1979 1843The Reactions of Molybdenum Oxo-complexes with Substituted Hydr-azines. Part 5.t The Preparation of Some Organodiazenido-complexesof MolybdenumBy Michael W. Bishop, Graham Butler, Joseph Chatt, Jonathan R. Dilworth, and G. Jeffery Leigh,"A.R.C. Unit of Nitrogen Fixation, The University of Sussex, Brighton BN7 9RQWe describe a series of complexes [Mo(N,Q)(S,CNMe,),] (Q = alkyl, aryl, or alkoxycarbonyl) and [Mo(N,Q),-(S,CNMe,),] prepared from [ MoO,(S,CNMe,),] and the appropriate hydrazine. Representative members of theformer class of compounds can be protonated, alkylated, and arylated at the diazenido-nitrogen remote from themetal. The latter compounds are formed via intermediates which are probably [Mo( N,H,Q) (N,Q) (S,CNMe,),].The electrochemical properties of the new complexes are discussed.THE organodiazenido-grouping, -N,R , has been con-sidered as helpful in understanding the chemistry ofboth N, and N0.l In fact, its chemistry, especially thestructure, protonation, and reduction, is sufficientlyinteresting and unusual on its own account withouthaving to justify real or imagined parallels to support itsstudy. Nevertheless, our study has as its basis theparallel between organodiazenido-complexes and those ofthe diazenide ion, HN=N-, which we consider to be thefirst reduction products of ligating dinitrogen but whichare not as accessible for study as the organo-derivatives.Organodiazenido-complexes can be synthesised by avariety of processes including the reactions of diazoniumsalts with a complex anion or neutral ~ o m p l e x , ~ ~ ~ theinsertion of diazonium salts into metal-hydrogen bondsfollowed by removal of the proton^,^?^ and oxidativeadditions of diazonium Further methods in-volve diazotisation of metal nitrosyl and protonation loor alkylation l1 of co-ordinated dinitrogen. Finally,there is a group of syntheses from substituted hydrazonesand a metal halide,12 from Me&-N=N-R (R = aryl) anda metal halide,13 diaryltriazenes and a metal halideJ5and the insertion of trimethylsilyldiazomethane into amolybdenum-h ydrogen or tungsten-hydrogen bond.14We report here a series of mono- and bis-(organodiaze-nido)-complexes of molybdenum , of types [Mo(N,R)-( d t ~ ) ~ ] and [Mo(N,R),(dtc),] , prepared from [MOO,-(dtc),] (dtc = diorganodithiocarbamate) and an appro-priate hydrazine, together with observations concerningtheir structures, modes of formation, and reactivitieswith both electrophiles and nucleophiles.RESULTS AND DISCUSSIONMono(ovganodiazenido) -cowzplexes.- ( a ) Preparation.The complexes [Mo(N,R)(dtc),] (see Table 1) are pre-pared by the reaction of the appropriate hydrazine,RNHNH, (ca.2 equivalents), with [MoO,(dtc),] in dryrefluxing methanol in the presence of 1 equivalent ofNa[dtc]. The compounds discussed here are those forwhich R = alkyl, aryl, or carboxycarbonyl. Those withR = acyl or aroyl will be described elsewhere becausetheir chemistry is very different and is still beingd e ~ e l o p e d . ~ ~ In the absence of Na[dtc], yields are of theorder of 40%, but reach 70-80% in its presence.t P a r t 4, M.W. Bishop, J. Chatt, J. R. Dilworth, M. B. Hurst-house, and M. Motevalli, J . C . S . Dalton, 1979, 1603.We do not yet understand in detail how the diazenido-complexes are formed. The simple condensation to yielda species Mo=N-NHR is plausible, but evidently someinternal redox step perhaps involving Mo-OH is neces-sary to remove the remaining hydrogen.The complexes are allmonomeric, diamagnetic , air-stable , crystalline solids.An X-ray structure analysis l6 of [Mo(N,Ph) (S,CNMe,),]shows it to be seven-co-ordinate, with a pentagonal-bipyramidal structure (Figure 1). It is likely that themajority of the complexes [Mo(N,R)(dtc),] have ana-logous structures.The plane of the phenyl carbons is(b) Structure and properties.FIGURE 1 The molecular structure of[Mo(NzPh)(SzCNMez),lbent away from the plane containing the Mo-N-N-Csystem by ca. 5", indicating that through-conjugationfrom C,H, to Mo is not maximised. If the 18-electronrule is obeyed by the complexes the N,R group must beformulated as a three-electron donor, and this is con-sistent with its essentially linear MoNN chain.The 13C n.m.r. spectra of the complexes as detailed inTable 2 show interesting features. This suggests thatthe chemical shifts, which may be assumed to beroughly proportional to the electron densities a t theindividual carbon atoms, are dependent upon X pro-vided the carbon atoms form part of the diazenido-ligands, but that the chemical shifts of the carbons of thedtc ligands do not vary.This means that the effect ofX cannot be making itself felt further than the molyb-denum atom. The chemical shifts at, say, C3 can b1844 J.C.S. Dalton TABLE 1Mono- and bis-organodiazenido-complexes of molybdenum and some related complexesM.!."Colour (€I,/ C)Black 262-264Green- 248-250Brown 243Red- 133Black 256-258purple(decomp .)brownBlack- 234Black 210Black- 109Black 229brown(decomp .)brownBlack- 228Brown 250brownBlack 258-260Black- 260Black- >260Green 162- 164brownbrownOrange 222Brown 252-254Green 155-158Green- 152-153Brown 255-257brownBlack 244-246Brown 146-148Purple 240Purple 172Orange- 135Orange 205red(decomp .)[Mo,(N,H,Ph) (NZPh) (S,CNMe2)21 Orange 172[Mo(N,H,Me) (N2Me) (S,CNMe2)21 Orange- 144[Mo(N2H2COOPh) (N,COOPh) (S2CNMe2) 2] Orange 173[Mo( N2H2COOE t) (N,COOEt) (S2CNMe2) 2] Yellow 174red[Mo(N2H2COOBut) (N2COOBut) - Orange 138(S2CNMe2) 21M bInsoluble643 (596)513 (499)722 (681)560 (583)973 (963)915 (871)Region v(NN)or v(CN) ,-.-(cm-') c C1 550br 32.4(32.1)1 545br 29.4(29.7)1505, 30.01 535br (29.7)1 505 29.6(29.7)1545 29.9(30.2)1515br 30.0(30.2)1515 30.1(30.2)1535br 31.1(31.1)1530 33.4(33.4)1520br 33.4(33.4)1515 33.5(33.4)1550 31.7(32.5)1 540 32.6(32.5)1525br 32.6(32.5)1592, 24.21 540 (24.1)1532, 28.61515 (28.7)1530 42.5(42.3)1583, 35.71510 (36.8)1570, 32.71 500 (33.0)1 550, 47.31 480 (47.9)1 540, 57 31 490 (57.3)1585, 54.71490 (55.1)1 570 (m), 38.91580 (m), (39.6)1610 (m),1 640 (m)1 565 (w), 30.51590 (m), (30.7)1 610 (w),1 640 (m)1 580 (m), 39.11605 (m) (39.6)1 600 (s), 22.81 660 (s) (22.8)1 570 (m),1 590 (m),1600 (m),1635 (m)1 565 (m), 44.01595 (m), (43.8)1 600 (m),1635 (m)Z 540 (m), 38.61630 (m) (39.5)1600 (m), 22.71650 (w) (22.6)1 665 ( s , br) 38.61 630 (s), 25.71 665 (w), (24.9)1 700 (s)1 635 (s), 32.31650 (m), (32.2)1 690 (s)(39.5)Analysis (yo) bH4.23.82.73.73.73.74.04.04.54.44.44.24.03.94.44.95.45.55.64.14.2(4.1)(3.6)(3.6)(3.6)(3.7)(3.7)(3.7)(3.8)(4.4)(4.4)(4-4)(4.2)(4.2)(4.2)(4-2)(4.6)(5.1)(5.3)(5.6)(4.0)N X12.6 34.2(12.5) (34.4) (S)13.5(13.7)13.8(13.7)13.8(11.7)11.6(11.7)11.712.012.012.111.4(11.8)11.8(11.8)11.7(11.8)13.9(14.0)11.810.4 28.5(10.3) (28.2) (S)11.0(11.3)11.68.97.5 19.8(12.1)(12.2)(12.2)(12.2)(12.0)(12.0)(8.0)(3.8) (7.3) (19.9) (S)4.0 6.7(3.8) (8.0)4.2 14.9(4.0) (15.4)3.4 11.4(2.9) (11.9)4.5 13.3(4.3) (13.9)4.4 19.5(4.3) (19.9)5.0 14.2(5.0) (13.9)4.7 14.8(4.4) (15.3)4.6 19.1(4.7) (19.8)4.7 14.8(4.4) (15.3)3.8 14.9(4.2) (14.5)5.4 14.1(5.4) (14.1)Generally with decomposition.6 Calculated values are given in parentheses. e Nujol mulls. d Sample identified b y spectro-scopic properties only1979 1845TABLE 2Carbon-13 n.m.r.chemical shifts for the complexes [Mo(N,C,H,X-P) (S,CNMe,),] in CD,CI, solution at ca.30 “C in p.p.m. relative to tetramethylsilaneXN IIC2c /d lCH3CH3-NX C’ C2 c3 C4W C5(7) C6 C8 Cb C C Cd-205.2 -200.2 -157.1 -119.8 -124.8 -142.5 -37.5 -38.3 -40.5-206.6 -200.0 -145.0 -128.4 -128.4 -128.1 -37.4 -38.3 -40.5 -40.8 c1F -206.8 -200.1 -142.7 -121.6 -114.7 -115.6 -37.4 -38.2 -40.0 -40.7H -206.8 -200.1 -147.9 -128.4 -120.7 -123.6 -37.4 -38.2 - 40.4Me - 206.0 - 200.0 .- 143.9 -37.3 -38.2 -40.4 -40.7OMe - 204.3 - 199.8 -121.6 -125.4 -114.4 -37.6 -38.4 - 40.5NO*correlated roughly with either Hammett function opor op+, and so the significance of such correlations is notclear.However, the oxidation potentials of the com-plexes correlate much more satisfactorily with the opfunctions of XI7 than with op+, and the activationenergies for methyl interchange of the dtc groups in thelH n.m.r. spectra also correlate with oP.l8 This alsoindicates 17*18 that both phenomena operate throughinductive effects transmitted only as far as the molyb-denum. In what is possibly a similar manifestation ofthis effect, the Ru(3pP) binding energies in [RuCl,-(N,C,H,X)(PPh,),] are believed to vary linearly with ofor X.19In contrast to this dependence on X the lowest-energycharge-transfer bands in the molybdenum complexes areall found at ca. 415 nm in solution in dichloromethane,independent of X, which is less easy to rationalise with-out a detailed analysis of the origin of these bands, whichwe have been unable to undertake.The complexes show one or two bands in the region1 480-1 600 cm-l which are assignable to v(N=N) of thediazenido- or v(C=N) of the dithiocarbamato-ligands.The complexes [MBr(N,R) (Ph,PCH,CH,PPh,),] (M =Mo or W; R = alkyl) also show complex bands in thisregion which do not allow easy assignment.ll Thecomplexes (20) and (21) (see Table 1) have v(C=N) a t(1 500 cm-l.The higher bands (at 1 550 and 1 540cm-l, respectively) disappear upon alkylation (see below)so that these higher bands are probably assignable tov(N=N).The monodiazenido-complexes can be oxidised by anexcess of dibromine to give [Mo(N,R) (dtc),]+. Theoxidation can be monitored electrochemically.Cyclicvoltammetry suggests a one-electron reversible oxid-ation. The precise value of the redox potentialdepends critically on the inductive electron-releasingproperties of the substituent X in [Mo(N,C,H,X) ( d t ~ ) ~ ] ,but is independent of mesomeric effects.17 None of thecomplexes can be reduced in the potential range acces-sible to us.The diazenido-ligand, when acting as a three-electrondonor, should be susceptible to electrophilic attack atthe nitrogen remote from the metal. Attack is notinvariably observed, however, witness the difference inreactivity towards protons of [ReCl,(N,Ph) (PMe,Ph),]and [ReCl,(N,Ph) (NH,) (PMe,Ph)]. The former doesnot react with protons whereas the latter, with a similardiazenido-ligand, does.1,The complexes [Mo(N,R)(dtc),] react with acids, HX,both gaseous and aqueous, to yield the hydrazido(2-)-complexes [Mo(N,HR) (dtc),]X or [Mo(N,HR) ( d t ~ ) ~ X ] ,depending upon X.For X = C1 or Br, non-electrolytesof the latter type are produced (Table 3). For X = BF,,electrolytes of the former class are formed. The protoncan be removed by bases. This behaviour parallels veryclosely the reversible protonation of [M(N,H) (Ph,PCH,-PPh,),X] lo and [M(N,R)(Ph,PCH,CH,PPh,),X] l1 (M =Mo or W; R = alkyl). Acylation and aroylation pro-ceed normally for R = Me, but for R = Ph protonationby adventitious acid is 0b~erved.l~The i.r. spectra of these hydrazido(2-)-complexes areunexceptional. It was not possible to assign bands un-equivocally to v(NH), even after deuteriation, andalthough v(N=H) must have disappeared in comparisonto the diazenido-complexes the continued presence ofv(C=N) from the dithiocarbamates effectively masks this.Similarly N-H protons could not be detected in the ’Hn.m.r.spectra. This is again not unusual.The complexes [Mo(N,R) ( d t ~ ) ~ ] also react with R’X[R’X = methyl iodide, benzyl bromide and, in one case1846 J.C.S. DaltonTABLE 3Products of the alkylation and protonation of molybdenum diazenido-complexes(34) [Mo(N,MePh) (S,CNMe,),]I(35) [Mo (NzMe2) (SaCNMe2) 31 I(36) [Mo{N,Me(CH,Ph)) (S,CNMe,),]Br(37) ['o(N2MePh) &CN(CH2)5)311(38) [Mo(N2EtPh){S2CN(CH2)5)31 P F 4 I(39) [Mo~N2[C6H3(No2)2-2~4~}{S2CN(CH2)5)31C1(40) [MoCl(N,MeH) (S2CNMe2)3]CH2C12(41) [Mo (N,MeH) (S2CNMe2) ,] [BF4].2H20(42) [MoCl(N,PhH) (S,CNMe,),](43) [MoC1(N,PhH){S,CN(CH2),},]CH,C12(44) [MoBr(N,PhH) {S,CN (CH,),),] .H20ColourYellowYellowYellowYellowGolden yellowRed-brownYellowYellowY ellow-brownRed-brownYellow-brownM.gd(%/ C) M21 2-2141 89-1 9 1193-1951 96-1 9 8228-2301 4 4 1 4 6> 2602 20-223248-250 531 (598)>260 663 (718)154-156 719 (762)Golden yellow 173-176 328 (787)Conductivity/ Analysis (yo)ohm-' cm2 Lmol-134.5In sol .c37.436.249.032.11.738.22.0 d2.0 d1.9 d35.0C H N X27.5 3.8 9.8(27.4) (3.7) (10.0)20.4 4.0 10.6(20.6) (3.8) (10.9)29.7 4.2 10.1(29.2) (4.3) (10.6)35.9 4.8 8.4(36.5) (4.6) (8.5)38.3 5.1 8.7(38.3) (5.2) (8.6)35.9 4.4 12.3(36.5) (4.4) (11.9)20.6 3.9 11.1(21.2) (3.9) (11.3)20.5 3.9 11.0(19.4) (3.7) (11.3)30.5 3.8 12.0(30.2) (4.0) (11.7)37.4 5.1 14.0(37.4) (4.7) (13.3)36.8 5.0 8.7 14.0(36.9) (4.9) (8.7) (13.3)36.0 4.9 8.7(35.8) (5.0) (8.7)(C1)With decomposition.Calculated values are given in parentheses. In solution in CH2C12. In solution in 1 ,2-dichloroethane.even 2,4-(NO,),C,H,Cl] to yield the dialkylhydrazido-(2-)-complexes [Mo(N,RR')(dtc),]X (Table 3). Thereaction with [OEt,] [BF,] gives an analogous product.Interestingly, although [Mo(N,),(Ph,PCH,CH,PPh,),]reacts with, for example, methyl bromide to give[MoBr(N,Me) (Ph,PCH,CH,PPh,),] ,11 the latter methyl-diazenido-complex shows no tendency to react furtherwith methyl bromide.The complexes [Mo(N,RR') (dtc),]+ form air-stable,diamagnetic, crystalline salts.The X-ray structureanalysis 2O of [Mo(N,EtPh){S,CN(CH,),},] [BPh,] con-firms that alkylation takes place on the nitrogen remotefrom the metal. The lH n.m.r. spectra of the diorgano-hydrazido(2-)-complexes are as expected. That of[Mo(N,Me,)(S,CNMe,),]I shows only one resonance ( T6.48) assignable to both N-methyls of the hydrazido(2-)-ligand, confirming that alkylation takes place on theremote nitrogen. The lH n.m.r. spectrum of [WBr-(N,Me,) (Ph,PCH,CH,PPh,),]+ is similar in this respect.llBis(organodiazenido)-complexes.-(a) Preparation. If[MoO,(dtc),] is treated with an excess of the hydrazinehydrochloride (ca.5 mol) and without the addition of anyNa[dtc], then complexes [Mo(N,R),(dtc),] are formed.These are monomeric, diamagnetic, air-stable, crystallinesolids (Table 1). In particular cases, and especiallywhen the hydrazine is a carbazate, ROCONHNH,, it ispossible to isolate complexes which we formulate as[Mo(N,H,CO,R) (N,CO,R) (dtc),]. These crystalline mat-erials are stable in the solid state and in solution in theabsence of air. Exposure of the solutions to air results ina clean conversion into [Mo(N,CO,R),(dtc),]. Thus themixed hydrazido-diazenido-complexes are apparentlyintermediates in the formation of the bis(diazenid0)-complexes.If the 18-electron rule ( b ) Structure and properties.is obeyed, then both N,R groups in [Mo(N,R),(dtc),]should have linear Mo-N-N systems, and N-N-C anglesof ca.120". The lH n.m.r. spectrum of [Mo(N,Ph),-(S,CNMe,),] shows that in solution in CD,Cl, a t 25 "Cthere are two distinct kinds of methyl groups each ofwhich gives rise to a singlet ( T 6.64, 6.58). Substitutedaryl compounds are similar (see Table 4). This is bestaccommodated on the basis of a cis structure (I). The13C n.m.r. spectra are also consistent with this [Table 5 ,which compares analogous mono- and bis-(diorgano-diazenido)-complexes] .The possibility that the cis-diazenido-groups arelinked to give some kind of tetrazene structure cannot beexcluded. However, the mass spectrum of [Mo(N,Ph),-(S,CNMe,),] shows ions with m/e corresponding to theparent mass A l , [M - (N,Ph)], and [M - (N,Ph),],making it unlikely that the two N,Ph groups are directlylinked within the complex molecule.In the i.r. spectraTABLE 4The 'H n.m.r. spectra (T) of cis-[Mo(N,R),(dtc),] inCD,Cl, at 28 "CDithio-Diazenido- carbamato-Complex protons * protons *[Mo(N,Ph) 2(S,CNMe,) 21 2.52 (10, m) 6.58 (6, s ) ;6.64 (6, s)[Mo(N,Ph),(S2CNEt2)21 2.60 (10, m) 6.18 (8, m);8.70 (12, m)8.60 (20, m)[Mo(N2Ph)2~SzCN(CH2),),1[Mo(C&4Br-9) 2 (S2CNMe2) 21 2.80 (8, q) 6.63 (6, s);6.66 (6, s)2.50- 8.2&3.00 (10, m)[Mo(N,C~H~OM~-~),(S,CNM~,)~] 2.80 (8, q) ; 6.54 (6, sj ;[Mo(N2Me)2(S2CNMe2)21 6.36 (6, s) 6.56 (12, s)6.18 (6, s) 6.60 (6, s )* Relative intensities and multiplicities in parentheses; s =singlet, q = quartet, m = multiplet1847 1979TABLE 5The 13C n.m.r.chemical shifts * of [MoQ(S,CNMe,),] and [MOQ~(S,CNM~,)~]Q = N,Me N,Ph N2Me N2Ph[MoQ (SzCNMe2) 31 WoQ2 (SzCNMe2) 21 Na[S2CNMe2]Dithiocarbamato C - 200.0 - 200.1 - 181.5 - 205.0 - 214.7- 206.8Dithiocarbamato-methyl C - 37.6 -37.4 -40.3 - 40.0 -44.8- 38.4 - 38.2 -40.1* I n CD2C12 at 25 "C, relative t o SiMe,.- 40.7 - 40.4(see Table 1) there are strong bands at ca. 1 600 cm-l thenormal region for v(NN) in singly bent diazenido-complexes. They are not nearly low enough to beconsidered characteristic of tetrazene-type ligands.( 1 )Electrochemically, the complexes of which cis-[Mo(N,Ph),(S,CNMe,),] is typical undergo an irreversibletwo-electron oxidation and a further reversible one-electron oxidation (see Scheme).The products of theseoxidations have not been identified. The complexes[ Product,P1[PI- Mo( N, P hI2 (S,CNMe 2)21'++1.069 V/C2e unstable[Mo(N2Phlz(S2C NMe2l21- Z e p - eK,: "*H*\*e JH*IM o( N Ph) ( N , H , Ph) (S,C N Me ,),I [M o ( N P h) , ( S, C NM e, ) , I-(Mo(N2 Ph) (N, HPh)( SzC N Me 2)21SCHEME Redox reactions of cis-[Mo(N,Ph),(S,CNMe,),] indimethylformamide (dmf) solution-0.2 niol dm-3 [NBu,] [BF,] ;measured at Pt electrodes, 25 "C, potential scan rage 0.45 V s-l,potentials with reference to s.c.e.can be reduced stepwise electrochemically, and generatethe complexes which may be the materials [Mo(N,R)-(N,H,R) (dtc),] considered in more detail below.The complexes [Mo(N,R),(dtc),] also react with acidsand other electrophiles, but the reactions are complexand have yet to be completely elucidated.The Complexes [Mo(N,R) (N,H,R) (dtc),] .-As dis-cussed above, if the reaction of [MoO,(dtc),] with anorganohydrazine hydrochloride in methanol is carried330 430 530 630h InmFIGURE 2 Isosbestic point in the conversion of [Mo(N2H2Ph)-(N2Ph) (S,CNMe,),] into [Mo(N,Ph),(S,CNMe,),] in dichloro-methane solution by aerial oxidationout with 5 mol equivalents of the hydrazine hydro-chloride and without addition of Na[dtc], the bis-(diazenid0)-derivatives [Mo(N,R),(dtc),] can be isolated.In the particular cases of carbazates, phenylhydrazine ,and methylhydrazine, when the reactions are carried outin the absence of air, intermediate complexes whichanalyse for [Mo(N,R) (N,H,R) (dtc),] can be isolated, asdetailed in Tables 1 and 6.That they are indeed inter-TABLE 6Spcctral characteristics of cis- [Mo (N,H,R) (N,R) ( d t ~ ) ~ ]Chemical shifts (7)h r-Complex v( N H) /cm-' (I N-H Dithiocarbamato-CH3'Mo(N,H,COOBut ) (N,COOBut) (S2CNMe2) ,] 6.56(3), 6.60(3), 6.62(3), 6.72(3)Mo(N,H,COOE t) (N,COOE t) (S,CNMe,) ,] 6.61(3), 6.64(3), 6.66(3), 6.76(3):Mo(N,H,Ph) (N2Ph) (S,CNMe,),] 3 14Ow, 3 260w, 3 370w 3.02(1) 6.56(3), 6.60(3), 6.66(3), 6.70(3)Mo(N2H2Me) (N2Me) (S,CNMe2)21 6.56(3). 6.59(3), 6.62(3), 6.64(3)3 17Ow, 3 260w, 3 30Ow3 170~1, 3 270w3 loow, 3 200wRelative intensities in parentheses; all signals are singlets.2.88(1), 4.84(1)2.80( 1)Nujol mulls, w = weak1848 J.C.S.Daltonmediates in the formation of the bis(diazenid0)-com-plexes is shown by the fact that exposure of solutions ofthe methyl and phenyl derivatives to air results in theformation of the bis(diazenid0)-complexes withoutfurther compounds being involved (see Figure 2).The formulation of these compounds as hydrazido-diazen.iido-complexes rests on the following spectro-scopic data. The compoiinds all have a medium-strong band in the i.r. spectrum in the range 1590-1 665 cm-l assignable to v(N=N), suggesting the presenceof at least one diazenido-ligand (Tables 1 and 6). Theyalso have bands at ca. 3 200 cm-l assignable to N-H,but in only one case, [Mo(N2COOBut) (N2H,COOBut)-(S,CNMe,),], were two signals, suggesting two distinctkinds of N-H, observed in the lH n.m.r.spectrum.Both disappeared when D20 was added to the testsolution. The methyl groups of the dtc give rise to fourdistinct singlets suggesting four different methylenvironments. A group of four signals in the 13C n.m.r.spectrum is consistent with this and the carbonylcarbons are also resolved although both But methylsignals are apparently coincident.,CH3H 3 C-N,c-s(1 1These data are not unequivocal. However, webelieve that they are best rationalised on the basis ofstructure (11), which we are attempting to confirm byX-ray structure analysis.EXPERIMENTALReactions were generally carried out under pure, drydinitrogen in dry dioxygen-free solvents. Microanalyses(C, H, N, and halogen) were by Mr.A. G. Olney (Universityof Sussex) or Mr. P. E. Meadows (A.R.C. Unit of NitrogenFixation). Analyses for S were by Dr. A. Bernhardt.N.m.r. spectra were recorded by Mr. B. A. J . Alexander orMr. P. E. Meadows using a JEOL PS-100 spectrometer ('H)and by Mr. M. Siverns using a JEOL PFT-100 spectrometer(1"). The internal standard was normally tetra-niethylsiiane. Infrared spectra were generally obtained asNujol mulls using Unicam SP 200 and 2000 machines.Melting points were determined with an ElectrothermalMelting Point Apparatus, conductivities on a PortlandElectronics Conductivity Bridge, and molecular weightswith a Hitachi-Perkin-Elmer 115 Osmometer and solutionsin 1,Z-dichloroethane. Electrochemical measurements weremade using Hi-Telc Instruments Potentiostat DT2101, aChemical Electronics Waveform Generator RB 1, and aBryans X-Y recorder, 26000 A3.Sodium salts of dithiocarbamates were prepared bycautiously adding carbon disulphide ( 1 : 1 equivalents) to thevigorously stirred aqueous solution of the appropriateamine ( 1 equivalent) and sodium hydroxide (1 equivalent).The crude dithiocarbamates were obtained as yellow to pinksolids which were recrystallised from acetone as whiteplates.Bis(dithiocarbamato)dioxomolybdenum complexes wereprepared as exemplified below.Bis(dimethyldithiocarbamato)dioxomolybdenum.21- Tomolybdenum trioxide (43.4 g, 0.301 mmol) was addedbutane-2,3-diol (250 cm3).This mixture was heated underreflux for 15 niin, the boiling stopped, and the hot mixturefiltered in air.The colourless, viscous filtrate was seeded t oyield white crystals of [MoO,(CH~CH(O)CH(OH)CH~}~]*2CH,CH(OH)CH(OH)CH3 (A) (42.1 g , 32%).z2To a solution of (A) (1 1 g) in methanol (50 cm3)'was addeda hot saturated solution of Na[S,CNMe,] (18 g) in methanol(50 cm3) with vigorous stirring. The yellow precipitate wasfiltered, washed with methanol and Et,O, and dried invacuo. Yield 7-10 g. Addition of a 1 : 20 solution ofconcentrated nitric acid-water to the filtrate precipitatedmore material which was treated as above (Found: C, 19.8;H, 3.6; N, 7.3. C,H,,MoN,O,S, requires C, 19.6; H, 3.3;N, 7.6%).Organohydrazines were obtained commercially or syn-thesised by published methods. The diazenidotris(dithi0-carbamato)-complexes were all prepared by the same basicmethod and only one example will be described in detail.Tris (dimetlzyldithiocarbamato) (p-nitrophenyldiazenido) -molybdenum, (2) .-To a mixture of [MoO,(S,CNMe,),](0.5 g, 1.36 mmol), Na[S,CNMe,] (0.36 g, 1.86 mmol), andp-NO,C,H,NHNH, (0.70 g, 2.00 mmol) was added methanol(50 cm3) and the resulting suspension heated under refluxfor 0.75 h.The solvent was then removed at minHg *to yield a purple solid which was recrystallised from dichloro-niethane-methanol to yield purple crystals, green by reflectedlight (0.49 g, 600/,).The following derivatives of tris(dimethy1dithiocarba-niato)molybdenum were prepared in a similar fashion (yieldsin parentheses) : phenyldiazenido (1) (73%) ; m-nitrophenyl-diazenido (3) (32%) ; o-nitrophenyldiazenido (4) (290/,) ;p-chlorophenyldiazenido (5) (2 1 "/o) ; m-chlorophenyldiazenido(6) (2 1 yo) ; o-chlorophenyldiazenido (7) (24%) ; p-fluoro-phenyldiazenido (8) (19%) ; p-tolyldzazenido (9) (14%) ; m-tolyldiazenido (10) (28%) ; o-tolyldiazenido ( 1 1) (20%) ; p-methoxyphenyldiazenido (12) (20%) ; m-methoxyphenyldi-azenido (13) ( I 6%) ; o-methoxyphenyldiazenido (14) (31 yo) ;methyldiazenido ( 15) (78%) ; and t-butoxycarbonyldiazenidoUsing appropriate starting materials and the methodoutlined for (2) , the following were also synthesised : phenyl-diazenidotris ( piperidine-N-dithiocarboxylato) molybdenum,( 17) (72 yo) ; methyldiazenidotris(piperidine-N-dithiocarb-oxy1ato)molybdenum ( 18) (69%) ; tris(diethy1dithiocarb-amato)methyldiazenidomolybdenum ( 19) (62%) ; p-methoxy-phenyldzazenidotris( methylphenyldithiocarbamato) molyb-denum (20) (6 1 yo) ; tris(dipheny1dithiocarbamato) -p-methoxy-pJzenyldiazenidomolybdenum (21) (82%) ; and tris(dipheny1-ditlziocarbamato)methyldiazenidomolybdenum (22) (7 1 yo).Bis (dimet hyldithiocarbamato) bis (pheny1diazenido)molyb-denum (23).-To a mixture of [MoO,(S,CNMe,),] (2.38 g,6.47 mmol) and PhNHNH,.HCl (4.67 g, 32.3 mmol), wasadded methanol (130 cm3).The suspension was stirred in* Throughout this paper: 1 mmHg z 13.6 x 9.8 Pa.(16) (22%)1979 1849air a t 25 “C for 2 d. The bulk of the solvent was removedfrom the purple solution at 10-3 mmHg, and the concen-trated solution held a t -20 “C until purple crystals wereformed.These were filtered off, washed with Et,O, anddried an vacuo.In a similar fashion the following bis(dimethyldithi0-carbamato) -derivatives were prepared : bis(p-bromophenyldi-azenido) (24) (22%) ; bis(p-methoxyphenyldiazenido) (25)(36%) ; and bis(methy1diazenido) (26) (63%). A similarmethod was used to prepare the following from appropriatestarting materials : bis (phenyldiazenido) bis (piperidine-N-dithiocarboxy1ato)molybdenum (27) ( 3 1 %) and bis(diethy1-dithiocarbamato)bis( pheny1diazenido)molybdenum (28) (23%).Bis(dimethy2dithiocarbamato) (phenyldiazenido) (N-phenyl-hydrazido-N’) molybdenum (29) .-To [MOO,( S,CNMe,) ,](4.67 g, 12.7 mmol) in methanol (250 cm3), was addedPhNHNH, (6.85 g, 63.4 mmol) and the resulting suspensionwas stirred a t 25 “C for 2 d.The orange precipitate wasfiltered off and washed with Et,O to yield an orange solid(8.27 g, 76%) which was obtained as deep orange crystalsfrom methanol.The following bis(dimethy1dithiocarbamato)molybdenumderivatives were prepared similarly : methyldiazenido-(methylhydrazido) (30) crystallised from the preparativesolution at - 20 “C (29%) ; phenoxycarbazato(phenoxycar-bonyldiazenido) ( 3 1 ) (76%) ; ethoxycarbazato(ethoxycarbony1-diazenido) ( 3 2 ) , the initial precipitate in this case being [Mo-(N,OCOEt,) (S,CNMe,),] and the product was obtainedfrom the filtrate a t -20 OC (13%) ; butoxycarbazato(butoxy-carbonyldiazenido) (33) (3504) .*Tris (dimethyldithiocarbamato) (ethoxycarbonyldiazenido) -molybdenum.-To a mixture of [MoO,(S,CNMe,),] (0.79 g,2.15 mmol) and EtOCONHNH, (1.16 g, 11.2 mmol) wasadded methanol (50 cm3) and the resulting suspensionstirred for 6 d.The suspension was then filtered and thefiltrate worked up to give [Mo(N,OCOEt) (N,H,OCOEt)-(S,CNMe,),] (see above). The precipitate was recrystallisedfrom CH,Cl,-MeOH as orange crystals, m.p. 120-124 “C(decomp.), 0.23 g (19%) (Found: C, 25.7; HI 4 . 5 ; N , 13.8.C,,H,,MoN,O,S, requires C, 25.8; H, 4 . 9 ; N , 12.6%). Thenature of this compound was confirmed by lH n.ni.r.spectroscopy and X-ray structural analysis. 23Tris (dimethyldithiocarbamato) [N-methyl-N-PhenyZhydva-zido(2-)-N’]molybdenum Iodide (34) .-Methyl iodide (0.50cm3) was added to ( 1 ) (0.40 g) in CH,Cl, (30 cm3) and themixture heated under reflux for 15 min.The solution wasevaporated to ca. 5 cm3 a t lo-, mmHg and the complexprecipitated as an orange-brown precipitate by addition ofEt,O (50 c1-11,). It was recrystallised from CH,Cl,-Et,O asyellow needles (0.30 g , 60%).In a similar fashion were prepared : [N-methyl-N-phenyl-hydrazido( 2 - ) -N’] (piperidine-N-dithiocarboxy1ato)moZyb-denum iodide ( 3 7 ) , from (17) and Me1 (68%) ; tris(dzmethyldi-thiocarbamato) [N,N-dimethylhydrazido ( 2 - ) -N’]molybdenumiodide (35), from (25) and Me1 (74%) ; [N-benzyl-N-methyl-hydrazido( 2 - ) -N’]tris (dirnethyldithiocarbamato) molybdenumbromide (36), from (14) and benzyl bromide (65%) ; [N-ethyl-N-phenylhydrazido ( 2 - ) -N’] (piperidine-N-dithiocarb-oxyZato)molybdenum tetrafluoroborate (38), from ( 1 7 ) and[OEt,] [BF,] (78%) ; and [N-(2,4-dinitrophenyl)-N-methyl-hydrazido( 2 - ) -N’] (pipendine-N-dithiocarboxy1ato)molyb-* Recommended alternative names for the carbazato-ligands ofcomplexes (31)-( 33) are N-phenoxycarbonylhydraz ido-N’, N-ethoxycarbonylhydrazido-N’, and N-butoxycarbonylhydrazido-N’ respectively.Yield 0.75 g, 21%.denum chloride (39), from (17) and l-chloro-2,4-dinitro-benzene, evaporating the mixture t o dryness, extractingwith CH,ClCH,CI, and precipitating the product from theextract with Et,O (66%).Chlorotris (dimethyldithiocarbamato) [N-methylhydrazido-( 2 -)-N’]moZybdenum-Dichloromethane ( 1 / 1 ) (40) .-Hydro-gen chloride was passed (30 s) into a solution of (15) (0.5 g)in CH,Cl, (10 cm3).The warm solution was quicklyfiltered, and the complex crystallised as yellow needles as thesolution cooled (0.41 g, 65%).dithiocarboxy1ato)molybdenum-Dichloromethane ( 1/ 1 ) (43),was prepared analogously from ( 1 8 ) .Tris (dimethyldithiocarbamato) [N-methylhydmzido ( 2 - ) -N’]molybdenum TetrafEuoroborate- Water ( 1/2) (41) .-Tetra-fluoroboric acid ( 1 cm3) was added to a suspension of (15)(0.5 g) in methanol (20 cm3) and the red solution heatedunder reflux for 10 min. The solvent was removed a t lo-,mmHg and the yellow residue recrystallised from dmf-Et,Oas yellow needles (0.34 g, 55%). [N-PhenylJzydrazido(2-)-N’]tris(~i~eridine-N-dithiocarboxylato)molybdenum tetra-fluoroborate-water ( 1 / 2 ) (45), was prepared analogously fromChlorotris (dimethyldithiocarbamato) [N-PhenyZJzydrazido-(2-)-N’]molybdenum (42) .-Concentrated HC1 (0.5 cm3)was added to ( 1 ) (0.4 g) suspended in methanol (20 cm3).The solution was heated under reflux for 15 min, and thesolvent then removed at lo-, mmHg.The residue was re-crystallised from CH,Cl,-Et,O as yellow-brown needles(0.28 g, 66%).dithiocnrboxy1ato)molybdenum-water ( 1/2) (44), was preparedanalogously from ( 1 7 ) and hydrobromic acid (61 yo).Chloro [N-methylhydrazido (2 - ) -N’] tris (piperidzne-N-(17)-Bromo[N-phenylhydrazido ( 2 - )-N‘ltris (Piperidine-N-[8/1396 Received, 27th July, 19781REFERENCESD. Sutton, Chem. Soc. Rev., 1975, 4, 443.M. B. Bisnette and R. B. King, J . Amer. Chem. 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