Synthesis and spectroscopy of cis-configured mononuclear palladium(II) and platinum(II) complexes of chalcogeno o-carboranes and structures of [Pt(SCboPh)2(dppm)], [Pt(SeCboPh)2(dppm)], [Pt(SCboS)(PMe2Ph)2] and [Pt(SCboS)(PMePh2)2]

The reactions of [MCl₂(P^∩P)] and [MCl₂(PR₃)₂)] with 1-mercapto-2-phenyl-o-carborane/NaSeCb^oPh and 1,2-dimercapto-o-carborane yield mononuclear complexes of composition, [M(SCb^oPh)₂(P^∩P)], [M(SeCb^oPh)₂(P^∩P)] (M = Pd or Pt; P^∩P = dppm (bis(diphenylphosphino)methane), dppe (1,2-bis(diphenylphosphino)ethane) or dppp (1,3-bis(diphenylphosphino)propane)) and [M(SCb^oS)(PR₃)₂] (2PR₃ = dppm, dppe, 2PEt₃, 2PMe₂Ph, 2PMePh₂ or 2PPh₃). These complexes have been characterized by elemental analysis and NMR (¹H, ³¹P, ⁷⁷Se and ¹⁹⁵Pt) spectroscopy. The ¹J(Pt–P) values and ¹⁹⁵Pt NMR chemical shifts are influenced by the nature of phosphine as well as thiolate ligand. Molecular structures of [Pt(SCb^oPh)₂(dppm)], [Pt(SeCb^oPh)₂(dppm)], [Pt(SCb^oS)(PMe₂Ph)₂] and [Pt(SCb^oS)(PMePh₂)₂] have been established by single crystal X-ray structural analyses. The platinum atom in all these complexes acquires a distorted square planar configuration defined by two cis-bound phosphine ligands and two chalcogenolate groups. The carborane rings are mutually anti in [Pt(SCb^oPh)₂(dppm)] and [Pt(SeCb^oPh)₂(dppm)].     

Synthesis, spectroscopy and structures of palladium(II) and platinum(II) complexes containing mercapto-o-carborane

The reactions of [M₂Cl₂(μ-Cl)₂(PMe₂Ph)₂] with mercapto-o-carboranes in the presence of pyridine afforded mono-nuclear complexes of composition, [MCl(SCb°R)(py)(PMe₂Ph)] (M = Pd or Pt; Cb° = o-C₂B₁₀H₁₀; R = H or Ph). The treatment of [PdCl₂(PEt₃)₂] with PhCb°SH yielded trans-[Pd(SCb°Ph)₂(PEt₃)₂] (4) which when left in solution in the presence of pyridine gave another substitution product, [Pd(SCb°Ph)₂(py)(PEt₃)] (5). The structures of [PdCl(SCb°Ph)(py)(PMe₂Ph)] (1), [Pd(SCb°Ph)₂(PEt₃)₂] (4) and [Pd(SCb^oPh)₂(py)(PEt₃)] (5) were established unambiguously by X-ray crystallography. The palladium atom in these complexes adopts a distorted square-planar configuration with neutral donor atoms occupying the trans positions. Thermolysis of [PdCl(SCb°)(py)(PMe₂Ph)] (2) in TOPO (trioctylphosphine oxide) at 200 °C gave nanocrystals of TOPO capped Pd₄S which were characterized by XRD pattern and SEM.     

Synthesis and spectroscopy of cis-configured mononuclear palladium(II) and platinum(II) complexes of chalcogeno o-carboranes and structures of [Pt(SCboPh)2(dppm)], [Pt(SeCboPh)2(dppm)], [Pt(SCboS)(PMe2Ph)2] and [Pt(SCboS)(PMePh2)2]

The reactions of [MCl₂(P^∩P)] and [MCl₂(PR₃)₂)] with 1-mercapto-2-phenyl-o-carborane/NaSeCb^oPh and 1,2-dimercapto-o-carborane yield mononuclear complexes of composition, [M(SCb^oPh)₂(P^∩P)], [M(SeCb^oPh)₂(P^∩P)] (M = Pd or Pt; P^∩P = dppm (bis(diphenylphosphino)methane), dppe (1,2-bis(diphenylphosphino)ethane) or dppp (1,3-bis(diphenylphosphino)propane)) and [M(SCb^oS)(PR₃)₂] (2PR₃ = dppm, dppe, 2PEt₃, 2PMe₂Ph, 2PMePh₂ or 2PPh₃). These complexes have been characterized by elemental analysis and NMR (¹H, ³¹P, ⁷⁷Se and ¹⁹⁵Pt) spectroscopy. The ¹J(Pt–P) values and ¹⁹⁵Pt NMR chemical shifts are influenced by the nature of phosphine as well as thiolate ligand. Molecular structures of [Pt(SCb^oPh)₂(dppm)], [Pt(SeCb^oPh)₂(dppm)], [Pt(SCb^oS)(PMe₂Ph)₂] and [Pt(SCb^oS)(PMePh₂)₂] have been established by single crystal X-ray structural analyses. The platinum atom in all these complexes acquires a distorted square planar configuration defined by two cis-bound phosphine ligands and two chalcogenolate groups. The carborane rings are mutually anti in [Pt(SCb^oPh)₂(dppm)] and [Pt(SeCb^oPh)₂(dppm)].     

Methyl- and phenyl-bis(tertiary phosphine) N-bonded carboxamido complexes of platinum(II)

Methyl- or phenylN-carboxamido-complexes of platinum(II) Pt(NHCOR')RL₂ (L = PEt₃, R = Me, R′ = Me, CH = CH₂; L = PEt₃, R = Ph, R′ = Me; L = PMe₂Ph, R = Ph, R′ = Me, Ph; L = PMePh₂, R = Ph, R′ =₃, R = Ph, R′ = Me) have been prepared by the reaction of KOH with cationic nitrile complexes [PtR(NCR′)L₂]BF₄. Thermally unstable hydrido-N-carboxamido-complexes could be detected spectroscopically. IR and NMR (¹H, ³¹P) spectra of some of the complexes indicate the existence of a solvent- and temperature-dependent equilibrium between syn-and anti-isomers arising from restricted rotation about the NC bond of the carboxamido-group. The anti-isomer is favoured by nonpolar solvents and by increasing bulk of L. In the complex [PtH(NCCH CH₂)(PEt₃)₂]BF₄, IR and NMR spectra show acrlonitrile to be bound through nitrogen, not through the olefinic CC bond.     

A cyclometallated iridium(III) dimethylphenylphosphine complex

[Ir(cod)Cl]₂ (cod = 1,5-cyclooctadiene) reacts with PMe₂Ph in CH₃CN to give the red cation [Ir(PMe₂Ph)₄]⁺. This complex in CH₃CN reacts with H₂ to give cis-[IrH₂(PMe₂Ph)₄]⁺, but on reflux for 6 h in the absence of H₂, it gives the first example of a cyclometallated PMe₂Ph complex fac-[IrH(PMe₂C₆H₄)(PMe₂Ph)₃]⁺, as shown by PMR spectroscopy and preliminary X-ray crystallographic data.     

Synthetic and spectroscopic studies of some mono-hydrido-bridged complexes of platinum(II)

The mono-hydrido-bridged complexes (PEt₃)₂(Ar)Pt(μ₂-H)Pt(Ar)(PEt₃)₂]-[BPh₄] (Ar = Ph, 4-MeC₆H₄ and 2,4-Me₂C₆H₃) have been obtained by treating trans-[Pt(Ar)(MeOH)(PEt₃)₂][BF₄] with sodium formate and Na[BPH₄]. The cations [PEt₃)₂(Ar)Pt(μ₂-H)Pt(Ar^b')(PEt₃)₂]^b+ (Ar = Ph and Ar^b' - 2,4-Me₂C₆H₃ and 2,4,6-Me₃C₆H₂ have bee identified in solution. Their ^b1H- and ^b31P-NMR data are reported. The X-ray crystal structure of [(PEt₃)₂(Ph)Pt(μ₂-H)Pt(Ph)(PEt₃)₂][BPh₄] is reported.     

Some diolefin complexes of iridium(I) and a trans-influence series for the complexes [IrCl(cod)L]

A high-yield synthesis of [IrCl(cod)]₂ (cod = 1,5-cyclooctadiene) is described. The ¹H and ¹³C NMR spectra of a number of complexes [IrCl(cod)L] are interpreted in terms of a trans-effect series Cl^? < sym-collidine < 2-picoline < PCy₃ < P-i-Pr₃ < Pet₃ ～ AsPh₃ < PMe₂Ph < PMePh₂ < PPh₂ <P(MeO)Ph₂ < PClPh₂ < P(OPh)₃ < PCl₂Ph. Some ligand exchange reactions of [IrCl(cod)L] are discussed. A number of complexes of the type [Ir(cod)L_n]PF₆ (L = a variety of amines (n = 2) and phosphines (n = 2 or 3)) are described. Exchange reactions of the sort: [Ir(cod)(PR₃)₂]PF₆ + [Ir(cod)(py)₂]PF₆ ? [Ir(cod)(PR₃)Py]PF₆ are reported in which, surprisingly, the isolable mixed ligand complexes are the only detectable species at equilibrium (py = pyridine).     

Preparative and NMR studies of 1,3-dienecobalt(I) complexes

The synthesis and the characterization of cobalt(I) complexes of the type [Co(diene)(phosphine)₃]Y (diene = 1,3-butadiene and isoprene; phosphine = PMe₃, PMe₂Ph, and HPPh₂; Y = ClO₄, BF₄, or BPh₄) are reported. The fluxional nature of the five-coordinate cations [Co(diene)(phosphine)₃]⁺ is shown by variable-temperature NMR spectroscopy (¹H and ³¹P). Low-temperature spectra are consistent with a square-pyramidal structure in which the diene occupies two basal coordination sites.     

The isolation of intermediates in hydrogen halide additions to some iridium complexes

The complexes [Ir(cod)L_n]PF₆(I, L = PPh₃, PMePh₂; n = 2. L = PMe₂Ph; n = 3) react with HX to give [IrHX(cod)L₂]PF₆ (II, L = PMePh₂ or PMe₂Ph) or [IrHX₂(cod)(PPh₃)] (III). The intermediates [IrX(cod)L₂] have, in two cases (L = PMePh₂, X = I, Br), been directly isolated from the reaction mixtures at 0°C, and are also formed from I with KX (L = PPh₃, X = Cl; L = PMePh₂, X = Cl, Br, I); these intermediates protonate to give II (L = PMePh₂), or an equimolar mixture of III and I (L = PPh₃, X = Cl). Surprisingly, I₂ reacts with I in MeOH to give III (L = PPh₃). The stereochemistries of II and III were determined by < ¹H NMR and especially by new methods using ¹³C NMR spectroscopy. The complexes I exhibit a Lewis acid reactivity pattern.     

Transition metalcarbon bonds XXXVII. platinum acetylide complexes formed from ethynyl alcohols or ethers

Several new platinum(II) acetylide complexes, trans-{Pt[CCCR₁R₂(OR₃)]₂-L₂} (R₁, R₂  H, Me, Et; CR₁R₂  cyclohexylidene; R₃  H, Me or Ph), trans-[Pt(CCCH₂CH₂OH)₂L₂], trans-[Pt(p-tolylacetylide)₂L₂] and trans-[PtX(p-tolylacetylide)L₂] (L  PMe₂Ph or in one case, AsMe₂Ph) have been prepared. Platinum(II) acetylide complexes with tertiary hydroxyl groups are easily dehydrated by acetic anhydride/pyridine to give platinum-enyne complexes. Analogous compounds with primary hydroxyl groups do not dehydrate but give acetates. ¹H and ¹³C NMR data are given and the shift reagent Eu(fod)₃ was used to analyse the ¹H NMR spectrum of trans-[Pt(CCCH₂CH₂OH)₂(PMe₂Ph)₂].     

Four- and five-coordinate palladium(II) complexes containing 1,10-phenanthroline and its 2,9-dimethyl derivative

A series of potentially five-coordinate Pd(II) complexes, [Pd(PMe₂Ph)₃(2,9-R₂-phen)][BF₄]₂ (R = H or Me; phen = 1,10-phenanthroline     

Phosphine carbonyl-technetium(I) and -technetium(III) complexes

Treatment of trans-[TcX₄L₂] (X Cl, Br and L PPH₃, PMe₂Ph) with carbon monoxide (1 atm) in boiling ethyleneglycol methyl ether, gives trans-[TcX-(CO)₃L₂]. Under these conditions the mer-[TcX₃(PMe₂Ph)₃] (X Cl, Br) gives a mixture of the trans-[TcX(CO)₃(PMe₂Ph)₂] and cis-[TcX(CO)₂(PMe₂Ph)₃] complexes, but when added free dimethylphenylphosphine is present only the second product is obtained. Carbon monoxide reacts with mer-[TcCl₃(PMe₂Ph)₃] in refluxing ethanol to give [TcCl₃(CO)(PMe₂Ph)₃] a C_{3 v} seven-coordinate technetium(III) complex.The stereochemistry of the complexes was determined from their IR and¹H NMR spectra.     

New cationic palladium (II) and rhodium (I) complexes of [Ph2PCH2C(Ph)N(2,6-Me2C6H3)]

Treatment of the bulky iminophosphine ligand [Ph₂PCH₂C(Ph)N(2,6-Me₂C₆H₃)] (L) with [M(CH₃CN)₂(ligand)]⁺ⁿ, where for M = Pd(II): ligand = η³-allyl, n = 1, and for M = Rh(I), ligand: 2(C₂H₄), 2(CO) or cod, n = 0, yields the mono-cationic iminophosphine complexes [Pd(η³-C₃H₅)(L)][BF₄] (1), [Rh(cod)(L)][BF₄] (2), [Rh(CO)(CH₃CN)(L)][BF₄] (3), and cis-[Rh(L)₂][BF₄] (4). All the new complexes have been characterised by NMR spectroscopy and X-ray diffraction. Complex 1 shows moderate activity in the copolymerisation of CO and ethene but is inactive towards Heck coupling of 4-bromoacetophenone and n-butyl acrylate.     

Fulvene—platinum complexes: x-ray crystal structure of [Pt(η2-C5H4CPh2)(PPh3)2]

Bis(cycloocta-1,5-diene)platinum reacts with 2,3,4,5-tetraphenylfulvene to afford the complex [Pt(η²-CH₂C₅Ph₄)(cod)] (cod  C₈H₁₂) in which the metal atom is coordinated to the exo-cyclic double bond of the fulvene. Related compounds [Pt(η²-CH₂C₅Ph₄L₂] (L  PPh₃, PMePh₂, PMe₂Ph, AsPh₃ or CNBu^t have also been prepared and characterised. Reaction of the complexes [Pt(C₂H₄)₂(L)] (L  P(cyclo-C₆H₁₁)₃, PPh₃ or AsPh₃) with 2,3,4,5-tetraphenylfulvene yields the compounds [Pt(C₂H₄)(η²-CH₂C₅PH₄)(L)]. NMR data for the new species are reported and discussed. 6,6-Diphenylfulvene reacts with [Pt(cod)₂] and PPh₃ ($\text{1}\text{2}$ mol ratio) to give the complex [Pt(η²-C₅H₄CPh₂)-(PPh₃)₂] in which the metal atom is bonded to carbon atoms C(2) and C(3) of the fulvene ring. This was established by an X-ray diffraction study. Crystals are monoclinic, space group P2₁/n, with Z  4 in a unit cell of dimensions a  13.761(4), b  21.653(13), c  17.395(6) Å, β,  104.46(2)°. The structure has been solved and refined to R  0.064 (R′  0.064) for 3139 independent diffracted intensifies measured at room temperature. The platinum atom is in a trigonal environment formed by the two ligated phosphorus atoms and the CC bond of the fulvene which is elongated to 1.52(3) Å. The c₅ fulvene ring is planar, and makes an angle of 108° with the coordination plane around the platinum. In this plane the metal atom is slightly asymmetrically bonded with PtC 2.15(2) and 2.24(2) Å, and PtP 2.280(6) and 2.301(6) Å.     

Six-membered cyclometallated derivatives of platinum(II) derived from 2-benzylpyridines. Crystal and molecular structure of [Pt(L)(Ph3P)Cl] (HL = 2-(1-methylbenzyl)pyridine)

The reaction of K₂[PtCl₄] with 2-(1-methylbenzyl)pyridine, HL, and 2-benzylpyridine, HL', affords the cyclometallated species [{Pt(L)Cl}₂] (1) and [{Pt(L')Cl}₂] (2), respectively. The chloride bridge in complex 1 can be split by neutral or anionic species to give the monomeric, [Pt(L)(Ph₃P)Cl], as two isomers, trans-P-Pt-C (3) and trans-P-Pt-N, (4), [Pt(L)(py)Cl] (5), [Pt(L)(CO)Cl] (6), [Pt(L)(CNCH₂SO₂C₆H₄CH₃-4)Cl] (7), [Pt(L)(acac)] (Hacac = 2,4-pentanedione) (8), [Pt(L)(dppm)][BF₄] (dppm = bis(diphenyl-phosphino)methane) (9), [Pt(L)(dppe)][BF₄] (dppe = bis(diphenylphosphino)ethane) (10) and [Pt(L)(dipy)][BF₄](dipy = 2,2'-dipyridine) (11). Similarly, compound 2, by reaction with Ph₃P, affords [Pt(L')(Ph₃P)Cl], as two isomers, trans-P-Pt-C (12) and trans-P-Pt-N (13). Reaction of compounds 1 or 4 with AgBF₄ in acetonitrile affords [Pt(L)(CH₃CN)₂IBF₄] (14) or [Pt(L)(Ph₃P)-(CH₃CN)][BF₄] (15). From these, [Pt(L)(Ph₃P)₂][BF₄] (16), [Pt(L)(Ph₃P)(CO)][BF₄] (17) and [Pt(L)(Ph₃P)(py)][BF₄] (18), can be obtained by displacement of the coordinated acetonitrile. The new complexes were characterized by IR, ¹H and ³¹P NMR and FAB-MS spectroscopic techniques. The NMR spectra at room temperature of most of the species derived from HL give evidence for the presence in solution of two diastereomers a and b. The structure of one diastereomer of complex 4 has been solved by single crystal X-ray diffraction, 4b. The platinum atom is in an almost square planar geometry with a P-Pt-N trans arrangement: Pt-N = 2.095(3), Pt-C = 1.998(4), Pt-P = 2.226(1) and Pt-Cl = 2.400(1) Å. The six-membered cyclometallated ring is in a boat conformation, with the CH₃ group in an equatorial position, i.e pointing away from the metal. Attempts to obtain [{Pt(L″)Cl}₂] (HL″ = 2-(dimethylbenzyl)pyridine), afforded an insoluble product heavily contaminated by platinum metal; treatment of this crude material with Ph₃P gave [Pt(L″)(Ph₃P)Cl] (19).     

Oxidative Coordination versus C3−C(O)Me Bond Cleavage in Acetylacetonate Iridium Complexes

Iridabicycles [Ir{κ³-N,C,O-(pyC(H)=C(C(O)Me)₂}(Cl)(L−L)](L−L=cod (cod=1,5-cyclooctadiene), 1 a ; bipy (bipy=2,2’-bipyridine), 1 b ) have been obtained by oxidative coordination of 3-(pyridine-2-yl-methylene)pentane-2,4-dione L1 , to the complexes [{Ir(μ-Cl)(cod)}₂] and [{Ir(μ-Cl)(coe)₂}₂] (coe=cis-cyclooctene), the latter in the presence of bipy. Remarkably, cleavage of the C³−C(O)Me bond of L1 has instead been achieved in the reaction with [Ir(Cl)(dmb)₂] (dmb=2,3-dimethylbutadiene), yielding a compound formulated as [Ir{κ²-N,C-(pyC(H)C(C(O)Me))}(CO)(μ-Cl)(Me)]₂, 2 . Treatment of dimer 2 with DMSO or PMe₃ produced the complexes[Ir{κ²-N,C-(pyC(H)C(C(O)Me)}(CO)Cl(Me)L] (L=DMSO, 3 a ; PMe₃, 3 b ). Plausible mechanisms for the reactions leading to complexes 1 and 2 are proposed by means of DFT calculations.     

New Rhodium Complexes Coordinated by Bidentate Imine Ligands with Benzothiazolyl Functionalities

The pseudo‐square‐planar complexes [Rh(cod)(Hbbtm)]BF₄ ( 3 ), [Rh(bbte)(cod)]BF₄ ( 4 ), [Rh(CO)₂(Hbbtm)]BF₄ ( 5 ), [Rh(bbte)(CO)₂]BF₄ ( 6 ), [Rh(bbtm)(cod)] ( 7 ) and [Rh(bbtm)(CO)₂] ( 8 ) (Hbbtm=bis(benzothiazol‐2‐yl)methane=2,2′‐methylenebis[benzothiazole], bbte=bis(benzothiazol‐2‐yl)ethane=2,2′‐(ethane‐1,2‐diyl)bis[benzothiazole], and cod=cycloocta‐1,5‐diene) were synthesized and characterized. Diastereotopic protons were observed for the protons at the bridge in the ¹H‐NMR of 3 and 5 . Twisting of the ethane‐1,2‐diyl bridge in 4 and 6 effects chemical equivalence of the CH₂ groups in solution. Unusually large downfield shifts occur on coordination of the deprotonated ligand Hbbtm as the negative charge is delocalized in 7 and 8 . The NMR signals of the cod ligand in 4 could be differentiated. The X‐ray crystal structures of 3, 4 , and 6 are reported.     

Some trimethyl phosphine and trimethyl phosphite complexes of tungsten(IV)

Direct reduction of WCl₆ with PMe₃ in toluene at 120°C in a sealed tube affords the complexes [WCl₄(PMe₃)_x] (x = 2, 3). [WCl₄(PMe₃)₃] abstracts oxygen from equimolar amounts of water in wet acetone or tetrahydrofuran to give [WOCl₂(PMe₃)₃] in very high yields. This procedure has been successfully applied to the high yield synthesis of other known oxotungsten(IV) complexes, [WOCl₂(PR₃)₃] (PR₃ = PMe₂Ph and PMePh₂). Metathesis reactions of [WOCl₂(PMe₃)₃] with NaX give [WOX₂(PMe₃)₃] (X = NCO, NCS) and [WOX₂(PMe₃)] (X = Me₂NCS₂). The synthesis of the trimethylphosphite analogue, [WOCl₂(P(OMe)₃)₃], is also described and the structures of the new complexes assigned on the basis of IR and ¹H and ³¹P NMR spectroscopy.     

Rhodium-catalyzed carbonyl allylations by allylic alcohols with tin(II) chloride

Rhodium complexes such as [RhCl(cod)]₂, [Rh(cod)₂]BF₄, and [Rh(cod)(CH₃CN)₂]BF₄ function as catalysts for carbonyl allylations by allylic alcohols with 1 equimolar amount of tin(II) chloride to each allylic alcohol and aldehyde in THF at 50 °C to produce the corresponding homoallylic alcohols.