Polychlorophenyl-platinum(II) complexes containing triphenylphosphine

A new method to prepare compounds of the type trans-[PtCl(R)(PPh₃)₂] (R = C₆H₅; 2,5-C₆H₃Cl₂; 2,3,4-, and 2,4,6-C₆H₂Cl₃; 2,3,4,5-, 2,3,4,6- and 2,3,5,6-C₆HCl₄ and C₆Cl₅) by reaction of cis-[PtCl₂(PPh₃)₂] and HgR₂ in the molten state is described.The reactions of the complexes with HCl, Cl₂ and I₂ have been examined in order to give information about the relative ease of cleavage of the various Ptaryl bonds. The replacement of Cl by NCS suggests an associative mechanism even for the complexes in which the polychlorophenyl ligand has chlorine atoms in both ortho positions.     

Platinum-mercury compounds as intermediates to mono- and di-arylplatinum(II) complexes

The reaction of HgR₂ (R = 2,5-C₆H₃Cl₂; 2,3,4- and 2,4,6-C₆H₂Cl₃; 2,3,4,5-,2,3,4,6- and 2,3,5,6-C₆HCl₄ and C₆Cl₅) with Pt(PPh₃)₃ gives the new stable compounds [(PPh₃)₂RPt(HgR)] containing PtHg bonds. When R contains an ortho chlorine atom (R = 2,5-C₆H₃Cl₂; 2,3,4-C₆H₂Cl₃ and 2,3,4,5-C₆HCl₄) refluxing xylene solutions of these compounds gives the complexes [PtR₂-(PPh₃)₂], with simultaneous precipitation of mercury. In the other cases the initial compounds are recovered unaltered. All the compounds containing the PtHg bond react readily with CF₃COOH to give a new series of compounds of formula [Pt(O₂CCF₃)R(PPh₃)₂].     

Demercuriation reactions of the complexes [(PPh3)2RPtHgR′] containing platinum-mercury bonds

The compounds [(PPh₃)₂,RPtHgR′] (R = CH₃, R′= 2,5-C₆H₃Cl₂, 2,3,4- and 2,4,6-C₆H₂Cl₃, 2,3,4,5-, 2,3,4,6- and 2,3,5,6-C₆HCl₄, C₆Cl₅; R = Et, R′ = 2,5-C₆H₃Cl₂, 2,4,6-C₆H₂Cl₃; R = 2-C₆H₄Cl, R′=2-C₆H₄(CH₃)) have been prepared by the reactions of RHgR′ with Pt(PPh₃)₃, in order to study their possible use as intermediates in the preparation of diorganoplatinum complexes with different organic ligands. The dependence of J(³¹P-¹⁹⁵Pt) on slight differences in the electronic character of the ligand R′ in the series of compounds [(PPh₃)₂(CH₃)Pt-HgR′] has been studied.     

Chlorinated organic derivatives containing MoHg and WHg bonds: Importance of the steric effects in their stabilization

A series of MoHg and WHg bonded complexes [RHgM(CO)₃Cp], (R = 2,4,6-C₆H₂Cl₃,2,3,5,6-C₆,HCl₄ and C₆Cl₅) have been prepared from ClHgR and the salts Na[M(CO)₃)Cp]. When R contains only one ortho chlorine atom (R = 2,5-C₆H₃Cl₂, 2,3,4-C₆H₂Cl₃ and 2,3,4,5-C₆HCl₄) a symmetrisation process occurs to give the corresponding HgR₂ and Hg[M(CO)₃Cp)₂2. These results indicate that steric effects are very important in the formation of compounds containing molybdenum- or tungsten—mercury bonds. Complexes of the type [(C₆Cl₅)HgM(CO)₂(PPh₃)Cp] (M = Mo and W) are obtained from [(C₆Cl₅)HgM(CO)₃Cp] and PPh₃ in boiling ethanol.     

The platinum—carbon bond strength in Pt(PPh3)2(Cl)(CPhCHPh)

The enthalpies of the reactions 1 and 2 have been determined as ΔH = Pt(PPh₃)₂(CPhCPh)_cryst. + HCl_g → Pt(PPh₃)₂(Cl)(CPhCHPh)_cryst. (1) Pt(PPh₃)₂(CPhCPh)_cryst. + 2HCl_g → cis-Pt(PPh₃)₂Cl_2cryst. + trans-CHPhCHPh_g (2) ?90.2 ± 6 and ΔH = ?139.0 ± 16 kJ mol^?1, respectively; dissociation energies of bonds involving platinum are expressed by the relationship: 41 kJ mol^?1 + D(Pt-tolane) = 2D(PtCPhCHPh) = {D₁(PtCl) + D₂(PtCl)} ?350 kJ mol^?1     

Preparation and properties of new ferrocenyl heterobimetallic complexes with counterion dependent NLO responses

New ferrocenyl-based bimetallic cationic compounds of the type of (E)-[CpFe(η⁵-C₅H₄)(CHCH)(C₆H₄)CNRuCp(PPh₃)₂]X (X=PF₆, BF₄) and of (E)-[CpFe(η⁵-C₅H₄)(CHCH)(C₆H₄)CNFeCp(CO)₂]PF₆ have been obtained and characterized. The crystal structure of (E)-[CpFe(η⁵-C₅H₄)(CHCH)(C₆H₄)CNRuCp(PPh₃)₂]BF₄ has been established by means of X-ray diffractometry. The NLO responses of the compounds have been studied by the hyper-Rayleigh scattering technique and the hyperpolarizability is found to be dependent on the nature of the counterion.     

Synthesis of ylideplatinum(II) complexes via α-functionalised alkylplatinum(II) intermediates and some comparative data on palladium(II) complexes; X-ray structure of trans-[Pt(CH2PEt3)I(PEt3)2]I

The reaction of [Pt(PEt₃)₃] with CH₂I₂ affords trans-[Pt(CH₂PEt₃)I(PEt₃)₂]I and is believed to proceed via the α-functionalised alkyl cis-[Pt(CH₂I)I(PEt₃)₂], because similar ylides are obtained from cis- or trans-[PT(CH₂X)(PPh₃)₂X] (XCl, Br, or I) with PR₃ (PEt₃, PBu₃ⁿ, PMePh₂, PEtPh₂, or PPh₃); cis-[Pd(CH₂I)-I(PPh₃)₂] does not react with excess PPh₃, but with PEt₃ yields trans-[Pd(CH₂PEt₃)I(PPh₃)₂]I; the X-ray structure of trans-[Pt(CH₂PEt₃)I(PEt₃)₂]I (current R = 0.045) shows PtP(1) 2.332(7), PtP(2) 2.341(8), PtC 2.08(2), and PtI 2.666(2) Å, and angles (a) C(1)PtI, P(1), P(2): 176.9(8), 91.6(6), 93.4(6), (b) IPtP(1), P(2): 87.1(2), 88.5(2), and (c) P(1)P(2), 166.8(3), and (d) PtC(1)P(3), 118(1)°.     

Reactivity of polychlorophenylmercury compounds with 1,10-phenanthroline

The action of 1,10-phenanthroline (phen) on the THF solutions of RHgCl (R = 2,5-C₆H₃Cl₂; 2,3,4? and 2,4,6-C₆H₂Cl₃; 2,3,4,5?, 2,3,4,6?, and 2,3,5,6-C₄HCl₄ and C₆Cl₅) gives RHgCl (phen) when R contains two chlorine substituents in ortho (R = 2,4,6-C₆H₂Cl₃; 2,3,4,6?, and 2,3,5,6-C₆HCl₄ and C₆Cl₅), but the symmetrisation reaction occurs when R = 2,5-C₆H₃Cl₂; 2,3,4-C₆H₂Cl₃ and 2,3,4,5-C₆HCl₄. The action of phen on HgR₂ only gives HgR₂ (phen) when R = 2,3,4,5-C₆HCl₄. Compounds of the type RHgMe do not react with phen. These results indicate that steric citects are as important as the electronegativity of R in the formation of tetracoordinated mercury compounds.     

The preparation of cis- and trans-[PtH(C6Cl5)(PEt3)2 and a study of the “hydride-donor capacity” of the complexes trans- [PtH(C6X5(PEt3)2] (X = F and Cl)

The preparations of cis- and trans-[PtH(C₆Cl₅)(PEt₃)₂] by thermal decomposition of cis- and trans-[Pt(OCHO)(C₆Cl₅)(PEt₃)₂], respectively, are reported. Also described are cis- and trans-[Pt(SnCl₃)(C₆Cl₅)(PEt₃)₂], obtained by treating SnCl₂ with cis- and trans-[PtCl(C₆,Cl₅)(PEt₃)₂], respectively. It is shown that while trans- [PtH(C₆Cl₅)(PEt₃)₂] does not form hydride-bridged complexes in the presence of trans-(PtH(MeOH)(PEt₃)₂]⁺, the corresponding complex trans-[PtH(C₆)(PEt₃)₂] reacts with the same solvento complex, in methanol, giving labile [(PEt₃)₂HPt(-μH)Pt(C₆F₅)(PEt₃)₂]⁺.     

Synthesis and redistribution reactions of asymmetric σ-arylplatinum(II) complexes containing 4,7-phenanthroline

The mononuclear σ-aryl complexes of the type trans-[Pt(σ-C₆H₄R)(4,7-phen)(PPh₃)₂]OTf (R=4-CO₂Si^tBuPh₂, 4-CONHMe, 3-CO₂Si^tBuPh₂, 3-CONHMe; OTf=trifluoromethanesulfonate) containing a monodentate 4,7-phenanthroline (4,7-phen) ligand were prepared by an oxidative addition reaction of an aryl iodide with Pt(PPh₃)₄ to yield the key iodoplatinum(II) precursors trans-[PtI(σ-C₆H₄R)(PPh₃)₂], followed by halogen metathesis with one equivalent of 4,7-phen. The reaction of trans-[Pt(σ-C₆H₄R)(4,7-phen)(PPh₃)₂]OTf with labile complexes of the type trans-[Pt(OTf)L₂(σ-C₆H₄R′)] (L=PEt₃, R′=H; L=PPh₃, R′=4-CO₂Si^tBuPh₂, 3-CO₂Si^tBuPh₂, 3-CONHMe) afforded the asymmetric dinuclear complexes of the type trans-[Pt(σ-C₆H₄R)L₂(μ-4,7-phen)Pt(σ-C₆H₄R′)L′₂](OTf) ₂ (L=PPh₃, R=4-CO₂Si^tBuPh₂, L′=PEt₃, R′=H; L=L′=PPh₃, R=4-CONHMe, R′=4-CO₂Si^tBuPh₂; R=4-CO₂Si^tBuPh₂, R′=3-CONHMe; R=3-CONHMe, R′=3-CO₂Si^tBuPh₂) in which the 4,7-phen acts as a bridging bidentate ligand. The novel dinuclear species undergo an unusual redistribution reaction that is essentially thermoneutral at 298 K. The exchange process involves facile cleavage of a Pt-N bond and the rapid exchange of trans-[PtL₂(σ-aryl)] units in the equilibrium mixture.     

Organoplumbio complexes of platinum(II)

The complex [Pt(C₂H₄)(PPh₃)₂] reacts with Pb₂Ph₆ to give cis-[PtPh(Pb₂Ph₅)(PPh₃)₂]; this decomposes in solution to cis-[PtPh(PbPh₃)(PPh₃)₂], which may also be obtained from the ethylene complex and PbPh₄. Lead compounds PbPhMe₃ and PbPh₃Br also give products of insertion into PbPh bonds, but PbMe₃Cl gives cis- and trans-[PtCl(PbMe₃)(PPh₃)₂]. The complex trans-[Pt(PbPh₃)₂(PEt₃)₂] reacts with 1,2-bis(diphenylphosphino)ethane (DPPE) to give [Pt(PbPh₃)₂(DPPE)] which readily decomposes in dichloromethane in presence of PEt₃ to give [Pt(PbPh₃)(PEt₃)(DPPE)]Cl and [PtPh(PEt₃)(DPPE)]Cl. The complex trans-[PtCl(PbPh₃)(PEt₃)₂] was detected in the products of reactions between trans-[PtCl₂(PEt₃)₂] and trans-[Pt(PbPh₃)₂(PEt₃)₂] or less than 2 moles of LiPbPh₃; it was not detected in the mixture after treatment of trans -[Pt(PbPh₃)₂(PEt₃)₂] with HCl. In contrast to an earlier report, we were unable to detect lead-containing complexes in the products of the reaction between trans-[PtHCl(PPh₃)₂] and Ph₃PbNO₃. The complexes and their decomposition products were identified by ^pre31P-{¹H} NMR spectroscopy.     

Synthesis and phosphorus 31 n.m.r studies of neutral and cationic compounds with platinum-mercury bonds

Summary The preparation and properties of the following neutral and cationic compounds containing Pt-Hg bonds is described: [(PPh₃)₂ClPt-HgR] (R=2,4,6-C₆H₂Cl₃; 2,3,4,6- and 2,3,5,6-C₆HCl₄ and C₆Cl₅), and [(PPh₃)₂LPt-Hg(C₆Cl₅)]ClO₄ (L=pyridine, , and -picoline; 2,4-lutidine and -colidine). All the compounds have been characterized by³¹P n.m.r. spectroscopy. The dependence of P, J(³¹P-¹⁹⁵Pt) and²J(³¹P-¹⁹⁹Hg) on the slight changes of the electronic properties of the ligands L and R has been studied.     

Metal-thiophen derivatives. Organometallic compounds of palladium and platinum

Thienylmercury(II)chloride reacts with [Pd(PPh₃)₂Cl₂], [Pd(PPh₃)₄] and [Pt(PPh₃)₄] to afford new compounds containing a metal-2-thienyl linkage. The compound [Pd(PPh₃)₂(2-C₄H₃S)Cl] probably has trans stereochemistry.2-Bromothiophen undergoes oxidative addition with [Pd(PPh₃)₄] and [Pt(PPh₃)₄], probably via a radical mechanism. With [Pd(CO)(PPh₃)₃], a carbonyl inserted product is obtained. The bromo-metal(II) complexes have trans stereochemistry. The course of the reaction between 3-methyl-2-bromothiophen and Pd(PPh₃)₄ is more complex. Thus, there is evidence of some cis bromopalladium(II) compounds amongst the products, also there is good evidence to support the view that some isomerisation of 3-methyl-2-thienyl to 4-methyl-2-thienyl occurs during the reaction, thus giving greater molar quantities of [Pd(PPh₃)₂(4-CH₃-2-C₄H₂S)Br] than can be accounted for from any initial 4-methyl-2-bromothiophen impurity.The metallation of the thiophen ring, probably in the 4-position, with palladium(II) is described for 3-theylidene-4-methylaniline.     

Trifluoromethylselenato(0) and trifluoromethyltellurato(0) complexes of platinum(II)

The series of cis/trans-trifluoromethylselenato complexes [Pt(SeCF₃)_2 − xCl_x(PPh₃)₂] (x = 0, 1) was identified by NMR spectroscopic methods. While in acetonitrile solution spectra are dominated by the resonances of the cis derivatives, those of pure cis-[Pt(SeCF₃)₂(PPh₃)₂] indicate cis-trans-isomerisation in CH₂Cl₂ solution. In contrast, exchange reactions of cis-[PtCl₂(PPh₃)₂] and [NMe₄]TeCF₃ only gave evidence for cis isomers. Molecular structures of cis- and trans-[Pt(SeCF₃)₂(PPh₃)₂] and cis-[Pt(TeCF₃)₂(PPh₃)₂] are discussed in comparison with related compounds.     

Hydridocyanoalkyl complexes of platinum(II). Insertion of olefins into the PtH bond

The preparation and spectroscopic properties are described of some platinum(II) complexes having a hydride ligand cis or trans to an sp³ carbon, viz. trans-PtH(YCN)(PPh₃)₂ and cis-PtH(YCN)(LL) with YCN = C₂H₄CN, n-C₃H₆CN, o-CH₂C₆H₄CN and LL = bis(diphenylphosphino)-ethene or -ethane. The complexes trans-PtH(YCN)(PPh₃)₂ can add a fifth ligand in solution; the resulting five-coordinate complex was observed by ³¹P NMR in the case of PtH(C₃H₆CN)(PPh₃)₃. Insertion of olefin (ethen, 1-cyanoethene, norbornadiene, allen) into the PtH bond of the trans-hydrido complexes occurs to give cis-dialkyl complexes, but the cis-hydrido complexes are unreactive. The mechanism of insertion is discussed in terms of the kinetics and the geometries of reactants and products.     

Ligand effects on the Pt(II) → Pt(0) reduction of dichlorobis(tertiary phosphine)platinum(II) complexes: Correlations between electrochemical data,spectroscopic data,and electronic ligand parameters

Cyclic voltammetry has been employed to study the diffusive, irreversible platinum(II) → platinum(0) reduction of three sets of structurally related complexes: cis-[PtCl₂P{p-C₆H₄X}₃)₂] (X = H, CH₃, Cl, F, OCH₃, N(CH₃)₂); cis-[PtCl₂(PPh₂R)₂] (R = CH₃, n-C₃H₇, n-C₅H₁₁, n-C₆H₁₃, n-C₁₂H₂₅) and cis-[PtCl₂(PR₃)₂] (R = CH₃, C₂H₅, CH₂ch₂CN). Relationships between the peak potentials for the Pt(II) → Pt(0) reduction and thermodynamic parameters which measure the electronic properties of the ligands are shown to exist for complexes of P{p-C₆H₄X}₃ ligands, implying a thermodynamic origin for the sensitivity of the peak potentials to structural change. Complexes of both P{p-C₆H₄X}₃ and PPh₂R ligands show correlations between peak potentials for reduction and the ³¹P{¹H} NMR spectroscopic parameter, ¹J(¹⁹⁵Pt, ³¹P). Correlations with values of δ(³¹P) exist in both cases, but a correlation with the coordination chemical shift, Δδ(³¹P), exists for complexes of PPh₂R, and not for complexes of P{C₆H₄X}₃. Complexes of PR₃ ligands show no correlation between the peak potentials measured for the Pt(II) → Pt(0) reduction and electronic or spectroscopic parameters, except possibly ¹J(¹⁹⁵Pt, ³¹P).     

Binuclear hydroxo-monopentahalophenyl complexes of palladium(II)

The novel binuclear hydroxo-bridged complexes trans-[R(PPh₃)Pd(μ-OH)₂Pd(PPh₃)R] and cis-[R(PPh₃)Pd(μ-OH)(μ-pz)Pd(PPh₃)R] (R = C₆F₅ or C₆Cl₅; pz = pyrazolate) have been prepared, and their structures assigned on the basis of NMR data.     

Cumulated double bond systems as ligands : IV. 1H and 13C NMR studies of the intra- and inter-molecular exchange processes of cationic dialkylsulfurdiimine compounds of RhI,IrI and PtII

The preparation and properties are described of trans-[(Ph₃P)₂(CO)M(RNSNR)] [ClO₄] (M  Rh^I, Ir^I; R  Me, Et, i-Pr, t-Bu) and of cis- or trans-[L₂Pt(RNSNR)X] [ClO₄] (X  Cl^?, L  Et₂S, PhMe₂As, PhMe₂P, R  Me, t-Bu; X  CH₃, L  PhMe₂P, R  Me).¹H and ¹³C NMR data show the existence of various isomers in solution which may interconvert via intra- and inter-molecular exchange processes. A general reaction scheme for the intramolecular exchange processes is discussed.     

Oxidative addition of boron–boron, boron–chlorine and boron–bromine bonds to platinum(0)

The synthesis and spectroscopic characterisation of the new diborane(4) compounds B₂(1,2-O₂C₆Cl₄)₂ and B₂(1,2-O₂C₆Br₄)₂ are reported together with the diborane(4) bis-amine adduct [B₂(calix)(NHMe₂)₂] (calix=Bu^tcalix[4]arene). B–B bond oxidative addition reactions between the platinum(0) compound [Pt(PPh₃)₂(η-C₂H₄)] and the diborane(4) compounds B₂(1,2-S₂C₆H₄)₂, B₂(1,2-O₂C₆Cl₄)₂ and B₂(1,2-O₂C₆Br₄)₂ are also described which result in the platinum(II) bis-boryl complexes cis-[Pt(PPh₃)₂{B(1,2-S₂C₆H₄)}₂], cis-[Pt(PPh₃)₂{B(1,2-O₂C₆Cl₄)}₂] and cis-[Pt(PPh₃)₂{B(1,2-O₂C₆Br₄)}₂] respectively, the former two having been characterised by X-ray crystallography. In addition, the platinum complex [Pt(PPh₃)₂(η-C₂H₄)] reacts with XB(1,2-O₂C₆H₄) (X=Cl, Br) affording the mono-boryl complexes trans-[PtX(PPh₃)₂{B(1,2-O₂C₆H₄)}] as a result of oxidative addition of the B–X bonds to the Pt(0) centre; the chloro derivative has been characterised by X-ray crystallography.     

Insertion of isocyanides into the palladium-(2-pyridyl) bond

The reaction of the pyridyl-bridged binuclear complex [PdBr(μ-2-C₅H₄N)(PPh₃)]₂ with isocyynides CNR (R  p-C₆H₄OMe, Me, C₆H₁₁) yields the complex $\text{PdBr}${(&2.dbnd;NR)C(&2.dbnd;NR) (2-C₅H₄N)}(PPh₃)] containing a C,N-chelated 1,2-bis(imino)-2-(2-pyridyl)ethyl group, which results from successive insertions of two isocyanides molecules into the palladium2-pyridyl bond. The mononuclear compound trans-[PdBr(2-C₅H₄N)(PMePh₂)₂] readily reacts with various CNR ligands (R  p-C₆H₄OMe, Me, C₆H₁₁, CMe₃) to give the imino(2-pyridyl)methylpalladium(II) derivatives, trans-[Pdbr{C(=NR)(2-C₅H₄N)} (PMePh₂)₂].