摘要:
Reactions of imido complexes of iridium, rhodium and rutheniumAndreas A. Danopoulos," Geoffrey Wilkinson,**' Tracy K. N. Sweet and Michael B. Hursthouse *9ba Johnson Matthey Laboratory, Chemistry Department, Imperial College, London S W7 2A Y, UKDepartment of Chemistry, University of Wales C a r d a PO Box 912, Cardiff CF13TB, UKInteractions of the known compounds Ir(q-C5Me5)(NR) (R = But l a or 2,6-Pri&H3 lb) with 2,6-xylylisocyanide [(xyl)NC], mesityl isocyanate and mesityl a i d e (mesityl = mes = C,H2Me3-2,4,6) have beenstudied. The bridged dimers [Ir(q -C Me ,)( p-NC H,)] 2 and [Ir,(q -C , Me ,) 2( p-NC6H ')(p-NHC,H 1)] C13 have been synthesized. Reactions of Ru(NR')(MeC,H,Pr'-p) (R' = 2,4,6-But3C,H2) with (mes)NCO and(mes)N, are reported. Attempts to isolate Rh(q-C,Me,)(NR) species failed but evidence for Rh(q-C,Me,)-m(2,6-Pr',C,H,)N3(mes)] was obtained in a trapping reaction in solution using (mes)N,. The crystalstructures of the compounds Ir(q -C , Me &q ' -Bu'NCNBu')(CNBu'), [Ir(q -C H ,)(p-NC, H,)] 2,3,[Ir2(q-CSMeS)(p-NC6Hl 1)(p-NHC6H, l)]Cl 3, Ir(q-C,Me,)~(xyl)CHN(2,6-Pri2C6H3)CNC,H3(Me)CH2] 4b,Ir(q-C,Me,)~(2,6-Pr',C,H3)C(0)N(mes)] 5, Ir(q-C,Me,)~(2,6-Pr',C,H3)N3(mes)] 6, Rum(2,4,6-BU'~C~H~)C(O)N(~~~S)](M~C,H,P~'-~) 8 and Ru~(2,4,6-Bu',C,H2)N,(mes)](MeC,H,Pri-p) 9 have beendetermined.A reaction mechanism for the formation of 4b is given.It was shown' that the interaction of the chromium(m)compound Cr(q-CSMe,)(=NC6H3Pr',-2,6) generated in situ,with an excess of 2,6-xylyl isocyanide in tetrahydrofuran gavethe compound shown in diagram I.Since the mechanismproposed for the formation involved sequential coupling ofthree isocyanide molecules it seemed likely that similarinsertions into the metal imido bonds could occur with thenucleophilic imido complexes of iridium(nI),2 Ir(q-C5Me5)-(=NR) (R = But la or 2,6-Pri2C6H3 lb). Reactions of theseimido complexes and of the ruthenium(r1) complex, Ru-(=NC,H,B~'~-2,4,6)(q-Mec~H,Pr'-p),~ with 2,6-xylyl isocya-nide, (mes)NCO and (mes)N, (mes = C,H,Me,-2,4,6) arenow described. Attempts to obtain rhodium analogues from'Rh(q-C,Me,)(NR)' species made in situ were unsuccessful.Physical and analytical data for new compounds are given inTable 1.Results and DiscussionIridium complexesThe interaction of compound l a with Bu'NC produces thepreviously reported carbodiimide compound Ir(q-C5Me5)(q2-Bu'NCNBu')(CNBu'), whose structural formulation was basedon IR and NMR data.2" In view of the quite different productsobtained when 2,6-xylyl isocyanide is used with either l a orl b as discussed below, the q2-carbodiimide structure wasconfirmed by X-ray diffraction.The structure was solved andsuccessfully refined in the monoclinic space group P2Jm. Adiagram of the structure is given in Fig. 1, with selected bondlengths and angles in Table 2. The C,Me, and terminalisocyanide ligands are bisected by the mirror plane, which alsocontains the metal; it also relates the two But groups on thecarbodiimide. Atom C(20) of this ligand also lies on the mirrorplane but the nitrogen N(2) is equally disordered over two sites,thus modelling the asymmetry of the N-C-N grouping arisingout of the q2 C-N bonding. Detailed discussion of the bondingof this ligand is not possible since it was necessary to constrainthe positions of the two half-nitrogens to achieve realistic N-C(But) distances.In order to find out if carbodiimides were formed in othercases, we first synthesized the cyclopentylimido complex [Ir(q-C,MeS)(p-NC,H9)]2 2 using reaction conditions similar tothose described.2 The structure was confirmed by X-rayIFig.1 The structure of Ir(q-C5Me,)(q2-Bu'NCNBu')(CNBu').Primed atoms are related to their unprimed equivalents by thecrystallographic mirror plane (see text)diffraction, see Fig.2 and Table 3. The core geometry issimilar to that found for the phenylimido- and 2,6-dimethylphenylimido-bridged dimers described by Dobbs andBergman2' in that the Ir2N2 group is folded (dihedral anglebetween the two IrN, planes = 76.14') and the two nitrogensare not planar [angle sums = 339.8' for N(l) and 351.8' forN(2)]. Possible reasons for these features were discussedpreviously.2b However, the structures show quite significantdifferences in detail. The Ir Ir distance in 2 is 2.6133(5) A,some 0.14-0.16 A shorter than in the aryl derivatives and theJ. Chem. SOC., Dalton Trans., 1996, Pages 3771-3778 377Table 1 Analytical and physical data for new compoundsAnalysis (%) *Compound M.p./OC C H2 CIr(T1-Cs Mes)(P-NGH9)1 2 209-2 1 1 44.0 (43.9) 6.1 (5.9)C1r2(ll-C5MeS)2(pL-NC6H1 I)(p-NHC6H1 l)lcl 187 43.8 (43.4) 6.0 (6.0)4a Ir(q-C,Me,)~(xyl)CHN(BuL)CNC,H,(Me)CH,] 169-1 7 1 58.0 (58.2) 6.2 (6.2)4b Ir(q-C,Me,)[N(xy~)CHN(~,6-~riz~6~,)~~~6H3(Me)CHz] 22 1-225 61.9 (61.7) 6.4 (6.3)5 1 r( q -Cs Me ,) m( 2, 6-Pri2 c6 H ,)C(O)N(mes)] 220 57.9 (57.9) 6.7 (6.9)6 Ir(~-C,Me,)~(2,6-Pr',C6H,)N,(mes)] 240 (decomp.) 56.2 (56.1) 6.5 (6.5)7 Rh(q-CSMes)m(2,6-Pri2C6H3)N3(mes)] 225 64.5 (64.8) 7.5 (7.5)8 Ru~(2,4,6-Bu',C6H2)C(0)N(mes)](MeC61-f,Pr'-p) > 240 69.5 (69.6) 8.2 (8.2)9 Ru~(2,4,6-Bu',C6H2)N,(mes)](MeC6H,Pr'-p) 98-100 67.7 (67.8) 8.2 (8.2)* Calculated values in parentheses.Mass spectral data are given in the Experimental section.N3.2 (3.4)3.0 (3.2)6.0 (6.4)5.4 (5.3)4.0 (4.2)8.2 (8.4)9.6 (9.8)4.1 (4.3)8.5 (8.5)Table 2 Selected bond lengths (A) and angles (") for Ir(q-CsMes)-(q2-Bu'NCNBu')(CNBu') with estimated standard deviations (e.s.d.s)in parenthesesIr-Cp( 1 *) 1.89(2) N(l)-C(lO) 1.137( 13)Ir-C( 10) 1.900(10) N(l)-C(ll) 1.430( 14)Ir-C(20) 2.017(9) C(2O)-N(2A) 1.199( 13)Ir-N(2A) 2.206( 10)Cp(1 *)-Ir-C(l0) 128.9(7) C( lO)-N( 1)-C( 1 1) 178.3( 10)Cp(l*)-Ir-N(2A) 123.3(7) N(l)-C(lO)-Ir 174.6(9)Cp( 1 *)-Ir-C(20) 139.4(7) Ir-N(2A)-C(20) 6 5.0( 7)C(lO)-Ir-N(2A) 99.2(3) Ir-N(2A)-C(21) 137.4(6)C( lO)-Ir-C(20) 9 1.8(4) Ir-C(20)-N(2A) 82.4(7)N(2A)-Ir-C(20) 32.6(3) Ir-C(20)-N(2B') 137.0(6)Cp( 1 *) represents the centroid of the C,Me, ring C( l), C(2), C(3), C( 1 '),C(2').Primed atoms are related to unprimed ones by the symmetrytransformation x, - y + i, z.Table 3 Selected bond lengths (A) and angles (") for [Ir(q-C,Me,)(NC,H,)], 2 with e.s.d.s in parenthesesIr( 1) Ir(2) 2.6133(5) Ir(2)-N(1) 2.049(7)Ir( 1 )-N( 1) 2.046(8) Ir(2)-N(2) 2.029(7)Ir(lFN(2) 2.010(8) Ir(2)-42p(2*) 1.84(2)Ir( 1 W P ( 1 *)N( 1 hIr( 1 k"2) 74.4(3) N( I)-Ir(2)-Cp(2*) 142.9(8)N(1)-Ir(l)-Cp(l*) 139.9(8) N(2)-Ir(2)-Cp(2*) 141.8(8)N(2)-Ir(l)-Cp(l*) 144.2(8) Ir(l)-N(l)-Ir(2) 79.3(3)N( 1 )-1rm-N(2) 74.0(3) Ir( l)-N(2)-Ir(2) 80.6(3)Cp( 1 *) represents the centroid of the C,Me, ring C( 1O)-C( 14), Cp(2*)that of the ring C(20)-C(24).1.83(2)-.-.,C(2QFig. 2 The structure of [Ir(q-CSMeS)(p-NC,H9)]2 2Ir-N distances are 2.0 10-2.046(8) A, compared with 1.97-1.99( 1) A in the aryls.More importantly, the orientations of thecyclopentyl groups in 2 are both approximately parallel to theIr Ir vector, whereas in both aryl complexes the rings areperpendicular to this direction. This difference is verysignificant in that steric interactions between the substituentson the imido functions and the CSMe, groups will be quitedifferent, likely to be much greater in 2. The resulting stericpressure on the C,Me, groups, which are symmetrically qsbound in both complexes, may thus have resulted in the greaterfolding about the N N vector in 2 leading to a shorterIr Ir bond.Fig. 3 The structure of the cation [Ir2(q-C5Me5)2(p-Nc6Hl &-NHC6H I)] + in 3Unfortunately compound 2 was unreactive towards cyclo-hexyl isocyanide and tert-butyl isocyanide even with prolongedrefluxing in tetrahydrofuran.In addition, interaction of [Ir(q-C5H5)C12]2 with 3 equiv-alents of Li(NHC6HI1) in thf as above gave low yields of 3, adimeric, cationic species with one cyclohexylimido and onecyclohexylamido function.Its identity was established byanalytical, spectroscopic ('H NMR) and crystallographicstudies. Although the crystals were of poor quality, thestructure determination clearly identifies all main features. Adiagram of the cation is shown in Fig. 3, whilst bond lengthsand angles are given in Table 4. The dimer cation has the samekind of folded (C,Me,)IrN,Ir(C,Me,) feature found for 2,with differences in detail, as might be expected. The differencesin the bridging groups are easily identified, with N( 1) the imido3772 J.Chem. SOC., Dalton Trans., 1996, Pages 3771-377nitrogen giving N-Ir distances of 1.85(3) and 1.92(3) A, and anangle sum of 356.6". The amido nitrogen, N(2), gives distancesto Ir of 2.02(3) and 2.11(3) A, and has an angle sum of 319.4".The cyclohexyl group on the amido is oriented in the 'parallel'mode, whilst that on the imido is roughly in the perpendicularorientation. We presume that the net effect is to reduce stericinteractions with the C5Me5 groups, since the fold at theN 0 N vector 67.7" is smaller than in 2, and the Ir Ir bondlonger, at 2.724(2) A.As noted above compounds l a and lb show differentbehaviour when 2,6-xylyl isocyanide is employed. In tetra-hydrofuran essentially quantitative (by NMR) yields of thecompounds 4a and 4b are obtained; both have the structureshown.The structure of 4b was determined by X-ray diffractionand is shown in Fig. 4; bond lengths and angles are given in Table5. For the most part the bond lengths and angles in the tridentateligand are consistent with the formalized structure shown exceptthat the planar amine nitrogen m(2)] shows some n conjugationwith the imine system involving N(3); thus the N(2)-C(101) andC( lOl)-N(3) distances are both short; N(2)-C( lo), however, issimilar to a single bond. The presence of the saturated, methylenecarbon [C( 121)] in the six-membered chelate ring gives this ringsome flexibility, so that it is folded at the N(1) C(121) vectorand the chelate bite angle is smaller, at 74.8(2)0, than the biteangle [77.1(2)"] in the planar five-membered chelate ring.TheIr-N and Ir-C distances associated with this ligand all indicateR 14a R = BU"4b R = 2, 6-F'ri2C6H3Table 4 Selected bond lengths (A) and angles (") for the cation [Ir,(?-C5Me5),(p-NC6H, ,)(p-NHC6H, in compound 3 with e.s.d.s inparenthesesIr( 1) Ir(2) 2.724(2) Ir(2)-N( 1) 1.85(3)Ir( 1 )-N(l) 1.92(3) Ir(2)-N(2) 2.1 l(3)Ir(l W P ( 1 *) 1.61(11)1 kN(2) 2.02(3) Ir(2)-Cp(2*) 1.86(10)N( 1 )-w 1 W ( 2 ) 74.0( 11) N( l)-Ir(2)-Cp(2*) 143(3)N(1)-Ir( 1)-Cp(l*) 148(4) N(2)-Ir(2)-Cp(2*) 144(3)N(2)-Ir(l)-Cp(l*) 137(4) Ir(l)-N(l)-Ir(2) 92.6(11)N(1)-W)-N(2) 73.2( 11) Ir( l)-N(2)-Ir(2) 82.4( 10)Cp( 1 *) and Cp(2*) as in Table 3.Table 5 Selected bond lengths (A) and angles (") for Ir(q-C5Me5)p(xyl)CHN(2,6-Pri2C6H3)CNC6H3(Me)CH2] 4b with e.s.d.sin parenthesesIr-C( 12 1 ) 2.1 14(6) N(2)-C(100) 1.433(7)Ir-C( 100) 2.0 1 9( 6) C( 1 OO)-N( 1) 1.277(7)Ir-Cp( 1 *) 1 .873( 1 3) C( 1 1 )-C( 1 2) 1.42 l(8)N 3 W ( 101) 1.303(7) C( 12)-C( 121) 1.502(9)C( 1 0 1 )-N(2)Ir-N(3) 2.102(5) N( l)-C( 1 1) 1.435(7)1.348(8)C(121)-1r43100) 74.8(2) N(3)-C(101)-N(2) 119.4(6)C( 121 )-1r-N(3) 95.0(2) C(lOl)-N(2)-C(lOO) 113.3(5)C( 12l)-Ir-Cp( 1 *) 126.3(6) N(2)-C( lOO)-N(l) 1 13.6(5)C( 1 00)-Ir-N( 3) 77.0(2) C(lOO)-N(l)-C(ll) 116.4(5)C(lOO)-Ir-Cp(l*) 136.0(5) N(l)-C(ll)-C(12) 119.0(5)N(3)-Ir-Cp( 1 *) 129.1(5) C(ll)-C( 12)-C( 121) 1 1 9 3 5 )Ir-N(3)-C( 10 1) 1 12.7(4) C( 12)-C( 121 )-Ir 109.5(4)Cp(l*) represents the centroid of the C5Me5 ring C(l)-c(5).normal single bonds.The C5Me5 ligand shows slight tilting, withIr-C distances of 2.186(7)-2.269(6) A.The NMR data are consistent with the structure in bothcases; assignments of the complicated 'H spectra were carriedout using two-dimensional correlation spectroscopy (COSY).Thus for both compounds 4a and 4b the methyl groups on thexylylimino group are diastereotopic giving rise to two separateresonances. The same applies to the methylene protons givingrise to an AB doublet of doublets. In addition, for 4b, theisopropyl methyls are inequivalent producing four doublets.The resonances of the remaining protons, e.g. of the C5Me5groups, methyls on cyclometallated xylyl, aromatics and tert-butyl (for 4a), are in normal positions.A mechanism for the formation of these compounds is shownin Scheme 1.The first step, a [2 + 21 cycloaddition, is the sameas that proposed for the reaction of Cr(q-C,Me,)(=NR) withisocyanide' and leads to the carbene intermediate A. Highlystabilized carbenes of the type shown in diagram I1 are wellknown in organic chemistry4" and as >C:+M donors inU24)C(9)Fig. 4 The structure of Ir(q-C,Me5)[?\l(xyl)CHN(2,6-Pri2C6H3)-CNC,H3(Me)CH2] 4b(C,Me,)lr- N R (C,Me,)lr=~ R I I I-(xyl)N-C:NIICBJbase -CJHUB+J. Chem. SOC., Dalton Trans., 1996, Pages 3771-3778 377Table 6 Selected bond lengths (A) and angles (") for Ir(q-C,Me,)~(2,6-Pr',C6H3)c(o)N(mes)] 5 with e.s.d.s in parenthesesIr-N( 1) 1.92(2) N( l)-C( 100) 1.56(2)Ir-N(2) 2.03(2) N(2)-C(21) 1.39(2)Ir-Cp( 1 *) 1.83(3) N(2)-C(100) 1.41(3)N(l)-C(ll) 1.27(3) C( 1 OO)-O 1.18(2)N( 1 )-Ir-N(2) 68.0(7) C(21)-N(2)-C(lOO) 123(2)N( 1 )-Ir-Cp( 1 *) 1 5 1.7( 1) Ir-N(2)-C( 100) 98.0( 13)N(2)-Ir-Cp( 1 *) 140.9(11) Ir-N(2)-C(21) 1 38.1 ( 1 4)C(11 )-N(l)-C(lOO) 116(2) N(l)-C(IOO)-N(2) 96(2)Ir-N( 1)-C( 100) 97.8( 1 3) N( 1 )-C( 1 OO)-O 129(2)Ir-N(l)-C(ll) 147(2) N(2)-C(100)-0 135(2)Cp( 1 *) as in Table 5.complexes of low-valent metals such as Ni', Pt',,' Sm" 9 E u ,Yb1I4' and Pd".4d This step is then followed by isocyanide co-ordination and insertion into the Ir-N: bond to give B.Required now is a sequence of transfers as in C where a base,presumably the isocyanide, deprotonates the o-CH~ group onthe xylyl ring leading to formation of the C-CH,-Ir moiety.The hydrogen on B+-H is then transferred to the carbene Catom with concomitant formation of a (xyl)N=C bond and adonor N : 4 r bond.There is no change in the oxidation state ofiridium in these sequences.The interaction of the imido compound l b with mesitylisocyanate at 110 "C in octane gives moderate yields of theblue, air-stable asymmetric N,N'-diarylureato complex Ir(q-C5Me,)[N(2,6-Pr',C,H,)C(O)N(rnes)] 5. Under similarconditions l a with (mes)NCO gives only intractable mixtures;the compound Os"(NBu')(MeC6H4Pri-p) on reaction withBu'NCO does, however, give a ureato complex.The structure of compound 5 was determined by X-raycrystallography and is shown in Fig.5; bond lengths and anglesare in Table 6. The crystal quality for this determination waspoor, and the resulting accuracy of structural parameters low.Nevertheless the main features are quite clear. The ureate ligandbonds in an almost symmetrical fashion. The Ir-N and Ir-C(C,Me,) distances are very similar to those in the isoelectroniccomplex Ir(q-C,Me,)@SJBu'C(O)O] described by Bergman andco-workers.2a The CSMe, bonding is symmetrical pentahaptoin both complexes; in the other ligands the substituents on theN atoms give large Ir-N-C angles (> 140') in both cases.However, other parameters indicate that this is a feature ofstrain (i.e. 'bent-bonding overlap') in the Ir-N bonding, arisingfrom the small ligand bite, rather than any steric straininvolving the substituent groups and the CSMe,.The interaction of compound l b with mesityl azide intetrahydrofuran (thf) at room temperature produces the N,N'-diaryltetrazene ' complex 6 by the usual 1,3-dipolar cycloaddi-tion in Scheme 2. The structure determined by X-ray diffractionis shown in Fig.6; bond lengths and angles are in Table 7. Thefive-membered IrN, ring has almost equal Ir-N bond lengthsand although the double bond seems to be localized atN(2)-N(3) [1.277(7) A], N(1) and N(4) are planar while theN( 1)-N(2) and N(3)-N(4) distances are slightly shorter thanexpected for normal single bonds; this indicates some electrondelocalization over the four N atoms. The C,Me, ligand bondssymmetrically, with Ir-C distances differing only by 0.02 A.The'H NMR spectrum has bands for mesityl and 2,6-disopropylphe-C(141)Fig. 5 The structure of Ir(q-C,MeS)~(2,6-Pri2C6H3)C(0)N(mes)] 5+Scheme2 R = 2,6-Pr',C6H3c mFig. 6 The structure of Ir(q-C,Me,)~(2,6-Pr',C6H3)N3(mes)] 6Table 7 Selected bond lengths (A) and angles (") for Ir(q-C, Me,)m( 2,6-Pr',C6H3)N3(mes)] 6 With e. s.d.s in parenthesesIr-N( 1) 1.925(5) N(l)-C(lI) 1.45 l(8)Ir-N(4) 1.940(5) N(2)-N(3) 1.277(7)1.367(6) Ir-Cp( 1 *) 1.821 (14) N(3)-N(4)N( 1 W ( 2 ) 1.371(6) N(4)-C(20) 1.441(8)N( l)-Ir-N(4) 74.1(2) N(l)-N(2)-N(3) 112.2(5)N(1)-Ir-Cp(l*) 143.5(6) N(2)-N(3)-N(4) 113.0(5)N(4)-Ir<p(l*) 142.5(6) N(3)-N(4)-C(20) 11 3.0(5)N(2)-N(l)-C(ll) 11 1.2(5) N(3)-N(4)-Ir 119.9(4)Ir-N( 1 )-C( 1 1) 127.9(4) C(20)-N(4)-Ir 127.0(4)Ir-N( 1)-N(2) 120.8(4)Cp( 1 *) as in Table 5.nyl groups in a 1 : 1 ratio and the isopropyl methyl groups arediastereotopic, as found for 5.The electron impact (EI) massspectrum shows the molecular ion. There is no sign of cleavageof the tetrazene moiety thermally or on photolysis even in thepresence of donors such as PMe,. Tetrazene osmium complexes3774 J. Chem. SOC., Dalton Trans., 1996, Pages 3771-377have been obtained by reaction of Os(NBu')(MeC6H,Pri-p)with azides.6Rhodium complexesAttempts to isolate rhodium analogues of l a and l b have failed.At temperatures above ca. 5 "C the red-brown solutions fromthe reactions of [Rh(q-CSMeS)C1,],* and various lithiumamido compounds, Li(NHR) (R = alkyl and aryl), that maypossibly contain Rh(q-C,Me,)(NR) species, decomposed togive purple solutions which on evaporation leave solids givingpurple solutions in hexane.Crystals could not be obtained froma range of solvents. The NMR spectra were uninterpretable andaddition of compounds such as tertiary phosphines, pyridine,etc., gave no identifiable adducts. Attempts to isolate Rh(q-C,Me,)(NR) species at low temperatures in polar or non-polarsolvents also failed.The only indication that Rh(q-C,Me,)(C6H,Pri,-2,6) couldexist, for a short time at any rate at 0 "C, was the interactionwith (mes)N, immediately after generation which produced therhodium tetrazene complex 7, which is analogous to that ofiridium and has similar spectroscopic properties. The yellow-brown crystalline product was air-stable; the mass spectrumshowed the molecular ion.The cobalt analogue Co(q-C,Me,)[(mes)N,(2,6-Pri2C6H3)] has been made similarly byH. Petersen in these laboratories.We have also tried to obtain imido species starting with othermaterials: [ R h( q -C , H JCl,]", { Rh[ HB(dmpz) ,]C12 1 , 9bC(16)Fig. 7 The structure of Ru~(2,4,6-Bu',C6H2)C(0)N(mes)]-(MeC,H,Pr'-p) 8Table 8 Selected bond lengths (A) and angles (") for Rum(2,4,6-Bu',C,H,)C(0)N(mes)](MeC6H4Pri-p) 8 with e.s.d.s in parenthesesRu-N( 1 ) 1.988(4) N(l)-C(100) 1.408(6)Ru-N(2) 2.023(4) N(2)-C(2 1) 1.434(6)Ru-Cw( 1 *) 1.68 1 (10) N(2)-C( 100) 1.390(6)N(1)-C(11) 1.411(6) C(lOO)-O 1.218(5)N( l)-Ru-N(2) 66.1(2) C(21 )-N(2)-C( 100) 127.5(4)N(1)-Ru-Cym(l*) 143.8(4) Ru-N(2)-C(100) 94.2(3)N(2)-Ru-Cym(l*) 149.8(4) Ru-N(2)-C(21) 138.0(3)C( 1 1)-N( 1 )-C( 100) 128.1(4) N( 1)-C( 100)-N(2) 102.8(4)Ru-N( 1 )-C( 100) 95.2(3) N( 1 )-C( lOO)-O 127.3(4)Ru-N( I)-€( 1 1) 133.5(3) N(2)-C(lOO)-O 129.8(4)Cym( 1 *) represents the centroid of the cymene ring C( ltC(6).(dmpz = 3,5-dimethylpyrazolyl), Rh(q -C ,Me,)(Me)Br(P-Me), 9c and Rh(q-C,Me,)(PMe,)(O, SCF,) , 9d under a varietyof conditions with the lithium salts from NH,Bu' and severalaromatic amines, but in all cases intractable materials wereobtained.The reason for the difference in stability or reactivity ofthe rhodium and iridium compounds is not clear; possiblyreduction to unstable or polymeric species is occurring with therhodium compounds.Ruthenium complexesThe interaction of Ru(NR)(Mec,H,Pr'-p), R = 2,4,6-Bu',C,H,,~ with (mes)NCO at room temperature shows thatthis complex is more reactive than the iridium(II1) species.Theasymmetric ureato complex 8 is obtained as thermally and air-stable blue crystals. The crystal structure is shown in Fig. 7;bond lengths and angles are in Table 8. The structure is asexpected, but with small deviations from idealized geometryarising out of some degree of steric strain involving the Pr'group on the cymene and Bu' groups on the ureate ligand. Thusthe cymene ring is tilted slightly, with Ru-C distances varyingfrom 2.139(5) [C(3)] to 2.265(5) A [C(l)], and Ru-N(2) issome 0.035 A longer than the Ru-N(1) bond length.TheRu-N(2)-C(21) angle to the R substituent is also ca. 5" greaterthan the equivalent angle Ru-N(1)-C(ll), but both are some10-15" smaller than in the iridium complex 5. The N-Cdistances in the ureate ligand are equal.The interaction of Ru(NR)(MeC,H,Pr'-p), R = 2,4,6-Bu',C,H,, with (mes)N, gave a yellow-brown tetrazenecomplex 9, characterized by analytical and 'H NMR data. Thelatter show distinct resonances for mesityl and R groups whilethe aromatic protons of the q6-arene ring appear as a doubletof doublets (AB) indicating that the asymmetric structure isnot present in solution, probably because of q6-arene ringrotations. The solid-state structure is shown in Fig. 8 and bondlengths and angles are given in Table 9.The structure and geometry are as expected, in view of theC(I 12)Fig.8 The structure of Ru[N(2,4,6-Bu',C,H2)N,(mes)]-(MeC,H&'-p) 9Table 9 Selected bond lengths (A) and angles (") for Rup(2,4,6-Bu',C,H2)N,(mes)](MeC,H4Pri-p) 9 with e.s.d.s in parenthesesRu-N( 1) 1.946(3) N(l)-C(ll) 1.439(4)N(lFN(2) 1.365(4) N(4)-C(20) 1.444(4)Ru-N(4) 1.967(3) N(2)-N(3) 1.288(4)Ru-Cym( 1 *) 1.709(8) N(3)-N(4) 1.358(3)N( 1 )-Ru-N(4) 74.08(11) N(l)-N(2)-N(3) 112.6(2)N(1)-Ru-Cym(l*) 140.5(3) N(2)-N(3)-N(4) 113.7(2)N(4)-Ru-Cym(l*) 145.4(3) N(3)-N(4w(20) 11 1.4(2)N(2)-N(l)-C(ll) 112.3(2) N(3)-N(4)-Ru 119.2(2)Ru-N( 1 )-C( 1 1) 127.0(2) C(2O)-N(4)-Ru 129.3(2)Ru-N( 1 )-N(2) 120.4(2)Cym( 1 *) as in Table 8.J. Chem. SOC., Dalton Trans,, 1996, Pages 3771-3778 377earlier work on complexes 6 and 7.The cymene ring is againslightly tilted, with Ru-C distances ranging from 2.170(4) to2.270(3) A, the longest to C(1), which is also bound to a Pr'substituent. It is interesting that the orientation of the cymenering, which appears to be fluxional in solution, places the Pr'group on the same side as the bulky R substituent, as in complex6. The structure of the ruthenium-tetrazene ring is analogous tothat found in 6, with the double bond localized at N(2)-N(3).The interaction of Ru(NR)(MeC,H,Pr'-p) with isocyanidesis very fast even in non-polar solvents like light petroleum andat low temperatures (-78 "C) as judged by changes in thesolution from green to brown. Since crystalline products couldnot be obtained, the reaction with Bu'NC in [2H,]toluene wasfollowed by 'H NMR spectra.Initially a species is formedinstantaneously at - 60 "C that has one Bu'NC per ruthenium.Shifts are observed for protons assignable to Bu', arylimido andq6-arene groups. This species begins to disappear at 0 "C beingreplaced by that of the final product (or products). The presenceof more than one Bu'NC resonance precludes any reliableconclusions on the nature of the product(s) and no crystalscould be isolated.Experiment a1Analyses were by the Imperial College microanalyticallaboratory. All operations were carried out under purified Ar orN,, under vacuum or in a Vacuum Atmospheres glove-box.General techniques have been described. loThe NMR data were obtained on a JEOL EX-270 or aBruker Avance DRX 300 spectrometer operating at 270 and300 MHz ('H) respectively and referenced to the residual 'Himpurity in the solvent (6 7.15, C6D6; 7.26, CDCl,).Massspectra were recorded using VG-7070E (EI) and V. G. Autospecspectrometers. Commercial chemicals were from Aldrich andFluka. The light petroleum used had b.p. 40-60 "C.Mesityl isocyanate" and mesityl azide', were made asreferenced.Bis [ (p-cyclopentylmido)( q-pentamethylcyclopentadieny1)-iridium(m)] 2To a solution of [Ir(q-C,Me,)Cl,], in thf (0.3 g, 0.37 mmol in30 cm3) at - 78 "C was added a solution of Li(NHC,H,) (0.14g, 1.5 mmol) in thf (ca. 10 cm3). The reaction suspension wasallowed to warm to room temperature and stirred for 2 h givingan orange solution. Evaporation of volatiles under reducedpressure, extraction of the residue in hot light petroleum(3 x 30 cm3), filtration and concentration of extracts andcooling (-20 "C) gave orange prisms.Yield: 0.1 g, cu. 35%.NMR (C6D,): 'H, 6 2.1 (s, 30 H, C5Mes), 1.2, 1.5, 1.8 and 2.5(groups of broad multiplets, 18 H, C,H,N).p-(C y clo hex ylamido)-p-(c yclohex ylimido)- bis(q-pentamethyl-cyclopentadienyl)diiidium(m) chloride 3To a solution of [Ir(q-C,Me,)Cl,], (0.3 g, 0.37 mmol) in thf(ca. 30 cm3) at -78 "C was added a solution of Li(NHC6Hl,)(0.12 g, 1.1 mmol) in thf (ca. 10 cm3). The suspension wasallowed to warm to room temperature and stirred for 1 h givinga yellow-orange solution. Evaporation of volatiles underreduced pressure, extraction of the residue in hot lightpetroleum (3 x 30 cm3), filtration, concentration of extractsand cooling ( - 20 "C) gave orange crystals.Yield: 0.08 g, 25%.C,Me,) and 1.8-1.2 (m, 22 H, C6H1 ').NMR (C6D6): 'H, 6 10.6 [S br, 1 H, NH(C,Hl')], 2.0 (s, 30 H,mmol) in thf (1 5 cm3). The yellow-orange reaction mixture wasrefluxed for 2 h and the volatiles removed under reducedpressure. The yellow-orange residue was recrystallized from hotlight petroleum. Yield: 0.3 g, 72%. Mass spectrum (EI): m/z 660(M+ + 1) and 604 (M' + 1 - isobutylene). NMR (C6D6):'H, 6 7.5-7.0 (m, 6 H, aromatic), 3.0 and 2.5 (d, 2 H,IrCH&H&k), 2.75, 2.51 and 2.1 (s, 3 H each, xylyl methyl),1.47 (s, 9 H, NCMe,) and 1.33 (s, 15 H, C,Me,).Interaction of Ir(q-C,Me,)(NC,H,Pri2-2,6) with 2,6-xylylisocyanide to give compound 4bCompound 4b was prepared as for 4a from Ir(q-C,MeS)(NC6H3Pri2-2,6) (0.3 g, 0.6 mrnol) and 2,6-xylylisocyanide (0.24 g, 1.8 mmol).After evaporating the thfsolution the yellow residue was recrystallized from diethylether. Yield: 0.37 g, 80%. Mass spectrum (EI): m/z 765 (M+ +6 7.6-6.90 (m, 9 H, aromatic), 3.60 and 3.10 (spt, 1 Heach, Me,CH), 3.40 and 2.55 (doublet of doublets, 2 H,IrCH,C,H,Me), 2.45, 2.40 and 2.0 (s, 3 H each, xylyl methyl),1.65, 1.40, 1.15 and 1 .OO (d, 3 H each, Me,CH) and 1.38 (s, 151) and 635 [M+ + 1 - C,H,(Me)CH,]. NMR (C6D6): 'H,H, CsMe,).[ N-(2,6-Diisopropylphenyl)-N-(2,4,6-trimethyIphenyl)-ureato] (q-pentamethylcyclopentadienyl)iridium(m) 5A solution of compound l b (0.25 g, 0.5 mmol) and (mes)NCO0.1 g, (ca.0.6 mmol) in octane was heated at 110 "C for 48 h.After removal of octane under reduced pressure the blue residuewas recrystallized from light petroleum to yield 0.21 g (ca. 65%)of green-blue 5. NMR (C6D6): 'H, 6 7.3 (m, 3 H, aromatic), 6.9(s, 2 H, aromatic), 3.8 (spt, 2 H, CHMe,), 2.6 (s, 6 H, o-Me), 2.3(s, 3 H, p-Me), 1.45 (doublet of doublets, 12 H, CHMe,) and1.05 (s, 15 H, CSMe,). IR (Nujol): 1650 cm-' [v(W)].[ 1 -(2,6-Diisopropylphenyl)-4-(2,4,6-trimethyIphenyl)-tetrazene-l,4diyl] (q-pentamethylcyclopentadien yl)iridium(m) 6To a solution of compound l b (0.25 g, 0.5 mmol) in thf (20 cm3)was added via cannula a thf solution of (mes)N3 (0.1 g, 0.6mmol in 5 cm3). The yellow reaction solution was stirred atroom temperature for 12 h.Removal of volatiles under reducedpressure and crystallization of the residue from light petroleumgave yellow needles. Yield: 0.28 g, 85%. Mass spectrum (EI):7.3 (m, 3 H, aromatic), 6.9 (s, 2 H, aromatic), 3.3 (spt, 2 H,CHMe,), 2.4 (s, 3 H,p-Me), 2.2 (s, 6 H, o-Me), 1.4 (doublet ofdoublets, 12 H, CHMe,) and 1.30 (s, 15 H, C,Me,).m/z 636 (M' - 28) and 622 (M' - 42). NMR (C6D6): 'H, 6[ 1 -(2,6-Diisopropylphenyl)-4-(2,4,6-trimethylphenyl)tetrazene-1 ,ediyl] (q-pentamethylcyclopentadienyl)rhodium(m) 7To a mixture of [Rh(q-C,Me,)Cl,], in thf (0.25 g, 0.4 mmol in30 cm3) at -78 "C was added a solution of LimH(C6H3Pri,-2,6)] (0.3 g, 1.62 mmol) in thf (10 cm3). The suspension wasallowed to warm to 0 "C when all solids dissolved. Stirring atthis temperature was continued for ca.0.5 h and the red-brownreaction mixture was cooled again to - 78 "C and a solution of(mes)N, (0.07 g) in thf (5 cm3) was added dropwise via cannula.After completion of the addition the reaction mixture wasallowed to warm and stirred at room temperature for 0.5 h.Removal of volatiles under reduced pressure, followed byextraction of volatiles with light petroleum (3 x 30 cm3),filtration, concentration to ca. 25 cm3 and cooling gave yellow-brown crystals. Yield: 0.1 g, 45%. Mass spectrum (EI): m/z 574aromatic), 6.9 (s, 2 H, aromatic), 3.2 (spt, 2 H, CHMe,), 2.4 (s, 3(M') and 546 (M+ - N2). NMR (C6D6): 'H, 6 7.4 (m, 3 H, Interaction of Ir(q-C,Me,)(NBut) yith 2,6-xylyl isocyanide togive compound 4aTo a solution of Ir(q-C,Me,)(NBu') (0.25 g, 0.63 mmol) in thf(20 cm3) was added a solution of xylyl isocyanide (0.25 g, 1.9H, p-Me), 2.2 (s, 6 H, o-Me), 1.4 (doublet of doublets, 12 H,CHMe,) and 1.30 (s, 15 H, C,Me,).3776 J.Chem. SOC., Dalton Trans., 1996, Pages 3771-377Table 10 Crystal data and structure refinement details for the carbodiimide and compounds 2,3,4b, 5,6,8 and 92 3 4b 5Formula C24H421rN3 C30H481r2N2 C32H53C11r2N2 C40H501rN3 C32H431rN20Mr 564.84 821.10 885.61 765.03 663.90Crystal system Monoclinic Orthorhombic Monoclinic Monoclinic TriclinicalA 9.708( 1) 21.836(1) 12.036(6) 9.811(6) 8.58(1)Space group p2 1 Im Pbca p2 1 In p2 1 In PfblAC I Aa10YI" 79.4(2)1 5.00 1 (2) 17.266(4) 21.539(10) 17.068(8) 11.22(3)9.965( 1) 15.480(3) 12.388( 1) 21.174( 10) 1 5.9 1 (3)83.5 l(6)PI" 118.67(1) 93.70( 3) 94.99( 8) 87.89(7)ul~3 1273(2) 5836(2) 3205(2) 3532(3) 1496( 5)Z 2 8 4 4 2DJMg m-3 1.473 1.869 1.835 1.439 1.474F ( c w 568 3168 1720 1552 668Crystal colour Beige Pale orange Orange Yellow TurquoiseCrystal size/mmp(Mo-Ka)/mm-' 5.075 8.8 15 8.1 14 3.680 4.334Reflections collected 5329 16 082 9459 12 543 5920Independent reflections (Rin,) 1993,0.0852 4474,0.0896 4580,0.1851 5301, 0.0563 4029,O.13 1 1Maximum, minimum correctionfactors 1.289, 0.840 1.881,0.756 1.241, 0.715 1.042,0.870 1.359,0.7690.24 x 0.09 x 0.05 0.48 x 0.24 x 0.09 0.15 x 0.12 x 0.06 0.12 x 0.12 x 0.09 0.12 x 0.09 x 0.02Data, restraints, parameters 1991,0, 156 4471,0,317 4577,0, 174 5298,0,453 4025,0,162Goodness of fit, Fz 0.985 1.051 0.994 0.732 0.700Observed data [I > 20(Z)] 1597 3764 2483 3502 1500R1, wR2 [I > 20(1)] 0.0440,0.0979 0.0471,0.1064 0.1 162,0.2590 0.0312,0.0559 0.0762,0.1519(all data) 0.0550,O.1025 0.0549,O. 1 114 0.1827,0.2899 0.0613,0.0613 0.1612,0.1930Largest difference peak and hole/e A-3 1.717, - 1.1 18 7.436, -2.01 5 8.687, - 3.509 1.868, - 0.607 1.784, - 1.352S = Dw(Foz - FC2)'/(n - p ) l f , R1 = C[(Fo - Fc)]/CFO, wR2 = pw(Fo2 - Fc2)2/Cw(Fo2)2]*, w = l/[02(Fo2) + (XP)~ + gP] and P = [max(Fo2)number of parameters, x = 0.0524,0.0615,0.1220,0,0.0188,0.0058,0.0670 and 0.1018 for the carbodiimide and compounds 2,3,4b, 5,6,8 and 9 respectivelq6-(p-Cymene) [ N-( 2,4,6-tri-tert-butylphenyI>ICP-o-,4,6-trimethylphenyl)ureato] ruthenium(r1) 8To a solution of (p-cymene)(2,4,6-tributylphenylimido)ruthe-nium3 in thf (0.3 g, 0.61 mmol in 20 cm3) at room temperaturewas added a solution of (mes)NCO (0.1 g, 0.65 mmol) in thf (10cm3).The green solution became green-brown and after stirringat room temperature for ca. 2 h, evaporation of volatiles underreduced pressure, extraction of the residue with light petroleum(2 x 20 cm3), filtration, concentration of filtrates (to ca. 5 cm3)and cooling (-20 "C) gave blue crystals. Yield: 0.14 g, 40%.Mass spectrum (FAB): m/z 665 (M') and 503 [M+ -(mes)NHCO]. NMR (C6D6): 'H, 6 7.6 (s, 2 H, aromatic), 6.9(s, 2 H, aromatic), 4.6-4.4 (doublet of doublets, 4 H, q6-PriC6H4Me), 2.6 (s, 6 H, o-Me2C6H2Me), 2.3 (s, 3 H, p-BUtC6H2But2) and 0.7 (d, 6 H, q6-PriC,H4Me).IR (Nujol):1 65 5 cm-' [v( GO)] .MeC6H2Me2), 1.8 (S, 18 H, O-BUt2C6H,BU'), 1.4 (S, 9 H, p-q6-(p-Cymene) [ 1 -( 2,4,6-tri-tert-butylphenyl)-4-(2,4,6-trimethylphenyl) tetrazene-l,4diyl] ruthenium@) 9To a solution of (p-cymene)(2,4,6-tri-tert-butylphenylimido)-ruthenium in light petroleum (0.3 g, 0.61 mmol in 40 cm3) at- 78 "C was added a solution of (mes)N, in the same solvent (0.1g, 0.65 mmol in 20 an3). The green solution, which becamebrown between - 78 and 0 "C, was stirred at room temperaturefor ca. 2 h. Evaporation of volatiles under reduced pressure,extraction of the residue with light petroleum (2 x 20 cm'),filtration, concentration of filtrates (to ca. 10 cm3) and cooling(-20 "C) gave yellow-brown crystals.Yield: 0.22 g, 55%. Massspectrum (EI) : m/z, 495 [M' - (mes)N,]. NMR (C6D6): 'H, 67.5 and 6.8 (s, 2 H each, aromatic), 4.8-4.5 [doublet of doublets,4 H, -q6-C6H4(Me)Pr'], 2.3 (s, 3 H,p-MeC6H2Me2), 2.1 (s, 6 H,H, p-BuLC6H2Buf2), 1.4 (s, 3 H, q6-MeC,H4Pri), 1.3 (s, 18 H, u-BuL2C6H2Bu') and 0.7 [d, 6 H, q6-C6H4Me(CHMe2)].O-kfe2C6H2Me), 2.0 [Spt, 1 H, q6-C6H,(Me)CHMe2], 1.5 (S, 9X-Ray crystallographyX-Ray data for all of the compounds were collected at 150 K. AFAST TV area detector diffractometer with Mo-Ka radiation(h = 0.710 69 A) was employed, as previously described. l3 Thestructures of compounds 2,6 and 8 were solved using the PATTinstruction of SHELXS 86,14 whilst those of the carbodiimideand 3,4b, 5 and 9 were solved via direct methods procedures ofthe same program.They were refined by full-matrix leastsquares on Fo2, using the program SHELXL 93." All dataused were corrected for Lorentz-polarization factors, andsubsequently for absorption using the program DIFABS l 6with maximum and minimum correction factors listed in Table10. The non-hydrogen atoms of the carbodiimide andcompounds 2, 4b and 6 were refined with anisotropic thermalparameters. Compounds 3 and 5 exhibited fragile crystals ofplaty morphology which gave rise to poor-quality data,therefore only the heavy atoms of these structures wereanisotropically refined. The non-hydrogen atoms of 8 and 9were refined with anisotropic thermal parameters, except forthe carbon atoms of the highly disordered solvate molecules,originating from light petroleum, and identified as pentane inboth compounds.The hydrogen atoms of the solvate moleculesin 8 and 9 were ignored. The phenyl hydrogen atoms of 8 and 9were experimentally located whilst the remainder were placed inidealized positions. The phenyl and isopropyl hydrogen atomsof 4b and 6 were experimentally located, whilst the remaininghydrogen atom positions were again calculated. All of thehydrogen atoms in the carbodiimide and compounds 2,3 and 5were included in idealized positions. Compounds 2 and 3exhibit large residual peaks in the difference map which lie inthe vicinity of the metal atoms. This arises from poor-qualitydata in the latter case, and due to a slight twinned componentin crystals of the former.The equations used in the refinement,the weighting scheme and parameters employed for eachcompound are included as a footnote to Table 10.Atomic coordinates, thermal parameters and bond lengthsand angles have been deposited at the Cambridge Crystallo-graphic Data Centre (CCDC). See Instructions for Authors,J. Chem. Soc., Dalton Trans., 1996, Issue 1. Any request to theCCDC for this material should quote the full literature citationand the reference number 186/ 186.AcknowledgementsWe thank the EPSRC for support (to A. A. D.) and provisionof X-ray facilities. We are indebted to Johnson Matthey plcfor loan of platinum group metals and to Professor W. B.Motherwell for discussions.References1 A.A. Danopoulos, G. Wilkinson, T. K. N. Sweet and M. B.Hursthouse, J. Chem. SOC., Dalton Trans., 1996,271.2 (a) D. S. Glueck, J. Wu, F. J. Hollander and R. G. Bergman, J. Am.Chem. 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Soc., Dalton Trans., 1991, 4855.14 G. M. Sheldrick, SHELXS 86, Acta Crystallogr., Sect. A, 1990,46,467.15 G. M. Sheldrick, SHELXL 93, Program for Crystal StructureRefinement, University of Gottingen, 1993.16 N. P. C. Walker and D. Stuart, Acta Crystallogr., Sect. A, 1983,39,158 (adapted for FAST geometry by A. Karaulov, University ofWales, Cardiff, 1991).Received 18th March 1996; Paper 6/01 850E3778 J. Chem. Soc., DaIton Trans., 1996, Pages 3771-377
ISSN:1477-9226
DOI:10.1039/DT9960003771
出版商:RSC
年代:1996
数据来源: RSC