Synthesis and Structures of Palladium and Platinum A-Frame Complexes Bridged by a Novel Binucleating Ligand, N,N‘-Bis[(2-diphenylphosphino)phenyl]- formamidine

Synthesis and Some Coordination Chemistry of Phosphane-Difunctionalized Bis(amidinato)-Heavier Tetrylenes: A Previously Unknown Class of PEP Tetrylenes (E = Ge and Sn)

The bis(amidinato)-heavier tetrylenes E(bzamP)2 (E = Ge (2a) and Sn (2b); bzamP = N-isopropyl-N'-(diphenylphosphanylethyl)benzamidinate), which are equipped with one heavier tetrylene (germylene or stannylene) and two phosphane fragments (one on each amidinate moiety) as coordinable groups, have been synthesized from the benzamidinum salt [H2bzamP]Cl and GeCl2(dioxane) or SnCl2 in 2:1 mol ratio. A preliminary inspection of their coordination chemistry has shown that their amidinate group can also be involved in the bonding with the metal atoms as tridentate ENP and tetradentate PENP' coordination modes have been observed for the ECl(bzamP)2 ligand of [Ir{κ3E,N,P-ECl(bzamP)2}(cod)] (E = Ge (3a) and Sn (3b); cod = η4-1,5-cyclooctadiene) and the E(bzamP)2 ligand of [Ni{κ4E,N,P,P'-E(bzamP)2}] (E = Ge (4a) and Sn (4b)), which are products of reactions of 2a and 2b with [IrCl(cod)]2 (1:0.5 mol ratio) and [Ni(cod)2] (1:1 mol ratio), respectively. These products contain a 5-membered NCNEM ring that results from the insertion of the metal M atom into an E-N bond of 2a and 2b. Additionally, while iridium(I) complexes 3a and 3b are chloridotetryl derivatives (insertion of the tetrylene E atom into the Ir-Cl bond has also occurred) that have an uncoordinated phosphane group, nickel(0) complexes 4a and 4b contain a tetrylene fragment that, maintaining the lone pair, behaves as a σ-acceptor (Z-type) ligand.

Selective coordination of coinage metals using orthogonal ligand scaffolds

Group 11 metal complexes with their ability to form metallophilic interations are widely pursued to develop multifunctional luminescent materials. Heteronuclear coinage metal complexes are promising candidates to tune electronic and optical properties which are not readily accessed by their homometallic congeners. In this review, we present the concept of orthogonal ligands which are rationally designed to access heteronuclear coinage metal complexes and studied in terms of their photophysical properties. Bifunctional ligands containing soft and hard donor atoms have the potential of providing different coordination modes to selectively synthesise heterobimetallic complexes in a predictable manner. This review deals with ligand sets composed of pyridine, bipyridine- or iminopyridine-substituted NHCs featuring C-N coordination modes, phosphine-based N-heterocycles and amidinate ligand scaffolds comprising of P-N functionalities and mixed phosphine-phosphine oxide with P-O donor sites. Therefore, the scope of this perspective is the discussion of heteronuclear coinage metal complexes supported by recently developed bifunctional ligands in terms of their synthesis, coordination geometries and tunability of optical properties when compared to their homometallic analogues.

Tetra- and hexanuclear string complexes of the coinage metals

Reaction of the PNNP ligand system N,N'-bis[(2-diphenylphosphino)phenyl]formamidinate (dpfam) featuring different coordination compartments with [AuCl(tht)], [CuMes]₅, [AgMes]₄, or [AuC₆F₅(tht)] (tht = tetrahydrothiophene) resulted in tetranuclear homo- and heterometallic coinage metal complexes, as well as a hexanuclear gold complex. All of them feature a metal string conformation. Photophysical investigation revealed a significant dependence of the photoluminescence properties on the metal composition. Below 100 K, the PL efficiency of three compounds approaches nearly 100%.

Hetero-bimetallic Lanthanide-Coinage Metal Compounds Featuring Possible Metal-Metal Interactions in the Excited State

Heterometallic complexes, combining metals of the outer rims of the d-block, for example lanthanides(III) (Ln) and coinage metals(I) (M) are scarcely reported, synthetically challenging and highly interesting in terms of their interactions. In this context, we synthesized hetero-bimetallic Ln-M compounds ligated by the phosphine functionalized amidinate system (N,N'-bis[(2-diphenylphosphino)phenyl]formamidinate, "dpfam"). The resulting compounds [dpfam3 LnM][OTf] (Ln = La, Nd and M = Ag, Au) feature a close proximity of the two metal centres and were investigated experimentally by photoluminescence spectroscopy and quantum chemical calculations. The latter showed rare La-Au interactions for the first excited state.

Alkali Metal Complexes of a Bis(diphenylphosphino)methane Functionalized Amidinate Ligand: Synthesis and Luminescence

A novel bis(diphenylphosphino)methane (DPPM) functionalized amidine ligand (DPPM-C(N-Dipp)2 H) (Dipp=2,6-diisopropylphenyl) was synthesized. Subsequent deprotonation with suitable alkali metal bases resulted in the corresponding complexes [M{DPPM-C(N-Dipp)2 }(Ln )] (M=Li, Na, K, Rb, Cs; L=thf, Et2 O). The alkali metal complexes form monomeric species in the solid state, exhibiting intramolecular metal-π-interactions. In addition, a caesium derivative [Cs{PPh2 CH2 -C(N-Dipp)2 }]6 was obtained by cleavage of a diphenylphosphino moiety, forming an unusual six-membered ring structure in the solid state. All complexes were fully characterized by single crystal X-ray diffraction, NMR spectroscopy, IR spectroscopy as well as elemental analysis. Furthermore, the photoluminescent properties of the complexes were thoroughly investigated, revealing differences in emission with regards to the respective alkali metal. Interestingly, the hexanuclear [Cs{PPh2 CH2 -C(N-Dipp)2 }]6 metallocycle exhibits a blue emission in the solid state, which is significantly red-shifted at low temperatures. The bifunctional design of the ligand, featuring orthogonal donor atoms (N vs. P) and a high steric demand, is highly promising for the construction of advanced metal and main group complexes.

Bright Luminescence in Three Phases-A Combined Synthetic, Spectroscopic and Theoretical Approach

Combining phase-dependent photoluminescence (PL) measurements and quantum chemical calculations is a powerful approach to help understand the influence of the molecular surroundings on the PL properties. Herein, a phosphine functionalized amidinate was used to synthesize a recently presented bimetallic gold complex, featuring an unusual charge separation. The latter was subsequently used as metalloligand to yield heterotetrametallic complexes with an Au-M-M-Au "molecular wire" arrangement (M=Cu, Ag, Au) featuring metallophilic interactions. All compounds show bright phosphorescence in the solid state, also at ambient temperature. The effect of the molecular environment on the PL was studied in detail for these tetrametallic complexes by comparative measurements in solution, in the solid state and in the gas phase and contrasted to time-dependent density functional theory computations.

Bi- and trinuclear coinage metal complexes of a PNNP ligand featuring metallophilic interactions and an unusual charge separation

A selective synthesis of bi- and trinuclear complexes featuring a tetradentate monoanionic PNNP ligand is presented. The binuclear coinage metal complexes show a typical fourfold coordination for Cu and Ag, which changes to a bifold coordination for Au. The latter is accompanied by an unusual charge separation. Optical properties are investigated using photoluminescence spectroscopy and complemented by time-dependent density-functional-theory calculations. All compounds demonstrate clearly distinguished features dependent on the metals chosen and differences in the complex scaffold.

Heterotridentate organodiphosphines in Pt(η3–P1X1P2)(Y) derivatives-structural aspects

This review covers over 30 examples of monomeric Pt(II) complexes of the types: Pt(η3–P1O1P2)(Y) (Y = PL, CL, OL), Pt(η3–P1N1P2)(Y) (Y = H, NL, CL, Cl, PL) and Pt(η3–P1P2N1)(Y) (Y = Cl). The heterotridentate donor ligands create 11 types of a couple chelate rings with common central atom O1 (η3–P1O1P2), N1 (η3–P1N1P2) and P2 (η3–P1P2N1). The most frequent is P1C2N1C2P2. Some cooperative effects between chelate rings and Y donor ligands were found and discussed. A degree of distortions of square-planar geometry about Pt(II) were also calculated.

Facile Fabrication of Ordered Component-Tunable Heterobimetallic Self-Assembly Nanosheet for Catalyzing "Click" Reaction

How to maximize the number of desirable active sites on the surface of the catalyst and minimize the number of sites promoting undesirable side reactions is currently an important research topic. In this study, a new way based on the synergism to achieve the successful fabrication of an ordered heterobimetallic self-assembled monolayer (denoted as BMSAM) with a controlled composition and an excellent orientation of metals in the monolayer was developed. BMSAM consisting of phenanthroline and Schiff-base groups was prepared, and its novel heterobimetallic (Cu and Pd) self-assembled monolayer anchored in silicon (denoted as Si-Fmp-Cu-Pd BMSAM) with a controlled composition and a fixed position was fabricated and characterized by UV, cyclic voltammetry, Raman, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), X-ray diffraction (XRD), inductively coupled plasma atomic emission spectroscopy (ICP-AES), and water-drop contact angle (WDCA) analyses. The effects of Si-Fmp-Cu-Pd BMSAM on its catalytic properties were also systematically investigated using "click" reaction as a template by WDCA, XPS, SEM, XRD, ICP-AES and in situ Fourier transform infrared analyses in a heterogeneous system. The results showed that the excellent catalytic characteristic could be attributed to the partial (ordered or proper distance) isolation of active sites displaying high densities of specific atomic ensembles. The catalytic reaction mechanism of the click reaction interpreted that the catalytic process mainly occurred on the surface of the monolayer, internal active site (Pd) and rationalized that the Cu(I) species and Pd(0) reduced from the Cu(II) and Pd(II) catalyst were active species, which had a proper distance between two different metals. The cuprate-triazole intermediate and the palladium intermediate, whose production is the key step, should lie in a proper position between the copper and active palladium sites, with which the reaction rate of transmetalation would be improved to increase the amount of the undesired Sonogashira coupling product.

Coordination of bis(azol-1-yl)methane-based bisphosphines towards RuII, RhI, PdII and PtII: synthesis, structural and catalytic studies

This paper describes the transition metal chemistry of three bis(X-diphenylphosphino-azol-1-yl)-based bisphosphines: bis(2-Ph₂P-imidazol-1-yl)methane (1), bis(5-Ph₂P-pyrazol-1-yl)methane (2) and bis(5-Ph₂P-1,2,4-triazol-1-yl)methane (3). These show versatility in their coordination behaviour.

Chemistry and biological activity of platinum amidine complexes

Platinum amidine complexes represent a new class of potential antitumor drugs that contain the imino moiety HN=C(sp(2)) bonded to the platinum center. They can be related to the iminoether derivatives, which were recently shown to be the first Pt(II) compounds with a trans configuration endowed with anticancer activity. The chemical and biological properties of platinum amidine complexes, and more generally of platinum imino derivatives, can be rationally modified through suitable synthetic procedures with the aim of improving their cytotoxicity and antitumor activity. The addition of protic nucleophiles to nitriles coordinated to platinum in various oxidation states can offer a wide variety of complexes with chemical, structural, and physical properties specifically tuned for a more efficacious biological response.

Rational synthesis of supramolecular assemblies based on tetraplatinum units: synthesis, characterization, and selective substitution reactions of four different Pt4 clusters

Four different types of square-planar Pt(4) clusters, trans-[Pt(4)(μ-OCOCH(3))(6)(μ-ArNCHNAr)(2)] (2: ArNCHNAr = N,N'-diarylformamidinate), [Pt(4)(μ-OCOCH(3))(7)(μ-ArNCHNAr)] (8), cis-[Pt(4)(μ-OCOCH(3))(6)(κ(4)-N(4)-DArBp)] (9: DArBp = 1,3-bis(arylbenzamidinate)propane), and [Pt(4)Cl(2)(μ-OCOCH(3))(5)(κ(4)-N(2),P(2)-dpfam)] (13: dpfam = N,N'-bis[(2-diphenylphosphino)phenyl]formamidinate), were successfully prepared by using selective substitution reactions of in-plane acetate ligands of [Pt(4)(μ-OCOCH(3))(8)] (1), which has four in-plane and four out-plane acetate ligands, with appropriate capping ligands. Fundamental substitution reactions of the remaining in-plane acetates with benzoic acid derivatives were also investigated. All newly prepared complexes were characterized from spectral and physical data and combustion analysis. X-ray crystallographic studies of some of the clusters were also performed. Electrochemical measurements of amidinate-modified Pt(4) clusters revealed stepwise oxidation processes of the Pt(4) core due to Pt(4)(9+)/Pt(4)(8+) and Pt(4)(10+)/Pt(4)(9+). Based on the lability of the in-plane acetate ligands of the modified Pt(4) clusters, reactions of cis-[Pt(4)(μ-OCOCH(3))(6)(κ(4)-N(4)-DArBp)] (9 c: Ar = C(6)H(4)tBu-4) with ferrocenedicarboxylic acid and p-phenylenedipropionic acid resulted in the selective formation of cyclic dimers 17 and 18 and the reaction of 13 with 4,4'-biphenyldicarboxylic acid afforded a linear dimer 20. The dimers were characterized by spectral data, as well as X-ray analyses for 17 and 18. The finding of two Fe(3+)/Fe(2+) redox couples in the electrochemical measurement of dimer 17 indicated that two ferrocenyl units in dimer 17 communicated electronically.

An approach to bimetallic catalysts by ligand design

New diphosphines based on benzofurobenzofuran and dibenzodioxocin backbones, forming exclusively bimetallic complexes were designed and synthesized. Depending on the ligand to metal ratio, face-to-face bimetallic complexes or syn-chloride bridged dimeric complexes were formed as main reaction products. The structures of the rhodium complexes of the new ligands 4, 7, 10, 13, 16 were established in solution by NMR, IR, and MS spectroscopy. The molecular structures of the syn-chloride bridged dimeric complexes [Rh(2)(CO)(2)(mu-Cl)(2)(4)] (22), [Rh(2)(CO)(2)(mu-Cl)(2)(10)] (24), and the face-to-face bimetallic complexes [Rh(CO)Cl(4)](2) (17), [Rh(CO)Cl(10)](2) (19), and [Rh(CO)Cl(13)](2) (20) were confirmed by X-ray crystallography. Ligands 4, 7, 10, 13, 16, and SPANphos were tested in rhodium catalyzed methanol carbonylation at 150 degrees C and 22 bar of CO gas, showing high activities under catalytic conditions.

Palladium-catalyzed cross-addition of triisopropylsilylacetylene to unactivated alkynes

Selective cross-addition of triisopropylsilylacetylene (TIPSA) to unactivated alkynes is catalyzed by dinuclear and mononuclear palladium complexes supported by a multidentate ligand, N,N'-bis[2-(diphenylphosphino)phenyl]formamidine (dpfamH). While the addition reactions of TIPSA to dialkylacetylenes using palladium catalysts supported by monodentate and bidentate ligands gives dimers of TIPSA as major products, the reactions with the palladium complexes supported by dpfam affords cross-adducts selectively, in which the yields of TIPSA dimers are less than 5 %. The addition of TIPSA to monoalkylacetylenes also gives cross-adducts as major products, although the selectivity and yield are moderate.

Palladium-catalyzed selective cross-addition of triisopropylsilylacetylene to internal and terminal unactivated alkynes

Dinuclear and mononuclear palladium complexes having N,N'-bis[2-(diphenylphosphino)phenyl]amidinate (DPFAM) as a ligand catalyzed the cross-addition of triisopropylsilylacetylene (TIPSA) to unactivated internal alkynes, giving enynes selectively. When palladium catalysts having PPh3, TDMPP, dppe, or dppf were used, dimers of TIPSA were obtained as major products. The reactions of TIPSA with several terminal alkynes also gave cross-adducts selectively, although the yields were moderate.

Crystal structures and solution behaviors of dinuclear d10-metal complexes containing anions of N,N′-bis(pyrimidine-2-yl)formamidine

The salts of Zn(II), Cd(ii) and Hg(II) react instantaneously with Kpmf (pmf(-) = anion of N,N'-bis(pyrimidine-2-yl)formamidine, Hpmf) in THF, producing bimetallic complexes of the types [M(2)(pmf)(3)](X) (M = Zn(II), X = I(3)(-), ; M = Zn(II), X = NO(3)(-), ; M = Zn(II), X = ClO(4)(-), ; M = Cd(II), X = NO(3)(-), ; M = Cd(II), X = ClO(4)(-), ) and Hg(2)(pmf)(2)X(2) (X = Cl, ; Br, ; I, ). New tridentate and tetradentate coordination modes were observed for the pmf(-) ligands and their fluxional behaviors investigated by measuring variable-temperature (1)H NMR spectra. Complexes and , which possess only tetradentate coordination modes for the pmf(-) ligands in the solid state show larger free energy of activation (DeltaG(c)( not equal)) for the exchange than complexes and with tetradentate and/or tridentate coordination modes. Complexes and are the first dinuclear Zn(II) and Hg(II) complexes containing formamidinate ligands. Moreover, the separation between the two Hg(II) atoms are 3.4689(9), 3.4933(13) and 3.5320(10) A for complexes , respectively, similar to the sum of van der Waals radii of two Hg(II) atoms which is 3.50(7) A. All the complexes exhibit emissions and the nature of the anions hardly change the emission wavelengths of the complexes with the same metal centers. The emission bands may be tentatively assigned as intraligand (IL) pi-->pi* transitions.

New coordination modes at molybdenum for 2-diphenylphosphinoaniline derived ligands

The complexes [MoCl3(1-N,2-Ph2P-C6H4)2] (1) and {MoCl(Nt-Bu)[1-micro(N),2-(Ph2P)C6H4]}2 (2) have been obtained from the reaction of 2-diphenylphosphinoaniline [1,2(NH2)(Ph2P)C6H4] with either sodium molybdate [Na2MoO4] (in the presence of Et3N and Me3SiCl) or [MoCl2(Nt-Bu)2(DME)]; the crystal structure of 1 reveals a novel MoNC2PN six-membered conjugated ring system derived from a P-N coupling reaction between two ligands, whilst that of 2 reveals bridging imido/terminal phosphine ligation.

Roof-Shaped Halide-Bridged Bimetallic Complexes via Ring Expansion Reaction

Binucleating behavior of rigid triptycene-based ligands has been studied. It has been demonstrated that trans-spanned transition-metal mononuclear complexes bearing 1,8-bis(diisopropylphosphino)triptycene (L1) and 1-diisopropylphosphino-8-diphenylphosphinotriptycene (L2) react with an appropriate transition-metal precursor via a ring-expansion pathway to form unusual bimetallic quasi-closed structures. New palladium and rhodium complexes featuring strongly bent (ca. 115 degrees ) M2(mu-Cl2) cores with very closely spanned metal centers (less than 3 A) have been prepared using the described ring-expansion reaction and have been fully characterized. Despite a constrained arrangement of the binuclear system, halogen bridges in all new compounds were stable in both the solid state and solution showing no tendency for dissociation even in the presence of added Lewis bases. Spontaneous resolution of the dissymmetric Pd2(mu-Cl)2Cl2(1-diisopropylphosphino-8-diphenylphosphinotriptycene) (2) into enantiopure antipodes is discussed as well.

Various coordination modes of the bis(di(o-N,N-dimethylanilinyl)phosphino)methane ligand in mononuclear and binuclear complexes of group 8 and group 9 metals

The synthesis and characterization of a series of compounds involving the bis(di(o-N,N-dimethylanilinyl)phosphino)methane (dmapm) ligand are described. The mononuclear complexes [MCl(CO)(P,N-dmapm)] (M = Rh, Ir) have a square-planar geometry in which the dmapm ligand chelates via a phosphine functionality and an adjacent amino group. The carbonyl ligand lies opposite the amine, while the chloro ligand is trans to the phosphine. The related complex [RhI(CO)(P,N-dmapm)] has also been prepared. All compounds are highly fluxional by at least three independent processes, as discussed for the rhodium-chloro species. A diiridium complex, [Ir(2)Cl2(CO)2(P,N,P',N'-dmapm)], and the closely related rhodium/iridium analogue, [RhIrCl2(CO)2(P,N,P',N'-dmapm)], have been prepared in which the metals are bridged by the diphosphine group while an amino group at each end of the diphosphine is also coordinating to each metal on opposite faces of the MIrP2 plane (M = Ir or Rh). For the Ir2 species, the carbonyl and chloro groups are again shown to be opposite the amine and phosphine functionalites, respectively. The mononuclear complex [Ru(CO)3(P,P'-dmapm)] has also been prepared. In contrast to the mononuclear species of rhodium and iridium, the dmapm group chelates the ruthenium center through both phosphorus atoms, occupying one axial and one equatorial site of Ru in a distorted trigonal bipyramidal geometry. Reaction of this Ru species with 1/2 equiv of the complexes [RhClL2]2 (L2 = COD, (C2H4)2, (CO)2) yields the unstable Rh/Ru product [RhRuCl(CO)3(P,N,P',N'-dmapm)].

Synthesis of a chelating hexadentate ligand with a P3N3 donor set. Crystal and molecular structure of [OC-6-22]-[Co{(RP*,RP*,RP*)-CH3C(CH2PPhC6H4NH2-2)3}](PF6)3

The first structurally authenticated example of a hexadentate chelating tertiary phosphine in which all six donors are bound to a single metal centre is described. The multidentate ligand (RP*,RP*,RP*)- and (RP*,RP*,SP*)-CH3C(CH2PPhC6H4NH2-2)3 has been prepared in 80% yield via the reaction of five equivalents of sodium (2-aminophenyl)phenylphosphide (generated in situ from (2-aminophenyl)phenylphosphine and sodium in thf) with 1,1,1-tri(bromomethyl)ethane in thf. The diastereomeric mixture has been complexed to cobalt(III) and the resulting pair of complexes, viz. [Co{(RP*,RP*,RP*)-CH3C(CH2PPhC6H4NH2-2)3}]Cl3 and [CoCl{(RP*,RP*,SP*)-CH3C(CH2PPhC6H4NH2-2)3}]Cl2, separated by ion exchange chromatography. The structure of the former (as the corresponding hexafluorophosphate salt) has been confirmed by X-ray crystallography and clearly shows all six donors of the P3N3 ligand coordinated to a single cobalt(III) centre. The related hexadentate ligand with internal N donors and terminal diphenylphosphino groups, viz. CH3C(CH2NHC6H4PPh2-2)3, has also been synthesised, albeit in low yield, via the reaction of [Li(tmeda)][2-NHC6H4PPh2] (generated in situ from (2-aminophenyl)diphenylphosphine, n-butyllithium and tmeda in diethyl ether) with 1,1,1-tri(iodomethyl)ethane in thf. No formation of a P3N3 ligand has been observed when either Na[2-PPhC6H4NH2] or [Li(tmeda)][2-NHC6H4PPh2] is reacted with the related tripodal substrate 1,1,1-tris(tolyl-4-sulfonyloxymethyl)ethane in thf. Rather the P-methyloxetane (+/-)-[3-{(2-aminophenyl)phenylphosphinomethyl}]-3-methyloxetane and the sulfonamide 2-(4-CH3C6H4SO2)NHC6H4PPh2 and the corresponding N-methyloxetane [3-{(2-diphenylphosphinophenyl)aminomethyl}]-3-methyloxetane have been isolated from the respective reactions. The structure of the sulfonamide has been confirmed by an X-ray analysis of the platinum(II) complex trans-[PtCl(CH3){2-PPh2C6H4NH(SO2C6H4CH(3-4)}2].

The synthesis of [FeRu(CO)2(μ-CO)2(η-C5H5)(η-C5Me5)] and convenient entries to its organometallic chemistry

The synthesis, fluxionality and reactivity of the heterobimetallic complex [FeRu(CO)2(mu-CO)2(eta-C5H5)(eta-C5Me5)] are described. Complex exhibits enhanced photolytic reactivity towards alkynes compared to its homometallic analogues, forming the dimetallacyclopentenone complexes [FeRu(CO)(mu-CO){mu-eta]1:eta3-C(O)CR"CR'}eta]-C5H5)(eta-C5Me5)]( R'= R"= H; R'= R"= CO2Me; R'= H, R"= CMe2OH). Prolonged photolysis with diphenylethyne gives the dimetallatetrahedrane complex [FeRu(mu-CO)(mu-eta2:eta2-CPhCPh)(eta-C5H5)(eta-C5Me5)], which contains the first iron-ruthenium double bond. Complexes containing a number of organic fragments can be synthesised using , and . Heating a solution of gave the alkenylidene complex [FeRu(CO)2(mu-CO){mu-eta]1:eta2-C=C(CO2Me)2}(eta-C5H5)(eta-C5Me5)] through an unusual methylcarboxylate migration. Protonation and then addition of hydride to gives the ethylidene complex [FeRu(CO)2(mu-CO)(mu-CHCH3)(eta-C5H5)(eta-C5Me5)] via the ionic vinyl species [FeRu(CO)2(mu-CO)(mu-eta]1:eta2-CH=CH2)(eta-C5H5)(eta-C5Me5)][BF4]. Compound exhibits cis/trans isomerisation at room temperature. Protonation of dimetallacyclopentenone complexes gives the allenyl species [FeRu(CO)2(mu-CO)(mu-eta1:eta2-CH=C=CMe2)(eta-C5H5)(eta-C5Me5)][BF4]. Compound exist as three isomers, two cis and one trans. The two cis isomers are shown to be interconverting by sigma-pi isomerisation. The solid state structures of these compounds were established by X-ray crystallography and are discussed.

Metal−Metal Bonded Homo- and Heterobimetallic Compounds of Pt(I) and Pd(I) Supported by a Bridging-N,P:N‘,P‘ Moiety of a Potentially Hexadentate Ligand

Reactions of metal-metal bonded homobimetallic (Pd(2)) and heterobimetallic (PtPd) complexes, supported by a P,P'-bridging-bis(P,N-chelating) coordination mode of the potentially hexadentate ligand 1,1-bis[di(o-N,N-dimethylanilinyl)phosphino]methane (dmapm), with CO, diethylacetylenedicarboxylate (DEAD), and thiols (RSH) in CH(2)Cl(2) are described. At room temperature, rac-Pd(2)Cl(2)(mu-N,P:P',N'-dmapm) gives the stable complexes Pd(2)Cl(2)(mu-CO)(2)(mu-P:P'-dmapm) and PdCl(eta2-DEAD)(mu-P:P',N-dmapm)PdCl (which is fluxional in solution), while rac-PtPdCl(2)(mu-N,P:P',N'-dmapm) disproportionates to PtCl(2)(P,P'-dmapm) and Pd metal, although at low temperature intermediate carbonyl species are detected in the CO reaction. The reactions with thiols in the presence of triflic acid (HOTf) generate rac-[MPdCl(2)(mu-SR)(mu-N,P:P',N'-dmapm)][OTf] and H(2) for both M = Pt and Pd. In CH(2)Cl(2), PdX(2)(dmapm) species (X = halide or CN) exist as equilibrium mixtures of P,P'- and P,N-ligated forms. For X = Cl, the P,P'-P,N equilibrium is governed by DeltaH degrees = -5.5 +/- 0.5 kJ mol(-1) and DeltaS degrees = 10 +/- 1 J mol(-1) K(-1), and the ring-strain energy within the P,P'-isomer is approximately 32 kJ mol(-1); the equilibrium increasingly favors the P,N-form with X = CN >> I > Br > Cl. The solid-state structures of rac-[PtPdCl(2)(mu-SEt)(mu-N,P:P',N'-dmapm)][OTf] and PdCl(2)(P,N-dmapm) are presented; the latter contains both bound and free N- and P-atoms of identical types in the same molecule and permits an assessment of sigma- and pi-bonding between these atoms and Pd.

Stereoselective cis-Addition of Aromatic C−H Bonds to Alkynes Catalyzed by Dinuclear Palladium Complexes

Reactions of alkynes with arenes proceeded in the presence of dinuclear palladium complexes and trialkylboranes to yield alkyne hydroarylation products with high stereoselectivity. In the reactions of monosubstituted benzenes, meta and para products were formed in statistical ratios, while no ortho isomers were detected.