J. CHEM. SOC. DALTON TRANS. 1988 257Metal Complexes of N-Aryl-N-nitrosohydroxylamines: Cleavage of N-N Bondsto give Metal Nitrosyl Species and Organonitrogen Compounds, and theCrystal Structure of [RhCl,{ONN(C,H,Me-p)o)( H,O)( PPh,)].0.5Me2CO tMushtaq Ahmed, Anthony J. Edwards,* Christopher J. Jones, Jon A. McCIeverty," Anne S.Rothin, and John P. TateDepartment of Chemistry, University of Birmingham, P. 0. Box 363, Birmingham B 75 211React ion of [ R h CI ( P P h,) ,I, [ R h, ( CO ) ,CI,] , [ R h, (q - C, M e,) ,CI,] , [ R u CI, ( P P h,) ,I, a nd [ Pd ( P h ) C I -(PPh,),] with Q[ONN(R)O] (Q = NH,orAg; R = Ph or C,H,Me-p) afforded [RhL,{ONN(R)O}](L = PPh, or CO), [Rh(q-C,Me,)CI{ONN(R)O}], [Ru(ONN(R)O},(PPh,),], and [PdPh{ONN(R)O}-(PPh,)]. Reaction of [Rh{ONN(R)O}(PPh,),] with ),gave [{Rhlx[ONN(R)O](PPh,),},] (R = Ph,x = 2, n = 1; R = C,H,Me-p, x = 1, n = unknown), and with CO gave [Rh(CO){ONN(R)O}(PPh,)].The latter was also prepared from [Rh(CO),(ONN(R)O}] and PPh,.Treatment of [Rh{ONN(R)O}-(PPh,),] and [Ru{ONN(R)O},(PPh,),] with RhCI, and RuC1,afforded [RhCI,{ONN(R)O}(H,O)-(PPh,)] and [RuCI{ONN(R)O},(PPh,),], respectively. The structure of [RhCI,(ONN(C,H,Me-p)O}-(H,O) ( PPh3)].0.5Me,CO was determined crystallographically, and the metal shown to be six-co-ordinate with a chelating N-aryl-N-nitrosohydroxylaminato ligand and water. Treatment of [ PdPh-{ONN( R)O}( PPh,)], [ Rh{ONN (C,H,Me-p)O}( PPh,),], and [ Ru{ONN (C,H,Me-p)O},( PPh,),]with HCI gave [Pd,CI,(PPh,),], [RhCI,(NO) (PPh,),], and [RuCI,(NO)(PPh,),], respectively, andthe organic products obtained from the complexes of Rh and Ru identified by gas chromatographyand mass spectrometry asp-MeC,H,NO, p-MeC,H,NH, (major component), and C,H,Me(NH,)CI.A possible mechanism of formation of the nitrosyl complexes and organonitrogen compounds isbrief I y discussed.The insertion of NO into metal-carbon bonds of do and d"transition-metal alkyls affords compounds containing N-alkyl-N-nitrosohydroxyiamido ligands, (1).For example, treatmentof [WMe,] and [ZnMe,] with NO gave [WMe,{ONN-(Me)O} ,I, whose structure was confirmed crystallographically,2and [Zn(ONN(Me)O),], which reacted with aqueous Cu2+giving [ Cu (ONN( Me)O} J.'A potential catalytic cycle for the formation of organonitrogencompounds involving the use of NO with metal alkylatingagents might involve the intermediacy of species containing (1).Consequently, a knowledge of the stability of metal complexesof these ligands, particularly towards N-N bond cleavage andformation of metal-free organonitrogen fragments, would beuseful.Complexes of N-nitroso-N-phenylhydroxylamine $ havebeen prepared, and the structures of such species as[Fe{ONN(Ph)O},] and [Cu{ONN(Ph)O},] determinedcrystallographically. The 'Cupferron ion,' [ONN( Ph)O] - , andits p-tolyl analogue, [O~N(C,H,Me-p)O] -, are readilyprepared, and, as a result of a chance observation that reactionsof [NH,][ONN(Ph)O] with certain rhodium(1) complexes onoccasion afforded rhodium nitrosyl species, we have system-atically examined the properties of several different metalcomplexes of ligands of type (l), where R = aryl.Relatedcomplexes of (1; R = Me) have also been described, andalthough these were obtained by reaction of NO with transition-metal methyl complexes, their decomposition to organonitrogencomplexes was not explored.6ExperimentalCupferron, [NH,J[ONN(Ph)O], and its p-tolyl and2-naphthyl analogues, [NH,] [ONN(C,H,Me-p)O] and[NH,][ONN(C,oH7)O], were prepared by methods describedin the literat~re.~Elemental analyses were carried out by the MicroanalyticalLaboratories of the Universities of Sheffield and Birmingham.1.r. spectra were obtained using a PE 297 spectrophotometer,and 'H n.m.r. spectra using OE R34 and Varian HA100instruments.Mass spectra were recorded using AEI-MS12 andKratos MS-80 instruments, the latter fitted with a Carlo Erba4200 gas chromatograph. Gas chromatographic work wascarried out using a Pye 104 instrument with flame ionizationdetection and an OV-17 column (3% on Ultrasorb) at 125 "C.All melting points were uncorrected, and yields are quotedrelative to the starting material. All reactions were carried outunder nitrogen.t Aquadichloro(N-nitroso-N-p-tolylhydroxylamido-OO')( triphenyl-phosphine)rhodium-acetone (2/ 1 ).Supplementary data available: see Instructions for Authors, J . Chem.Soc., Dalton Trans., 1988, Issue 1 , pp. xvii-xx.$ [NH,][ONN(Ph)O] is known as Cupferron, a well establishedanalytical agent for Fe and Cu.Ag[ONN(Ph)O].-To a solution of AgNO, (0.5 g, 2.9 mmol)in water (5 cm3) was added a solution of [NH,][ONN(Ph)O](0.46 g, 3 mmol) in ethanol (20 cm3).The mixture was stirredvigorously in the absence of light for 15 min, and the suspensiontreated with n-hexane to complete precipitation of the salt. Thewhite solid so formed was filtered off, washed with diethyl ethe258 J. CHEM. SOC. DALTON TRANS. 1988and n-hexane, and dried in vucuo (0.53 g, 74% based on[NH,][ONN(Ph)O]}. The salt Ag[ONN(C,H,Me-p)O] wasprepared similarly, and both compounds were stored in thedark and used as soon as possible after their precipitation.[Rh{ ONN(Ph)O}(PPh,),].-The compounds [RhCl-(PPh,),] (0.46 g, 0.5 mmol) and [NH,][ONN(Ph)O] (0.08 g,0.5 mmol) were heated in degassed anhydrous ethanol(30 cm3) at 40-45 "C for 3 h, and the mixture then cooled toroom temperature.The orange solid was filtered off, washedwith a small amount of ethanol, and dried in uucuo (yield 1.52 g,90%). The related complexes [Rh{ ONN(C,H,Me-p)O}-(PPh,),] and [Rh{ONN(C,,H,)O}(PPh3)2] were obtainedsimilarly, as orange solids.[ Rh(CO), { ONN( Ph)O}] .-The compounds [R h ,(CO),Cl,](0.19 g, 0.7 mmol) and [NH,][ONN(Ph)O] (0.16 g, 1.0 mmol)in anhydrous ethanol (30 cm3) were stirred at room temperaturefor 15-20 min, during which time a yellow solid precipitated.This was collected by filtration and recrystallised from ethanol,affording the complex as yellow crystals (yields variable). Thecompound [Rh(Co),{oNN(C,H,Me-p)O}] was preparedsimilarly as yellow crystals.[Rh(CO){ONN(Ph)O}(PPh,)].-A suspension of [Rh-(CO),{ONN(Ph)O}] (0.1 g, 0.3 mmol) and PPh, (0.09 g,0.3 mmol) in anhydrous ethanol (30 cm') was stirred at roomtemperature for 15 min.The yellow precipitate which formedwas filtered off and dried in air (yield 0.12 g, 68%).[Rh(CO){ONN(C,H,Me-p)O}(PPh,)].-Method I . Thiscomplex was prepared in the same way as its phenyl analogueabove (yields 60%).Method 2. Carbon monoxide was bubbled through a stirredsolution of [Rh{ONN(C,H,Me-p)O}(PPh3)z] (0.14 g) inrefluxing toluene (30 cm3) for 5 h. The dark red solution wasthen evaporated in vucuo to ca. 10 cm3 and kept at 0 "C for 1week. The solid which had formed was filtered off andrecrystallised from dichloromethane-n-hexane mixtures. Thecomplex was obtained as greenish yellow crystals (0.07 g, 66%).[Rh12{ONN(Ph)O}(PPh,),].-A suspension of [Rh{ONN-(Ph)O}(PPh,),] (0.2 g, 0.25 mmol) and iodine (0.06 g, 0.1mmol) in light petroleum (b.p.80-100 "C; 25 cm3) wasstirred for 18 h. The brown precipitate was then filtered off andrecrystallised from dichloromethane-n-hexane mixtures,affording the complex as brown crystals (0.19 g, 75%).[ { R hI { ONN(C,H,Me-p)O}(PPh,),},].-This compoundwas prepared in the same way as the phenyl compound above,using [Rh{ ONN(C,H,Me-p)O}(PPh,),] (0.26 g, 0.3 mmol)and iodine (0.04 g, 0.16 mmol), and was obtained as browncrystals (yield 0.2 g, 66%).[ R hC1, { ONN( Ph)O} (H 20)( PPh 3)] .-A mixture of [ R h-{ ONN(Ph)O}(PPh,),] (0.19 g, 0.2 mmol) and RhCl3*3H,O(0.07 g, 0.2 mmol) in ethanol (30 cm3) was stirred at roomtemperature for 18 h.The brown solid which had formed wasfiltered off, dissolved in acetone, and chromatographed on silicagel (acetone-n-hexane mixtures as eluant). The brown fractionwas collected, the solvent evaporated in vacuo, and the residuerecrystallised from acetone-n-hexane mixtures affording thecomplex as a brown solid (yield 0.1 g, 68%). The compound[ R hC1 { ONN( C ,H,Me-p)O } (H 0)( PP h ,)]-O. 5 Me ,CO wasobtained similarly using [Rh{ ONN(C,H,Me-p)O}(PPh,),](0.19 g, 0.2 mmol) and RhCl,-3H2O (0.07 g, 0.2 mmol) andisolated as brown crystals (yield 0.1 g, 60%).[Rh(q-C,Me,)Cl{ONN(Ph)O}].-The compounds [{Rh-(q-C5Me5)C12},] (0.15 g, 0.03 mmol) and [NH,][ONN(Ph)O](0.15 g, 1.0 mmol) in ethanol (30 cm3) were stirred togetherat 40-45 "C for 3 h.The solid which had precipitated wasthen filtered off, washed with ethanol, and dried in uacuo,affording the complex as an orange powder (yield quantitative).The compound [Rh(q-C,Me,)Cl(ONN(C,H,Me-p)O}] wasprepared similarly.[Ru{ONN(P~)O},(PP~,)~].-T~~ compounds [RuCI,-(PPh,),] (0.32g,OSmrnol)and [NH,][ONN(Ph)O] (0.21 g, 1.4mmol) in methanol (30 cm3) were stirred at 40-45 "C for 3 h.The mixture was then cooled to room temperature, and the red-brown complex filtered off and dried in vacuo (yields 40-50%).The compound [Ru{ONN(C,H,Me-p)O},(PPh,),] wasprepared similarly using [RuCl,(PPh,),] (2.0 g) and[NH,][ONN(C,H,Me-p)O] (1.14 g), as a red-brown solid(yield 0.85 g, 44%).[RuCl{ONN(Ph)O},(PPh,),l.-A mixture of [Ru{ONN-(Ph)O},(PPh,),] (0.1 1 g, 0.1 mmol) and RuCl3*3H,O (0.03 g,0.1 mmol) in methanol (30 cm3) was stirred and refluxed at70 "C for 18 h.On cooling to room temperature (r.t.), a brownsolid precipitated and this was filtered off, dissolved in acetone,and chromatographed on silica gel using acetone-n-hexanemixtures as eluant. The brown fraction was collected and thesolvent evaporated in vucuo. The residue was recrystallised fromacetone-n-hexane mixtures, giving the complex as brownmicrocrystals (yield 0.1 g, 85%). The compound [RuCl-{ONN(C,H,Me-p)O} 2(PPh3)2] was prepared similarly using[Ru{ONN(C,H,Me-p)O},(PPh,),l (0.12 g) and RuC1,=3H2O(0.03 g), as a brown solid (yield 0.09 g, 75%).[PdPh{ONN(Ph)O}(PPh,),l.-The salt Ag[ONN(Ph)O](0.17 g, 0.7 mmol) was added to a solution of [Pd(Ph)Cl(PPh,),](0.5 g, 0.7 mmol) in benzene (30 cm').The mixture was stirredvigorously overnight at r.t. in the absence of light. The resultingsolution was filtered affording white [(AgCl(PPh,),] and a paleyellow filtrate. The filtrate was reduced to low bulk in vucuo andtreated with n-hexane. Further evaporation in vucuo gave acream-yellow solid which was filtered off and recrystallised fromdichioromethane-n-hexane mixtures. The solid was dried invucuo affording the cream complex (yield 0.28 g, 71%). Thecompound [Pd(Ph){ ONN(C,H,Me-p)O}(PPh,)] was pre-pared similarly using [Pd(Ph)Cl(PPh,),] (0.5 g) andAg[ONN(C,H,Me-p)O] (0.18 g), and isolated as a cream solid(yield 0.3 g, 75%).Reactions of Various Complexes containing [O"(C,H,-Me-p)O] - with Concentrated HC1.-(a) A suspension of[PdPh{ ONN(C,H,Me-p)O}(PPh,)] (0.75 g) in concentratedHCl (30 cm3) was stirred and heated at 80-90 "C for 12 h.After cooling to r.t., the orange solid formed was filtered off andcrystallised from chloroform-light petroleum (b.p.40-60 "C)mixtures. The orange microcrystalline product, which was driedin vacuo, was identified as [Pd,Cl,(PPh,),] (yield 0.27 g, 49%).(b)The compound [Rh{ONN(C6H,Me-p)O}(PPh,),l(O.7 g)was suspended in diethyl ether (25 cm3) and concentrated HCl(0.16 cm3) was added. The mixture was stirred and refluxed for3 h, and the resulting suspension cooled to room temperatureand filtered.The solid residue was washed with diethyl etherand dried in vacuo, affording [RhCl,(NO)(PPh,),] (yield 0.61 g,92%). The ether extracts were studied using gas chromatographyand mass spectrometry (see below).(c) The compound [Ru{ ONN(C,H,Me-p)O) ,( PPh,),] (0.3g) and concentrated HCl (0.12 cm3) were refluxed together indiethyl ether (25 cm3) for 12-15 h. The resulting suspensionwas cooled and filtered in air, the solid residue being washeJ. CHEM. SOC. DALTON TRANS. 1988with diethyl ether. The yellow-brown complex, obtained byrecrystallisation from dichloromethane-n-hexane mixtures, wasidentified as [RuCl,(NO)(PPh,),] (yield 0.22 g, 87%).Gas Chromatographic-Mass Spectral (g.c.-m.s.) Studies ofEther Extracts obtained after Treatment of Complexescontaining [ONN(C,H,Me-p)O] - with Concentrated HC1.-( a ) Products obtained from [Rh{ONN(C,H,Me-p)O}(PPh,),l.Three g.c.peaks were detected. Peak 1 was identified as p-nitrosotoluene by peak matching with an authentic sample; m/z121 (73), 91 (loo), 89 (12), 65 (85), 63 (20), 51 (15), and 50 (1 1%);p-MeC,H,NO gives m/z = 121 (84, [w'), 91 (100, [C,H,]'),89 (12), 65 (70, [C,H,]'), 63 (15), 51 (8), and 50 (7%). Peak 2was identified in the same way as p-toluidine; m/z = 107 (75),106 (loo), 91 (3), 89 (2), 77 (12), 65 (3), 63 (3), and 53 (8%); p-MeC,H,NH2 gives m/z = 107 (72, [hfl'), 106 (100, [ M -[C,H5]'), 63 (2), and 53 (4%). Peak 3: m/z = 143 (32), 142 (39,141 (loo), 140 (79), 106 (91), 79 (lo), 77 (28), and 52 (18%); 2-amino-4-chlorotoluene gives m/z = 143 (33, [MJ' based on37Cl), 141 (100, [M'] based on ,'Cl), 140 (35, [ M - HI'), 106(91, [ M - Cl]'), 79 (ll), 77 (26), and 52 (12%).( b ) Products obtained from [Ru{ ONN(C,H,Me-p)O},(PPh,),].Three g.c. peaks were identified. Peak 1 wasidentified as in ( a ) above as p-MeC,H,NO: m/z = 121 (100,and 50 (3%). Peak 2 was identified as in ( a ) above as p-MeC,H,NH,: m/z = 107 (65, [W +), 106 (100, [ M - HI+), 91and 53 (3%). Peak 3 was identified as 2-amino-4-chlorotoluene:m/z = 143 (34, [MJ' based on 37Cl), 142 (35, [ M - HI'), 141(100, [MJ' based on 35Cl), 140 (85, [ M - HI'), 106 (80,[ M - Cl]'), 79 (9, 71 (17), and 52 (3%).g1 (3, [C,H,I'), 89 (21, 77 (11, [C,H,]+), 65 (3,CWI'h91 (83, [c,H7]'), 89 (81777 (2), 65 (30, [C,H,]'), 51 (3),(2, [c7H,]'), 89 (3), 77 (6, [C,H,]'), 65 (2, [C,H,]'), 63 (2),Crystallographic Determination of [RhCI,{ONN(C,H,Me-p)O)(H20)(PPh,)]~0.5Me,C0.-Crystals were obtained fromacetone-n-hexane mixtures as dark red blocks.Unit-cell andspace-group data were initially investigated photographically,and intensity data and accurate cell dimensions subsequentlymeasured with a diffractometer.Crystal data. C,,H,,CI,N,03PRh~0.5(CH,),C0, M = 63425 9(excluding solvent, 605), triclinic, a = 10.581(2), h = 10.626( l ) ,U = 1 365 A', Z = 2, D, = 1.54 g ~ m - ~ , F(000) = 612, spacegroup PT (C:, no. 2), Mo-K, radiation (A = 0.7107 A, p = 8.4cm-').Intensity data. After the preliminary photographic investig-ations the crystal was mounted on an Enraf-Nonius CAD-4diffractometer of the Crystallography Unit, Universities ofAston and Birmingham.Accurate cell dimensions and intensitydata were obtained by the standard methods describedpreviously.* Within the range 2 < 28 < 55", 4 261 independentreflections having I > 2 . 5 o ( I ) were observed. Two standardreflections were measured every hour and showed no variationwith time. Data were corrected for Lorentz and polarisationfactors but not for absorption.Structure determination. The structure was solved byconventional Patterson-Fourier techniques. The scatteringfactors used were those for neutral atoms.g Refinement by full-matrix least-squares methods was carried out initially with allatoms vibrating isotropically. Although the complete identity ofthe compound was not known when the analysis was started,the two chlorine atoms and the triphenylphosphine andONN(C,H,Me-p)O- ligands were easily recognised, and thepresence of a water molecule in the sixth octahedral co-ordination position was deduced from the size of the peak in adifference synthesis, and from the normal value for the thermalparameter on refinement of the oxygen atom position.After the initial refinement was complete ( R = 0.086),anisotropic thermal parameters were introduced for therhodium, phosphorus, and chlorine atoms, and hydrogen atomsin calculated positions included in the structure-factorcalculations, without refinement, and with a common, isotropicthermal parameter. A difference synthesis showed some smallfeatures near to the oxygen atom of the water molecule, but notin positions assignable to hydrogen atoms. Four larger peaks atca.2-3 e A-3 also appeared around the special position ( t , j , 1)and were assigned to a disordered acetone molecule. Thedisorder appeared not to be simple, as no geometric relation-ship between the peaks could be deduced. However, these fourpeaks, and the four peaks related by the centre of symmetry, areapproximately planar, in line with the assumption of an acetonemolecule. A model with the oxygen and two methyl carbonc = 13.148(10) A, x = 99.00(4), p = 108.89(4), y = 95.24(1)",Table 1. Final atomic positional parameters with estimated standard deviations (e.s.d.s) in parentheses for the compound [RhC1,( ONN(C,H,-Me-p)O}( H,O)( PPh,)]*OSMe,COXia0.007 8 1 (3)0.1 17 6(1)-0.187 7(1)- 0.054 7( 1 )-0.095 2(3)0.071 l(3)0.172 7(3)0.178 9(4)0.232 5(4)0.222 9(5)0.232 9( 5)0.326 O(5)0.270 6(5)0.332 3(5)0.286 9(5)0.1 17 5 ( 5 )0.341 2(5)0.394 O(6)0.201 l(4)Ylb0.387 16(3)0.240 4( 1)0.314 2( 1)0.253 9( 1)0.536 l(3)0.527 6(3)0.478 O(3)0.601 6(3)0.579 9(4)0.710 7(5)0.714 5(4)0.935 2(5)0.821 9(5)0.934 3(5)0.825 3(5)0.345 O ( 5 )0.308 8(4)0.326 l(5)0.382 O(6)Z I C0.170 14(3)0.255 O( 1)0.200 5( 1)-0.002 9(1)0.091 9(3)0.307 7(3)0.151 6(2)0.303 8(3)0.230 O(3)0.493 O(4)0.390 3(4)0.552 3(4)0.574 6( 5)0.448 3(4)0.365 3(4)0.462 2(4)0.402 l(4)0.455 7(4)0.569 7(5)Xia0.171 4(5)0.3 12 3(6)0.015 8(4)0.040 6(5)-0.026 6(5)-0.079 6(5)-0.145 7(5)-0.1172(5)0.248 7(4)0.357 l(5)0.243 6(5)0.458 9(6)0.454 l(6)0.344 4(6)0.374 O(6)0.34880.43 100.57990.4370Ylb0.398 8(5)0.416 8(5)0.090 8(4)0.038 7(4)-0.081 O ( 5 )-0.096 7(5)-0.149 6(5)0.022 7(5)0.189 l(4)0.277 6(5)0.060 4( 5)0.239 5(5)0.1 12 9(5)0.022 6(6)1.056 3(6)0.41930.50200.50360.6270Z I C0.575 4(5)0.627 l(5)0.252 5(4)0.347 7(4)0.341 9(5)0.153 2(4)0.148 6(5)0.242 8(4)0.202 8(4)0.207 O(4)0.157 3(4)0.1 70 3( 5)0.126 7( 5)0.1 18 8(5)0.642 4(5)0.9 1 540.99101.01381.0662* Included at half occupancy260 J.CHEM. SOC. DALTON TRANS. 1988Table 2. Analytical and m.p.data for new compoundsCompoundAnalysis/".,Found Required -- A cC H N C H N M.p./ C66. I 4.866.0 4.767.6 4.632.6 1.934.7 2.556.3 4.257.0 4.250.5 a 3.456.8' 4.257.3 4.352.gd 4.746.9 5.147.91 5.464.0 4.464.5 4.562.9 4.862.3h 4.361.6 4.562.6 4.949.5 3.659.7 4.356.2 4.03.83.83.29.59.05.35.02.63.05.04.47.06.86. I5.86.26.14.54.22.01.866.066.367.832.534.956.657.449.557.057.4'50.246.848.164.164.761.6%62.361.862.449.259.456.74.6 3.74.8 3.64.6 3.41.7 9.52.3 9.03.8 5.34.1 5.23.5 2.84.1 3.14.1 5.24.3 4.44.9 6.85.2 6.64.5 6.24.8 6.04.3 6.04.6 5.84.3 4.84.6 4.73.44.2 1.94.0 1.81331481228286160184158166122I 701 90(decomp.)180(decom p.)I35143155146a I: found 25.0, calc. 24.9%. I: found 14.8, calc. 14.0%. ' CI: found 11.6, calc. 12.0%. C1: found 11.0, cak. 11.1%. C1: found 8.6, calc. 8.6%. C1: found8.4, calc. 8.4%. C1: found 3.5, calc. 3.8%. C1: found 3.8, calc. 3.7%.atoms assigned to three of these peaks and the central carbonatom in a calculated position (all at half occupancy) gavereasonable bond lengths and an acceptable geometry, whileonly raising R to 0.042, compared with a value of 0.041 when thefour peaks were refined as carbon atoms at half occupancy. Thistwo-fold disordered molecule thus accounts for the mainfeatures, but probably does not represent a complete descriptionof the disorder.In the final stages weights derived from thecounting statistics were found appropriate, giving a satisfactoryanalysis of the variation of wA2 with increasing (sin€I)/h andwith increasing fractions of IFJ. Final parameter shifts were<O.lo, the final R was 0.041 and R' { = [Cw(lF,( - lFc1)2]*} =0.047. The calculations were carried out on an ICL 1906Acomputer at Birmingham University Computer Centre and on aCDC 7600 computer at the University of Manchester RegionalComputer Centre using the program SHELX 76." Finalpositional parameters with their estimated standard deviationsare listed in Table 1.Results and DiscussionSynthesis and Spectral Characterisation of Complexescontaining [ONN(R)O] - (R = Ph or C,H,Me-p).-Treat-ment of [ RhCl( PPh,),], [ Rh2( C0),Cl2], [ Rh,( q-C Me5)2C141,and [RuCI,(PPh,),] with [NH,][ONN(R)O] afforded thecomplexes [Rh{ ONN(R)O}( PPh,),], [Rh(CO),{ ONN(R)O}],[Rh(q-C,Me,)Cl(ONN(R)O}], and [Ru(ONN(R)O),-(PPh3)J (analytical and m.p.data in Table 2). Thephenylpalladium(1I) complexes [PdPh(ONN(R)O)( PPh,)]were obtained from [Pd(Ph)CI(PPh,),] using Ag[ONN(R)O].The i.r. spectra of these complexes exhibited strongabsorptions in the regions 1 380-1 330, 1 305-1 265, 1 215-1 170, and 94C900 cm-' (for selected complexes, see Table 3).These spectra were very similar to those observed for[Fe{ONN(Ph)O},] and [Cu{ ONN(Ph)O},].' ' The bands inthe region 9 4 k 9 0 0 cm-' may be associated with N-0 or N-Nstretching modes, or combinations of these, and those in theranges 1305-1 265 and 1215-1 170 cm-' with N=Ovibrations although the NO bond order in these complexes isprobably lower than 2 [v(NO) for RNO at 1564 (R = Me),1 558 (R = C6H1,), and 1488-1 513 cm-' (R = aryl)].Thecomplexes [PdPh{ ONN(R)O}(PPh,)] also exhibited a sharpband of medium intensity at 1 565 cm-', which is characteristicof the Pd-Ph group, being probably the C-H out-of-planebending mode. l 2 Those complexes containing CO groupsexhibited strong bands in the region 1960-2 100 cm-' (seeTable 3).The 'H n.m.r. spectra of the new complexes containing the[ONN(R)O]- ligands (R = Ph or C,H,Me-p) were generallyuninformative, since most of the resonances overlapped withthose of PPh,.Reactions of [M(ONN(R)O},(PPh,),] (M = Rh, x = 1;M = Ru, x = 2).-During the preparation of [Rh{ ONN(R)O}-(PPh,),] we occasionally observed the formation of [Rh(NO)-(PPh,),] and [RhCl,(NO)(PPh,),].In an effort to understandthese reactions, which appear to involve decoupling of the N-Nbond in the MONN(R)O ring, we investigated the behaviourof [Rh{ONN(R)O)(PPh,)2] with some nucleophiles andelectrophiles which might conceivably have been present asimpurities in the [RhCI(PPh,),] used as precursor for these'Cupferron' complexes.There was no apparent reaction between [Rh(ONN(R)O)-(PPh,),] and various molar ratios of PPh, (1 : 1, 1 :2, 1 :4, 1 :8,or 1 : 16). When CO was passed into refluxing toluene solutionscontaining [Rh{ ONN(C,H,Me-p)O)( PPh,),], the monocar-J. CHEM. SOC. DALTON TRANS.1988 26 1Table 3. Infrared spectral data (cm-') obtained for selected complexes (KBr discs)Bands characteristicCompound Of [ONN(C6H,Me-p)O][NH41[oNN(C6H4Me-p)ol 1 330vs, 1 278vs,Ag [ ONN( C ,H4Me-p)O]CRh{ 0NN(C6H4Me-p)0}(PPh3)211215vs, 918vs1 335s, 1275s,1 230s, 920s1 340s, 1 285s,1 190s, 912s[Rh(CO),(ONN(C6H,Me-p)Ofl 1335s, 1285s,1 19Os, 915s1 3&, 1 27%122Os, 918s[ Rh(CO){ ONN(C,H,Me-p)O}( PPh,)]CRu{ 0NN(C6H4Me-p)0} Z(PPh3)21 13&, 1300s,[ PdPh(ONN(C,H4Me-p)O}(PPh3)] 13&, 1290%CRhCI,WO)(PPh,),l1 280s, 1 19Os,91Os, 902s1 19Om, 912sCRuCI3(NO)(PPh&JOther bands3 250-2 800vs, br (NH,'), 1500s, 1 450-1 390s, br.1310s, 1 120m, 106os, 1015w, 830m, 810% 795s. 625vs3 050w, 2925w, 1 500s, 1415m, 1310m.1 15Ow, 1 1 2 0 ~ .1 105w, 1 062m, 835m, 815vs, 800m. 630s3 075w, 3060m, 1 59Ow, 1 575w, 1 502m, I 480m, 1438s131Om, 1 175m, 1 100vs, 1065w, 1035w, 1020w. 1 0 0 5 ~ .822s, 750s, 705s, 700s3 050w, 2 925w, 2 080s (CO), 2 040s (CO), 1 500s, 1 41 5m.131Om, 1 150w, 1 12Ow, 1 105w, 1 M2m, 835m. 815vs,8OOm, 630s3 070w, 2 930w, 1975s (CO), 1590m, 1 575w, 1 500m.1475m, 1440s, 131Om, 1 18Om, 1 105vs, 1 W w , 1 0 3 5 ~ .1025w, 1 OOOw, 822s. 750s, 71Os, 700s3 075w, 3 060m, 1 590w, 1 575w, 1501m, 1482m, 1435s,1 16Om, 1095s, 1042w, 1020w, 820s, 75Om, 742m, 700vs,63 5m3 060m, 2 925w, 1 565s, 1 501m, 148Om, 1475m, 1440s,1 31Om, 1 100s, 1055m, 102Om, 1 Ooow, 83Om, 800w, 7%699vs, 64Om1 630vs (NO)1 860vs (NO)bony1 [Rh(CO){ ONN(C,H,Me-p)O}(PPh,)] was formed, andthis could also be prepared by reaction of [Rh(CO),{ONN-(R)O}] with PPh,.However, in none of these reactions wasdegradation of the { RhONN(R)O} ring observed. Similartreatment of [Rh(q-C,Me,)Cl{ONN(R)O}] and [Ru{ONN-(R)O},(PPh,),] also failed to cause break-up of the{MONN(R)O} ring, and so it would appear that PPh, is notresponsible for the formation of nitrosyl species from thesecomplexes.Reaction of [Rh(ONN(R)O}(PPh,),] with iodine affordedtwo complexes, depending on the nature of R. When R = Ph,the species [RhI,(ONN(Ph)O}(PPh,),], which appears to be aconventional oxidative-addition adduct, was formed. WhenR = C,H,Me-p, however, a compound whose analytical datawere consistent with the formulation [RhI{ONN(C,H,Me-p)O}( PPh,),] was isolated.Because of the compound'sinsolubility and involatility, we were unable to obtainspectroscopic information which could confirm the formulation.The compound could be binuclear, with a Rh-Rh bond and/orRh-I-Rh bridges. However, iodine, as a relatively mildoxidising agent, is clearly not capable of decoupling the N-Nbond in [ONN(R)O]-.When [Rh{ ONN(R)O}(PPh,),] was treated with RhC1,-3H,O in ethanol at room temperature, [RhCI,( ONN(R)O}-(H,O)(PPh,)] was formed. The nature of these species wasfirmly established by an X-ray crystallographic study of thecompound where R = C,H,Me-p (see below).We also noted that [Ru{ONN(R)O},(PPh,),] reactedsimilarly with RuCI,.3H2O in methanol giving the ruthenium-(111) complexes [RuC~{ONN(R)O},(PP~,)~].The formation ofthese species must presumably arise via ligand exchange but themetalkhelate ring appears to remain intact.However, when [PdPh(ONN(R)O)(PPh,)] was treatedwith concentrated aqueous HCI at 8&90 "C both the phenyland chelate ring were lost, and [Pd,Cl,(PPh,),] was isolated.No attempt was made to identify the fate of the nitrogen-containing fragments of this reaction.Treatment of [Rh(ONN(C,H,Me-p)O}(PPh,),] with con-centrated aqueous HCl in refluxing ether over 3 h afforded[RhCI,(NO)(PPh,),] which was identified by analyticalmethods and by comparison (i.r. spectra, mixed m.p.) with anI -authentic sample. Similar treatment of [Ru{ ONN(C,H,Me-p)O},(PPh,),] afforded [RuCl,(NO)(PPh,),]. Both thenitrosyl complexes were formed in high yields (92 and 87%,respectively). It would appear, therefore, that the occurrence ofnitrosyl complexes during attempts to prepare Cupferroncomplexes of Rh' and Ru" may have been due to the presence oftraces of acid in the reaction mixtures.The occurrence of[Rh(NO)(PPh,),] in reactions involving [Rh{ ONN(R)O}-(PPh,),] may be explained by reduction of [RhCl,(NO)-(PPh3)J either by PPh, released from [RhCl(PPh,),] in theformation of the Cupferron complex, or by the Cupferroncomplex itelf. Traces of [Rh(NO)(PPh,),] can be detected indirect reactions involving these species.The organic products of the acid decomposition of[M{ONN(C,H,Me-p)O},(PPh,),] (M = Rh, x = 1; M =Ru, x = 2) were identified using a combination of gaschromatographic (g.c.) and g.c.-mass spectrometric (m.s.)techniques. These were p-nitrosotoluene, p-toluidine, andchlorotoluidine.p-Toluidine was the main component of thethree, and only very small amounts of chlorotoluidine, probablya mixture of isomers, were detected. The overall yield of thesecompounds in the rhodium system was 45-50% of thetheoretical value, and lower yields were obtained from theruthenium complex. We were not able to detect any otherorganic compounds in the reaction mixture. The relatively lowyield of organonitrogen products may be due to deficiencies inthe work-up procedure or to variability in the reaction con-ditions leading to incomplete degradation of the MONN(R)Oring. In proposing a mechanism for the formation of the nitrosylcomplexes and the organonitrogen products, we suggest thatprotonation of the MONN(R)O ring occurs first, followed byN-N bond cleavage and formation of an arylhydroxylamine asan intermediate [equations (1) and (2)].We did not detect--[Rh(ONN(R)O)(PPh,),] + 2HCl-[RhCl,(NO)(PPh,)J + RNHOH (1)[RU(ONN(R)O),(PP~,),] + 4HC1-[RuCI,(NO)(PPh,),] + RNHOH + (NOCl) (2262 J. CHEM. SOC. DALTON TRANS. 1988Q RiBFigure. The molecular structure of [RhC1,{ONN(C,H4Me-p)O}-(H,O)(PPh,)] showing the atom numbering, with 50% thermalellipsoidsp-tolylhydroxylamine in the reaction mixture but this mightreflect the rapidity with which it is converted into otherproducts under the conditions of the reaction and in thepresence of transition-metal species.Thus, phenylhydroxylamine is known l 3 to react with HCIin alcohols to give aniline, chloroaniline, and other products.In the absence of air at room temperature, p-tolylhydroxylamineis converted into p-nitrosotoluene and p-toluidine [equation2RNHOH RNO + RNH, + H 2 0 (3)(3)].Although this reaction is usually slow (of the order of days),it may be accelerated by transition-metal species and/or heat. Itis conceivable that the toluidine derivatives could arise from p-nitrosotoluene, generated by scission of the N-N bond in the{ MONN(R)O} ring. p-Nitrosotoluene is known l o to bereduced in the presence of high concentrations of HCI, giving p-toluidine and chlorotoluidines. However, we feel that this routeis less likely than that via p-MeC,H,NHOH, principallybecause reduction of p-MeC,H,NO requires higher concentra-tions of HCI than were Dresent in the reactions described herein,-and because the { MONN(R)O} ring seems remarkably stableexcept in the presence of HCI.Put another way, the Cupferronspecies were stable to nucleophiles under conditions whichmight have been expected to lead to elimination of p-MeC,H,NO, e.g. as in equation (4).[Rh{ONN(R)O)(PPh,),] + PPh, - [Rh(NO)(PPh,),] + RNO (4)An alternative mechanism for the formation of the nitrosyland organonitrogen species might involve oxidative addition ofHCI to the rhodium(1) species, giving [RhCI(H){ ONN(R)O)-Table 4. Bond distances (A) and angles (") with e.s.d.s in parentheses(a) Co-ordination sphereRh-CI( 1) 2.319( 1)Rh-CI( 2) 2.338( 1)Rh-P 2.250( 1)C1( 1 )-Rh-P 91.4(1)C1(2)-R h-P 92.q 1)Cl( 1)-Rh-C1(2) 94.0( 1)CI(l)-Rh-O(l) 89.2(1)C1(2)-Rh-O( 1) 89.0( 1)0(2)-Rh-CI( 1) 92.9( 1)(b) Triphenylphosphine ligandP-C( 22) 1.839(4)P-C(3 I ) 1.827(4)P-C(41) 1.825(4)R h-P-C(22) 109.7( 1)Rh-P-C( 3 1 ) 1 17.2( 1)Rh-P-C(41) 1 1 3 3 1)C(22)-P-C(3 1) 103.9(2)C(22)-P-C(41) 106.9(2)C(31)-P-C(41) 104.9(2)( c ) [ONN(C,H,Me-p)O] - ligandW t N ( 1) 1.346( 5)0(3)-N(2) 1.3 19(5)N( 1 t N(2) 1.275(5)1.444(6) N( 1 >-C( 12)Rh-O(2)-N( 1) 106.5(2)Rh-O(3)-N(2) 112.6(3)0(3)-N(2)-N( 1) 1 15.4(4)N( 1 )-C( 12)-C( 1 1) 1 19.3(4)N(l)-C(12)-C(16) 118.0(4)Rh-O( 1 )Rh-O(2)Rh-O(3)0(2)-R h-O( 3)0(2)-Rh-P0(3)-Rh-P0(2)-Rh-O( 1 )0(3)-Rh-0(1)0(3tRh-C1(1)min. C-Cmax.C-Cmean C-Cmin. P-C-Cmax. P-C-Cmean P-C-Cmin. C-C-Cmax. C-C-Cmean C-C-CC(5)-C(13)min. C-Cmax. C-Cmean C-CC( 5)-C( 1 3FC( 14)C(5>-C(13)-C(15)min. C-C-Cmax. C-C-Cmean C-C-C2.202( 3)2.033( 3)2.019(3)80.4( 1 )94.2( 1 )94.7( 1)83.9( 1 )84.4( 1 )91.9(1)1.359(8)1.425(8)1.393(8)117.1(3)123.7(4)120.4( 3)1 17.9(4)121.9(6)120.6( 5)1.527(7)1.387(7)1.404( 7)1.394(7)1 18.8(5)122.2( 5 )1 16.9( 5)122.7(5)120.0( 5)(PPh,),]. Our experiments with I, confirmed that such a type ofreaction could occur and it cannot be ruled out in this case.However, a similar reaction with the ruthenium complex, whilenot impossible, seems less likely.Structure of [ RhCl, (ONN(C,H,Me-p)O}( H,O)( PPh,)].OSMe,CO.-The X-ray study has established the identity of thecomplex. The asymmetric unit consists of a molecule of thecomplex and half a solvent molecule of crystallisation (Figure).Selected bond lengths and angles are given in Table 4.The co-ordination geometry of the rhodium(rI1) atom isoctahedral, with distortions produced by the various ligands.The two chlorine ligands are in cis positions, opposite thechelating [O~N(C,H,Me-p)O] - ligand.The water moleculeand triphenylphosphine group complete the co-ordination inpositions trans to one another. The geometries of thetriphenylphosphine and [O"(C,H,Me-p)O] - ligands areunremarkable, that of the latter being very similar to that of thecorresponding [ONN(Ph)O] - in the iron c ~ m p l e x .~ Theacetone molecule may be involved in hydrogen bonding withthe co-ordinated water molecule since the only significantintermolecular interaction is 0 ( 1 ) O(s1) at 2.74 A.A useful comparison can be made with the structure l 4 of therhodacyclopentenedione complex [RhCl(H,O)( PMe,Ph),-(C,O,CI,)] (2). Thus the distances Rh-P 2.250( l), Rh-O(H,O)2.202(3), and Rh-CI 2.319(1) and 2.338(1) A in the presentcomplex are all shorter than the corresponding distances of 2.35,2.28, and 2.50 8, respectively (no estimated standard deviationsgiven) in the reference compound. This shortening can berationalised in terms of the strong trans influence in thJ. CHEM. SOC. DALTON TRANS. 1988 2630I10PMe2PhR h 1,PMe,Ph I‘0%C Ireference compound of the Rh-C bonds opposite theRh-O(H,O) and Rh-Cl bonds, and the Rh-P bonds opposite toeach other.AcknowledgementsWe are grateful to the S.E.R.C. for the support of this work, toMr. A. Pemberton and Dr. J. Hobson for assistance with massspectrometric and g.c. measurements, and to the staff atBirmingham University Computer Centre for their assistance.The loan of RhCl,, RuCl,, and PdC12 from Johnson Mattheyplc is gratefully acknowledged.References1 J. A. McCleverty, Chem. Rev., 1979, 79, 53.2 A. J. Shortland and G. Wilkinson, J. Chem. Soc., Dalron Trans.. 1973.3 E. Frankland, Liebigs Ann. Chem., 1856, 99, 345.4 D. van der Helm, L. L. Merritt, R. Degeith, and C. H. MacGillavry.5 L. M. Shkol’nikova and E. A. Shugam, Zh. Srrukr. Khim., 1963.4.380.6 A. R. Middleton and G. Wilkinson, J. Chem. Soc., Dalron Trans.,7 C. S . Marvel and 0. Kamm, Org. Synrh., 1956, Coll. Vol. 1. 177.8 A. J. Edwards and K. I. Khallow, J. Chem. SOC., Dalton Trans., 1984,9 ‘International Tables for X-Ray Crystallography,’ Kynoch Press,10 G. M. Sheldrick, SHELX 76, Program for Crystal Structure873.Acta Crystallogr., 1965, 18, 355.1981, 1898.2541.Birmingham, 1974, vol. 4.Determination, Cambridge University, 1976.R. S. Bottei and R. G. Schneggenberger, J. Inorg. Nucl. Chem., 1970,32, 1525; T. Urbanski and M. Piskorz, Biul. Wojsk. Akad. Tech.,1961,10,109; J. W. Linnett and R. M. Rosenberg, Tetrahedron, 1964,20, 53.D. R. Coulson, Chem. Commun., 1968, 1530.‘The Chemistry of the Nitro and Nitroso Groups,’ ed. H. Feuer,Interscience, New York, 1969, part 1; N. V. Sidgwick, ‘The OrganicChemistry of Nitrogen,’ Oxford University Press, 1937; ‘TheChemistry of Carbon Compounds,’ 2nd edn., ed. E. C. Rodd, ElsevierScientific, Amsterdam, 1974, vol. 3B.P. D. Frisch and G. P. Khare, J. Am. Chem. Soc., 1978, 100,8267.Received 4th March 1986; Paper 6143