The reactions of Ir(CO)Cl(PPh3)2 with HSnPh3

A reinvestigation of the reaction of Ir(CO)Cl(PPh₃)₂, 1 with HSnPh₃ has revealed that the oxidative-addition product Ir(CO)Cl(PPh₃)₂(H)(SnPh₃), 2 has the H and SnPh₃ ligands in cis-related coordination sites. Compound 2 reacts with a second equivalent of HSnPh₃ by a Cl for H ligand exchange to yield the new compound H₂Ir(CO)(SnPh₃)(PPh₃)₂, 3. Compound 3 contains two cis- related hydride ligands. Under an atmosphere of CO, 1 reacts with HSnPh₃ to replace the Cl ligand with SnPh₃ and one of the PPh₃ ligands with a CO ligand and also adds a second equivalent of CO to yield the 5-coordinate complex Ir(CO)₃(SnPh₃)(PPh₃), 4. Compound 4 reacts with HSnPh₃ by loss of CO and oxidative addition of the Sn-H bond to yield the 6-coordinate complex HIr(CO)₂(SnPh₃)₂(PPh₃), 5 that contains two trans-positioned SnPh₃ ligands.     

The tris(triphenylphosphine)osmium zerovalent complexes Os(CO)2(PPh3)3, .Os(CO)(CNR)(PPh3)3, Os(CO)(CS)(PPh3)3, Os(CS)(cNR)(PPh3)3 and derived compounds

Detailed procedures for the syntheses of Os(CO)₂(PPh₃)₃, Os(CO)(CNR)-(PPh₃)₃ (R = p-tolyl), Os(CO)(CS)(PPh₃)₃ and Os(CS)(CNR)(PPh₃)₃, together with the derived complexes Os(CO)₂(CS)(PPh₃)₂, Os(CO)(CS)(CNR)(PPh₃)₂, Os(η²-C₂H₄)(CO)(CNR)(PPh₃)₂, Os(η²-C₂H₄)(CO)(CS)(PPh₃)₂, Os(η²CS₂)(CO)₂-(PPh₃)₂, Os(η²CS₂)(CO)(CS)(PPh₃)₂, Os(η²-CS₂)(CO)(CNR)(PPh₃)₂, Os(η²PhC₂Ph)(CO)₂(PPh₃)₂ and OsH(C2Ph)(CO)₂(PPh₃)₂ are described.     

Propionyl complexes of ruthenium derived from the reaction of ethylene with RuHCl(CO)2(PPh3)2

RuHCl(CO)₂(PPh₃)₂ reacts with ethylene under mild conditions (25 psi, 80°C) to yield a propionyl derivative RuCl(C[O]C₂H₅)(CO)(PPh₃)₂ which is believed to be coordinatively unsaturated. Unlike the acetyl analogue, RuCl[C[O]C₂H₅(CO)-(PPh₃)₂ does not isomerize to RuCl(C₂H₅)(CO)₂(PPh₃)₂ in solution. Under one atmosphere of carbon monoxide, RuCl(C[O]C₂H₅(CO)(PPh₃)₂ exists in equilibrium with two species believed to be RuCl(C[O]C₂H₅)(CO)₂(PPh₃)₂ and [Ru(C[O]C₂H₅)(CO)₃(PPh₃)₂]Cl. RuCl(C[O]C₂H₅)(CO)(PPh₃)₂ reacts with CO/ AgClO₄ to give mer-[Ru(C[O]C₂H₅)(CO)₃(PPh₃)₂]ClO₄, p-tolylisocyanide (RNC) and NaClO₄ to give cis-[Ru(C[O]C₂H₅)(CO)(CNR)₂(PPh₃)₂ClO₄, and hydrochloric acid to yield the hydroxycarbene complex, RuCl₂(CO)(C[OH]C₂H₅)(PPh₃)₂.     

Molybdenum and tungsten complexes with the heteroallyl-like Ph2P(O)C(S)NR− (R  Me,Ph) as ligand. X-ray structural analysis of Mo(CO)2(PPh3)(Ph2P(O)C(S)NPh)2 · CH2Cl2; A 4 : 3 piano-stool configuration

Ph₂P(O)C(S)N(H)R (R  Me, Ph) reacts with M(CO)₃(η⁵-C₅H₅)Cl (M  Mo, W) in the presence of Et₃N to give M(CO)₂(η⁵-C₅H₅)(Ph₂P(O)C(S)NR). The deprotonated ligand coordinates in a bidentate manner through N and S to give a four-membered ring system. M(CO)₃(PPh₃)₂Cl₂ (M  Mo, W) reacts with Ph₂P(O)C(S)N(H)R (R  Me, Ph) in the presence of Et₃N to give complexes in which the central metal atoms are seven coordinate through two ligands bonded via O and S to form five-membered ring systems, one PPh₃, and two CO groups. The complexes were characterised by elemental analyses, IR, ¹H NMR, and ³¹P NMR spectroscopy, and an X-ray structural analysis of Mo(CO)₂(PPh₃)(Ph₂P(O)C(S)NPh)₂ · CH₂Cl₂.     

Synthesis of [TpRu(CO)(PPh3)]2(μ-CHCHCHCHC6H4CHCHCHCH) from Wittig reactions

Treatment of [Ru(CHCHCH₂PPh₃)X(CO)(PPh₃)₂]⁺ (X=Cl, Br) with KTp (Tp=hydridotris(pyrazolyl)borate) and NaBPh₄ produced [TpRu(CHCHCH₂PPh₃)(CO)(PPh₃)]BPh₄. Reaction of RuHCl(CO)(PPh₃)₃ with HCCCH(OEt)₂ produced Ru(CHCHCH(OEt)₂)Cl(CO)(PPh₃)₂, which reacted with KTp to give TpRu(CHCHCHO)(CO)(PPh₃). Treatment of [TpRu(CHCHCH₂PPh₃)(CO)(PPh₃)]BPh₄ with NaN(SiMe₃)₂ and benzaldehyde produced TpRu(CHCHCHCHPh)(CO)(PPh₃). The later complex was also produced when TpRu(CHCHCHO)(CO)(PPh₃) was treated with PhCH₂PPh₃Cl/NaN(SiMe₃)₂. The bimetallic complex [TpRu(CO)(PPh₃)]₂(μ-CHCHCHCHC₆H₄CHCHCHCH) was obtained from the reaction of [TpRu(CHCHCH₂PPh₃)(CO)(PPh₃)]BPh₄ with NaN(SiMe₃)₂ and terephthaldicarboxaldehyde.     

Syntheses, reactions, and structures of osmium(II) distannyl complexes, LnOs-SnMe2SnR3 (R = Me, Ph), from reaction between LnOs-SnClMe2 and either LiSnMe3 or KSnPh3

Reaction between Os(SnClMe₂)(κ²-S₂CNMe₂)(CO)(PPh₃)₂ and either LiSnMe₃ or KSnPh₃ produces the distannyl complexes, Os(SnMe₂SnMe₃)(κ²-S₂CNMe₂)(CO)(PPh₃)₂ (1) or Os(SnMe₂SnPh₃)(κ²-S₂CNMe₂)(CO)(PPh₃)₂ (3), respectively. Similarly, reaction between Os(SnClMe₂)Cl(CO)₂(PPh₃)₂ (6) and KSnPh₃ produces the distannyl complex, Os(SnMe₂SnPh₃)Cl(CO)₂(PPh₃)₂ (7). In the ¹¹⁹Sn NMR spectra of these stable osmium(II) distannyl complexes both the α-Sn and β-Sn atoms show well-resolved ¹¹⁹Sn-¹¹⁹Sn and ¹¹⁹Sn-¹¹⁷Sn coupling. Each of these three distannyl complexes can be selectively functionalised at the α-Sn atom by reaction with SnCl₂Me₂ giving Os(SnClMeSnMe₃)(κ²-S₂CNMe₂)(CO)(PPh₃)₂ (2), Os(SnClMeSnPh₃)(κ²-S₂CNMe₂)(CO)(PPh₃)₂ (4), and Os(SnClMeSnPh₃)Cl(CO)₂(PPh₃)₂ (8), respectively. Treatment of compounds 3 or 7 with iodine also cleaves one α-methyl group, selectively, to give Os(SnIMeSnPh₃)(κ²-S₂CNMe₂)(CO)(PPh₃)₂ (5), or Os(SnIMeSnPh₃)Cl(CO)₂(PPh₃)₂ (9). Crystal structures for complexes 3 and 7 have been determined.     

The polymerization of propadiene by Ni(acac)2, C3H4, RnAlX3−n catalysts

Catalyst formation in the system Ni(acac)₂, C₃H₄, R_nAlX_3?n was studied. Polymerization experiments showed that, by replacing ionic groups such as acac^?, Br^?, Cl^? with alkyl or hydride groups, an active catalyst is obtained. Electrolysis of Ni(acac)₂ in tetrahydrofuran also gives an active catalyst. Lewis acids like (iBu)₃Al and Et₃Al increase the polymerization rate, while Lewis bases like pyridine and triphenylphosphine not only decrease the rate but also change selectivity. The selectivity is not changed if different transition metals (e.g. Co, Pd, Ni) are used. Kinetic measurements show a first order dependence on Ni. The dependence on (iBu)₃Al changes from first to zero order with increasing $\text{Al}\text{Ni}$ ratio. This can be explained by assuming that the very active catalyst is formed via an equilibrium between a nickel complex and (iBu)₃Al. A first order deactivation of the nickel catalyst is observed; it is faster during polymerization than during ageing of the catalyst.     

Synthesis and structural characterization of [Bse]Ni(PPh3)(NO), a nickel complex with a bent nitrosyl ligand

The nickel nitrosyl compound [Bse^Me]Ni(PPh₃)(NO) has been synthesized by the reaction of Ni(PPh₃)₂(NO)Br with potassium bis(2-seleno-1-methylimidazolyl)hydroborate, [Bse^Me]K. X-ray diffraction studies demonstrate that (i) the B–H group of the [Bse^Me] ligand interacts with the nickel center and (ii) the nitrosyl ligand is bent, with Ni–N–O bond angles of 149.1(3)° and 153.1(3)° for the two crystallographically independent molecules. The bent nature of the nitrosyl ligand in [Bse^Me]Ni(PPh₃)(NO) is in marked contrast to the linearity observed for the tris(2-seleno-1-mesitylimidazolyl)hydroborato counterpart [Tse^Mes]NiNO (180.0°). Density functional theory geometry optimization calculations demonstrate that the Ni?H–B interaction is not responsible for causing the nitrosyl ligand to bend, but rather the difference between [Tse^Mes]NiNO and [Bse^Me]Ni(PPh₃)(NO) is due to the [Tse^Mes] ligand allowing the former molecule to adopt a structure with C₃ symmetry. In contrast, the steric and electronic asymmetry of [Se₂P] donor array of the [Bse^Me] and PPh₃ ligand combination prevents [Bse^Me]Ni(PPh₃)(NO) from having C₃ symmetry and the nitrosyl ligand bends to stabilize the occupied M–N σ^∗ antibonding orbital.     

Role of B(C6F5)3 in activating the nickel-methyl complex (η-C5H5)Ni(CH3)(PPh3) to initiate the vinyl polymerization of norbornene

The Ni-methyl complex (η⁵-C₅H₅)Ni(CH₃)(PPh₃) (1) reacted with B(C₆F₅)₃ to give an unstable contact ion-pair complex with a μ-methyl bridge between the Ni and B atoms. Formation of the B-CH₃ bond was confirmed by the reaction of this complex with PPh₃ to give [(η⁵-C₅H₅)Ni(PPh₃)₂][B(CH₃)(C₆F₅)₃] which was structurally characterized. Spontaneous decomposition of the contact ion-pair complex yielded (η⁵-C₅H₅)Ni(C₆F₅)(PPh₃) which is very stable and does not show any reactions with norbornene with or without added B(C₆F₅)₃. ¹⁹F NMR study showed that the polynorbornene obtained by the catalysis of 1/B(C₆F₅)₃ system has the C₆F₅ end-group. A series of reactions, which includes CH₃/C₆F₅ exchange between the Ni and B centers with concomitant dissociation of PPh₃ to accept coordination of a norbornene monomer, is proposed as the route to active species that can initiate vinyl polymerization of norbornene.     

Carbonylvanadium complexes of the tripod ligands MeC(CH2PPh2)3 and P(CH2CH2PPh2)3

UV irradiation of [Et₄N] [V(CO)₆] in the presence of the tripod ligands (L) MeC(CH₂PPh₂)₃ (cp₃) and P(CH₂CH₂PPh₂)₃ (pp₃) yields [Et₄N] [V(CO)₅L], cis-[Et₄N] [V(CO)₄L] and mer-[Et₄N] [V(CO)₃L] (where the meridional configuration for L = cp₃ is uncertain). Except for [Et₄N] [V(CO)₅cp₃], all these species were isolated. The complexes are characterized by their IR, ³¹P and ⁵¹V NMR spectra.     

Chelate structures of 5-(H/Br)-2-hydroxybenzaldehyde-4-allyl-thiosemicarbazones (H2L): Synthesis and structural characterizations of [Ni(L)(PPh3)] and [Ru(HL)2(PPh3)2]

The reactions of 5-R-2-hydroxybenzaldehyde-4-allyl-thiosemicarbazone {R: H (L¹); Br (L²)} with [M^II(PPh₃)nCl₂] (M = Ni, n = 2 and M = Ru, n = 3) in a 1:1 molar ratio have given stable solid complexes corresponding to the general formula [Ni(L)(PPh₃)] and [Ru(HL)₂(PPh₃)₂]. While the 1:1 nickel complexes are formed from an ONS donor set of the thiosemicarbazone and the P atom of triphenylphosphine in a square planar structure, the 1:2 ruthenium complexes consist of a couple from each of N, S and P donor atoms in a distorted octahedral geometry. These mixed-ligand complexes have been characterized by elemental analysis, IR, UV–Vis, APCI-MS, ¹H and ³¹P NMR spectroscopies. The structures of [Ni(L²)(PPh₃)] (II) and [Ru(L¹H)₂(PPh₃)₂] (III) were determined by single crystal X-ray diffraction.     

The structure and formation of niobocene carbonyl heteronuclear derivatives. The molecular structures of Cp2Nb(CO)(μ-CO)Mn(CO)4, Cp2Nb(CO)(μ-H)Ni(CO)3 and [Cp2Nb(CO)(μ-H)]2Mo(CO)4

The heteronuclear Cp₂Nb(CO)(μ-CO)Mn(CO)₄ (I), Cp₂Nb(CO)(μ-H)Ni(CO)₃ (II) and [Cp₂Nb(CO)(μ-H)]₂M(CO)₄ (III, M = Mo;IV, M = W) complexes were prepared by reaction of Cp₂NbBH₄/Et₃N with Mn₂(CO)₁₀ in refluxing toluene, direct reaction of Cp₂NbBH₄ with Ni(CO)₄ in ether, and reaction of Cp₂NbBH₄/Et₃N with M(CO)₅. THF complexes (M = Mo or W) in THF/benzene mixture. An X-ray investigation of compounds I–III was performed. It is established that in I the bonding between Mn(CO)₅ and Cp₂Nb(CO) (with the angle (α) between the ring planes being 44.2(5)°) fragments takes place via a direct NbMn bond (3.176(1) Å) and a highly asymmetric carbonyl bridge (MnC_co 1.837(5) Å, NbC_co 2.781(5) Å). On the other hand, in complex II the sandwich Cp₂Nb(CO)H molecule (angle α = 37.8°) is combined with the Ni(CO)₃ group generally via a hydride bridge (NbH 1.83 Å, NiH 1.68 Å, NbHNi angle 132.7°) whereas the large Nb?Ni distance, 3.218(1) Å, shows the weakening or even absence of the direct NbNi bond. Similarly, in complex III two Cp₂Nb(CO)H molecules (with α angles equal to 41.4 and 43.0°, respectively) are joined to the Mo(CO)₄ group via the hydride bridges (NbH 1.83 and 1.75 Å and MoH 2.04 and 2.06 Å) producing a cis-form. The direct NbMo bonds are probably absent, since the Nb?Mo distances are rather long (3.579 and 3.565 Å). The effect of electronic and steric factors on the structure of heteronuclear niobocene carbonyl derivatives is discussed.     

Coordination,oligomerisation and transfer hydrogenation of acetylenes by some ruthenium and osmium carboxylates: Crystal and molecular structures of bis(trifluoroacetato)carbonyl-(methanol) bis(triphenylphosphine)ruthenium(II) and (1,4-diphenylbut-1-en-3-yn-2-yl)trifluoroacetato-(carbonyl) bis(triphenylphosphine)ruthenium(II)

The hydrides [MH(O₂CCF₃)(CO)(PPh₃)₂] (M = Ru or Os) react with disubstituted acetylenes PhCCPh and PhCCMe to afford vinylic products [M{C(Ph)CHPh}(O₂CCF₃)(CO)(PPh₃)₂] and [M{C(Ph)CHMe}(O₂CCF₃)(CO) (PPh₃)₂]/[M{C(Me)CHPh}(O₂CCF₃)(CO)(PPh₃)₂] respectively. Acidolysis of these products with trifluoroacetic acid in cold ethanol liberates cis-stilbene and cis-PhHCCHMe respectively thus establishing the cis-stereochemistry of the vinylic ligands. The complexes [M(O₂CCF₃)₂(CO)(PPh₃)₂] formed during the acidolysis step undergo facile alcoholysis followed by β-elimination of aldehyde to regenerate the parent hydrides [MH(O₂CCF₃)(CO)(PPh₃)₂] and thereby complete a catalytic cycle for the transfer hydrogenation of acetylenes. The molecular structure of the methanol-adduct intermediate, [Ru(O₂CCF₃)₂(MeOH)(CO)(PPh₃)₂] has been determined by X-ray methods and shows that the coordinated methanol is involved in H-bonding with the monodentate trifluoroacetate ligand [MEO-H---OC(O)CF₃; O...O = 2.54 Å]. The hydrides [MH(O₂CCF₃)(CO) (PPh₃)₂]react with 1,4-diphenylbutadiyne to afford the complexes [M{C(CCPh)CHPh} (O₂CCF₃)(CO)(PPh₃)₂]. The ruthenium product, which has also been obtained by treatment of [RuH(O₂CCF₃)(CO)(PPh₃)₂] with phenylacetylene, has been shown by X-ray diffraction methods to contain a 1,4-diphenylbut-1-en-3-yn-2-yl ligand. The osmium complexes [Os(O₂CCF₃)₂(CO)(PPh₃)₂], [OsH(O₂CCF₃)(CO)(PPh₃)₂] and [Os{C(CCPh)CHPh}(O₂CCF₃)(CO)(PPh₃)₂] all serve as catalysts for the oligomerisation of phenylacetylene. Acetylene reacts with [Ru(O₂CCF₃)₂(CO)(PPh₃)₂] in ethanol to afford the vinyl complex [Ru(CHCH₂)(O₂CCF₃)(CO)(PPh₃)₂].     

Influence of the order of introduction of protonic acids on the formation of active complexes in the Ni(PPh3)4/BF3 · OEt2 catalytic system

The influence of the order of introduction of promoters (complex protonic acids) on the formation of active complexes in the Ni(PPh₃)₄/BF₃ · OEt₂ catalytic system and the activity of these systems in ethylene oligomerization have been studied. The activity of the systems in which nickel exists mainly as cationic Ni(I) complexes is more than one order of magnitude higher than the activity of the systems where nickel exists mainly in the form of Ni(II) hydride complexes. The role of alcohols as promoters in the Ni(PPh₃)₄/BF₃ · OEt₂ catalytic system is elucidated. The alcohols are the source of Ni(II) hydrides and, more importantly, the source of strong Brønsted acids, which efficiently ensure the coordinative unsaturation of the cationic Ni(I) complexes.     

Reactions of nitrosyl chloride with [Ni(PPh3)2X2] (X=Cl,Br, NCS or NO3)

Summary Nitrosyl chloride has been treated with [Ni(PPh₃)₂X₂] (X = Cl, Br, NCS or NO₃) to obtain [Ni(PPh₃)XCl]₂ (X=Cl, Br, NCS or NO₃) and [Ni(OPPh₃)(SCN)Cl]₂. The compounds obtained were characterised by analyses, infrared (including far i.r.) and visible spectral studies, magnetic moment and conductivity measurements and many chemical reactions. It is proposed that the compounds have a dimeric structure with a distorted tetrahedral environment around the nickel atom and chloro-bridges.     

New complexes of the fac-{(CO)3Re} fragment bearing a diaminediphosphine ligand

The mono- and binuclear hydride compounds fac-[ReH(CO)₃L] (1a) and [{ReH(CO)₄}₂(μ-L)] (1b) have been prepared by reaction of [ReH(CO)₅] with Ph₂PN(CH₃)(CH₂)₂N(CH₃)PPh₂ (L) under UV light. Protonation reactions of the hydride compound 1a with equimolar amounts of HSO₃CF₃ or HCl yielded the triflato or the chlorido compounds fac-[Re(OSO₂CF₃)(CO)₃L] (2) and fac-[ReCl(CO)₃L] (3), respectively. The compounds have been characterised by elemental analysis, IR and NMR spectroscopic data, and mass spectrometry. Their structures have been confirmed by X-ray crystallography.     

Preliminary communicationCatalytic olefin hydrogenation with nonacarbonyltris(triphenylphosphine)triruthenium and its derivatives. Crystal structure of [Ru2(CO)5(PPh3)(μ-PPh2)(μ-OCPh)]

The complexes [Ru₃(CO)₇(PPh₂)₂(C₆H₄)] and [Ru₂(CO)₅(PPh₃)(μ-PPh₂)(μ-OCPh)] were obtained by pyrolysis of [Ru₃(CO)₉(PPh₃)₃] and tested as catalysts for the hydrogenation of cyclohexene and 2-cyclohexen-1-one. The structure of [Ru₂(CO)₅(PPh₃)(μ-PPh₂)(μ-OCPh)] was established by a single crystal X-ray diffraction study.     

Aryl- and acetylene-nickel(I) complexes

Reduction of various pentafluorophenylnickel(II) complexes in the presence of phosphines gives unstable nickel(I) compounds but Ni(C₆F₅)(CO)₂(PPh₃)₂ is isolated in the presence of CO. Similar NiR(CO)₂(PPh₃)₂ (R = C₆F₅,C₆Cl₅, 2,3,5,6-C₆Cl₄H) are obtained by reaction of the halogenonickel(I) complex with MgRBr or LiR. Reduction of NiX₂L₂ in the presence of acetylenes gives [NiXL₂]₂(μ-PhCCR) (R = H, X = Cl and R = Ph, X = Cl, Br) when L = P-n-Bu₃ but only NiX(PPh₃)₃ are recovered when L = PPh₃. No reaction with the alkyne is observed for [NiX(PPh₃)₂]_n but [NiCl(PPh₃)]_n reacts with RCCR′ to give paramagnetic NiCl(PPh₃)(CRCR′) (R = Ph, R′= H, COOEt), diamagnetic [NiCl(PPh₃)]₂(μ-PhCCPh) and cyclotrimerization when R = R′ = COOMe. Chemical and structural behaviour of the new nickel(I) complexes is described.     

pentahapto- UND trihapto- cycloheptadienylkobalt(I)-komplexe

Treatment of [CoH(N₂)(PPh₃)₃] with cycloheptatriene in diethyl ether affords [Co(1—5-η-C₇H₉)(PPh₃)₂] (I). An etherical solution of (I) reacts with CO at room temperature and under normal pressure to yield the carbonyl complex [Co(1—3-η-C₇H₉)(CO)₂(PPh₃)] (II). These compounds are characterized by their PMR and IR spectra.     

Reductively induced homolytic carbon-carbon bond cleavage in Co(CO)3(PPh3)(COCF3)

The chemical or electrochemical reduction of the trifluoroacetyl complex Co(CO)₃(PPh₃)(COCF₃) involves a single electron transfer yielding trifluoromethyl radical and an anionic cobalt carbonyl complex. The mechanism is proposed to involve electron transfer followed by initial dissociation of either a carbonyl or phosphine ligand from the 19-electron [Co(CO)₃(PPh₃)(COCF₃)]⁻ anion. The resulting 17-electron intermediate undergoes subsequent one-electron reductive elimination of trifluoromethyl radical by homolytic cleavage of the carbon-carbon bond of the trifluoroacetyl group. The radical can be trapped by either benzophenone anion, forming the anion of α-(trifluoromethyl)benzhydrol, or Bu₃SnH, yielding CF₃H. The ultimate organometallic product is an 18-electron anion, either [Co(CO)₄]⁻ or [Co(CO)₃(PPh₃)]⁻, depending upon which ligand is initially lost. Fluorine-containing products were identified and quantitated by ¹⁹F NMR while cobalt-containing products were determined by IR.