Mononuclear Pt(II) and Pd(II) 1,4-dithiolato complexes. Crystal structures of [Pt((−) DIOS) (PPh3)2] and [Pd(S(CH2) 4S)(Ph2P(CH2) 3PPh2)]. Application in styrene hydroformylation

Addition of 1,4-dithiols to dichloromethane solutions of [PtCl₂(P-P)] (P-P = (PPh₃)₂, Ph₂P(CH₂)₃PPh₂, Phd₂P(CH₂)₄PPh₂; 1,4-dithiols = HS(CH₂)₄SH, (−)DIOSH₂ (2,3-O-isopropylidene-1,4-dithiol-l-threitol), BINASH₂ (1,1′-dinaphthalene-2,2′-dithiol)) in the presence of NEt₃ yielded the mononuclear complexes [Pt(1,4-dithiolato)(P-P)]. Related palladium(II) complexes [Pd(dithiolato)(P-P)] (P-P=Ph₂P(CH₂)₃PPh₂, Ph₂P(CH₂)₄PPh₂; dithiolato = ⁻S(CH₂)₄S⁻, (−)-DIOS) were prepared by the same method. The structure of [Pt((−)DIOS)(PPh₃)₂] and [Pd(S(CH₂)₄S)(Ph₂P(CH₂)₃PPh₂)] complexes was determined by X-ray diffraction methods. Pt—dithiolato—SnC1₂ systems are active in the hydroformylation of styrene. At 100 atm and 125°C [Pt(dithiolate)(P-P)]/SnCl₂ (Pt:Sn = 20) systems provided aldehyde conversion up to 80%.     

Synthesis and structures of heterobimetallic Ir2M (M=Pd, Pt) sulfido clusters and their catalytic activity for regioselective addition of alcohols to internal 1-aryl-1-alkynes

The heterobimetallic trinuclear sulfido clusters [(Cp*Ir)₂(μ₃-S)₂MCl₂] (M=Pd (3), Pt (4); Cp*=η⁵-C₅Me₅) were synthesized from the dinuclear hydrogensulfido complex [Cp*IrCl(μ-SH)₂IrCp*Cl] (2) and [MCl₂(COD)] (COD=cycloocta-1,5-diene), while the reaction of 2 with [Pd(PPh₃)₄] afforded the cationic trinuclear cluster [(Cp*Ir)₂(μ₃-S)₂PdCl(PPh₃)]Cl (5). Clusters 3 and 4 reacted with PPh₃ to give a series of mono and dicationic clusters including 5, while the dicationic clusters [(Cp*Ir)₂(μ₃-S)₂M(dppe)][BPh₄]₂ (M=Pd (9), Pt (10); DPPE=Ph₂PCH₂CH₂PPh₂) were obtained by the reaction with dppe followed by anion metathesis. The molecular structures of 5·CH₂Cl₂, 9·CH₃COCH₃, and 10·CH₃COCH₃ were determined by X-ray crystallography. Clusters 3 and 4 were found to catalyze the addition of alcohols to alkynes to give the corresponding acetals. Internal 1-aryl-1-alkynes were transformed by cluster 3 into the corresponding 2,2-dialkoxy-1-arylalkanes with high regioselectivity up to 99:1, while cluster 4 was a much less regioselective catalyst.     

Synthesis of a tripalladium cluster containing an η:η:η-bridging butadienyl ligand stabilized by a zwitterionic structure

An η¹-butadienyl complex [trans-η¹-CH₂=C(Me)C=CH₂Pd(PPh₃)₂Cl] (1) reacted with [(μ-η²:η²-1,3-butadiene)Pd₂(PPh₃)(μCl)Cl] (2) to result in displacement of the diene ligand of 2 accompanied by exchange of PPh₃ of 1 with Cl anion of 2 producing a butadienyl tripalladium cluster [(μ-CH₂=C(Me)C=CH₂)Pd(PPh₃)Cl₂ · Pd₂(PPh₃)₂(μ-Cl)] (3) stabilized by the zwitterionic structure in moderate yield. The X-ray structure analysis of 3 revealed rigid binding of [Pd₂(PPh₃)₂(μ-Cl)]⁺ and [CH₂ =C(Me)C=CH₂Pd(PPh₃)Cl₂]⁻ through the π-bond coordination of the butadienyl group to the dipalladium cation.     

Syntheses, spectroscopic characteristics and thermolytic rearrangements of bis-[(trimethylgermyl)methyl]platinum(II) and bis-[(trimethylstannyl)methyl]platinum(II) complexes

The preparations and spectroscopic characteristics are reported of a series of (trimethylgermyl)methyl- and (trimethylstannyl)methylplatinum(II) complexes with diene and P-donor ancillary ligands, cis-Pt(CH₂GeMe₃)₂L₂ (L = PPh₃ or PPh₂Me; L₂ = dppe or cod) and cis-Pt(CH₂SnMe₃)₂L₂ (L = PPh₃; L₂ =cod). Thermolysis of toluene solutions of cis-Pt(CH₂GeMe₃)₂(PPh₃)₂ leads to cis-Pt(Me)(CH₂GeMe₂CH₂GeMe₃)(PPh₃)₂ via β-alkyl migration, after (non-rate-limiting) phosphine dissociation. Estimated activation parameters (ΔH_{298 K}^‡ = 126 ± 3 kJ mol⁻¹, ΔS^‡ = + 17 ± 7 J mol⁻¹ K⁻¹ and hence Δ_{298 K}^‡ = 121 ± 5 kJ mol⁻¹) suggest that this system is more migration labile than its silicon analogue, primarily as a result of a lower activation enthalpy. While cis-Pt(CH₂GeMe₃)₂(PPh₂Me)₂ reacts similarly but less readily, Pt(CH₂GeMe₃)₂(dppe)₂ is inert at operable temperatures. Thermolysis of Pt(CH₂GeMe₃)₂(cod) generates 1,1,3,3,-tetramethyldi-1,3-germacyclobutane as the major organogermanium product, while from cis-Pt(CH₂SnMe₃)₂(PPh₃)₂, 1,1,3,3-tetramethyldi-1,3-stannacyclobutane predominates. Mechanistic implications are discussed.     

Synthesis, characterization and catalytic activity in Heck-type reactions of orthometallated Pd and Pt complexes derived from (1R,2R)-1,2-diaminocyclohexane

The chiral bis-imine (1R,2R)-C₆H₁₀-[E---N=CH---C₆H₃---3,4-(OMe)₂]₂ 1 (LH) reacts with [Pd(OAc)₂] (1:1 molar ratio; OAc=acetate) giving the orthometallated [Pd(OAc)(C₆H₂---4,5-(OMe)₂---2-CH=N-(1R,2R)-C₆H₁₀---N=CH---C₆H₃-3′,4′-(OMe)₂-κ-C,N,N)] 2 (abbreviated as [Pd(OAc)(L-κ-C,N,N)]), through C---H bond activation on only one of the aryl rings and N,N-coordination of the two iminic N atoms. 2 reacts with an excess of LiCl to give [Pd(Cl)(L-κ-C,N,N)] 3. The reaction of 3 with AgClO₄ and neutral or anionic ligands L′ (1:1:1 molar ratio) affords [Pd(L-κ-C,N,N)(L′)](ClO₄) (L′=PPh₃ 4a, NCMe 5, pyridine 6, p-nitroaniline 7) or [Pd(I)(L-κ-C,N,N)] 8. Complex 4a reacts with wet CDCl₃ giving [Pd(C₆H₂---4,5-(OMe)₂---2-CH=N-(1R,2R)---C₆H₁₀---NH₂-κ-C,N,N)(PPh₃)](ClO₄) 4b as a result of the hydrolysis of the C=N bond not involved in the orthometallated ring. The molecular structure of 4b·CH₂Cl₂ has been determined by X-ray diffraction methods. Cleavage of the Pd---N bond trans to the C_aryl atom can be accomplished by coordination of strongly chelating ligands, such as acetylacetonate (acac) or bis(diphenylphosphino)ethane (dppe), forming [Pd(acac-O,O′)(L-κ-C,N)] 9 and [Pd(L-κ-C,N)(dppe-P,P′)](ClO₄) 12, while classical N,N′-chelating ligands such as 1,10-phenantroline (phen) or 2,2′-bipyridyl (bipy) behave as monodentate N-donor ligands yielding [Pd(L-κ-C,N,N)(κ¹-N-phen)](ClO₄) 10 and [Pd(L-κ-C,N,N)(κ¹-N-bipy)](ClO₄) 11. Treatment of 1 with PtCl₂(DMSO)₂ (1:1 molar ratio) in refluxing 2-methoxyethanol gives Cl₂Pt[(NH₂)₂C₆H₁₀---N,N′] 13a and [Pt(Cl)(C₆H₂---4,5-(OMe)₂---2-CH=N-(1R,2R)---C₆H₁₀---NH₂-κ-C,N,N)] 13b, while [Pt(Cl)(L-κ-C,N,N)] 14 can be obtained by reaction of [Pt(μ-Cl)(η³-2-Me---C₃H₄)]₂ with 1 in refluxing CHCl₃. Complexes 2 and 3 catalyzed the arylation of methyl acrylate giving good yields of the corresponding methyl cinnamates and TON up to 847 000. Complex 3 also catalyzes the hydroarylation of 2-norbornene, but with lower yields and without enantioselectivity.     

Synthesis and characterization of hydroxo, pyrazolato and carboxylato derivatives of the PdR(PPh3)moiety (R = C6F5 or C6Cl5)

The hydroxo-complexes [{PdR(PPh₃)(μ-OH)}₂] (R = C₆F₅ or C₆Cl₅) have been obtained by reaction of the corresponding [{PdR(PPh₃)(μ-Cl)}2] complexes with NBu₄OH in acetone. In this solvent, the reaction of the hydroxo-bridged complexes with pyrazole (Hpz) and 3,5-dimethylpyrazole (Hdmpz) in 1:2 molar ratio leads to the formation of the new complexes [{Pd(C₅F₅)(PPh₃)(μ-azolate)}2] and [{Pd(C₆Cl₅)(PPh₃)}₂(μ-OH)(μ-azolate)] (azolate = pz or dmpz). The reaction of the bis(μ-hydroxo) complexes with Hpz and Hdmpz in acetone in 1:1 molar ratio has also been studied, and the resulting product depends on the organic radical (C₆F₅ or C₆Cl₅) as well as the azolate (pz or dmpz). The identity of the isomer obtained has been established in every case by NMR (¹H, ¹⁹F and ³¹P) spectroscopy. The reaction of the bis(μ-hydroxo) complexes with oxalic (H₂Ox) and acetic (HOAc) acids yields the binucle ar complexes [{PdR(PPh₃)}2(μ-Ox)] (R = C₆F₅ or C₆Cl₅) and [{Pd(C₆F₅)(PPh₃)(μ-OAc)}2], respectively. [{Pd(C₆F₅)(PPh₃)(μ-OH)}₂] reacts with PPh₃ in acetone in 1:2 ratio giving the mononuclear complex trans-[Pd(C₆F₅) (OH)(PPh₃)₂], whereas the pentachlorophenylhydroxo complex does not react with PPh₃, even under forcing conditions.     

Synthesis, structure and hydrogenation catalytic activity of [Ru3(μ3,η-ampy)(μ,η:η-PhC=CHPh)(CO)6(PPh3) (Hampy = 2-amino-6-methylpyridine)

The compound [RU₃(μ₃,η²- -ampy)(μ₃η¹:η²-PhC=CHPh)(CO)₆(PPh₃)₂] (1) (ampy = 2-amino-6-methylpyridinate) has been prepared by reaction of [RU₃(η-H)(μ₃,η²- ampy) (μ,η¹:η²-PhC=CHPh)(CO)₇(PPh₃)] with triphenylphosphine at room temperature. However, the reaction of [RU₃(μ-H)(μ₃, η² -ampy)(CO)₇(PPh₃)₂] with diphenylacetylene requires a higher temperature (110°C) and does not give complex 1 but the phenyl derivative [RU₃(μ₃,η²-ampy)(μ,η ¹:η² -PhC=CHPh)(μ,-PPh₂)(Ph)(CO)₅(PPh₃)] (2). The thermolysis of complex 1 (110°C) also gives complex 2 quantitatively. Both 1 and 2 have been characterized by0 X-ray diffraction methods. Complex 1 is a catalyst precursor for the homogeneous hydrogenation of diphenylacetylene to a mixture of cis- and trans -stilbene under mild conditions (80°C, 1 atm. of H₂), although progressive deactivation of the catalytic species is observed. The dihydride [RU₃(μ-H)₂(μ ₃,η²-ampy)(μ,η¹:η²- PhC=CHPh)(CO)₅(PPh₃)₂] (3), which has been characterized spectroscopically, is an intermediate in the catalytic hydrogenation reaction.     

Synthesis and reactions of 4-vinyl pyridine derivatives of ruthenium(II)

4-Vinyl pyridine (4-Vp) reacts with RuHClCO(PPh₃)₃ (I) in THF to give RuHClCO(PPh₃)₂(4-Vp) (II, which reacts with sodium derivatives of bidentate chelating ligands to afford substitution products, [RuH(CO)(PPh₃)₂(L)]. The bindentate ligands used are 2-hydroxybenzaldehyde, 2-hydroxy-3-methoxybenzaldehyde, trifluorothenoylacetone and 8-hydroxyquinoline. Insertion reactions of the Ru---H bond of II with activated olefins such as acrylonitrile [giving RuCl(CO)(CH₃CHCN)(PPh₃)₂(4-Vp)], 2-vinyl pyridine, dimethyl fumarate and monobromodiethyl fumarate have been carried out to obtain chelated Ru---C bonded complexes. RuCl₂(PPh₃)₃ reacts with an excess of 4-Vp to give an octahedral ruthenium addition complex containing two vinyl pyridine ligands. The dimer [RuClCO(CH₃CHCN)(PPh₃)(4-Vp)]₂ is obtained by the reaction of [RuClCO(CH₃CHCN)(PPh₃)₂]₂ with an excess of 4-Vp. Stereochemical assignments have been made for these new complexes on the basis of IR and ¹H NMR data.     

Synthesis and properties of some diruthenium acetate compounds

The compound [Ru₂(μ-O₂CCH₃)₄(THF)₂]BF₄ (I) containing the Ru₂⁵⁺ unit was prepared by reaction of Ru₂Cl(μ-O₂CCH₃)₄ with AgBF₄ in THF. This compound, in contrast with Ru₂Cl(μ-O₂CCH₃)₄, is soluble in several polar organic solvents and reacts in THF with OPPh₃ and PPh₃ giving [Ru₂(μ-O₂CCH₃)₄(OPPh₃)₂]BF₄·CH₂Cl₂ (II) and [Ru(μ-O₂CCH₃)(O₂CCH₃)(PPh₃)]_n (III), respectively. The complex II has been also obtained as hexafluorophosphate [Ru₂(μ-O₂CCH₃)₄(OPPh₃₂]PF₆·CH₂Cl₂ (IV) by treatment of Ru₂Cl(μ-O₂CCH₃)₄ with an excess of NOPF₆ and PPh₃ in methanol. In this reaction the triphenylphosphine oxide is generated by oxidation of the triphenylphosphine.     

Heterobimetallic Mo---Sn complexes. Reactions of [Mo(CO)3(CH3CN)2(Cl)(SnRCl2)] (R = Me, Ph) with 4(4-XC6H4)3 (X = Cl, F, H, Me, MeO)

Three families of heterobimetallic compounds were obtained by reaction of [Mo(CO)₃(CH₃CN)₂(Cl)(SnRCl₂)] (R = Ph, Me) with P(4-XC₆H₄)₃ (X = Cl, F, H, Me, MeO). The type of compound obtained dependent on the solvent and concentration of the starting compound. So, [Mo(CO)₂(CH₃COCH₃)₂(PPh₃)(Cl)(SnRCl₂)]·nCH₃COCH₃ (R = Ph, n = 0.5; R = Me, n = 1) (type I) and [Mo(CO)₃{P(4-XC₆H₄)₃}(μ-Cl)(SnRCl₂)]₂ (R = Ph, X = Cl, F, H, Me, MeO; R = Me, X = Cl, F) (type II) were isolated from acetone solution in ca 0.05 M and 0.1 M concentrations, respectively. However, [Mo(CO)₃(CH₃CN) {P(4-XC₆H₄)₃}(Cl)(SnRCl₂)] (R = Ph, X = H; R = Me, X = Cl, F, H) (type III) were obtained from dichloromethane solution independently of the concentration used. All new complexes showed a seven-coordinate environment at molybdenum, containing Mo---Cl and Mo---Sn bonds. Mössbauer spectra indicated a four-coordination at tin for type III complexes.     

Complexes of ruthenium(II) and -(III) with dimethylsulphoxide—III. Bis-iodo-tetrakis- dimethylsulphoxide ruthenium(II) and some other iodo complexes of ruthenium(II)

The ruthenium(II) complex [RuI₂(Me₂SO)₄] was synthesized and characterized. The Me₂SO ligands are all S-bonded. Reactions of RuI₂(Me₂SO)₄ with ligands containing P, N and S donor atoms have been carried out and the complexes obtained were characterized using different physical methods. [RuI₂L₄] (L= CH₃CN, Me₂SO and py), [RuI₂(CH₃CN)₂(PPh₃)₂] and [RuI₂(CS)(PPh₃)₃] have been synthesized using RuI₃ as the source material and characterized as above.     

Attempts at stepwise reduction of the carbon-nitrogen triple bond of a nitrile at two metal centres: study of the reactivity of [(CO)(PPh3)2Re( (μ-NCHPh)Ru(PPh3) 2(PhCN)] towards tetrafluoroboric acid and dihydrogen

The reaction of [(CO)PPh₃)₂Re(μ-H)₂(μ-NCHPh)Ru(PPh₃)₂(PhCN)] (2) with HBF₄-Me₂O generates [(CO)PPh₃)₂Re(μ- H)₂(μ,η¹,η²HNCHPh)Ru(PPh₃)₂(PhCN)][BF₄] (3). Monitoring the reaction by NMR spectroscopy shows the intermediate formation of [(CO)(PPh₃)₂ HRe(μ-H)₂(μ-NCHPh)Ru(PPh₃)₂(PhCN)][BF₄] (4). Attempted reduction of the imine ligand by a nucleophile (H⁻ or CN⁻) failed, regenerating 2. Under dihydrogen at 50 atm, 3 is slowly transformed into [(CO)(PPh₃)₂HRe(μ-H)₃Ru(PPh₃)₂(PhCN)][BF₄] (5) with liberation of benzyl amine.     

Metal imidazolato polymers: synthesis, characterization and crystal structure of new silver(I) triphenylphosphine derivatives

When the polymeric complex [Ag(im)]_n (Him = imidazole) is reacted with PPh₃ (PPh₃ = triphenylphosphine), it yields the [Ag₂(μ₂-im)₂(PPh₃)₃]_n and [Ag(μ₂-im)(PPh₃)₂]_n species, shown to contain wavy chains of metal ions, singly bridged by N,N′-exo-bidentate imidazolate ligands. The former, crystallised as the CH₂Cl₂ solvate, contains two non-equivalent silver(I) ions, differing in the number of coordinated phosphines (one, in trigonal planar stereochemistry, or two, having tetrahedral geometry). The latter has a unique independent silver(I) ion in a tetrahedral environment, with two coordinated PPh₃ ligands. The reactivity of known silver(I) azolates with PPh₃, as well as the solution behaviour and (when available) the crystal structures of the corresponding derivatives are taken into consideration for a due comparison.     

Steric effects of the 2-(diphenylphosphino)pyridine bridging ligand in the synthesis of binuclear palladium(II) complexes

Treatment of [Pd{CH₂C(CH₃)CH₂}(Ph₂PPy)Cl] (Ph₂PPy = 2-(diphenylphosphino)pyridine) with cis-[Pd(^tBuNC)₂Cl₂] in dichloromethane affords the mixed isocyanide-tertiary phosphine complex cis-[Pd(^tBuNC)Ph₂PPy)Cl₂], in which the Ph₂PPy is a monodentate P-donor, and [{Pd[CH₂C(CH₃)CH₂]Cl}₂]. The steric effects of the Ph₂PPy bridging ligand in determining the reaction course is discussed. The complex cis-[Pd(^tBuNC)(Ph₂PPy)Cl₂] was crystallographically characterized: P2₁/n, a = 15.143(2), b = 9.527(1), c = 17.517(4) Å, β = 113.96(1)°, V= 2309.4(7) ų, Z = 4. The final R value was 0.044, R^w= 0.046 for the 3078 reflections with I > 3σ(I).     

Multiple ligand transfer reaction between [CpRu(L)(AN)2][PF6] (L=AN, CO, P(OMe)3; AN=acetonitrile) and CpFe(CO)L′X (L′=CO, PMe3, PMe2Ph, PMePh2, PPh3, P(OPh)3; X=Cl, Br, I)

Treatment of ruthenium complexes [CpRu(AN)₃][PF₆] (1a) (AN=acetonitrile) with iron complexes CpFe(CO)₂X (2a–2c) (X=Cl, Br, I) and CpFe(CO)L′X (6a–6g) (L′=PMe₃, PMe₂Ph, PMePh₂, PPh₃, P(OPh)₃; X=Cl, Br, I) in refluxing CH₂Cl₂ for 3 h results in a triple ligand transfer reaction from iron to ruthenium to give stable ruthenium complexes CpRu(CO)₂X (3a–3c) (X=Cl, Br, I) and CpRu(CO)L′X (7a–7g) (L′=PMe₃, PMe₂Ph, PMePh₂, PPh₃, P(OPh)₃; X=Br, I), respectively. Similar reaction of [CpRu(L)(AN)₂][PF₆] (1b: L=CO, 1c: P(OMe)₃) causes double ligand transfer to yield complexes 3a–3c and 7a–7h. Halide on iron, CO on iron or ruthenium, and two acetonitrile ligands on ruthenium are essential for the present ligand transfer reaction. The dinuclear ruthenium complex 11a [CpRu(CO)(μ-I)]₂ was isolated from the reaction of 1a with 6a at 0°C. Complex 11a slowly decomposes in CH₂Cl₂ at room temperature to give 3a, and transforms into 7a by the reaction with PMe₃.     

The reaction of (μ-H)2Os3(CO)9(PPh3) with ethylene affords the ethylidene complex (μ-H)2Os3(CO)9(PPh3)(μ-CHCH3)

The product isolated from the reaction of (μ-H)₂Os₃(CO)₉(PPh₃) with ethylene is shown to be the ethylidene complex (μ-H)₂Os₃(CO)₉(PPh₃)(μ-CHCH₃) (1) rather than the ethylene complex (μ-H)(H)Os₃(CO)₉(PPh₃)(C₂H₄), as previously claimed. The characterization of 1 is based on a combination of ¹H and ¹³C NMR results. The ¹H NMR data (δ 6.84 (1 H_D), 2.53 (3 H_C), J(CD) = 7.4 Hz) establish the presence of the ethylidene moiety, whereas detailed analysis of the 1-D and 2-D ¹³C NMR spectra of ¹³CO-enriched 1 indicates the relative positions of the ethylidene, hydride, and phosphine ligands on the triosmium framework.     

Regioselective addition of chalcogenol to an η-propargyl/allenyl complex via formation of the carbon-chalcogen bond leading to new chalcogenoxyallyl species

Regioselective addition of chalcogenol to an ν³-propargyl complex Pt(PPh₃)₂(η³-C₃H₃)](BF₄) (2) via the formation of the C---O, C---S, or C---Se bond generates new cationic chalcogenoxyallyl species {Pt(PPh₃)₂[η³CH₂C(ER)CH₂]}(BF₄) (E = O, R = Me 4(a), Et (4b, ⁱPr (4c), ¹Bu (4d), Ph (4e); E=S, E=Et (5b), ^tBu (5d, Ph (5e); E=Se, R=Ph (6e )) respectively in good yields. Thiol and selenol react with complex 2 much faster than alcohol; and 2 reacts with p-(HO)C₆H₄(SH) to exclusively yield the thioxyallyl product {Pt(PPh₃)₂[η³-CH₂C(SC₆H₄OH)CH₂]}(BF₄) (5f). Among the alcoh and phenol, thereactivity follows the order MeOH > EtOH >, ⁱPrOH >, ^tBuOH > PhOH. A mechanism comprising a preceding coordination step is postulated. The X-ray structures of 4b, 4e, 5b, 5e and 6e are provided.     

Synthesis, structure and characterization of M---Sn (M=Mo, W) bonded heterobimetallic complexes containing bis(pyrazol-1-yl)methane ligands

The reaction of bis(pyrazol-1-yl)methane tetracarbonylmolybdenum(0) or tungsten(0) complexes with RSnCl₃ (R=Ph, Cl) at room temperature yielded heterobimetallic complexes CH₂(Pz)₂M(CO)₃(Cl)(SnCl₂R) (Pz represents substituted pyrazole; M=Mo or W; R=Ph or Cl) in good yields, which have been characterized by elemental analysis, ¹H NMR and IR spectroscopy. The reaction of bis(3,5-dimethyl-4-halopyrazol-1-yl)methane tetracarbonyl tungsten with PhSnCl₃ did not take place even in refluxing CH₂Cl₂. The electronic and steric characteristics of substituents on the pyrazole ring remarkably influence the structures of the products. The structures of CH₂(3,5-Me₂-4-BrPz)₂W(CO)₃(Cl)(SnCl₃) (8) and CH₂(4-BrPz)₂Mo(CO)₃(μ-Cl)(SnCl₂Ph) (17) (Pz: pyrazole) determined by X-ray crystallography show that no chlorine-bridged W---Sn bond is observed in complex 8, while one chlorine-bridged Mo---Sn bond exists in complex 17. The Sn---M bond length is 2.7438(5) Å in complex 8 (W---Sn) and 2.7559(4) Å in complex 17 (Mo---Sn).     

Synthesis of Re-Ru heterobimetallic polyhydride complexes. Study of the influence of ligands bonded to the monometallic precursors on the nature of the isolated binuclear complexes

The reaction of K[H₆ReL₂] with [RuHCl(CO)(PPh₃)_3−x {P(OPrⁱ}₃)_x](L₂ = (PMePh₂)₂, dppe, (AsPh₃)₂, or (PPh₃)₂; x = 0, 1 or 2) leads to [L₂(CO)HRe(μ-H)₃RuH(PPh₃)_2−y{P(OPrⁱ)₃}_y] (x = 0 or 1, Y = 0; X = 2, Y = 1(L₂ = PPh₃)) in a first step. Under the reaction conditions most of these complexes react rapidly with the liberated phosphine giving [L₂(CO)Re(μ-H)₃Ru(PPh₃)_3−y- {P(OPrⁱ)₃}_y] (L₂ = (PMePh₂)₂ or dppe, Y = 0; L₂ = (PPh₃)₂, Y = 1) as the only iso complexes. The structure of [(PMePh₂)₂(CO)Re(μ-H)₃Ru(PPh₃)₃] has been establishedby X-ray structure analysis. The complex [(PPh₃)₂(CO)Re(μ-H)₃Ru(PPh₃)₂(P(OPrⁱ)₃)] reacts with molecular hydrogen under pressure to generate [L₂(CO)HRe(μ-H)₃RuH(PPh₃)(P(OPrⁱ)₃) as the sole product.     

Ab initio study of 1,1-(methylphosphinylidene) bis(methanamine) and vibrational assignment of its N,N′-coordinated Pt(II) and Pd(II) chloro complexes

Infrared and Raman spectra of 1,1-(methylphosphinylidene) bis(methanamine) [mpbm, (CH₃)PO(CH₂NH₂)₂] and its N,N′-coordinated Pt(II) and Pd(II) have been studied in the 4000–200 cm⁻¹ frequency range. Ab initio calculations have been carried out for different conformations of the mpbm at HF/6-31G* level of the theory from which structural parameters, conformational stability and predicted infrared and Raman spectra have been obtained. A complete vibrational assignment of the lowest energy conformer, tttg⁻, as well as of its N,N′-coordinated Pt(II) and Pd(II) chloro-complexes was done on the basis of the calculated frequencies, relative infrared intensities, Raman activities and potential energy distribution (PED). The theoretical predictions are compared with the experimental results where appropriate.