摘要:
JOURNALOFTHE CHEMICAL SOCIETYDALTON TRANSACTIONSInorganic ChemistryTransition-metal Complexes containing Phosphorus Ligands. Part V1.lConvenient Synthesis of Some Tertiary Phosphine (and Arsine) NitrosylHalide Derivatives of Ruthenium and OsmiumBy S. D. Robinson + and M. F. Uttley, Department of Chemistry, King’s College, Strand, London WC2R 2LSA selection of ruthenium and osmium nitrosyl halide complexes, MX3(NO)(AR3)2 [M = Ru, 0 s : X = CI, Br:A = P, R = alkyl, aryl, or mixed alkyl aryl ; A = As, R = phenyl] have been prepared by a convenient single-stagesynthesis involving addition of ruthenium or osmium halides and N-methyl-N-nitrosotoluene-p-sulphonamide orpentyl nitrite to a solution of the appropriate tertiary phosphine or arsine in a boiling alcoholic solvent.Attempts toprepare the tri-iodo-derivatives, MI3( NO) (AR,),. by this technique using ruthenium or osmium chlorides in thepresence of a large excess of lithium iodide gave the required products, the corresponding chlorodi-iodo-derivativesor a mixture of complexes, depending on the nature of the neutral ligands present. A mechanism for the nitrosylformation, involving ruthenium(1V) and osmium(w) monohydrides, MX3H (AR,),, as intermediates is discussed,and an explanation for the formation of the mixed chlorodi-iodo derivatives is advanced. E.s.r. and i.r. spectroscopicevidence for the formation of a paramagnetic nitrosyl, tentatively formulated RuCI,( NO) ( PPh,) 2, as a minor productin the synthesis of RuCI,(NO) (PPh3)2 is reported.IN a recent publication we disclosed a convenientsingle stage synt hesis of the triphenylphosphine nitrosylchloride complexes M’Cl,(NO)(PPh,), [M’ = Rh, Ir]and MC1,(NO)(PPh3), [M = Ru, Os] based on the useof N-methyl-N-nitrosotoluene-9-sulphonamide (here-after referred to as mnts) or pentyl nitrite as sources ofnitrosyl ligands.The present paper describes theapplication of this technique of synthesis to the prepar-ation of a wide range of ruthenium and osmium nitrosylhalide complexes, MX,(NO) (AR,),, containing a varietyof alkyl, aryl, and alkylaryl phosphines or triphenyl-arsine as neutral ligands. Spectroscopic evidence forthe formation of a paramagnetic nitrosyl derivative,tentatively formulated as RuCl,(NO) (PPh,),, in traceamounts is also presented.Similar syntheses of relatedrhodium and iridium nitrosyl halide derivatives, M’X,-(NO) (ARJ,, have been reported in a previous paper.,Although the remarkable affinity of ruthenium fornitrosyl ligands has been known for many years4 thefirst nitrosyl derivatives of the type, RuX,(NO)(AR,),,1 Part V, E. W. Ainscough, S. D. Kobinson, and J. J. Levison,2 J. J. Levison and S. D. Robinson, J . Chem. SOC. ( A ) , 1970,S. D. Robinson and M. F. Uttley, J . Chem. SOG. ( A ) , 1971,B. F. G. Johnson and J. A. McCleverty, Pvogv. Inovg. Chem.,J . Chem. SOC. ( A ) , 1971, 3413.2947.1254.1966, 7, 277 and references therein.have only recently been reported. The synthesisoriginally employed 5 for the chloro-derivatives involvesreaction of preformed hydrated [RuCl,(NO)], or Na2-[RuC15(N0)J with the appropriate tertiary phosphineor arsine ligand in an alcoholic solvent, and this methodhas subsequently been extensively e m p l ~ y e d .~ ~ ~ Thecorresponding bromo- and iodo-complexes were pre-pared by metathetical exchange.s More recently reac-tions of the complexes RuX(N0) (CO) (PPh,), andRuX(NO)(PPh,), with halogens Y, have been used tosynthesise the products RuXY,(NO) (PPh,), (X = C1;Y = C1, Br, I; X = Br, Y = Br).Osmium nitrosyl halide complexes, OsX3(NO) (APh,),[X = C1, Br, I] have been prepared by reaction of theappropriate osmium salt M,OsX,, and neutral ligandwith nitric oxide in 2-methoxyethanol (A = P, As),or by treatment of the preformed complexes, OsX3-(SbPh,), with nitric oxide in benzene (A = Sb).l0*l16 M.B. Fairy and R. J. Irving, J . Chem. SOC. ( A ) , 1966,475.6 J. Chatt and B. L. Shaw, J. Chem. Soc. ( A ) , 1966, 1811.7 (a) M. C. Baird, Inorg. Chim. Acta, 1971, 5, 46; (b) R. E.8 K. R. Laing and W. R. Roper, Chem. Comm., 1968, 1556;9 M. H. B. Stiddard and R. E. Townsend, Chem. Comm., 1969,Townsend and K. J. Coskran, Inorg. Chem., 1971,10, 1661.J . Chem. SOC. ( A ) , 1970, 2149.1372.10 A. ArAneo and C. Bianchi, Gazzetta, 1967, 97, 885.11 A. ArAneo, V. Valenti, and F. Cariati, J . Inorg. NuclearChem., 1970, 32, 18772 J.C.S. DaltonOther, related osmium nitrosyls recently characterised prepared in ethanol solution, however, syntheses of theinclude OsCl,(OH) (NO) (PPh,),, OsCl(C0.J (NO) (PPh,),,12 corresponding osmium derivatives require more vigorous[OsCI(NO,) (NO) (PMe,Ph),] +, OsCl,(NO,) (NO) (PMe,- conditions and were performed in boiling 2-methoxy-Ph),,13 OsCI,(NHOH) (NO) (PPh,), l4 and OsCl,(HgCI)- ethanol.Poor yields, and difficulties experienced in(NO)(PPh3),.l6 isolating several of the products from alcoholic media,Prefiaration of Ruthenium and Osmium Nitrasyl probably arise because of a tendency for salt formationChZoride and Bromide Complexes MX3(N0)(AR3),.- to occur (see Ref. 7b) ; this aspect is currently beingThe method of synthesis employed in the present work investigated.offers substantial advantages over those previously In several syntheses the complexes, MX,(NO) (AR3)2,published since it involves a single step reaction only, deposited were contaminated by small amounts (ca.Melting point, i.r., analytical, and molecular weight data for some halogenonitrosyl complexes of ruthenium and osmiumFound RequiredBrBr bI, Cl* c1Br c1c1BrI, ClCBr c1Br c1Brc1BrRuX,( NO) (PR,R') , BrRuX,(NO)(AsR,), C1BrI c1c1 bOsX,(NO) 2Brc1c1RPhPhPhPhPhp-C,H,Mep-C,H,Mep-C,H,OMeP-CeHdCl$-C,H,ClP-C,H,Clg y 4 FEtPr'PriBunBunPh,MePhPhPhPhPhPhp-C,H,MeBunPhPh$-C,H,ClM.p. v(N0)O290 187618761871286-288 1865272-276 1834274-276 1871278-279 1864205-208 1863247-250 1845267-269 1878299-300 1871(190-207) d 1874(125-130) 1829118-121 1836178 18401826,185776-77 1835210-215 1867(95-100) 1834293-296 1874310-312 1869300-302 1866325-326 18501860decomp.1850300340-342 1805295-297 1863(72-76) 1811310-315 1845328-330 1842C-56.248.746.469.8661.753.844.839.436-8543.3531.024439-031-4545.3537.7540.361.143.7538-3551.244.254.141-5539.8645-840.65H N4.1 1.82.054.0 1.41:463-26 1.666.1 1.464.4 1-364-4 1.72-36 1-352.0 1.12-35 1-32.6 1-666.2 2.85.157.5 3.26- 08-66 2.37.2 1.83-55 1-953.75 1.463-25 1.42.53.7 1.71-83.34.9 1.62.66 1.27.65 1.753.6 1.353.1 1.45- M870816101690 110211195116361054867072610839331129986E-56.848.346-7559.651.553.6644.6539-2537.6543.130.423.7638.7531-2544.937.1540.550.8543.9538.4550.8543.953.640.8539.446-0540.3H N4-0 1-851-853-4 1.651-653.15 1.54-95 1.654.3 1-464.5 1.62.5 1.462.2 1-32.1 1.22.4 1.46.4 2.95.07.6 2.56-18.5 2.27.05 1.83.4 1.83.65 1-653-05 1.42.73.55 1.651.653.055-16 1.52.3 1-37.46 1.93.25 1.62.8 1.3- M9448469799419701103116060755769 164211249341056938,a Nujol mulls.b Samples prepared using pentyl nitrite. e RuClI,(NO)(PPh,), found C1, 3.95; I, 27.1; required C1, 3.75;I, 26.85. RuClI,(NO)[P(C,H,Cl),~, found C1, 21.3; I, 22.3; required C1, 21.66; I. 22.05. d Melting points in parentheses deter-mined in air; all other m.p.s under nitrogen.All m.p.s accompanied by decomposition.and eliminates the use of nitric oxide11 or preformednitrosyl halide ~omplexes.~~6,7a The technique appearsto be capable of application to the synthesis of nitrosylchloride or bromide complexes containing a wide varietyof tertiary phosphine or arsine ligands.The basic reaction employed in this work involvesrapid, successive addition of alcoholic solutions ofmetal halide (ruthenium) or halide salt (osmium),and mnts or pentyl nitrite to a solution of the appropriatetertiary phosphine (or arsine) in a boiling alcoholicsolvent. The mixture is boiled for a further 10-30min, concentrated if necessary, then cooled to give therequired complex which may be subsequently recrys-tallised as necessary. The ruthenium complexes areK.R. Laing and W. R. Roper, Chem. Comm., 1968, 1568.J. Chatt, D. P. Melville, and R. L. Richards, J . Chem. SOC.( A ) , 1971, 1169.I-lO%) of a second nitrosyl-containing species u(N0)ca. 1750 cm-l, which was removed by recrystallisationfrom dichloromethane-methanol. In the case ofRuCI,(NO) (PPh,), the presence of this impurity im-parted a green colour to the product and was associatedwith the appearance of an e.s.r. pattern centred at2.145 G. Fairy and Irving, in their original reporton the complexes, RuX,(NO) (PR,),, noted the presenceof a ' feeble paramagnetism ' in some of their productsbut did not record any extraneous v(N0) bands. Wetentatively formulate these minor products, which wehave been unable to isolate, as the dihalides MX,(NO)-(AR,),.Some related di-iodo-derivatives have pre-K. R. Grundy, C. A. Reed, and W. R. Roper, Chem. Comm.,l5 G. A. Bentley, K. R. Laing, W. R. Roper, and J. M. Waters,1970, 1601.Chem. Comm., 1970, 9981972 3viously been reported but were found to be essentiallydiamagnetic and were therefore tentatively formulatedas metal-metal bonded dimers.l8 It is also interestingto note that a recent synthesis of the related, diamagneticrhodium nitrosyl dichloride, RhCl,(NO) (PPh,),, affordedtraces of the paramagnetic trichloride RhCI,(NO)-(PPh3)2.7aStructural and Physical Properties of the ProductsMX,(NO)(AR,), (X = C1, Br).-I.r.>9l1 lH n,m.r.8, anddipole moment data 6,11 have previously been cited insupport of an octahedral structure (I) with trans-phosphine or arsine ligands for the ruthenium andosmium nitrosyl halide complexes, MX,(NO) (AR3)2.The nitrosyl ligand has been assigned as formally NO+NO NO1 /pI---ICfI/p X-M-X'I 'I p xin these complexes, on the basis of i.r.data.5,6 Valuesof v(N0) reported in this work for the ruthenium andosmium complexes, MX,(NO) (AR3)2, span the ranges1829-1876 and 1811-1853 cm-l respectively, and arein close agreement with values reported previously forsimilar complexes. Likewise, therefore, we assign ourcomplexes as formal NO+ derivatives of octahedralruthenium( 11) and osmium(r1) with trans-phosphine or-arsine ligands [stereochemistry (I)]. A recent paper 7breports reactions of RuCl,( NO) with (APh,Me,-,)[A = P or As; 1.2 = 1 or 21 in alcoholic media leading toproducts of st oicheiometries RuCl, (NO) (APh,Me,-,) ,and [RuCI,(NO)(APh,Me,-,),]Cl.N.m.r. (virtual coup-ling) data show that several of the former complexesmay exist in two stereoisomeric forms; one with amer-trihalide configuration (I, see above), the otherwith a fac-trihalide configuration. Related bromo-and iodo-derivatives are also reported. In view of thesefindings it is possible that some of our products, par-ticularly those containing trialkylphosphines, may alsopossess the fac-trihalide stereochemistry. Molecular-weight data confirm that the complexes are mono-meric in benzene solution.Mechanism of Formation of Nz'trosyl Halide ComplexesMX,(NO) (AR,),.-The reactions of mnts l 7 or pentylnitrite l8,l9 with preformed metal hydride complexes toyield nitrosyl derivatives have been known for manyyears.We suggest that in the syntheses under dis-cussion the formation of nitrosyl complexes occursby attack in situ on ruthenium(1v) or osmium(1v) hydridel6 R. J. Irving and P. G. Laye, J . Chem. SOC. ( A ) , 1966, 161.17 T. S. Piper and G. Wilkinson, J . Inorg. Nuclear Chem., 1956,18 W. Hieber, W. Beck, and H. Tengler, Z. Naturforsch., 1960,19 W. Hieber and H. Tengler, Z . anorg. Chem., 1962, 818, 136. ** J . Chatt, G. J. Leigh, and D. M. P. Mingos, Chem. and Ind.,3, 104.lSb, 411.1969, 109 and references therein.intermediates formed by reaction of the correspondinghalides with the alcoholic solvent employed or with theexcess of phosphine or arsine ligand present.Partici-pation by hydridic species of this nature appears feasiblesince osmium(1v) hydrides, OSHC~,(PR,)~ 20*21 andOsH,Cl,(PR,), 21 have recently been isolated andrelated tetrahydrides of ruthenium(Iv), RuH,(PPh,), 22and osmium(Iv), OsH,(PR,), 23p24 are also known.The mechanism proposed above parallels the onesuggested previously for the formation of the rhodiumand iridium nitrosyls, M'X,(NO) (AR3)2 under similarcondition^.^ If correct, this mechanism suggests thatmnts has potential value as a trap for detecting form-ation of unstable hydridic intermediates.Attempted Preparation of Ruthenium and OsmiumNitrosyl Tri-iodide Derivatives : Synthesis of MixedHalide Products.-In the absence of suitable, solubleruthenium or osmium iodo-species preparation of theiodo-nitrosyl derivatives, MI,(NO) (AR3)2, by the single-stage procedure was attempted using ruthenium tri-chloride or sodium chloro-osmate respectively in thepresence of a large excess of lithium or potassium iodide.The success of this approach appears to depend to someextent on the nature of the neutral ligands present.In several instances products analysing as chlorodi-iodo-complexes MClI,(NO) (AR,), were deposited (seeTable) while in others, mixtures of products were ob-tained.An analytically pure tri-iodo-derivative wasisolated in only one instance.It is well known that the nitrosyl ligand, like carbonmonoxide, is strongly trans-directing 4925 and prefersto co-ordinate trans to the ligand of weakest trans-influence in a given ~omplex.~ Therefore we assignto these chlorodi-iodo-derivatives the stereochemistry(11), since the trans-influence of chloride is less than thatof iodide, and we suggest that in the presence of anexcess of chloride and iodide the equilibrium betweenMI,(NO)(AR,), and MI,Cl(NO) (AR,), favours the lattercomplex in most instances. In the light of theseobservations it is interesting to note that Chatt andShaw apparently experienced no difficulty in convertingthe complexes RuCl,(NO)(AR,), [AR, = PEt,Ph,AsEt,] to the corresponding tri-iodides by metatheticalexchange. In contrast Fairy and Irving failed toachieve a similar conversion of RuCl,(NO) (PBu,), tothe tri-iodo analogue.5EXPERIMENTAL1.r. spectra were recorded using a Perkin-Elmer 457grating spectrometer.Molecular weights were measuredin benzene solution at 43.7' using a Perkin-Elmer-Hitachi*I J. Chatt, D. P. Melville, and R. L. Richards, J . Chem. SOC.2* W. H. Knoth, J . Amer. Chem. SOC., 1968, 90. 7172.23 P. G. Douglas and B. L. Shaw, Chem. Comm.. 1969, 624;( A ) , 1971, 895..I. Chem. SOC. ( A ) , 1970, 334.- *4 G. J. Leigh, J. J. Levison, and S. D. Robinson, Chem. Comm.,1969, 705.2s D. A. Snyder and D. L. Weaver, Chem. Comm., 1969, 1425J.C.S. Daltonvapour pressure osmometer. M.p.s were recorded on aKofler hot stage (in air) or on a Buchi melting pointdetermination apparatus (under nitrogen). Analyses byDr. Strauss, Oxford.Tri-9-tolyl-, tri-p-anisyl-, tri-P-chlorophenyl-, methyl-diphenyl- and triethyl-phosphines (Maybridge ChemicalCo.), triphenyl-phosphine and -arsine (B.D.H.), tri-iso-propyl- and tri-n-butyl-phosphines (Geigy) were usedwithout further purification.Platinum metal salts werepurchased from Johnson Matthey Ltd.Analyses, m.p.s and molecular weights are given in thetable.Trichloronitrosylbis( tripheny1~hosphine)ruthenium.-Warm solutions of ruthenium trichloride (0.13 g) in ethanol(10 ml), and mnts (0-2 g ) in ethanol (5 ml) were addedsuccessively to a boiling solution of triphenylphosphine(0.54 g) in ethanol (20 ml) and the mixture was heatedunder reflux for 10 min. After cooling, the precipitatewas washed successively with ethanol, water, and methanol,and dried in vacuo as green crystals.These showed anextra i.r. band at 1744 cm-l and an e.s.r. signal at 2.145 Gattributed to the presence of a paramagnetic nitrosylimpurity. Recrystallisation from dichloromethane-methanol removed this impurity and the associated spectro-scopic features, to afford the required product as orange-brown platelets (86%).The following were similarly prepared : trichloronitrosyl-bis(tri-p-toly1phosphine)ruthenium as yellow microcrystals(57 %) ; trichloronitrosylbis(tri-p-anisylphosphine)rutheniumas brown prisms (64%) ; trichloronitrosylbis(tri-p-chloro-pheny2phosphine)ruthenium as orange-brown platelets(60 yo) ; trichloronitrosylbis(tri-iso~ro~yl~hosphine)ruthenium,obtained after evaporating the solution to small volume andcooling to 0 "C, as brown crystals (50%) ; trichloronitro-sylbis(tripheny1arsine)ruthenium as khaki microcrystalsThe following were similarly prepared using rutheniumtribromide: tribromonitrosylbis(tripheny2phosphine)ruthen-ium as brown microcrystals (80%) ; tribromonitrosyl-bis(tri-p-toly1phosphine)ruthenium as brown micro-crystals(45%) ; tribromonitrosylbis(tri-p-chlorophenylPhosphine)lfuthenium as orange brown microcrystals (89%) ;t yibromonitrosy lbis (tri-p-fluorop heny lp hosphine) rutheniumas orange microcrystals (19%) ; tribromonitrosylbis(tri-iso-propylphosphine)ruthenium, obtained after evaporatingthe solution to small volume and cooling to 0 "C, as brownneedles (38 yo) ; trib~omonitrosylbis(tripheny1arsine)ruthen-ium as light brown microcrystals (60%).Trichloronitrosylbis(triethy1phosphine) ruthenium .- Warmsolutions of ruthenium trichloride (0.13 g) in ethanol (10 ml),and mnts (0-2 g) in ethanol (5 ml) were added successivelyto a boiling solution of triethylphosphine (0-24 g) in ethanol-water (10 ml, 1 : 1 v/v).The mixture was heated underreflux for 10 min, then concentrated t o small volume whenthe required product separated as light brown prismsSimilarly prepared was trichloronitrosylbis(tri-n-butyl-phosphine)ruthenium, obtained after evaporation of thesolution and dilution of the resultant oil with ethanol-wateras light brown microcrystals (15%).The following were similarly prepared using rutheniumtribromide: tribromonitrosylbis(methyldi~heny1phosphine)-ruthenium recrystallised from dichloromethane-methanolas dark brown crystals (55%) ; tribromonitrosylbis(~~iet~yZ-bhosbhinebutheniuw as brown microcwstals (66O/,) : tri-(43%).(25%).bromonitrosylbis(tri-n-buty1phosphine)ruthenium recrystal-lised from dichloromethane-methanol as yellow-brownplatelets (14%).Chlorodi-iodonitrosylbis (triphenylphosphine) ruthenium.-Ruthenium trichloride (0-13 g ) and potassium iodide(2.0 g) were boiled together in ethanol-water (25 ml,4 : 1 v/v) for two minutes.To the boiling solution wereadded successively warm solutions of triphenylphosphine(0.62 g) in ethanol (10 ml), and mnts (0.2 g) in ethanol(6 ml). The mixture was heated under reflux for 20 min,cooled and the precipitate washed with ethanol, water, andmethanol, then dried in vacuo and recrystallised from di-chloromethane-methanol as brown platelets (95%).Similarly prepared was chlorodi-iodonitrosylbis(tri-p-chloroplteny2phosphine)ruthenium as brown needles (95%).Tri-iodonitrosylbis(tri~henyla~sine)~utheniun~.- Lithiumiodide (2.0 g) in ethanol (10 ml) and ruthenium trichloride(0.13 g) in ethanol (10 ml) were refluxed together for 5 min.To the boiling solution were added successively warmsolutions of triphenylarsine (0.6 g) in ethanol (20 ml) andmnts (0.2 g) in ethanol (5 ml).The mixture was heatedunder reflux for 15 min then, after cooling, the precipitatewas washed successively with ethanol, water, and methanol,dried in vacuo and recrystallised from dichloromethane-methanol as brown platelets (84%).Trichloronitrosylbis(tr~~henyl~hos~hine)os~~ziu~~~.- Warmsolutions of sodium chloro-osmate (0.19 g) in 2-methoxy-ethanol (10 ml) and mnts (0.2 g) in 2-methoxyethanol(5 ml) were added successively to a boiling solution oftriphenylphosphine (0.36 g) in 8-methoxyethanol (10 ml).The mixture was heated under reflux for 30 min.Methanol(20 ml) was added and, after cooling, the precipitate waswashed successively with ethanol, water, and methanolthen dried in vacuo as brown mi~rocrystals (91 yo).The following were similarly prepared : tyichloronitrosyl-bis (tri-p-toly1phosphine)osmium as salmon-pink micro-crystals (64%) ; trichloronitrosylbis(tri-p-chZoroPheny1-phosphine)osmium obtained from solution, upon carefuldilution with water, as salmon-pink needles (56%) ; tri-chloronitrosylbis(2ri-n-butylphosplaine)osmium, obtained fromsolution upon evaporation to an oil and dilution withethanol-water, as orange-brown crystals (31 yo) ; trichloro-nitrosyZbis(triphe~y1arsirte)osmium as brown microcrystalsThe following were similarly prepared using ammoniumbromo-osmate : tribrornonitrosylbis (triphenylphosphirte) -osmium as brown crystals (77 yo) ; tribromonitrosylbis(tri-pheny2arsine)osmium as dark brown crystals (57%) fromdichloromethane-methanol.Trichloronitrosylbis(triphenylphosphine)ruthenium, Syn-thesis involving n-Pentyl Nitrite.-To a boiling solutionof triphenylphosphine (0.54 g) in ethanol (20 ml) wereadded successively a warm solution of ruthenium tri-chloride (0.13 g) in ethanol (10 ml), and n-pentyl nitrite(2-0 ml). The mixture was heated under reflux for 5 min.After cooling, the precipitate was washed successively withethanol, water, and methanol then dried in vacuo as greencrystals showing an extra i.r.band at 1744 cm-l attributedto a nitrosyl-containing impurity (see above). Recrystal-lisation from dichloromethane-methanol removed this+purity to yield the required product as orange-brownplatelets (687;). Tribromonitrosylbis(tripheny1phosphine)-ruthenium was similarly prepared, using ruthenium tri-bromide, as light brown microcrystals (22%).Trichloronitrosylbis(trifihenylfihosfihine)osmium, Synthesis(64%)1972 5involving n-Pentyl Nitrite.-Sodium chloro-osmate (0.19 g)in 2-methoxyethanol (10 ml), and n-pentyl nitrite (2 ml)were successively added to a boiling solution of triphenyl-washed successively with ethanol, water, and methanol,dried in vacuo and recrystallised from dichloromethane-methanol as brown microcrystals (70%).with methanol (20 ml). After cooling, the precipitate was [1/1361 Received, August 3vd, 1971
ISSN:1477-9226
DOI:10.1039/DT9720000001
出版商:RSC
年代:1972
数据来源: RSC