Reactivity of [trans-R2MoO(NNPhR′)(o-phen)] toward R′PhNNH2 and R′PhNNH3+Cl−, R=Me,Ph and R′=Me,Ph. X-ray structure of [trans-MeClMoO(NNPh2)(o-phen)]

The reactivities of [trans-R₂MoO(NNPhR′)(o-phen)], R=R′=Me (1); R=Me, R′=Ph (2); R=Ph, R′=Me (3); R=R′=Ph (4), toward (i) neutral 1,1-disubstituted hydrazines, R′PhNNH₂ and (ii) 1,1-disubstituted hydrazine hydrochlorides, R′PhNNH₂·HCl, R′=Me, Ph, were studied in acetonitrile. In the first case, no condensation reaction of the free oxo group was observed under different experimental conditions. In the second case, using a 1:1 precursor/hydrazine hydrochloride molar ratio, the oxo group was also unreactive, instead one methyl or phenyl group bonded to molybdenum was displaced as methane or benzene and was subsequently substituted by one chloride ligand affording complexes formulated as [trans-RClMoO(NNPhR′)(o-phen)], R=R′=Me (5); R=Me, R′=Ph (6); R=Ph, R′=Me, (7)·MeCN; R=R′=Ph, (8)·MeCN. Finally, when a 1:2 precursor/hydrazine hydrochloride molar ratio was used, both methyl and phenyl groups were substituted affording complexes formulated as [trans-Cl₂MoO(NNPhR′)(o-phen)], R′=Me (9), R=Ph (10). The new organometallic compounds were characterised by IR, UV–Vis and ¹H NMR spectroscopy while the crystal and molecular structure of 6 was determined by X-ray diffraction analysis.     

Synthesis characterisation and stability of mixed aryldichalcogenide bis(diphenylphosphino)ethanenickel(II) complexes. X-ray structure of Ni(dppe)(SeC6H4S)

Mixed chalcogenide complexes of the type Ni(dppe)(SeC₆H₄S) (dppe=bis(diphenylphosphino)ethane), Ni(dppe)(SC₅H₃NCO₂) and Ni(dppe)(EC₅H₃NE′) (E=NH, E′=O; E=E′=NH) have been prepared from the reactions of Ni(dppe)Cl₂ with the appropriate aryldichalcogen or pyridine-based compound, using Et₃N as a base. The relative solution and thermal stabilities of the above compounds, other mixed chalcogen ones, Ni(dppe)(SC₆H₄O), Ni(dppe)(SC₆H₄CO₂) and Ni(dppe)(SC₆H₄NH), and the homoleptic compounds Ni(dppe)(EC₆H₄E′) (E=E′=O, E=E′=S; R=H, Me), were established by a combination of electron impact mass spectrometry (EIMS) and fast atom bombardment (FABMS). The most stable ones were the compounds with homoleptic sulfur ligands.     

Synthesis and spectral studies of diorganotin(IV) dialkyldithiophosphates

Two series of diorganotin(IV) dialkyldithiophosphates, [RR′Sn{SSP(OR″)₂}₂](R = Me or Et; R′= Ph; R″ = Et, Prⁿ, Prⁱ or Buⁿ) and [RR′Sn(Cl){SSP(OR″)₂}] (R = R′= Me, Et or Ph; R″ = Ph; R″ = Et, Prⁱ or Buⁿ) were prepared and characterised by i.r. and NMR (¹H, ¹³C, ³¹P, ¹⁹⁹Sn) spectroscopy. The NMR data indicate five and six coordinate geometries for [RR′Sn(Cl){SSP(OR″)₂}] and [RR′Sn{SSP(OR″)₂}₂] complexes, respectively. The chloro complexes showed ²J (PSn) whereas such couplings were not observed in the spectra of [RR′Sn{SSP(OR″)₂}₂].     

Synthesis and spectra of bis(tertiaryphosphine) derivatives of cycloheptatrienyltungsten complexes

Reaction of [WI(CO)₂(η⁷-C₇H₇)] with dppm (dppm = Ph₂PCH₂PPh₂) or dppe (dppe = Ph₂PCH₂CH₂PPh₂) gives the trihaptocycloheptatrienyl complexes [WI(CO)₂(L-L)(η³-C₇H₇)] [L-L = dppm, (A₁); L-L = dppe (A₂)]. The complex A₁ reacts with NH₄PF₆ to give the unidentate biphosphine complex [W(CO)₂(dppm-P)(η⁷-C₇H₇)][PF₆] (B) which yields [W(CO)(dppm)(η⁷-C₇H₇)][PF₆] (C) on reaction with Me₃NO·2H₂O. Substitution of a carbonyl ligand in [W(CO)₃(η⁷-C₇H₇)][PF₆] with the organometallic phosphine ligand [Mo(CO)₂(dppe-P)(η⁷-C₇H₇)][PF₆] yields the heterobimetallic [{W(CO)₂(η⁷-C₇H₇)}(μ-dppe){Mo(CO)₂(η⁷-C₇H₇)}x][PF₆]₂ (D).     

Syntheses and Structures of trans-bis(Alkenylacetylide) Ruthenium Complexes

A series of ruthenium alkenylacetylide complexes trans-[Ru{C≡CC(=CH₂)R}Cl(dppe)₂] (R=Ph ( 1 a ), ^cC₄H₃S ( 1 b ), 4-MeS-C₆H₄ ( 1 c ), 3,3-dimethyl-2,3-dihydrobenzo[b]thiophene (DMBT) ( 1 d )) or trans-[Ru{C≡C-^cC₆H₉}Cl(dppe)₂] ( 1 e ) were allowed to react with the corresponding propargylic alcohol HC≡CC(Me)R(OH) (R=Ph ( A ), ^cC₄H₃S ( B ), 4-MeS-C₆H₄ ( C ), DMBT ( D ) or HC≡C-^cC₆H₁₀(OH) ( E ) in the presence of TlBF₄ and DBU to presumably give alkenylacetylide/allenylidene intermediates trans-[Ru{C≡CC(=CH₂)R}{C=C=C(Me)}(dppe)₂]PF₆ ([ 2 ]PF₆). These complexes were not isolated but deprotonated to give the isolable bis(alkenylacetylide) complexes trans-[Ru{C≡CC(=CH₂)R}₂(dppe)₂] (R=Ph ( 3 a ), ^cC₄H₃S ( 3 b ), 4-MeS-C₆H₄ ( 3 c ), DMBT ( 3 d )) and trans-[Ru{C≡C-^cC₆H₉}₂(dppe)₂] ( 3 e ). Analogous reactions of trans-[Ru(CH₃)₂(dmpe)₂], featuring the more electron-donating 1,2-bis(dimethylphosphino)ethane (dmpe) ancillary ligands, with the propargylic alcohols A or C and NH₄PF₆ in methanol allowed isolation of the intermediate mixed alkenylacetylide/allenylidene complexes trans-[Ru{C≡CC(=CH₂)R}{C=C=C(Me)}(dmpe)₂]PF₆ (R=Ph ([ 4 a ]PF₆), 4-MeS-C₆H₄ ([ 4 c ]PF₆). Deprotonation of [ 4 a ]PF₆ or [ 4 c ]PF₆ gave the symmetric bis(alkenylacetylide) complexes trans-[Ru{C≡CC(=CH₂)R}₂(dmpe)₂] (R=Ph ( 5 a ), 4-MeS-C₆H₄ ( 5 c )), the first of their kind containing the dmpe ancillary ligand sphere. Attempts to isolate bis(allenylidene) complexes [Ru{C=C=C(Me)R}₂(PP)₂]²⁺ (PP=dppe, dmpe) from treatment of the bis(alkenylacetylide) species 3 or 5 with HBF₄ ⋅ Et₂O were ultimately unsuccessful.     

The preparation and characterisation of a series of cationic bimetallic linear triphos-bridged complexes of the type [Mo (CO) (L,L′ or L″–P) (η2-RC2R′)Cp] [BF4] {L,L′ or L″= [WI2 (CO){PhP(CH2CH2PPh2)2–P,P′} (η2-RC2R′)] (L,R=R′=Me; L′,R=R′=Ph; L″,R=Me,R′=Ph}

Equimolar quantities of [Mo (CO) (η²-RC₂R′)₂Cp] [BF₄] (R=R′=Me Ph R=Me R′=Ph) and L L′ or L″ {L L′ or L″= [WI₂ (CO){PhP(CH₂CH₂PPh₂)₂-PP′} (η²-RC₂R′)]} (L R=R′=Me L′ R=R′=Ph L″ R=Me R′=Ph) react in CH₂Cl₂ at room temperature to give the new bimetallic complexes[Mo (CO) (L L′ or L″–P) (η²-RC₂R′)Cp] [BF₄] (1–9) via displacement of the alkyne ligand on the molybdenum centre The complexes have been characterised by elemental analysis IR and ¹ H NMR spectroscopy and in selected cases by ³¹ P NMR spectroscopy.     

The polymer [OsCl2 (cod)]x as a route to hydrazine- and hydrazone-osmium(II) complexes; The crystal structure of [Os(cod)(CNBut)2(NH2NCMe2)2] (BPh4)2·(acetone)2

The salts, [OsCl(cod)(NH₂NR₂)₃]X (R = H, X = BPh₄; R = Me, X = PF₆) and [Os(cod)(NH₂NH₂)₄](BPh₄)₂, formed from [OsCl₂(cod)]_x and hydrazines, can be converted into a range of hydrazine- and hydrazone-osmium(II) complexes with isocyanides and tertiary phosphorus ligands. The crystal structure of [Os(cod)(CNBu^t)₂(NH₂NCMe₂)₂](BPh₄)₂·(acetone)₂ has been elucidated.     

Metallacumulenylidene complexes in the [(η5-C5Me5)(η2-dppe)Fe(=C(=C)nR2)]X (n = 0, 1, 2) series: investigations of the iron-carbon bonding by Mössbauer spectroscopy and X-ray analyses

The synthesis of the iron allenylidene complexes [(η⁵-C₅Me₅)(η²-dppe)Fe(=C=C=C(Ph)Ph)][X] (5a, X = PF₆, 95%; 5b, X = BPh₄, 91%; dppe = 1,2-bis(diphenylphosphino)ethane) was achieved by reacting the complex (η⁵-C₅Me₅)(η²-dppe)FeCl (10) with 1 equiv of 1,1-diphenyl-prop-2-yn-1-ol in methanol in the presence of KPF₆ or NaBPh₄. Surprisingly, when the reaction was carried out in the presence of the tetraphenylborate anion, the final product contained both 5b and the hydroxyvinylidene [(η⁵-C₅Me₅)(η²-dppe)Fe(=C=C(H)C(OH)(Ph)₂)][BPh₄] (14b) in the 1:1 ratio. Further treatment of the mixture with Amberlyst 15 in methanol provided the allenylidene 5b as a pure sample. The allenylidene complexes [(η⁵-C₅Me₅)(η²-dppe)Fe(=C=C=C(Me)Ph)][PF₆] (6) and [(η⁵-C₅Me₅)(η²-dppe)Fe(=C=C=C(Me)Et)][PF₆] (7) were prepared according to the same procedure and they were isolated as purple powders in 90% yield. The X-ray crystal structures were determined for the vinylidene complexes [(η⁵-C₅Me₅)(η²-dppe)Fe(=C=CH₂)][PF₆] (3) and [(η⁵-C₅Me₅)(η²-dppe)Fe(=C=C(Ph)H)][PF₆] (4), and the allenylidene derivative 5a. In the homogeneous series of complexes [(η⁵-C₅Me₅)(η²-dppe)Fe(=(C)_n(R)R’)][PF₆], (n = 1, R = H, R′ = Me, X = PF₆, 1; n =1, R = H, R’ = OMe, X = PF₆, 2a; n = 1, R = H, R’ = OMe, X = CF₃OSO₂, 2b; n = 2, R = R′ = H, X = PF₆, 3; n = 2, R = H, R′ = Ph, X = PF₆, 4; n = 3, R = R′ = Ph, X = PF₆, 5a; n = 3, R = R′ = Ph, X = BPh₄, 5b; n = 3, R = Me, R′ = Ph, X = PF₆, 6; n = 3, R = Me, R′ = Et, X = PF₆, 7; n = 3, R = Me, R′ = OMe, X = BPh₄, 8), an empiric relationship between the Mössbauer parameters, δ and QS, was found. This observation would indicate that the positive charge on the iron nucleus decreases with the Fe=C bond order. Moreover, in this series of iron cumulenylidene derivatives, comparison of the variation of the metal–carbon bond distances determined by X-ray analyses with the Mössbauer QS values allows the observation of a linear correlation (R = 0.99). To cite this article: G. Argouarch et al., C. R. Chimie 6 (2003).     

Pentamethylcyclopentadienyl ruthenium(II) complexes of para-substituted N-(pyrid-2-ylmethylene)-phenylamine ligands: syntheses,spectral and structural studies

The reaction of [(η⁵-C₅Me₅)Ru(PPh₃)₂Cl] (1) with acetonitrile in the presence of excess NH₄PF₆ leads to the formation of the cationic ruthenium(II) complex [(η⁵-C₅Me₅)Ru(PPh₃)₂(CH₃CN)]PF₆ (2). The complex (2) reacts with a series of N,N′ donor Schiff base ligands viz. para-substituted N-(pyrid-2-ylmethylene)-phenylamines (ppa) in methanol to yield pentamethylcylopentadienyl ruthenium(II) Schiff base complexes of the formulation [(η⁵-C₅Me₅)Ru(PPh₃)(C₅H₄N-2-CHN-C₆H₄-p-X)]PF₆ [3a]PF₆–[3f]PF₆, where C₅Me₅ = pentamethylcylopentadienyl, X = H, [3a]PF₆, Me, [3b]PF₆, OMe, [3c]PF₆, NO₂, [3d]PF₆, Cl, [3e]PF₆, COOH, [3f]PF₆. The complexes were isolated as their hexafluorophosphate salts. The complexes were fully characterized on the basis of elemental analyses and NMR spectroscopy. The molecular structure of a representative complex, [(η⁵-C₅Me₅)Ru(PPh₃)(C₅H₄N-2-CHN-C₆H₄-p-Cl)]PF₆ [3e]PF₆, has been established by X-ray crystallography.     

Synthesis and structure of new compounds with Pt-Ga bonds: Insertion of the bulky gallium (I) bisimidinate Ga(DDP) into Pt-Cl bond

Reactions of the sterically bulky mono-valent group 13 bisimidinate gallium(I), Ga(DDP) (1) (DDP = 2-{(2, 6-diisopropylphenyl)amino}-4-{(2, 6-diisopropylphenyl)imino}-2-pentene, HC(CMeNC₆H₃-2,6-ⁱPr₂)₂) with olefin supported group 10 complexes, [(diene)PtCl₂] [diene = 1,5-cyclooctadiene (COD), endo-dicyclopentadiene (dcy)] and [(COD)Pd(Me)(OTf)] (OTf = O₃SCF₃) are reported. These reactions afforded [(COD)Pt(Cl){ClGa(DDP)}] (2), [(dcy)Pt(Cl){ClGa(DDP)}] (3) and [(DDP)Ga(Me)(OTf)] (4) in moderate yields. Compounds 2-4 were characterized by elemental analysis, NMR (¹H, ¹³C) spectroscopy and also by single crystal X-ray structural analysis. The solid state structures of complexes 2 and 3 reveal the oxidative insertion of Ga(DDP) into the Pt-Cl bond without altering the π-coordinated double bonds in the olefin.     

Areneruthenium(II) Complexes with Functionalized Phosphines Coordinating as Mono‐, Bi‐ or Tridentate Ligands

Areneruthenium(II) compounds [Ru(p‐cym)Cl₂{κ‐P‐ⁱPrP(CH₂CH₂OMe)₂}], 3 , and [Ru(arene)Cl₂{κ‐P‐RP(CH₂CO₂Me)₂}] 4 – 7 (arene=p‐cym (=1‐methyl‐4‐isopropylbenzene), mes (=1,3,5‐trimethylbenzene); R=ⁱPr, ^tBu) were prepared from the dimers [Ru(arene)Cl₂]₂ and the corresponding functionalized phosphine. Treatment of 6 and 7 with 1 equiv. of AgPF₆ affords the monocationic complexes [Ru(mes)Cl{κ²‐P,O‐RP(CH₂C(O)OMe)(CH₂CO₂Me)}]PF₆, 10 and 11 , while the related reaction of 5 – 7 with 2 equiv. of AgPF₆ produces the dicationic compounds [Ru(p‐cym){κ³‐P,O,O‐^tBuP(CH₂C(O)OMe)₂}](PF₆)₂ ( 12 ) and [Ru(mes){κ³‐P,O,O‐RP(CH₂C(O)OMe)₂}](PF₆)₂, 13 and 14 . Partial hydrolysis of one hexafluorophosphate anion of 12 – 14 leads to the formation of [Ru(arene){κ²‐P,O‐RP(CH₂C(O)OMe)(CH₂CO₂Me)}(κ‐O‐O₂PF₂)]PF₆, 15 – 17 , of which 17 (arene=mes; R=^tBu) has been characterized by X‐ray crystallography. Compounds 13 and 14 react with 2 equiv. of KO^tBu in ^tBuOH/toluene to give the unsymmetrical complexes [Ru(mes){κ³‐P,C,O‐RP(CHCO₂Me)(CH=C(O)OMe)}], 18 and 19 , containing both a five‐membered phosphinoenolate and a three‐membered phosphinomethanide ring. The molecular structure of compound 18 has been determined by X‐ray structure analysis. The neutral bis(carboxylate)phosphanidoruthenium(II) complexes [Ru(arene){κ³‐P,O,O‐RP(CH₂C(O)O)₂}], 20 – 23 are obtained either by hydrolysis of 18 and 19 , or by stepwise treatment of 4 and 5 with KO^tBu and basic Al₂O₃. Novel tripodal chelating systems are generated via insertion reactions of 19 with PhNCO and PhNCS.     

Organodiiron(II)-complexes containing a long conjugated hydrazonato spacer. Synthesis, characterization, electrochemical and structural studies

Organometallic hydrazines of general formula [(η⁵-Cp)Fe(η⁶-p-RC₆H₄NHNH₂)]⁺PF₆⁻ (Cp=C₅H₅; R=H, (1)⁺PF₆⁻; Me, (2)⁺PF₆⁻; MeO, (3)⁺PF₆⁻; Cl, (4)⁺PF₆⁻) react with equimolar quantities of (E)-4-(2-ferrocenylvinyl)-benzaldehyde, (E)-[(η⁵-Cp)Fe(η⁵-C₅H₄)CHCHC₆H₄CHO], to afford stereoselectively, the new homodimetallic hydrazones formulated as (E)-[(η⁵-Cp)Fe(η⁶-p-RC₆H₄)NHNCHC₆H₄CHCH(η⁵-C₅H₄)Fe(η⁵-Cp)]⁺PF₆⁻ (R=H, (5)⁺PF₆⁻; Me, (6)⁺PF₆⁻; MeO, (7)⁺PF₆⁻; Cl, (8)⁺PF₆⁻). These compounds were fully characterized by elemental analysis and spectroscopic techniques (¹H- and ¹³C-NMR, IR and UV-vis) and, in the case of complex (6)⁺PF₆⁻, by single crystal X-ray diffraction methods. The rotations of the ferrocenyl unit by 37.2° out of the NHNCHC₆H₄CHCH spacer and coordinated phenyl ring planes, may generate an unfavorable structure to allow π-electron delocalization along the entire hydrazonato backbone between the two metals separated through bonds by more than 1.8 nm, as confirmed by the electrochemical data.     

Hydrolytic disproportionation of coordinated white phosphorus in [CpRu(dppe)(η-P4)]PF6 [dppe = 1,2-bis(diphenylphosphino)ethane]

The reaction of [CpRu(dppe)Cl] (1), dppe = 1,2-bis(diphenylphosphino)ethane, with one equivalent of P₄ in the presence of TlPF₆ affords the stable complex [CpRu(dppe)(η¹-P₄)]PF₆ (2) which contains the tetrahedral P₄ molecule η¹-bound to the metal. The tetraphosphorus ligand readily reacts with water upon mixing acetone or THF solutions of the complex with excess water. The complexes [CpRu(dppe)(PH₃)]PF₆ (5) and [CpRu(dppe){P(OH)₃}]PF₆ (6), identified among the hydrolysis products, contain the PH₃ molecule and, respectively, the unstable P(OH)₃ tautomer of the phosphorous acid bound to the CpRu(dppe) fragment. In CH₂Cl₂ the coordinated P(OH)₃ molecule in 6 easily yields the compound [CpRu(dppe){PF(OH)₂}]PF₂O₂ (8), via hydrolysis of the hexafluorophosphate anion and F/OH substitution in the coordinated P(OH)₃ molecule. All the compounds have been characterized by elemental analyses and NMR measurements. The crystal structures of 2 and 8 have been determined by X-ray diffraction methods.     

Zur Reaktion von Metall-koordinierten Kohlenmonoxid mit Yliden XXII. Bis(diphenylphosphino)methanid-Eisen-Komplexe Cp(L)Fe(Ph2PCHPPh2) (L = CO,Me3P)

The reaction of [Cp(CO)(dppm)Fe]BF₄ (1a) with the phosphorus ylide Me₃PCH₂ yields the novel bis(phosphino)methanideiron complex Cp(CO)Fe(Ph₂PCHPPh₂) (2), which upon photolysis in the presnece of Me₃P is converted into Cp(Me₃P)Fe(Ph₂PCHPPh₂ (3). Reaction of 2 with MeOSO₂CF₃ gives a mixture of the iron salts [(Cp(CO)Fe(Ph₂PCR(R′)PPh₂)]CF₃SO₃ (R = R′ = H (1b), R = R′ = Me (6) and R = H, R′ = Me (syn/anti-4)).     

Chloride substitution of [CpRu(dppf)Cl] with sulfur-containing ligands

The reactions of CpRu(dppf)Cl (1) with the sulfur-containing ligands, thiophenol HSPh, 2-mercaptopyridine C₅H₄N(SH), thiourea SC(NH₂)₂, vinylene trithiocarbonate SCS(CH)₂S and ethylene trithiocarbonate SCS(CH₂)₂S, yielded chloro-substituted derivatives, viz. the mono-ruthenium(II) complexes CpRu(dppf)(SPh) (2), [CpRu(dppf)(SC₅H₄NH)]BPh₄ (3)BPh₄, [CpRu(dppf)(SC(NH₂)₂]PF₆ (4)PF₆, [CpRu(dppf)(SCS(CH)₂S)]Cl (5)Cl and [CpRu(dppf)(SCS(CH₂)₂S)]Cl (6)Cl, respectively. Treatment of 1 with AuCl(SMe₂) in the presence of NH₄PF₆ gave [(CpRu(dppf)(SMe₂)]PF₆ (7)PF₆. The reaction of 1 or 6 with SnCl₂ resulted in cleavage of chloro and dithiocarbonate ligands, respectively, to give CpRu(dppf)SnCl₃ (8). All complexes were spectroscopically characterized and the structures of 2 and cationic complexes 4-7 were determined by single-crystal diffraction analyses.     

Proton transfer to nickel-thiolate complexes. 1. Protonation of [Ni(SC(6)H(4)R-4)(2)(Ph(2)PCH(2)CH(2)PPh(2))] (R = Me, MeO, H, Cl, or NO(2))

The kinetics of the equilibrium reaction between [Ni(SC(6)H(4)R-4)(2)(dppe)] (R= MeO, Me, H, Cl, or NO(2); dppe = Ph(2)PCH(2)CH(2)PPh(2)) and mixtures of [lutH](+) and lut (lut = 2,6-dimethylpyridine) in MeCN to form [Ni(SHC(6)H(4)R-4)(SC(6)H(4)R-4)(dppe)](+) have been studied using stopped-flow spectrophotometry. The kinetics for the reactions with R = MeO, Me, H, or Cl are consistent with a single-step equilibrium reaction. Investigation of the temperature dependence of the reactions shows that DeltaG = 13.6 +/- 0.3 kcal mol(-)(1) for all the derivatives but the values of DeltaH and DeltaS vary with R (R = MeO, DeltaH() = 8.5 kcal mol(-)(1), DeltaS = -16 cal K(-)(1) mol(-)(1); R = Me, DeltaH() = 10.8 kcal mol(-)(1), DeltaS = -9.5 cal K(-)(1) mol(-)(1); R = Cl, DeltaH = 23.7 kcal mol(-)(1), DeltaS = +33 cal K(-)(1) mol(-)(1)). With [Ni(SC(6)H(4)NO(2)-4)(2)(dppe)] a more complicated rate law is observed consistent with a mechanism in which initial hydrogen-bonding of [lutH](+) to the complex precedes intramolecular proton transfer. It seems likely that all the derivatives operate by this mechanism, but only with R = NO(2) (the most electron-withdrawing substituent) does the intramolecular proton transfer step become sufficiently slow to result in the change in kinetics. Studies with [lutD](+) show that the rates of proton transfer to [Ni(SC(6)H(4)R-4)(2)(dppe)] (R = Me or Cl) are associated with negligible kinetic isotope effect. The possible reasons for this are discussed. The rates of proton transfer to [Ni(SC(6)H(4)R-4)(2)(dppe)] vary with the 4-R-substituent, and the Hammett plot is markedly nonlinear. This unusual behavior is attributable to the electronic influence of R which affects the electron density at the sulfur.     

Preparation of Dimethyl and Chloro/Methyl Complexes of Platinum(II) Supported by α‐Diimine Ligands: Trends in the Ease of Oxidation to Platinum(IV)

α‐Diimine ligands react with the platinum(II) alkyl complexes [(Me₂S)PtMe₂]₂ and (Me₂S)₂PtClMe to form (RDAB^R′)PtMe₂ and (RDAB^R′)PtClMe (RDAB^R′=RN=CR′−CR′=NR; R=2,6‐Me₂Ph, 2,6‐(CHMe₂)₂Ph, 3,5‐Me₂Ph, 3,5‐(CF₃)₂Ph, C₆H₁₁; R′=Me, H). The oxidation of these complexes with Cl₂, I₂, N‐chlorosuccinimide, [PtCl₆]²⁻ and (TMEDA)PtMe₂I₂ has been investigated. Attempts to determine the oxidation potentials of the Pt^II complexes electrochemically yielded only irreversible one‐electron oxidations. However, a qualitative ordering of increasing difficulty of oxidation has been determined for the series (RDAB^R′)PtMe₂<(RDAB^R′)PtClMe<(RDAB^R′)PtCl₂≪(RDAB^R′)PtMe(solvent)]⁺. The oxidation proceeds via a two‐electron inner‐sphere electron transfer from a bridged binuclear intermediate. The oxidation of (RDAB^R′)PtMe₂ by (TMEDA)PtMe₂I₂ exhibits characteristic third‐order kinetics, first‐order each in [Pt^II], [Pt^IV] and [I⁻]. Oxidation by a one‐electron process in MeCN solution results in a rapid subsequent disproportionation to Pt^IIMe and Pt^IVMe₃ cations with MeCN occupying the fourth or sixth coordination sites. Single‐crystal X‐ray structure determinations for [(2,6‐Me₂PhDAB^Me)PtMe₃(MeCN)]⁺[PtCl₆]_0.5(MeCN) and [(CyDAB^H)PtMe₃(MeCN)]⁺[PtCl₆]_0.5(MeCN) are reported.     

NEW RUTHENIUM(II) COMPLEXES CONTAINING ORGANODISULFIDE LIGANDS

Abstract

The new complexes [CpRu(PPh₃)₂(RSSR)PF₆ R=CH₃, iso-Pr, CH₂C₆H₅ and C₆H₅ have been prepared from the reaction of CpRu(PPh₃)₂Cl with RSSR in CH₃OH in presence of NH₄Cl. This result contrasts with the oxidative additions of RSSR to CpFe(dppe)1 dppe=PPh₂ (CH₂)₂PPh₂ to give [CpFe(dppe)SR]PF₆ (C. Diaz et al., J. Organomet. Chem. 516, 59 (1996)). Huckel calculations on model fragments CpFe(PPh₃)₂ and CpRu(PPh₃)₂ suggest that the higher electron density of iron could explain the differences observed in reactivity. Possible biological implications are discussed.     

Iridium(iii)-(hydrido)cyclometallated-imine complexes and metal-promoted hydrolytic cleavage of imines

The room temperature reaction of the complex cis,trans,cis-[Ir(H)₂(PPh₃)₂(Solv)₂]PF₆ (Solv is a solvent) with the imine PhCH₂N=CHPh in acetone generates (with loss of H₂) the orthometallated complex [Ir(H){PhCH₂N=CH(o-C₆H₄)}(PPh₃)₂(Me₂CO)]PF₆ (3) containing a five-membered cyclometallated imine moiety. In MeOH, the reaction at an imine : Ir ratio = 1 leads to the corresponding MeOH analog of 3, while with excess imine, the mixed orthometallated imine/bezylamine complex [Ir(H){PhCH₂N=CH(o-C₆H₄)}(PPh₃)₂(PhCH₂NH₂)]PF₂ (4) is formed; the source of the coordinated amine is an Ir-promoted hydrolysis of the imine, the water likely coming from imine. Complexes 3 and 4 are fully characterized by elemental analysis, ¹H and ³¹P{¹H} NMR spectroscopy, and X-ray crystal structure analysis.     

Synthesis and structural characterization of Ni(II) complexes with the chiral CpH(PNMent) tripod ligand

Treatment of NiCl₂ with the tripod ligand (L_Ment,S_C)-1H led to (L_Ment,S_C)-[Cp(PN_Ment)NiCl] in which the potentially tridentate ligand coordinated to the metal center in a bidentate way via the cyclopentadienyl system and the phosphorus atom. In the presence of NH₄PF₆ [(L_Ment,S_C)-[Cp(PN_Ment)NiCl] readily underwent Cl/PPh₃ exchange to give (L_Ment,S_C)-[Cp(PN_Ment)NiPPh₃]PF₆. Reaction of (L_Ment,S_C)-[Cp(PN_Ment)NiCl] with 0.5 eq. of dppe afforded [{(L_Ment,S_C)-[Cp(PN_Ment)Ni]}₂dppe](PF₆)₂. (L_Ment,S_C)-[Cp(PN_Ment)NiPPh₃]PF₆ and [{(L_Ment,S_C)-[Cp(PN_Ment)Ni]}₂dppe](PF₆)₂ were characterized by NMR and MS spectroscopy, and also by single crystal X-ray diffraction. The cyclopentadienyl ligand of (L_Ment,S_C)-[Cp(PN_Ment)NiPPh₃]PF₆ shows a distortion intermediate between the ene-allyl and diene types, while the two cyclopentadienyl ligands of [{(L_Ment,S_C)-[Cp(PN_Ment)Ni]}₂dppe](PF₆)₂ have intermediate and diene distortions, respectively. According to the temperature dependent NMR spectra of (L_Ment,S_C)-[Cp(PN_Ment)NiPPh₃]PF₆ and [{(L_Ment,S_C)-[Cp(PN_Ment)Ni]}₂dppe](PF₆)₂ two different conformations of the tether in the Cp(PN_Ment)Ni system could be frozen out at low temperatures.