Mononuclear Complex Trans Research Articles

Palladium(II) Complexes of (2,6‐Dibenzhydryl‐4‐methylphenyl)diphenyl‐phosphane: Synthesis, Structural Studies, and Catalytic Arylation of Imidazoles Under Aerobic Conditions

AbstractThe synthesis and structural studies of palladium(II) complexes of sterically demanding mono‐phosphine Ar*PPh2 (1) (Ar*=2,6‐dibenzhydryl‐4‐methylphenyl) are described. The reactions of 1 with [Pd(COD)Cl2] and [Pd(η3‐C3H5)Cl]2 in 2 : 1 molar ratios afforded mononuclear complexes trans‐[PdCl2{(PPh2Ar*)‐κ1‐P}2] (2) and [Pd(η3‐C3H5)Cl{(PPh2Ar*)‐κ1‐P}] (3), respectively. Both the complexes have been fully characterized through NMR spectroscopy, elemental analyses, and single‐crystal X‐ray analysis. The molecular structures of 2 and 3 showed C−H⋅⋅⋅π interactions between methine hydrogen of one of the Ph2CH groups with the centroid of one of the phenyl rings of the PPh2 group. Complex 2 also showed intramolecular π⋅⋅⋅π stacking interactions between the phenyl rings of Ph2CH and PPh2 groups. In addition, complex 2 also showed C−H⋅⋅⋅Pd anagostic interaction between the methine hydrogen of one of the Ph2CH groups and the palladium center. The palladium complex 2 is found to be an efficient catalyst for the direct C‐5 arylation of imidazole derivatives under aerobic conditions.

Mononuclear cobalt(III) azido complex containing a tetradentate amine: one pot synthesis, structure and thermal behavior

One hexacoordinated mononuclear complex trans-[Co(L)(N3)2] PF6 (1) [L = N,N′-bis(3-aminopropyl)- 1,2-ethanediamine] is prepared by using one-pot reactions of the building units and characterized. X-ray analysis shows that cobalt center in 1 adopts a distorted octahedral geometry with CoN6 chromophore ligated through four N atoms of tetradentate amine (L) and the two N atoms of terminal azides in mutual trans orientation. In the crystalline state, double N-H…N and multiple N-H…F hydrogen bondings result in 2D sheet structure. The compound has a thermal stability up to 193°C.
 Bangladesh J. Sci. Ind. Res. 57(2), 109-116, 2022

Solvent-Dependent Reactivity and Photochemistry of Dinuclear and Mononuclear Platinum(IV) Azido Triazaolato Complexes.

Reaction between the platinum(IV) azido complex trans,trans,trans‐[Pt(py)2(N3)2(OH)2] (1) and 1,4‐diphenyl‐2‐butyne‐1,4‐dione 2 in MeCN produces the intermediate peroxide‐bridged dimeric platinum(IV) azido triazolato species (5), which has been characterised by X‐ray crystallography. However, if the reaction between 1 and 2 is conducted in MeOH it results in decomposition. Over time in MeCN, dimer (5) converts into mononuclear complexes trans,trans,trans‐[Pt(py)2(N3)(triazole)(OH)2] (3 a/3 b), which are in dynamic exchange. If resuspended in protic solvents (MeOH,H2O), 3 a/3 b undergo a slow (22 d) irreversible rearrangement to a cyclised platinum(IV) species 4 which contains a formally N,O‐chelated ligand. Conversion of 3 a/3 b to 4 in d 4‐MeOH can be accelerated (384x) by irradiation with visible light, although continued irradiation also produces N3 . and OH. radicals, and the [4‐N3]+ species can be readily detected by ESI‐MS. Solvent choice significantly effects both the cycloaddition reaction between 1 and 2, and the stability of the resultant complexes.

The heterotopic divergent ligand N-oxide-4,4′-bipyridine (bipyMO) as directing-agent in the synthesis of oligo- or polynuclear heterometallic complexes

The simple but rarely used heterotopic divergent ligand N-oxide-4,4′-bipyridine (bipyMO) has been exploited, for the first time, for the preparation of heterometallic derivatives, showing the ability to selectively use its two potential coordination sites in dependence of the metal ion nature. By reacting in refluxing acetonitrile ∞1[Cu(hfac)2(bipyMO)] with ∞1[Mn(hfac)2(bipyMO)] (herein completely characterized), the heterometallic self-assembled monodimensional coordination polymer containing the two regularly alternated moieties Cu(hfac)2[N]2 and Mn(hfac)2[O]2 was obtained in high yield and purity and structurally characterized. On the other hand, a molecular heterometallic compound was obtained using, as a ligand, the here prepared mononuclear complex trans-[PtCl2(bipyMO)(PPh3)], with the hypodentate bipyMO ligand coordinated to platinum through the nitrogen atom. Reaction with [Zn(hfac)2(DME)] afforded the heterometallic trinuclear complex trans[Zn(hfac)2{trans-PtCl2(PPh3)(bipyMO)}2] that was structurally characterized.

Oxidative addition of some mono, di or tetra haloalkanes to organoplatinum(II) complexes

Dimethylplatinum(II) complexes [PtMe2(NN)] {NN = bpy (2,2′-bipyridine), phen (1,10-phenanthroline) or bu2bpy (4,4′-di-tert-butyl-2,2′-bipyridine)} were reacted with alkyl halides (RX = EtI or EtBr, NN = bu2bpy; RX = nBuBr, NN = bpy; RX = CHPh2Br, NN = bpy, phen, or bu2bpy) to yield the Pt(IV) complexes [PtMe2RX(NN)]. On the basis of NMR data, the Pt(IV) product of each reaction contains almost exclusively the kinetic trans isomer, and only in a few cases, very small traces of the thermodynamic cis isomers are observed. The binuclear complexes [Pt2Me4Br2{μ-(CH2)2}(NN)2] (NN = bpy, phen) were obtained from reaction of [PtMe2(NN)] with 1,2-dibromoethane. Notably, the mononuclear complex fac-[PtMe3Br(bpy)], obtained as a byproduct during the reaction of [PtMe2(bpy)] with 1,2-dibromoethane, was characterized by X-ray crystallography from the reaction of [PtMe2(bpy)] with 1,2-dibromoethane. On the other hand, the reaction of [PtMe2(bu2bpy)] with 1,2-dibromoethane resulted in formation of the mononuclear complex trans-[PtMe2Br{(CH2)2Br}(bu2bpy)]. The reaction of [PtMe2(NN)] with 1,2-bis(dibromomethyl)xylene in a 1:1 or 2:1 mol ratio afforded the mononuclear complexes [PtMe2(CHBr-o-C6H4CHBr2)Br(NN)] (NN = bpy, phen, or bu2bpy) or binuclear complexes [Pt2Me4Br2{μ-o-(CHBr)2C6H4}(NN)2] (NN = bpy, or phen), respectively. Finally, 1,3-dibromobutane was oxidatively added to the organoplatinum(II) complexes [PtR2(NN)] (R2 = (CH2)4, NN = bpy, or phen; R = Me; NN = bpy) via an SN2 mechanism from the less sterically hindered C–Br side to yield the complexes trans-[PtR2Br{(CH2)2CHBrCH3}(NN)]. The products were fully characterized by 1H and 13C NMR spectroscopy and elemental analysis. The platinacycle complex [Pt(CH2)4(bpy)] was shown to react faster, as compared to the dimethyl analogue complex [PtMe2(bpy)], by a factor of 3.8–4.2. The reactions of [Pt(CH2)4(bpy)] or [Pt(CH2)4(phen)] with 1,3-dibromobutane were faster as compared to those with 1,4-dibromobutane, due to the activation effect of the platinum.

First microwave-assisted synthesis of an electron-rich phosphane and its coordination chemistry with platinum(II) and palladium(II)

The P–O ligand 3-(di(2-methoxyphenyl)phosphanyl)propionic acid (HL) was synthesized by a microwave-assisted reaction of a secondary phosphane. The coordination of HL to PtII yielded the neutral mononuclear complex trans-[PtCl(κ2-P,O-L)(κ-P-HL)] (1), while the reaction of PdClMe(η4-COD) (COD=1,4-cyclooctadiene) with HL in the presence of NEt3 gave the anionic PdII compound of the formula (HNEt3)[PdClMe(κ2-P,O-L)] (2). Upon crystallization of the latter compound the neutral chloride-bridged dimetallic compound cis-[Pd(μ-Cl)Me(HL)]2 (3) was obtained. HL, 1 and 3·CH2Cl2 have been characterized by single crystal X-ray structure analyses.

Structure and magnetism of mono-, di-, and trinuclear benzoato cobalt(II) complexes

Three cobalt(II) – benzoato ( bz) complexes have been prepared and structurally characterized. In the mononuclear complex trans-[Co( bz) 2(H 2O) 2( nca) 2] the benzoato ligand is unidentate ( nca = nicotinamide). The dinuclear complex [(μ 2- bz) 4{Co( qu)} 2] is a structural analog of the copper acetate ( qu = quinoline) where four bidentate benzoato ligands link two cobalt(II) pentacoordinate centers. The trinuclear complex of the composition [Co 3( bz) 6( inca) 6] contains a central hexacoordinate {( bz) 2Co( inca) 2( bz) 2} unit in which the bidentate benzoato ligands held the central and peripheral cobalt(II) centers ( inca = iso-nicotinamide); the peripheral hexacoordinate {( bz)Co( inca) 2<} units contain the terminal benzoato ligand in its bidentate function. The magnetic susceptibility data down to T = 2 K and the magnetization data up to B = 7 T reveal a considerable magnetic anisotropy due to the single-ion zero-field splitting.

Dynamic behaviour of Ru and Ru–Pt complexes containing tetrahedro-P4 ligand

Dynamic processes involving the P(4) cage coordinated to transition metal fragments were observed for the mononuclear complex trans-[Ru(dppm)(2)(H)(η(1)-P(4))]BF(4) and for the bimetallic derivative trans-[Ru(dppm)(2)(H)(μ ,η(1:2)-P(4)){Pt(PPh(3))(2)}]BF(4) as demonstrated by NMR experiments and DFT calculations.

Mononuclear and dinuclear iridium and heterodinuclear iridium–rhodium complexes derived from 1,4-C 6H 4(C [tbnd]CSiMe 3) 2 as precursor

The labile iridium(I) precursor trans-[IrCl(C 8H 14)(P iPr 3) 2] ( 2), prepared in situ from [IrCl(C 8H 14) 2] 2 ( 1) and P iPr 3, reacted with equimolar amounts of 1,4-C 6H 4(C CSiMe 3) 2 ( 3) at 60 °C to give the mononuclear vinylidene complex trans-[IrCl( C C(SiMe 3)C 6H 4C CSiMe 3)(PiPr 3) 2] ( 4). From 2 and 3 in the molar ratio of 2:1, the dinuclear compound trans,trans-[(P iPr 3) 2ClIr( C C(SiMe 3)C 6H 4C(SiMe 3) C )IrCl(P iPr 3) 2] ( 5) was obtained. Reaction of 4 with [RhCl(P iPr 3) 2] 2 ( 6) at room temperature afforded the heterodinuclear alkyne(vinylidene) complex trans,trans-[(P iPr 3) 2ClIr( C C(SiMe 3)C 6H 4C CSiMe 3)RhCl(P iPr 3) 2] ( 7), which on heating at 45 °C was converted to the bis(vinylidene) isomer trans,trans-[(P iPr 3) 2ClIr( C C(SiMe 3)C 6H 4C(SiMe 3) C )RhCl(P iPr 3) 2] ( 8).

Benzothiazolin‐2‐ylidene and Azole Mixed‐Ligand Complexes of Palladium

AbstractA series of mixed‐ligand, mononuclear complexes trans‐[PdX2(NSHC)(azole)] [NSHC = N,S‐heterocyclic carbene; azole = imidazole, 1‐(2,4,6‐trimethylphenyl)‐1H‐imidazole, benzimidazole, benzothiazole and benzoxazole] have been prepared and characterised by X‐ray single‐crystal diffraction. These complexes catalyse the sp2–sp3 cross‐coupling of fluoroaryl halides with arylboronic acid to give diarylmethanes with good yields and high turnovers. (© Wiley‐VCH Verlag GmbH &amp; Co. KGaA, 69451 Weinheim, Germany, 2009)

Synthesis, structure and thermochemical behavior of bis-(1,1,1,5,5,5-hexafluoro-2,4-pentanedionato)-(1,4,7,10,13,16-hexaoxa-cyclooctadecane)-strontium in comparison with its structural and thermochemical analogous

The trans-[M(18-crown-6)(C 5HO 2F 6) 2] (M = Ca, Sr, Ba, Pb) complexes have been synthesized and identified. The crystal structure of the Sr complex has been determined by X-ray diffraction. The basic structural unit is the mononuclear complex trans-[Sr(18-crown-6)(C 5HO 2F 6) 2]. The thermal properties of the complexes have been correlated to their structure. The melting and decomposition ranges of the Ca, Sr and Ba complexes and their sublimation temperatures at ∼10 −2 mm Hg have been determined. Experimental evidence is presented that the complexes are similar in volatility.

Sn–S and Ru–Ru bonds cleavage reactions between [Ph 3SnS(CH 2) 3SSnPh 3] and Ru 3(CO) 12: X-ray crystal structures of [Ph 3SnS(CH 2) 3SSnPh 3] and trans-[Ru(CO) 4(SnPh 3) 2

The organotin complex [Ph 3SnS(CH 2) 3SSnPh 3] ( 1) was synthesized by PdCl 2 catalyzed reaction between Ph 3SnCl and disodium-1,3-propanedithiolate which in turn was prepared from 1,2-propanedithiol and sodium in refluxing THF. Reaction of 1 with Ru 3(CO) 12 in refluxing THF affords the mononuclear complex trans-[Ru(CO) 4(SnPh 3) 2] ( 2) and the dinuclear complex [Ru 2(CO) 6(μ-κ 2-SCH 2CH 2CH 2S)] ( 3) in 20 and 11% yields, respectively, formed by cleavage of Sn–S bond of the ligand and Ru–Ru bonds of the cluster. Treatment of pymSSnPPh 3 (pymS = pyrimidine-2-thiolate) with Ru 3(CO) 12 at 55–60 °C also gives 2 in 38% yield. Both 1 and 2 have been characterized by a combination of spectroscopic data and single crystal X-ray diffraction analysis.

Bridging MCl Bonds with Ambiphilic Phosphine–Borane Ligands

A combined experimental/theoretical study provides insight into the bridging coordination of M-Cl bonds with the ambiphilic phosphine-borane ligands iPr(2)P-o(C(6)H(4))-BR(2) (PBCy(2): R = Cy; PBMes(2): R = Mes). Reaction of [PdCl(allyl)(PBCy(2))] (3) with HCl affords the related dinuclear complex [PdCl(mu-Cl)(PBCy(2))](2) (5). Subsequent cleavage of the chloride bridge by PPh(3) leads to the heteroleptic mononuclear complex trans-[PdCl(2)(PPh(3))(PBCy(2))] (6). The solid-state structures of complexes 5 and 6 substantiate the propensity of the PBCy(2) ligand to bridge Pd-Cl bonds via P-->Pd--Cl-->B interactions. DFT calculations carried out on both the model mononuclear complexes 3* and 6* reveal that in each system the energy of the linkage isomer with a Cl-->B interaction is very similar to that without. A comparison of the solution and solid-state (11)B NMR spectroscopic data for complexes 3 and 6 suggests the possible interconversion of the bridging and B-pendant forms in solution. Bridging coordination of the PBCy(2) ligand across a Rh-Cl bond is observed in the solid-state structure of the related complex [RhCl(nbd)(PBCy(2))] (7). Replacement of the Cy groups at boron by Mes substituents illustrates the role of steric factors on the participation of the Lewis acid upon coordination, no Cl-->B interaction being observed in the complex [PdCl(allyl)(PBMes(2))] (8).

Studies towards the catalytic anti-Markovnikov functionalisation of alkenes

In 1986 Jensen and Trogler reported that a biphasic system containing the mononuclear complex trans-[(Me3P)2PtHCl] and NaOH catalysed the anti-Markovnikov hydration of 1-hexene to 1-hexanol. The unusual method of preparation could also give rise to dinuclear complexes with bridging hydride ligands. We have tested some dinuclear complexes for catalytic activity and discovered that on heating these yield trinuclear complexes. Using the independently prepared trinuclear complex [(dppe)3Pt3H3]+, we found that it acted as a catalyst for the reaction between 1-octene and methanol to give 1-methoxyoctane, although the results were somewhat erratic. A cause of the erratic behaviour was found to be the presence of varying amounts of hydroperoxide impurities, which underwent a Hock rearrangement in acidic conditions.

The Iminophosphorane‐Phosphane Ph2PC6H4OC6H4PPh2=NP(O)(OPh)2: Synthesis, Reactivity, and Catalytic Activity in Suzuki Cross‐Coupling and the Homogeneous Hydrogenation of Olefins

AbstractThe iminophosphorane‐phosphane ligand Ph2PC6H4OC6H4PPh2=NP(O)(OPh)2 (1) has been synthesized by partial imination of bis[2‐(diphenylphosphanyl)phenyl] ether (DPEphos) with phosphoryl azide (PhO)2P(O)N3. A similar reaction in a 1:2 stoichiometry affords the bis(iminophosphorane) O{C6H4PPh2=NP(O)(OPh)2}2 (2). The chalcogen derivatives O{C6H4P(E)Ph2}2 [E = S (3) and Se (4)] and Ph2P(E)C6H4OC6H4PPh2=NP(O)(OPh)2 [E = S (5) and Se (6)] are also synthesized by treating DPEphos and 1 with elemental sulfur and selenium, respectively. The mononuclear complexestrans‐[MCl2{κ1‐P‐Ph2PC6H4OC6H4PPh2=NP(O)(OPh)2}2][M = Pt (7) Pd (8)] and trans‐[Rh(CO)Cl{κ1‐P‐Ph2PC6H4OC6H4PPh2=NP(O)(OPh)2}2] (12) are prepared by the reaction of 1 with [Pt(COD)Cl2], [Pd(COD)Cl2], and [{Rh(CO)2Cl}2], respectively. Treatment of 1 with [Pd2(dba3)] (dba = dibenzylideneacetone) affords the mononuclear complex [Pd0{κ2‐P,O‐Ph2PC6H4OC6H4PPh2=NP(O)(OPh)2}2] (9) in which ligand 1 coordinates through its P and O centers in a κ2‐P,O chelating fashion. The monocoordinated AuI complex [AuCl{κ1‐P‐Ph2PC6H4OC6H4PPh2=NP(O)(OPh)2}] (10) has been prepared by the reaction of 1 and [AuCl(SMe2)] and its structure has been confirmed by X‐ray crystallography. The reaction of 1 with [{Rh(COD)Cl}2] in the presence of AgOTf affords the cationic RhI complex cis‐[Rh(COD){κ2‐P,O‐Ph2PC6H4OC6H4PPh2=NP(O)(OPh)2}][OTf] (11). The catalytic activity of the Pd0 complex 9 has been investigated in Suzuki cross‐coupling reactions. Homogeneous catalytic hydrogenation of olefins has also been studied using the cationic RhI complex 11.(© Wiley‐VCH Verlag GmbH &amp; Co. KGaA, 69451 Weinheim, Germany, 2007)

Convenient Entry to Mono- and Dinuclear Palladium(II) Benzothiazolin-2-ylidene Complexes and Their Activities toward Heck Coupling

Under solventless conditions, benzothiazole reacts with benzyl bromide to give near-quantitative yield of the salt N-benzylbenzothiazolium bromide (A), which is a convenient air-stable heterocyclic carbene precursor. Treatment of A with Pd(OAc)2 in CH3CN affords the bis(carbene) complex cis-[PdBr2(NHC)2] (1) (NHC = N-benzylbenzothiazolin-2-ylidene). In DMSO, this reaction yields an unprecedented dinuclear N,S-heterocyclic carbene complex, [PdBr2(NHC)]2 (2). Complex 2 undergoes bridge cleavage reactions with CH3CN and DMF to give the mononuclear and solvated monocarbene complexes trans-[PdBr2(NHC)(Solv)] [Solv = CH3CN (3) and DMF (4)]. All compounds have been fully characterized by 1H and 13C NMR spectroscopy, ESI or FAB mass spectrometry, and elemental analysis. The molecular structures of A and 1−4 have been determined by X-ray single-crystal diffraction. The catalytic activities of 1−4 toward Mizoroki−Heck coupling reactions of aryl bromides with tert-butyl acrylate are described and compared.

Synthesis and Structural Characterisation of Palladium and Group‐12 Metal Complexes with a Hybrid Phosphanylphosphonate Ferrocene Ligand

AbstractDiethyl [1′‐(diphenylphosphanyl)ferrocenyl]phosphonate (1) was synthesised by stepwise metallation/functionalisation of 1,1′‐dibromoferrocene and studied as a ligand for palladium(II) and group‐12 metals. Treatment of [PdCl2(cod)] (cod = η2:η2‐cycloocta‐1,5‐diene) with 1 in 1:1 or 1:2 molar ratios gave, respectively, the dinuclear, chloride‐bridged complex [{Pd(μ‐Cl)Cl(1‐κP2)}2] (2) and the mononuclear complex trans‐[PdCl2(1‐κP2)2] (3), where 1 coordinates exclusively through the phosphane function. The reactions between 1 and group‐12 metal bromides MBr2 in a 1:1 molar ratio gave the adducts [MBr2(1)] [M = Zn (4), Cd (5), and Hg (6)], whose crystal structures change considerably with the metal ion. Thus, whereas 4 is a molecular complex with 1 coordinating as an O1,P2‐chelate, its cadmium(II) analogue is a polymer built up from symmetric {CdBr(μ‐Br)}2 units interconnected by pairs of O1,P2‐bridging phosphanylphosphonate ligands. Finally, the mercury(II) complex 6 is a halide‐bridged dimer, [{Hg(μ‐Br)Br(1‐κP2)}2]. However, this compound is structurally fluxional in solution (NMR spectra) and, in the crystal, it attains a structure similar to 5 owing to weak interactions between mercury and phosphonate‐O1 atoms from adjacent molecules. An isomer to 6, [{HgBr2(1‐κ2O1,P2)}2] (7), was isolated from attempted alkylation of 6 and structurally characterised as a dimer, where ligands 1 bridge two {HgBr2} units. All compounds were studied by spectroscopic methods (IR, NMR, mass) and the solid‐state structures of 1, 2·${1 \over 2}$ H2O, 3·4 CHCl3, 4, 5, 6·5 C6H6, and 7 have been determined by single‐crystal X‐ray diffraction. (© Wiley‐VCH Verlag GmbH &amp; Co. KGaA, 69451 Weinheim, Germany, 2006)

Special effects of ortho-isopropylphenyl groups. Diastereoisomerism in platinum(ii) and palladium(ii) complexes of helically chiral PAr3 ligands

The coordination chemistry of the four phosphines, P{C6H3(o-CH3)(p-Z)}3 where Z = H (1a) or OMe (1b) and P{C6H3(o-CHMe2)(p-Z)}3 Z = H (1c) or OMe (1d) with platinum(II) and palladium(II) is reported. Mononuclear complexes trans-[PdCl2L2](L = 1a,b) and trans-[PtCl2L2](L = 1a-c) have been prepared and the crystal structures of trans-[PdCl2(1b)2] and trans-[PtCl2(1c)2] as their dichloromethane solvates have been determined. The structures show that in these complexes, the ligands adopt g+ g+ a conformations. Examination of the Cambridge Structural Database confirms this to be one of only two conformer types that tri-o-tolylphosphines adopt and the only viable conformer in 4 and 6 coordinate complexes. The binuclear complexes trans-[Pd2Cl4L2](L = 1c,d) are formed even when an excess of the bulky 1c,d is used in the synthesis and the crystal structure of trans-[Pd2Cl4(1c)2] as its chloroform solvate is reported. Reaction of [PtCl2(NCBu(t))2] with 1b-d in refluxing toluene gave the cycloplatinated species [Pt2Cl2(L - H)2] where L - H is phosphine 1b-d deprotonated at one of the ortho-methyl carbon atoms. Variable temperature 31P and 1H NMR spectroscopy reveals that all the complexes reported are fluxional. The processes are analysed in terms of restricted P-C and P-M rotations that give rise to diastereoisomeric rotamers because of the helically chiral orientations of the aryl substituents. For the complexes of the bulky ligands 1c,d, rotation about the P-C bond is slow on the NMR timescale even up to 75 degrees C. The crystal structure of the cyclometallated complex [Pt2Cl2(1d - H)2] has been determined.

Polymetalated Aromatic Compounds. 1. Synthesis of Mono-, Di-, and Tripalladated Mesitylene Derivatives

The reaction of 1,3,5-triiodomesitylene (C6Me3I3) with a mixture of [Pd(dba)2] and PR3 leads to the mononuclear complexes trans-[Pd(C6Me3I2)I(PR3)2] (R = Ph (1), R3 = Me2Ph (2)) or the dinuclear complex [{trans-PdI(PMe2Ph)2}2(μ2-C6Me3I)] (3), depending on the nature of the phosphine, the temperature, and the molar ratio of the reagents. All attempts to prepare trinuclear complexes, using this method of synthesis, were unsuccessful. However, addition of C6Me3I3 to a mixture of [Pd(dba)2] and L2 gives at room temperature [(PdIL2)3(μ3-C6Me3)] (L2 = 2,2‘-bipyridine (bpy) (4), 4,4‘-di-tert-butyl-2,2‘-bipiridine (tbbpy) (5)), even if substoichiometric amounts of Pd were used. Complex 5 does not react with PPh3 or PMe2Ph, but it does react with PMe3 to give [trans-{PdI(PMe3)2}3(μ3-C6Me3)] (6). The crystal structures of 1, 2, and 5 have been determined by X-ray diffraction studies.

A series of new fluororhodium(I) complexes †

The reaction of [Rh{η2-O2S(O)CF3}(PPri3)2] 1 with terminal alkynes RCCH (R = Ph or But) led to the formation of the vinylidene compounds trans-[Rh{η1-OS(O)2CF3}(CCHR)(PPri3)2] 2a,2b, which on treatment with tetrabutylammonium fluoride hydrate or KF gave the fluororhodium(I) complexes trans-[RhF(CCHR)(PPri3)2] 3a,3b in ca. 70% yield. An alternative route for the preparation of 3a (R = Ph) is based on the reaction of phenylacetylene with the dimer [{Rh(µ-F)(PPri3)2}2] 4, the latter being obtained from 1 and [NBu4]F hydrate as starting materials. Compound 4 reacts smoothly with L′ = CO, CNC6H3Me2-2,6, C2Ph2 and C2H4 to afford the mononuclear complexes trans-[RhF(L′)(PPri3)2], of which that with L′ = C2H4 was characterized by X-ray crystallography. In contrast to the hydroxo compound trans-[Rh(OH)(CCHPh)(PPri3)2], which on treatment with acids HX (X = CF3SO3, CH3CO2, PhO or PhCC) gave trans-[RhX(CCHPh)(PPri3)2], the fluoro derivative 3a reacts only with CF3SO3H and PhCCH by ligand substitution to yield the corresponding compounds. Acetic acid and phenol interact with 3a via XH· · ·FRh hydrogen bridges to form 1∶1 adducts, of which that with X = CH3CO2 rearranges to give trans-[Rh(O2CMe)(CCHPh)(PPri3)2] and probably trans-[Rh(FHF)(CCHPh)(PPri3)2].