid [Pd(cod)Cl,] (0.100 g, 0.350 mmol)was added to a stirred dichloromethane (50 cm3) solutioncontaining dpnapy (0.240 g, 0.700 mmol).Immediately complex2 precipitated in high yield.cis-[Pt(dpnapy),CI,] 3. Compound 3 was obtained byreaction of dpnapy with [Pt(cod)Cl,] or cis-[Pt(drnso),Cl,]by following the procedures used for 2. Yield 80% (Found:C, 56.00; H, 4.05; C1, 7.60; N, 6.00. C,,H3,Cl,N,P,Ptrequires C, 55.60; H, 4.10; C1, 7.45; N, 5.90%. IR (Nujol mull,CsI): v(Pt-Cl) 296 and 317 cm-'. NMR (room temperature,CD,CI,): 'H, 6 2.75 (s, 3 H, 2-Me) and 2.56 (s, 3 H, 4-Me);I3C, 6 25.55 (2-Me) and 18.61 (4-Me); 31P, 6 11.5 ['J(Pt-P) =3660 Hz]; 19'Pt (CDC13) 6 -4433.53.Reactions of trans-[Pd(dpnapy),Cl,] 2.- With [{ Rh(CO),-Cl},]. Complex 2 (0.100 g, 0.116 mmol) was treated with[(Rh(CO),CI},] (0.023 g, 0.058 mmol) in dichloromethane(40 cm3) and the resulting mixture left to stir for ca.30 min.During this time an orange precipitate was formed. It wasfiltered off, washed four times with dichloromethane and thenwith diethyl ether and dried in vacuo. It was identified as cis,cis-[{Rh(CO)(p-dpnapy)Cl} ,] by comparison of its spectroscopicdata with those of an authentic sample., Yield 0.054 g (92%).Addition of hexane to the mother-liquor gave trans,trans-[{Pd(p-dpnapy)Cl,),]. Yield 0.055 g (91%).With cis-[Pt(dmso),Cl,]. Solid cis-[Pt(dmso),Cl,] (0.049 g,0.1 16 mmol) was added to a dichloromethane mixturecontaining complex 2 (0.100 g, 0.116 mmol). The resultingmixture was left to stir for ca. 2 h, during which time the initialcolourless solution became yellow-orange while a light brownsolid precipitated. This was filtered off and to the filtrate hexane(20 cm3) was added inducing the precipitation of trans,trans-[ { Pd(p-dpnapy)Cl,},].Yield 0.050 g (83%, based on palladium).X-Ray Data Collection and Structure ReJinement.-Diffrac-tion data for dpnapy and trans,trans-[(Pd(p-dpnapy)Cl,} ,] 1were collected at 298 K with a Siemens R3m/V automaticfour-circle diffractometer using graphite-monochromated Mo-Ka radiation (h = 0.71073 A). To avoid loss of solvent, a0.13 x 0.38 x 0.42 mm crystal of 1 was sealed in a Lindemanntube and then used for intensity data collection. Latticeparameters were obtained from least-squares refinement of thesetting angles of 25 reflections in the range 15 < 28 < 30".Information concerning the conditions of crystallographic datacollection and structure refinement is summarized in Table 3.A total of 3635 (dpnapy) and 8674 (1) reflections werecollected by the variable-speed 0-28 scan method in the range28 3 < 28 < 50" with hkl ranges 0-15, 0-12, - 16 to 16(dpnapy) and 0-15, 0-21, -22 to 22 (1); 3240 (dpnapy) and7857 (1) were unique and, from these, 2017 (dpnapy) and 4983(1) were assumed as observed [I 3 3o(I)] and used for therefinement of the structures. Examination of three standardreflections, monitored after every 150, showed no sign of crystaldeterioration.Both data sets were corrected for Lorentz-polarization effects. y-Scan absorption corrections ' wereapplied to the intensity data for 1 (maximum and minimumtransmission factors 0.614 and 0.547).The structure of dpnapy was solved by direct methods whilethat of complex 1 was solved by standard Patterson methodswith the SHELXTL PLUS program l4 and subsequentlycompleted by Fourier recycling.The full-matrix least-squaresrefinement was based on IFo\. All non-hydrogen atoms wererefined anisotropically. All hydrogen atoms were set incalculated positions and refined as riding atoms, with acommon thermal parameter. The final full-matrix least-squaresrefinement, minimizing the function Zw(lFol - IF,\), with w =1/[02(Fo) + q(F0),], where q = 0.0010 (dpnapy) and 0.0020(l), converged at R and R' values of 0.0487 and 0.0568 fordpnapy and 0.0437 and 0.0462 for 1. The corresponding ratios(observed reflections) : (refined parameters) were 8.9 and 9.7 : I ,respectively.Neutral-atom scattering factors and anomalousdispersion corrections were taken into account.' The lastgeometrical calculations were performed with the (locallymodified) PARST program. l 6 The final atomic co-ordinatesfor non-hydrogen atoms are given in Tables 4 and 5 andselected bond lengths and angles in Tables 1 and 2 for dpnapyand compound 1.Additional material available from the Cambridge Crystallo-graphic Data Centre comprises H-atom coordinates, thermalparameters, and remaining bond lengths and angles.Results and DiscussionSynthesis, Characterization and Reactivity of the Metallo-cycle trans, trans-[{ Pd(p-dpnapy)CI,},] 1 .-The addition of anequivalent of dpnapy to a yellow dichloromethane solution of[Pd(cod)Cl,] results in a dark orange solution from whichthe metallocycle trans,trans-[(Pd(p-dpnapy)Cl,),] 1 can berecovered.Compound 1 is an air-stable orange crystalline solidwhich dissolves easily in chlorinated solvents and sparingly iJ. CHEM. SOC. DALTON TRANS. 1994 3137acetone and alcohols. It was characterized by IR and NMRspectroscopic methods as well as by an X-ray diffractioninvestigation which showed that 1 is composed of two transCl-Pd-Cl moieties joined by two dpnapy ligands in a head-to-tail arrangement. The NMR spectra indicate the solutiongeometry is the same as that in the crystal structure. The ,'PNMR spectrum shows a single resonance centred at 6 21.69,while the 'H and 13C spectra show the resonances due to the2-Me protons and carbons at 6 3.53 and 29.13, respectively,significantly downfield with respect to the corresponding valuesexhibited by free dpnapy (6 2.73 and 25.60).As we havepreviously pointed o ~ t , ~ * ~ 3 ~ when dpnapy co-ordinates to ametal through N(l) the 2-Me protons and carbons resonatemuch more downfield than those of the corresponding freedpnapy owing to the magnetic anisotropy of the metal.'As evidenced by the 31P NMR spectra, the addition of1 equivalent of dpnapy to complex 1 in CDC1, at roomtemperature (r.t.) does not produce any change. On warming(60°C, 24 h) rupture of the metallocycle and formation oftrans-[Pd(dpnapy),Cl,] 2 is observed.Attempts to include species such as HgCl,, SnC1, or AgX(X = BF, and CF3C0,) in the cavity of the palladiummetallocycle failed.These results are in keeping with the X-raydiffraction findings which show that the constraints of the cavitypreclude the inclusion of a metal ion.The mechanism of the reaction between [Pd(cod)Cl,] anddpnapy leading to the formation of complex 1 is unknown. The3 1 P NMR spectra revealed that the reaction occurs through theformation of many, not isolated species which over a period ofca. 2 h rearrange giving 1 as the only final product.Reaction of dpnapy and trans-[Pd(PhCN),Cl,] in 1 : 1 MolarRatio.-Unexpectedly, when trans-[Pd(PhCN),Cl,] is used asstarting palladium complex a different product is obtained.The addition of an equivalent of dpnapy to CH,Cl, solution oftrans-[Pd(PhCN),Cl,] affords a dark yellow microcrystallineprecipitate in good yield.Owing to its low solubility asatisfactory spectroscopic characterization is prevented. Itsformulation is tentatively proposed on the basis of microanalysisand IR spectroscopic data. The microanalytical data yield theformulation Pd(dpnapy)Cl, while the solid IR spectrum,displaying two Pd-Cl stretches. at 342 and 291 cm-', isindicative of a cis configuration of chlorines. Further in-formation was obtained by monitoring the reaction by 'HNMR spectroscopy (CDCl,, r.t.) before precipitation of thecomplex occurs. This reveals the presence of a species exhibitinga resonance at 6 3.35 for the 2-Me protons, indicative of N( 1)co-ordination. On the basis of these observations we supposethat this compound may be the cis,cis isomer of the metallo-cycle 1 displaying an overall geometry similar to that foundin ~is,cis-[(Rh(CO)(p-dpnapy)Cl),],~ although a formulationas a polynuclear species cannot be excluded.Mixtures of unidentified compounds have been obtainedfrom the reactions of dpnapy and [Pt(cod)Cl,] or cis-[Pt(dmso),Cl,] in 1 : 1 ligand-to-metal molar ratio.Synthesis of the Complexes [M(dpnapy),Cl,J (M = Pd 2 orPt 3).-Treatment of [Pd(cod)Cl,] or trans-[Pd(PhCN),Cl,]with 2 equivalents of dpnapy in dichloromethane solutionaffords the mononuclear complex trans-[Pd(dpnapy),CI,] 2,in which dpnapy acts as a P-monodentate ligand. Complex 2 isa light yellow solid insoluble in the most common solvents. Itsformulation is based on microanalytical data while the transconfiguration, with two dangling dpnapy-P, is assigned on thebasis of the single v(Pd-Cl) absorption observed at 366 cm-'.Steric demands" of dpnapy can account for the formationof the trans isomer, usually less stable than the cis fordiphosphinepalladium dihalide complexes.The cis-[Pt(dpnapy),Cl,] 3 isomer is obtained from thereaction of cis-[Pt(dmso),Cl,] or [Pt(cod)Cl,] with 2 equiv-alents of dpnapy.It is a white crystalline solid soluble inchlorinated solvents. The solid-state IR spectrum shows twov(Pt-C1) absorptions at 296 and 317 cm-', while the 31P NMRspectrum displays a sharp resonance at 6 11.5 with a couplingconstant of 3660 Hz to '"Pt satellites. The coupling constantis consistent with the presence of two phosphorus atoms inmutually cis positions.20"*2 ' The "Pt NMR spectrum displaysa sharp resonance at 6 -4433.5.Reactivity of the Complexes [M(dpnapy),Cl,] (M = Pd 2 orPt 3).-Platinum(11) and palladium(1r) complexes containingdangling bidentate ligands have been used in a number ofinstances to prepare homo- and hetero-binuclear complexes.In this context 1,2-bis(diphenyIphosphino)methane and thehetero bidentate 2-(dipheny1phosphino)pyridine and (diphenyl-arsino)(diphenylphosphino)methane have been very use-fu1.20b.c.22 Our attention then turned to the prospect ofsynthesizing homo- and hetero-bimetallic metallocycles bytreating 2 and 3 with appropriate metal complexes.The reaction of trans-[Pd(dpnapy),Cl,] 2 with an equivalentof [Pd(cod)Cl,] or [Pd(PhCN),Cl,] readily produces themetallocycle trans,trans-[{Pd(p-dpnapy)Cl,),] in quantitativeamount.Complex 1 is also the main product (83%, based onpalladium), together with other unidentified Pt-containingspecies, of the reaction between 2 and cis-[Pt(dmso),Cl,].These reactions are very fast and no information on theirmechanism was obtained by NMR spectroscopy even at lowtemperature. However it is evident that the reaction leading to 1occurs with substantial ligand rearrangement. On the contrary,the resultant palladocycle would have dpnapy in a head-to-headrather than head-to-tail arrangement.Complex 2 reacts with 1 equivalent of [{Rh(CO),CI),]affording quantitatively the dpnapy metallocycles cis,cis-[{ Rh-(CO)(p-dpnapy)Cl),] and tvans,trans-[{Pd(p-dpnapy)Cl,},].The formation of the metallocycles requires the transfer of adpnapy molecule from palladium to rhodium with breaking ofthe Pd-P bond.Monitoring of the reaction by IR and protonNMR spectroscopy indicates that the first step involves attackof N(1) on rhodium with likely formation of the species[Cl,(dpnapy)Pd(p-dpnapy)Rh(CO),Cl] I. Consistent with theproposed structure two v(C0) bands are observed in the IRspectrum (CH,Cl,) at 2070 and 2003 cm-', characteristic of aneutral cis dicarbonylrhodium species. The ' H NMR spectrum(CDCl,, r.t.) shows two signals at 6 3.2 and 2.75 for the 2-Meprotons of dpnapy. The former value, as previously described,is indicative of N( 1) co-ordination to the metal.Once formedthe intermediate I readily evolves to the rhodium and palladiummetallocycles.The complex cis-[Pt(dpnapy),Cl,] 3 reacts with 0.5 mol of[(Rh(CO),CI},] affording, in agreement with the IR andNMR spectroscopic data [v(CO) 2072 and 2005 cm-'; 'HNMR (CDCl,, r.t.) 6 3.3 and 2.65 (2-Me)] [Cl,(dpnapy)-Pt(p-dpnapy)Rh(CO),Cl] which, differently from the palladiumanalogous species, in solution transforms into unidentifiedspecies. From the reaction of 3 with [Pd(cod)Cl,] or trans-[Pd(PhCN),Cl,] unreacted 3 together with unidentifiedpalladium species were recovered. It seems that platinum(r1) likeMeI&.CI CI.1CI' I y-coNvNvP C31382 trans -[Pd(dpnapy),CId + [{Rh(CO)&r)AdFig. 1 Molecular structure and atomic numbering of dpnapy.Thermalellipsoids are drawn at 50% probability while the hydrogen-atom size isarbitraryiridium(r) complexes have no tendency to form metallocycleswith dpnapy.The above results allow us to make some conclusions on themechanism operating in these reactions which seems to proceedvia transfer and ligand rearrangement. Transfer and successivereorientation of heterobifunctional phosphine ligands from onemetal centre to another is not an unknown process. Usually itis assisted by another bridging ligand and accompanied by theformation of a metal-metal bond. 2067c*4f Furthermore Balchand co-workers ,Obqc have shown that the analagous reactionsbetween [M(NC,H,PPh,),Cl,] [M = Pd or Pt; NC5H4P-Ph, = 2-(diphenylphosphino)pyridine] and [{ Rh(CO),Cl},],leading to the head-to-tail binuclear complex [MPd(p-NC,-H4PPh,),(CO)C13], initially proceed via formation of theintermediate [MRh(NC,H,PPh2),C1][Rh(CO),C1,] by trans-fer of a chloride from palladium or platinum to rhodium. Wecannot invoke the same mechanism because there is no evidencefor the formation of a similar ionic intermediate.On thecontrary our results can reasonably be explained if thedissociation of one dpnapy molecule occurs. In this light thereaction between trans-[Pd(dpnapy),Cl,] and [(Rh(CO),Cl} ,]could proceed initially, as mentioned before, via formation ofthe intermediate I. Subsequent breakage of a Pd-P bond,favoured by the trans effect exercised by the second danglingdpnapy-P, generates the two moieties trans-Pd(dpnapy-P)-C1, I1 and cis-Rh(CO),(dpnapy-N)C1 111 which dimerizegiving the homometallocycles trans,trans-[ { Pd(p-dpnapy)-Cl,},] and cis,cis-[(Rh(CO)(p-dpnapy)Cl},], respectively(Scheme 1).The same mechanism may be operating in the reaction ofcomplex 2 with [Pd(cod)Cl,] or trans-[Pd(PhCN),Cl,].In thiscase, after the initial attack of N( 1) on the incoming palladiumC(1J. CHEM. SOC. DALTOP 1 TRANS. 1994111)Fig. 2 Molecular structure and atomic numbering of complex 1. Thetwo water molecules are omitted for clarity. Other details as in Fig. 1Table 1with estimated standard deviations (e.s.d.s) in parenthesesSelected interatomic distances (A) and angles (") for dpnapy1.846(3)1.830(3)1.369(4)1.488(5)1.419(5)1.4 16(4)1.353(4)1.405(4)C(7)-P-C( 13) 102.2( 1 )C( 13)-P-C( 19) 102.7( 1)N(l)-C(2)-C(3) 122.5(3)C(3)-C(2)-C( 12) 120.1(3)C(3)-C(4)-C(lO) 117.1(3)C(lO)-C(4)-C(ll) 120.9(3)C(4)-C(lO)-C(5) 124.9(3)N( 1 )-C( 9)-C( 10) 1 23.1 (3)C( lO)-C(9)-N(8) 122.3(3)N(8)-C(7)-C(6) 122.8(3)C( lO)-C(5)-C(6) 120.4(3)P-C(7)-N( 8) 112.7(2)1.823(4)1.3 16(5)1.41 5(5)1.363( 5 )1.502(5)1.40 l(4)1.320(4)1.356(5)101.1(1)1 17.4(3)117.5(3)121.5(3)122.0(3)118.1(3)116.9(3)114.6(3)1 18.6(3)124.4(2)1 18.9(3)117.1(3)centre, the intermediates [Pd(dpnapy-P)Cl,] and [Pd(dpnapy-N ) ( q 2-~od)C12] or [Pd(dpnapy-N)(PhCN)Cl,] are, respec-tively, formed.These readily dimerize giving the palladiummetallocycle 1.The reactions of cis-[Pt(dpnapy),CI,] with [Pd(cod)Cl,],trans-[Pd(PhCN)Cl,] or [{Rh(CO),Cl},], whichdonot producemetallocycles, proceed in a different way very likely as aconsequence of the inertness of the Pt"-P bond compared withthe Pd"-P one and the different geometry of 3 from that of thepalladium analogue.Molecular Structure of dpnapy.-The molecule is constitutedby a 2,4-dimethyl-l,8-naphthyridine moiety linked to a di-phenylphosphine group in position 7, as illustrated in Fig.1.The atoms of the two fused pyridine rings lie almost on a planefrom which the maximum deviation is 0.058(4) A for atom C(3).With respect to this mean plane the two phenyl rings of thephosphine, C( 13kC( 18) and C( 19)-C(24), form dihedral anglesof 69.9( 1) and 85.6( l)O, respectively.The phosphorus atomshows the expected very distorted tetrahedral geometrcharacterized by an average P-C bond distance of 1.833(3J. CHEM. soc. DALTON TRANS. 1994 3139Table 2 Selected interatomic distances (A) and angles (") for complex 1 with e.s.d.s in parentheses2.234(2)2.317(2)2.22 1 (2)2.308(2)1.850(7)1.803(7)1.82 1 (7)1.327(9)1.403( 10)1.367( 1 1)P( 1 )-Pd( 1 )-C1( 1) 89.8( 1 )C1( 1 )-Pd( 1 )-N( 1 ) 88.4(2)P( la)-Pd( la)-C1(2a) 90.8(1)C1(2a)-Pd( 1 a w l ( 1 a) 168.6( 1)C1(2a)-Pd( 1a)-N( la) 88.5(2)Pd( 1 )-P( 1)-C(7a) 1 1 1.7(2)C(7a)-P(l)-C(13a) 102.3(3)C(7a)-P( 1 )-C( 19a) 107.4(3)Pd( 1 a)-P( 1 a)-C( 7) 1 1 1 3 2 )C(7)-P(la)-C(l3) 110.2(3)C(7)-P( 1a)-C(19) 102.6(3)C(2)-N(l)-C(9) 118.4(6)N( 1 )-C(2)-C( 12) 1 1 7.6(6)C(2W(3)-c(4) 122.8(7)Cl( 1)-Pd( 1)-C1(2) 168.4( 1)Pd( 1 )-N( 1 )-C( 2) 124.6(5)C(3)-C(4)-C( 11) 121.7(7)2.298(2)2.1 18(5)2.303(2)2.095(6)1.824(7)1.845(7)1.808(7)1.373(8)1.489( 1 1)1.428( 10)P( 1 )-Pd( 1 )-C1(2) 90.8( 1)C1(2)-Pd( 1)-N( 1) 91.3(2)P( 1 a)-Pd( 1 a w l ( 1 a) 89.6( 1 )P(1a)-Pd(1a)-N(1a) 178.1(2)C1( 1 a)-Pd( 1 a)-N( 1 a) 9 1 S(2)Pd(l)-P(l)-C(13a) 115.9(2)Pd(l)-P(l)-C(l9a) 11242)C(13a)-P(l)-C(19a) 106.2(3)Pd( 1 a)-P( l a w ( 13) 1 1 1.8(2)Pd( 1 a)-P( 1 a)-C( 19) 1 1 5.2(2)C( 13)-P( 1 a)-C( 19) 104.9(3)Pd(l)-N(l)-C(9) 116.9(4)C(3)-C(2)-C( 12) 121.1(7)C(3)-C(4)-C( 10) 1 16.4(6)C(lO)-C(4)-C(ll) 122.0(7)P(1)-Pd(1)-N(1) 177.6(2)N( 1 )-C(2)-C(3) 12 1.3(7)1.494(11)1.422( 10)1.325(8)1.410(9)1.38 l(9)1.502( 10)1.433(10)1.362( 10)I .40 l(9)1.352(8)C(6 )-C(5)-C(lO) 119.9(6)P(la)-C(7)-C(6) 125.5(5)C(6)-C(7)-N(8) 123.6(6)N(l)-C(9)-N(8) 114.3(6)N(8)-C(9)-C(10) 123.2(6)C(4)-C(lO)-C(9) 118.5(6)Pd( 1 a)-N( 1 a)-C(2a) 125.0(5)C(2a)-N( 1 a)-C(9a) 1 18.7(6)N(la)-C(2a)-C(12a) 119.4(7)C(2a)-C(3a)-C(4a) 120.6(7)C(3a)-C(4a)-C( 1 1 a) 12 1.1(7)C(sa)-C(Sa)-C( 10a) 120.6(6)P(l)-C(7a)-C(6a) 123.7(5)C(6a)-C(7a)-N@a) 122.9(6)N(la)-C(9a)-N(8a) 113.7(6)N(8a)-C(9a)-C( 10a) 124.3(6)C(4a)-C( lOa)-C(9a) 1 18.9(6)C(5)-C(6)C(6)-C(7)N(8)-C(9)N( 1 a)-C(2a)C(2a)-C(3a)C( 3a)-C(4a)C(4a)-C( 1 1 a)C(5a)-C( 10a)C( 7a)-N( 8a)C(9a)-C( 10a)1.360( 10)1.398(9)1.356(8)1.313(9)1.432( 10)1.358( 10)1.489(11)1.405( 10)1.330(8)1.397(9)C(5FC(6)-C(7) 11 8.8(6)P(la)-C(7)-N(8) 110.8(5)C(7)-N(8)-C(9) 1 17.7(6)C(4)-C(lO)-C(5) 125.1(6)C(5)-C(lO)-C(9) 116.4(6)Pd(la)-N(la)-C(9a) 116.2(4)N( 1 a)-C(2a)-C(3a) 1 22.1 (7)C(3a)-C(2a)-C(12a) 118.5(7)C(3a)-C(4a)-C( 10a) 1 17.6(6)C( 10a)-C(4a)-C( 1 1 a) 12 1.4(6)C(5a)-C(6a)-C(7a) 118.8(6)P(l)-C(7a)-N(8a) 113.3(5)C(7a)-N(8a)-C(9a) 117.3(6)N( la)-C(9a)-C( 1 Oa) 122.0(6)C(4a)-C( lOa)-C(Sa) 125.1(6)C(Sa)-C(lOa)-C(9a) 116.0(6)N( l)-C(9)-C( 10) 12246)Table 3 Crystallographic data for dpnapy and complex 1 *FormulaMalAblAC I API O u/A3D, /g cm-F( 000)Crystal sizeimmp( Mo-Ka)/cmRR'SMaximum shiftlerrorMaximum differencepeak, hole/e AdPnaPYC22H19N2P342.41 3.190(2)10.262( 2)13.548(2)95.06(2)1826.7(5)1.2457200.45 x 0.32 x 0.381.560.04870.05681.580.03 10.25, -0.3011075.41 2.8 1 O(2)18.148(3)19.076(3)91.59(2)4433(1)1.61121600.13 x 0.38 x 0.421 1.660.04370.04621 .oo0.1741.01, -1.25C44H42C14N402P2Pd2* Details in common: space group P2,/n; monoclinic; 2 = 4; R =V F O I - l ~ c l ~ / w o l ,IFcI)2/(N, - N , ) ] & , where No, N , = numbers of observations andparameters.R' = C~(lF,I - IFcI)2PWFo21f; s = c c W W o I -and a mean bond angle 102.0(1)", in agreement with valuesreported for similar compounds.No distortion has been found in the naphthyridine planecaused by lone-pair repulsion, as found in free naphthyridinewhich appears to be slightly n ~ n - p l a n a r .~ ~ The authorsexplained its chelating action by co-ordination effects which,deforming the electron-density distribution of the two lonepairs and then decreasing their repulsion, allow the system toassume the observed planarity in the corresponding complexes.The naphthyridine mean plane forms with the plane passingthrough C(7), C(13) and C(19) a dihedral angle of 134.2(1)0instead of the expected 90". As a consequence the lone pair onP is directed away from the naphthyridine plane on which thetwo nitrogen lone pairs lie. The expected linear tridentate co-ordination might then be possible only if the diphenylphosphineTable 4 Final atomic coordinates ( x lo4) for dpnapy with e.s.d.s inparenthesesY3028( 1)271 O(2)2794(3)3249(3)367 1 (3)3614(2)3092(2)2934(2)3297(2)3863(3)40 16( 3)4169(3)2391(3)1686(3)11 12(3)107(4)- 357(3)185(3)1197(3)3660(3)4689( 3)5255(3)4800(3)3778(3)3212(3)Y1 54 1 ( 1)4853( 3)60 18(4)7077(4)6930(3)5673(3)4682(3)3483(3)3225(3)4132(3)5340(3)8042(4)6196(4)1631(3)5 15(4)460(5)1536(6)2664(5)2723(4)1511(3)1232(4)1255(4)1494(4)1744(4)1749(4)z1099(1)- 1535(2)- 1925(3)- 1383(3)-435(3)- 5(2)- 571(2)- 198(2)720(2)1319(2)953(2)143(3)13 15(2)11 39(2)1316(3)I663(3)1 829(3)1 654( 3)2356(2)2442(3)4 1 80( 3)4 1 2 1 (3)3222(2)- 2977(3)3 337( 3)group rotates around the P-C(7) bond until the above di-hedral angle is close to 90".In this way the three lone pairsare oriented in the same direction.A rotation of the diphenylphosphine group of 180" withrespect to this ideal trinucleating geometry still leaves thephosphorus lone pair on the naphthyridine plane but directedin the opposite direction with respect to that of the nitrogenatoms. Such an arrangement has been found in the binuclearcomplex [{ Ir(cod)Cl),(p-dpnapy)] where dpnapy co-ordinatestwo iridium centres on opposite sites, via the phosphorus andthe 'terminal' N(l) atoms.3 140 J . CHEM. SOC. DALTON TRANS. 1994(a 1Fig. 3 Views of (a) trans,tran~-[(Pd(p-dpnapy)Cl~}~] and (6) cis,cis-[{ Rh(CO)(p-dpnapy)C1)2], evidencing the different arrangement of the ligandsaround the metal centres in the two metallocyclesTable 5 Final atomic coordinates ( x 1 04) for complex 1 with e.s.d.s in parenthesesX1329( 1)- 731( 1)- 112(1)- 68( 1)1050(2)1 8 1 7( 2)750(2)2662(4)3601(6)4433(6)4344(5)31 1 l(6)21 16(6)1 342( 5)1533(4)2527( 5)3 3 50( 5)5240(6)3734(6)- 2337( 1)- 307(5)- 900(6)- 1195(7)- 864( 8)- 280(8)20(7)- 584(5)- 296(7)- 768(7)Y1337( 1)3 169( 1)661(1)3848(1)1346( 1 )1121(1)3 156( 1)3386(1)2006(3)1753(4)2234(4)2983(4)40 14(4)42 19(4)3677(3)2963(3)2754(3)3259(4)3483(5)4827(3)5021(4)5760(5)6286(5)6087(4)5362(4)3656(3)301 5(4)2835(5)939(4)Z1693( 1)2725( 1)1 8 1 O( 1)1877( 1)498( 1 )2854(1)2152(1)3410(1)1 5 50( 3)1399(4)1275(4)1326(4)1633(4)177 l(4)1791(3)1733(3)1605(3)1521(3)1 184(5)1347(5)2010(4)2576(4)2676(5)2222(6)1657(6)1552(4)1005(3)65 1(4)X- 1480(7)- 1777(8)- 1338(7)- 1361(4)- 1820(6)- 23 18(6)- 2309(6)- 1634(6)- 11 19(6)- 745(5)- 845(4)- 1330(5)- 1765(5)- 2859(7)- 1836(7)- I167(5)- 1353(7)-2143(8)- 27 16(7)- 25 19(7)- 1738(6)145(6)1 174(6)1386(6)607( 7)-41 l(7)- 642(6)4197(10)424 1 (1 3)Y3297(5)39 1 3(6)4099( 5)2500(3)2742(4)2256(4)1 5 1 5( 4)496(4)295(4)847( 3)1562( 3)1 244( 4)1 007( 5)837(4)527( 5)1 1 64(6)1 640( 5)1482(4)- 3 15(4)1749(4)3555(4)359(5)- 566(4)- 1313(4)- 1812(4)- 1590(4)- 843(4)6847(7)5356(9)7- 303(4)48(5)679( 5)3502(3)4064(4)4543(4)443 8 (4)3677(4)3092(4)2651(3)2788(3)3383(3)3844(3)49 17(4)4212(4)1171(4)6 18(4)I 29( 5)1 78( 5)726(4)121 2(4)1705(4)1656(4)1697(4)1756(4)679(6)1 774( 3)1797(4)445wMolecular Structure of trans, trans-[(Pd(p-dpnapy)Cl,) J-2H20 1.-The crystal packing of compound 1 consists of[(Pd(p-dpnapy)Cl,) 2 ] and water molecules of crystallizationin 1 :2 ratio with no significant interaction of the latter withthe complex. The crystal structure can formally be described asbuilt up of two trans-PdC1, fragments connected through twobridging dpnapy groups in a head-to-tail arrangement, asshown in Fig.2. The bridging function of the ligand is realizedthrough the phosphorus and N( 1) atoms.Each palladium centre atom is in a square-planar arrange-ment, being linked to two chlorine atoms and to the phosphorusand terminal nitrogen atoms of two different dpnapy molecules.The Pd-Cl, Pd-N and Pd-P distances are similar to thosefound in related compounds and do not require special com-ment.Atoms Pd(1) and Pd(1a) are out of the correspondingco-ordination planes [largest deviation 0.174( 1) and 0.167( 1) A,respectively] which form a reciprocal dihedral angle of 15.5( 1)”.The central cavity of the complex is almost a regular square: thePd(1) 9 Pd(1a) distance is 4.710(1) A while the separationbetween the central unco-ordinated N(8) and N(8a) atomJ. CHEM. SOC. DALTON TRANS. 1994 3141is 4.487(8) A. Each fragment formed by naphthyridine, thephosphorus and the metal atom is almost planar and thedihedral angle between the two corresponding mean planes,intersecting at the two phosphorus atoms, is 51.8' [see Fig.It is instructive to compare the structure of complex 1 withthat of [{Pt(p-dppy)I,},] 24 as both compounds display a transdisposition of the two halides and of the two bridging ligands.The two metals and bridging ligands determine a quasi-planartwelve-membered metallocycle, in the cavity of which a metalatom may be located.As already stated the co-ordination of ametal ion in the cavity of a metallocycle requires the transdisposition of the two tridentate bridging ligands. For com-parison in Fig. 3 are shown views of trans,trans-[{Pd(p-dpnapy)Cl,),] and cis,cis-[{Rh(CO)(p-dpnapy)Cl] fromwhich the direction of the lone pairs of the central bindingsites can be proposed.In agreement, the trans,trans-[(Rh(CO)-(p-dppy)C1),I8 metallocycle co-ordinates a SnCl' moiety in itscavity by formation of Sn-N and Sn-Rh bonds.The dppy metallocycle shows a cavity larger than that in thedpnapy complex, mainly due to the longer phosphorus-metalbond length with respect to the nitrogen-metal interaction.Indeed the N . . . N distance in [(Pt(p-dppy)I,},] is 5.057 8,(the reported value of 3.123 8, is wrong), which is significantlylarger than the 4.487 A as found in 1. This difference seems todepend more on the bond distances than on the value of thedihedral angle between the pyridine planes in [(Pt(p-dppy)-I,),], which is larger than the angle between the naphthyridineplanes in 1 (7 1.9 us.46"). In [Cl,(CO)Rh(p-dppy),(p-SnC1)Rh-(CO)(SnCI,)] the corresponding dihedral angle is 21.6' with aN N distance of 5.038 8,. Nevertheless, the contraction of thecavity and the shortening of the N N distance in complex 1is not so large that insertion of a metal atom into the cavity isforbidden by simple steric hindrance effects.In conclusion, as already mentioned, the failed attempts atinclusion of metal ions in the cavity of complex 1 may beexplained in terms of (i) the asymmetry of dpnapy and (ii) thedihedral angle between the naphthyridine planes, which seemstoo large to allow bond interaction between N(8) and N(8a)with the incoming metal ion.For [(Pt(p-dppy)I,},] displayinga dihedral angle of 71.9' no example of inclusion was reported.3 ~ 1 .AcknowledgementsWe thank the Minister0 per I'Universita e la Ricerca Scientificae Tecnologica (MURST) and the Consiglio Nazionale delleRicerche (CNR) for financial support.References1 J. S. Miller (Editor), Extended Linear Chain Compounds, Plenum,New York and London, 1981-1983, vols. 1-3; R. Hoffmann, Angew.Chem., Int. Ed. Engl., 1987, 26, 846 and refs. therein; Y. Jiang,S. Alvarez and R. Hoffmann, Inorg. Chem., 1985,24,749; A. L. Balch,M. M. Olmstead, D. E. Oram, P. E. Reedy, jun., and S. H. Reimer,J . Am. Chem. SOC., 1989, 111,4021 and refs. therein.2 M. Grassi, G. De Munno, F. Nicolo and S. Lo Schiavo, J. Chem. SOC.,Dalton Trans., 1992,2367.3 M.Munakata, M. Maekawa, S. Kitagawa, M. Adachi andH. Masuda, Znorg. Chim. Acta, 1990, 167, 181; A. Tiripicchio,M. Tiripicchio Camellini, R. Uson, L. A. Oro, M. A. Ciriano andF. Viguri, J. Chem. Soc., Dalton Trans., 1984, 125 and refs. therein;J. P. Collin, A Jouaiti, J. P. Sauvage, W. C. Kaska, M. A.McLoughlin, N. L. Keder, W. T. A. Harrison and G. D. Stucky,Inorg. Chem., 1990, 29, 2238; A. T. Baker, W. R. Tikkanen,W. C. Kaska and P. C. Ford, Inorg. Chem., 1984,23,3254.4 ( a ) G. Bruno, S. Lo Schiavo, E. Rotondo, P. Piraino and F. Faraone,Organometallics, 1987, 6, 2502 and refs. therein; (b) E. Rotondo,S. Lo Schiavo, G. Bruno, C. G. Arena, R. Gobetto and F. Faraone,Inorg. Chem., 1989, 28, 2944; (c) G. Bruno, S. Lo Schiavo,E.Rotondo, C. G Arena and F. Faraone, Organometallics, 1989,8886; ( d ) S. Lo Schiavo, E. Rotondo, G. Bruno and F. Faraone,Organometallics, 1991, 10 , 1613; ( e ) E. Rotondo, G. Bruno,F. Nicolo, S. Lo Schiavo and P. Piraino, Znorg. Chem., 1991, 30,1195; cf, C. G. Arena, E. Rotondo, F. Faraone, M. Lanfranchi andA. Tiripicchio, Organometallics, 1991, 10, 3877.5 A. L. Balch, Pure Appl. Chem., 1988, 60, 555 and refs. therein;A. L. Balch, V. J. Catalano, M. A. Chatfield, J. K. Nagle,M. M. Olmstead and P. E. Reedy, jun. J. Am. Chem. SOC., 1991,113, 1252 and refs. therein.6 S. Lo Schiavo, M. Grassi, G. De Munno, F. Nicolo and G. Tresoldi,Inorg. Chim. Acta, 1994,216,209.7 S. Lo Schiavo, M. S. Sinicropi, G. Tresoldi, C. G. Arena andP. Piraino, J. Chem. Soc., Dalton Trans., 1994, 1517.8 A. L. Balch, H. Hope and F. E. Wood, J. Am. Chem. SOC., 1985,107,6936.9 D. Drew and J. R. Doyle, Znorg. Synth., 1972, 13, 52.10 J. R. Doyle, P. E. Slade and H. B. Jonassen, Znorg. Synth., 1960,6,2 18.1 I D. Drew and J. R. Doyle, Inorg. Synth., 1972, 13,47.12 C. Eaborn, K. Kundu and A. Pidcock, J. Chem. SOC., Dalton Trans.,13 G. Kopfmann and R. Huber, Acta Crystallogr., Sect. A , 1968,24,348.14 SHELXTL PLUS, version 4.2, Siemens Analytical X-Ray Instru-15 International Tables for X-Ray Crystallography, Kluwer Academic16 M. Nardelli, Comput. Chem., 1983,7,95.17 D. E. Chebi and I. P. Rothwell, Organometallics, 1990,9, 2948 andrefs. therein.18 N. J. De Stefano, D. K. Johnson and M. L. Venanzi, Helv. Chim.Acta, 1976,59,2683; A. J. Pryde, B. L. Shaw and B. Weeks, J. Chem.SOC., Dalton Trans., 1976, 322; B. E. Mann, B. L. Shaw andR. M. Slade, J. Chem. SOC. A, 1971, 2976; A, H. Norbury andA. I. P. Sinha, J. Inorg. Nucl. Chem., 1973,35, 121 1.1981,933.ments, Madison, WI, 1991.Publishers, Dordrecht, 1992, vols. A and C.19 A. W. Verstuyft and J. H. Nelson, Znorg. Chem., 1975, 14, 1501.20 (a) P. E Garrou. Chem. Rev., 1981, 81, 229; ( b ) J. P. Farr,21222324M. M. Olmstead and A. L. Balch, Inorg. Chem., 1983, 22, 1229;( c ) J. P. Farr, M. M. Olmstead, F. E. Wood and A. L. Balch,J. Am. Chem. SOC., 1983,105,792.P. S. Pregosin and R. W. Kunz, "P and 13C NMR of TransitionMetal Phosphine Complexes, Springer, Berlin, 1979, pp. 94-97.F. S. M. Hassan, D. P. Markham, P. G. Pringle and B. L. Shaw,J. Chem. Soc., Dalton Trans., 1985,279; A. T. Hutton, P. G. Pringleand B. L. Shaw, J. Chem. SOC., Dalton Trans., 1985, 1677;R. R. Guimerans, F. E. Wood and A. L. Balch, Inorg. Chem., 1984,23, 1308.A. Clearfield, M. J. Sims and P. Singh, Acta Crystallogr., Sect. B,1972,28,350.F. E. Wood, J. Hvoslef, H. Hope and A. L. Balch, Znorg. Chem., 1984,23,4309.Received 29th March 1994; Paper 4/0 1880
ISSN:1477-9226
DOI:10.1039/DT9940003135
出版商:RSC
年代:1994
数据来源: RSC