Complex RhCl Research Articles

N‐Heterocyclic Phosphido Complexes of Rhodium Supported by a Rigid Pincer Ligand

The diphosphine, N‐heterocyclic phosphenium/phosphido (NHP+)/(NHP–)‐containing ligand (PPP+/–) has been coordinated to rhodium to study the coordination chemistry of group 9 metals and NHP+/– fragments. Addition of the chlorophosphine ligand PPClP to [Rh(COD)Cl]2 produces the complex (PPClP)RhCl (2), which can be reduced to form (PPP)Rh(PMePh2) (3), the asymmetric dimer [(PPP)Rh]2 (4), and the asymmetric dimer [(PPP)Rh(CNtBu)]2 (5). Analysis of the solid‐state structures and computational studies have provided insight into the electronic structure and bonding in 3–5, revealing that the NHP+/– fragments in 3, 4, and 5 are best described using an NHP–/RhI description. Both 3 and 5 were found to be reactive towards the S–H bond of thiophenol, generating (PPP)RhSPh (6) and (PPP)Rh(SPh)(CNtBu) (7), respectively.

Operando XAFS Studies on Rh(CAAC)-Catalyzed Arene Hydrogenation

Rh K-edge X-ray absorption fine structure (XAFS) spectroscopy was used to examine the Rh-catalyzed arene hydrogenation of diphenyl ether by a combination of stoichiometric reactions of [(CAACCy,Dipp)Rh(COD)Cl] (Rh–Cl) (CAACCy,Dipp = cyclic alkyl amino carbene) and operando XAFS kinetics studies. Our results unequivocally show that Rh nanoparticles, generated from the single-site Rh complex Rh–Cl, catalyze the arene hydrogenation. Operando XAFS studies illuminate the role of silver cation on the precatalyst reactivity, the effect of increasing H2 pressure on increasing the catalytic efficiency, the stabilizing influence of Ph2O on the relative rate of formation of active Rh nanoparticles, and the absence of soluble single-site Rh species that might leach from bulk heterogeneous Rh nanoparticles. We gained insights into the divergent deactivation pathways mediated by substoichiometric benzothiophene and excess KOtBu toward H2 activation, which is a key step en route to Rh nanoparticles for arene hydrogenati...

Chelate Silylene-Silyl Ligand Can Boost Rhodium-Catalyzed C-H Bond Functionalization Reactions.

The first N-heterocyclic silylene (NHSi)-silane scaffold LSi-R-Si(H)Mes2 (1) (L=PhC(NtBu)2 ; R=1,12-xanthendiyl spacer; Mes=2,4,6-Me3 C6 H2 ) was synthesized and used to form the unique rhodium(III) complex (LSi-R-SiMes2 )Rh(H)Cl 2 through its reaction with 0.5 molar equivalents of [Rh(coe)2 Cl]2 (coe=cyclooctene). An X-ray diffraction analysis revealed that 2 has a (SiII SiIV )Rh(H)Cl core with three short Rh⋅⋅⋅H-C contacts with Me groups of the ligand 1, which cause a distorted pentagonal bipyramidal coordination of the Rh center. Unexpectedly, the reaction of 2 with tBuONa gives the new bis(silyl)hydridorhodium(III) complex 4. Due to the strong donor ability of the chelate SiII -SiIV ligand, 2 and 4 can act as highly efficient pre-catalysts in the Rh-mediated selective C-H functionalization of 2-phenylpyridines with C-C unsaturated organic substrates under mild reaction conditions.

Pentacoordinated Rhodium(I) Complexes Supported by Coumarin-Functionalized N-Heterocyclic Carbene Ligands

New coumarin-tethered benzimidazolium (BzICouRHCl) and imidazolium (ICouRHCl) salts have been prepared as precursors for coumarin–NHC rhodium(I) complexes RhCl(NHC)(cod). Trigonal bypiramidal pentacoordinated bis-coumarin–NHC rhodium(I) species, RhCl(NHC)2, can be obtained by heating rhodium-cod derivatives in the presence of coumarin–azolium salts and a base. These unusual species are stabilized by coordination of the unsaturated bond of both coumarin moieties by the same enantioface. The allyl substituent on doubly functionalized NHC competes for coordination with coumarin wingtips. DFT calculations upon coordination of the olefin moieties support the experimental results.

Role of Regioisomeric Bicyclo[3.3.0]octa-2,5-diene Ligands in Rh Catalysis: Synthesis, Structural Analysis, Theoretical Study, and Application in Asymmetric 1,2- and 1,4-Additions.

In order to study the impact of regioisomeric diene ligands on the formation and catalytic activity of Rh complexes, a series of C2- and CS-symmetric 2,5-disubstituted bicyclo[3.3.0]octa-2,5-dienes C2-L and CS-L, respectively, were synthesized from Weiss diketone by simultaneous deprotonation/electrophilic trapping of both oxo functions, and the catalytic behavior was studied in the presence of [RhCl(C2H4)2]2. Complexes [RhCl(C2-L)]2 bearing C2-symmetric ligands catalyzed effectively the asymmetric arylation of N-tosylaldimines to (S)-diarylamines with yields and ee values up to 99%. In Hayashi-Miyaura reactions, however, the complexes showed poor catalytic activity. When complexes [RhCl(CS-L)]2 with CS-symmetric ligand or mixtures of [RhCl(C2-L)]2 and [RhCl(CS-L)]2 were employed in 1,2-additions, racemic addition products were observed, suggesting a C═C isomerization of the diene ligands. X-ray crystal structure analysis of both Rh complexes formed from the [RhCl(C2H4)2]2 precursor and ligands C2-L and CS-L revealed that only the C2-symmetric ligand C2-L coordinated to the Rh, whereas CS-L underwent a Rh-catalyzed C═C isomerization to rac-C2-L, which then gave the racemic [RhCl(rac-C2-L)]2 complex. DFT calculations of the relative stabilities of the Rh complexes and the proposed intermediates provided a mechanistic rationale via Rh-mediated hydride transfer.

Synthesis of Rh(III) complexes for the study of C–O bond forming reactions: a key step for the conversion of hydrocarbons to alcohols.

The partial oxidation of hydrocarbons into alcohols is an economically attractive reaction for the production of commercial chemicals and fuels, particularly intriguing in an area like West Virginia where more efficient use of natural gas would be desirable. For a catalytic system to facilitate this reaction, a transition metal must be able to break a C–H bond of an alkane and form a new C–O bond to yield the alcohol product. Most catalytic systems that have been reported to mediate the partial oxidation of hydrocarbons are based on platinum. One possible approach to improve catalytic reactivity is to investigate transition metals that are less electrophilic than platinum, such as rhodium. While many rhodium systems have been reported to facilitate C–H bond-breaking, there is a relative dearth of complexes capable of C–O bond formation. The current work is an ongoing project that focuses on the synthesis of novel rhodium complexes. The complex (pip2NNN)RhCl [pip2NNN = 2,6-bis(piperidylmethyl)pyridine] has been synthesized and characterized by NMR spectroscopy. Oxidation from this Rh(I) complex to Rh(III) using CH3X [X = halide] is currently underway in order to study C–O bond formation reactivity.

Conclusive evidence on the mechanism of the rhodium-mediated decyanative borylation.

The stoichiometric reactions proposed in the mechanism of the rhodium-mediated decyanative borylation have been performed and all relevant intermediates isolated and characterized including their X-ray structures. Complex RhCl{xant(P(i)Pr2)2} (1, xant(P(i)Pr2)2 = 9,9-dimethyl-4,5-bis(diisopropylphosphino)xanthene) reacts with bis(pinacolato)diboron (B2pin2), in benzene, to give the rhodium(III) derivative RhHCl(Bpin){xant(P(i)Pr2)2} (4) and PhBpin. The reaction involves the oxidative addition of B2pin2 to 1 to give RhCl(Bpin)2{xant(P(i)Pr2)2}, which eliminates ClBpin generating Rh(Bpin){xant(P(i)Pr2)2} (2). The reaction of the latter with the solvent yields PhBpin and the monohydride RhH{xant(P(i)Pr2)2} (6), which adds the eliminated ClBpin. Complex 4 and its catecholboryl counterpart RhHCl(Bcat){xant(P(i)Pr2)2} (7) have also been obtained by oxidative addition of HBR2 to 1. Complex 2 is the promoter of the decyanative borylation. Thus, benzonitrile and 4-(trifluoromethyl)benzonitrile insert into the Rh-B bond of 2 to form Rh{C(R-C6H4)═NBpin}{xant(P(i)Pr2)2} (R = H (8), p-CF3 (9)), which evolve into the aryl derivatives RhPh{xant(P(i)Pr2)2} (3) and Rh(p-CF3-C6H4){xant(P(i)Pr2)2} (10), as a result of the extrusion of CNBpin. The reactions of 3 and 10 with B2pin2 yield the arylBpin products and regenerate 2.

Rigid, non-porous and tunable hybrid p-aminobenzoate/TiO2 materials: Toward a fine structural determination of the immobilized RhCl(Ph3)3 complex

By exchange of ligands, Wilkinson complex RhCl(PPh3)3 are immobilized on p-aminobenzoate/TiO2 with different organic loading (6, 11 and 16%). This new hybrid material exhibit a linear correlation between the ligand content of the starting TiO2 and the rhodium loading, showing the accessibility of all surfaces amines fonctions on the non-porous parent materials. 1H, 13C, and 1D, 2D INAQUEDATE refocused and J-resolved 31P solid-state NMR confirm the well-defined structure [(≡TiO)2(ɳ2-O2C–C6H4–NH2)RhCl-cis-(PPh3)2]. New immobilized catalysts show interesting activity in cyclohexene hydroformylation.

N-Heterocyclic Carbenes with aN-2,4-Dinitrophenyl Substituent: Comparison with PPh3and IPr

Synthesis and characterization of N-heterocyclic carbenes (NHCs) bearing a 2,4-dinitrophenyl (DNP) substituent on an NHC framework were performed. The treatment of 1-(2,4-dinitrophenyl)-1H-imidazole (1) with 1-bromo-2,4-dinitrobenzene or methyl triflate afforded imidazolium salts 2a·HBr or 2b·HOTf, respectively, which were corresponding precursors of NHC ligands 1,3-bis(2,4-dinitrophenyl)-1H-imidazol-2-ylidene (2a) and 1-(2,4-dinitrophenyl)-3-methyl-1H-imidazol-2-ylidene (2b). Rh and Au complexes—RhCl(2a)(cod) [3a (cod = 1,5-cyclooctadiene)], RhCl(2b)(cod) (3b), RhCl(2a)(CO)2 (4a), RhCl(2b)(CO)2 (4b), and AuCl(2a) (5a)—were synthesized using 2a·HBr and 2b·HOTf. IR, NMR, and crystallographic analysis of the Rh complexes demonstrated that the DNP substituent remarkably decreased the σ-donating ability of the carbenic carbon and increased the π-accepting ability. In addition, IR spectroscopy of Rh dicarbonyl complexes revealed that the average CO stretching frequency of 2a was equal to that of PPh3. Au complex 5a exhibited a significantly higher catalytic activity than AuCl(PPh3) 5d in the Au(I)-catalyzed hydroalkoxylation of cyclohexene. The computational analysis of the Au(I) complexes supported the experimental data, and the results suggested that the Au–Ccarbene π-back-bonding interaction energy of 5a was 17–20% larger than that of 5d.

Preparation, Hydrogen Bonds, and Catalytic Activity in Metal-Promoted Addition of Arylboronic Acids to Enones of a Rhodium Complex Containing an NHC Ligand with an Alcohol Function

The complex RhCl(COD){3-benzyl-1-(2-hydroxy-2-phenylethyl)imidazol-2-ylidene} has been prepared by reaction of the dimer [Rh(μ-OMe)(COD)]2 with 3-benzyl-1-(2-hydroxy-2-phenylethyl)imidazolium chloride and characterized by X-ray diffraction analysis. The structure reveals that 75% of the molecules are associated through intermolecular O–H···Cl hydrogen bonds between the OH group of the NHC substituent of one molecule and the chloride ligand of the adjacent molecule. This complex catalyzes the addition of arylboronic acids to cyclic and acyclic enones in anhydrous toluene. The alcohol function of the substituent of the NHC ligand plays the role assigned to water in previous cases.

Interaction between water-soluble rhodium complex RhCl(CO)(TPPTS)2 and surfactants probed by spectroscopic methods

The interactions of rhodium complex RhCl(CO)(TPPTS)2 [TPPTS=P(m-C6H4SO3Na)3] with cationic, nonionic, and anionic surfactants have been investigated by UV–vis, fluorescence and 1H NMR measurements. The presence of four different species of RhCl(CO)(TPPTS)2 in cationic cetyltrimethylammonium (CTAB) solution has been demonstrated: free rhodium complex, rhodium complex bound to CTAB monomer, rhodium complex bound to CTAB premicelles, rhodium complex bound to CTAB micelles. The spectroscopy data show that RhCl(CO)(TPPTS)2 can adsorb on the interface of cationic CTAB micelles by strong electrostatic attraction, weakly bind to the nonionic polyoxyethylene (20) sorbitan monolaurate (Tween 20) micelles by hydrophobic interaction, and does not interact with anion sodium dodecyl sulfate (SDS) micelles due to the strong electrostatic repulsion.

Synthesis of a Rhodium(III) Diethyl μ-Carbonato Complex in the Reaction of CO2, H2O, and Ethylene

The reaction of the Rh(I) ethylene complex RhCl(CH2═CH2)2(PMe3)2 (2) with excess CO2 and H2O afforded a novel binuclear ethyl μ-carbonato complex, [(Me3P)4Rh2Cl2(C2H5)2(μ-CO3)] (3), in high yield. The structure of 3 was fully characterized by X-ray crystallography as well as by ordinary methods (NMR, IR, and elemental analysis). By using D2O in place of H2O, selective deuteration at the methyl position of the ethyl ligand was observed. Complex 3 reacted readily with CH2Cl2 to cleave the C–Cl bond.

Reactivity of Novel N,N′-Diphosphino-Silanediamine-Based Rhodium(I) Derivatives

The coordination abilities of the novel N,N'-diphosphino-silanediamine ligand of formula SiMe(2)(NtolPPh(2))(2) (SiNP, 1) have been investigated toward rhodium, and the derivatives [RhCl(SiNP)](2) (2), [Rh(SiNP)(COD)][BF(4)] (3), and Rh(acac)(SiNP) (4) have been synthesized. The stability of the dinuclear frame of [RhCl(SiNP)](2) (2) toward incoming nucleophiles has been shown to be dependent on their π-acceptor ability. Indeed, the mononuclear complexes RhCl(SiNP)(L) (L = CO, 5; CN(t)Bu, 6) have been isolated purely and quantitatively upon reaction of 2 with CO and CN(t)Bu, respectively. Otherwise, PPh(3) and RhCl(SiNP) equilibrate with Rh(Cl)(SiNP)(PPh(3)) (7). Carbon electrophiles such as MeI and 3-chloro-1-proprene afforded the oxidation of rhodium(I) to rhodium(III) and the formation of RhCl(2)(η(3)-C(3)H(5))(SiNP) (8) and Rh(Me)(I)(SiNP)(acac) (10), respectively. The methyl derivative 10 is thermally stable and does not react either with CO or with CN(t)Bu even in excess. Otherwise, RhCl(2)(η(3)-C(3)H(5))(SiNP) (8) is thermally stable but reacts with CO, affording 3-chloro-1-proprene and RhCl(SiNP)(CO) (5). Finally, upon reaction of Rh(acac)(SiNP) (4) and 3-chloro-1-proprene, RhCl(acac)(η(1)-C(3)H(5))(SiNP) (9a) and [Rh(acac)(η(3)-C(3)H(5))(SiNP)]Cl (9b) could be detected at 233 K. At higher temperatures, 9a and 9b smoothly decompose, affording the dinuclear derivative [RhCl(SiNP)](2) (2) and the CC coupling product 3-allylpentane-2,4-dione.

Synthesis of a Square-Planar Rhodium Alkylidene N-Heterocyclic Carbene Complex and Its Reactivity Toward Alkenes

The first rhodium alkylidene square-planar complex stabilized by an N-heterocyclic carbene ligand, RhCl(═CHPh)(IPr)PPh3 (2; IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-carbene), has been prepared by reaction of RhCl(IPr)(PPh3)2 (1) with phenyldiazomethane and its dynamic behavior in solution studied. Treatment of 2 with alkenes results in the formation of the η2-olefin complexes RhCl(η2-CH2═CHR)(IPr)PPh3 (3, R = H; 4, R = Ph; 5, R = OEt) and new olefins arising from the coupling of the alkylidene with the alkenes, likely via a metallacyclobutane intermediate.

Parahydrogen-Induced Polarization in Heterogeneous Hydrogenations over Silica-Immobilized Rh Complexes

The use of heterogeneous catalysts for parahydrogen-induced polarization (PHIP) of nuclear spins opens new horizons for production of hyperpolarized substances. Immobilization of homogeneous hydrogenation catalysts is a promising approach for designing the efficient heterogeneous catalytic systems capable of PHIP generation. Herein, we study the formation of PHIP in the gas-phase and in the liquid-phase hydrogenations of propyne and propylene catalyzed by silica-immobilized Rh complexes synthesized by the ligand-exchange anchoring of the Wilkinson’s complex RhCl(PPh3)3, the binuclear complex Rh2Cl2(C8H12)2 and the cationic complex [Rh(C8H12)2]+[BF4]− to the phosphine-modified silica gel. We consider the stability and the mechanistic aspects of the hydrogenation over the immobilized Wilkinson’s catalyst in terms of PHIP observation. Using a PASADENA (parahydrogen and synthesis allow dramatically enhanced nuclear alignment) effect, it is found, in particular, that liquid-phase propyne hydrogenation over the immobilized Wilkinsons’s catalyst at 70°C proceeds in a stable regime with a stereoselective cis addition of a hydrogen molecule, while in the gas phase at the same temperature the hydrogenation stereoselectivity is observed only for a short time after the reaction is started, and then the catalyst rapidly loses its activity. The reasons of the catalyst deactivation are discussed based on the literature data, the results of infrared spectroscopy study, and the comparison to the behavior of the immobilized binuclear and cationic Rh complexes. In addition, it is shown that the immobilized Wilkinson’s catalyst is reduced as temperature increases in the range of 90–130°C, as confirmed by X-ray photoelectron spectroscopy.

Selective hydrogenation of nitrile-butadiene rubber catalyzed by thermoregulated phase transfer phosphine rhodium complex

Hydrogenation of polymer having CC double bond can be carried out with the metal–organic complex as catalyst, which has the property of themoregulated phase transfer. In this study, a new complex RhCl[PPh[(OCH2CH2)5≤n≤6CH3]2]3 (Rh/AEOPP) was synthesized with a good yield, which was further used as catalyst to selectively hydrogenated nitrile-butadiene rubber (HNBR). This is the first time that Rh/AEOPP complex was synthesized and applied in nitrile-butadiene rubber (NBR) hydrogenation. The result shows that hydrogenation degree of product (HNBR) can be extended to 90%, when the condition is [Cat] = 3% (based the weight of NBR), L2: Cat (Weight Ratio) = 2, [NBR] = 5% (based on the weight of xylene solution), P (H2) = 1.5 MPa, T = 155°C, and t = 8 h. Also, by adjusting temperature, the catalyst could be easily separated from products with 89% catalyst complex recovery. In addition, 1H-NMR and infrared (IR) spectra showed that CC double bonds in NBR was successfully hydrogenated without causing reduction of the CN group. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Early–late heterobimetallic Rh–Ti and Rh–Zr complexes via addition of early metal chlorides to mono- and divalent rhodium

Addition of TiCl(4) or ZrCl(4) to (PNP)Rh(CH(2)==CH(t)Bu) (1) rapidly gives complexes (PNP)Rh(MCl(3))(Cl) (M = Ti, 2; Zr, 3) in 75-77% yield (PNP = (4-Me-2-((i)Pr(2)P)-C(6)H(3))(2)N). Compound 2 can also be synthesized via a reaction of (PNP)RhCl with TiCl(3) or of (PNP)TiCl(3) with 1/2 [(cod)RhCl](2).

Dicyclopentadiene Hydroformylation in an Aqueous/Organic Two Phase System in the Presence of a Cationic Surfactant

Dicyclopentadiene (DCPD) hydroformylation catalyzed by the water soluble rhodium complex RhCl(CO)(TPPTS) 2 (TPPTS: P(m-C 6 H 4 SO 3 Na) 3 ) was studied in an aqueous/organic two phase system containing a cationic surfactant. The effects of various reaction parameters such as reaction temperature, catalyst concentration, water soluble phosphine TPPTS or TPPDS (C 6 H 5 P(m-C 6 H 4 SO 3 Na) 2 ), and surfactant structure were examined. The catalytic activity was better with the ligand TPPTS than with TPPDS. The reaction was accelerated by the addition of the cationic surfactant C 16 H 33 N(CH 3 ) 2 C n H 2 n +1 Br( n = 1, 8, 12, 16) but the accelerating effect was attenuated with an increase of the n value. In the presence of the surfactant, the DCPD conversion increased initially and then decreased as the rhodium concentration increased in the range of 0.05–5.00 mmol/L. The catalyst containing aqueous phase was reused four times without significant decrease in activity and regioselectivity. ： 研究了在阳离子表面活性剂存在下水/有机两相中水溶性铑配合物 RhCl(CO)(TPPTS) 2 (TPPTS: P(m-C 6 H 4 SO 3 Na) 3 ) 催化双环戊二烯氢甲酰化反应, 考察了反应温度、催化剂浓度、不同水溶性膦配体 TPPTS 和 TPPDS (C 6 H 5 P(m-C 6 H 4 SO 3 Na) 2 ), 以及表面活性剂结构对催化反应的影响. 结果表明, 配体 TPPTS 比 TPPDS 表现出更好的助催化效果; 阳离子表面活性剂 C 16 H 33 N(CH 3 ) 2 C n H 2 n +1 Br ( n = 1, 8, 12, 16) 的加入可大大加速反应, 但加速作用随着其中 C n H 2 n +1 Br ( n = 1, 8, 12, 16) 链长的增加而减弱; 在阳离子表面活性剂 (0.05-5.00 mmol/L) 存在下, 双环戊二烯的转化率随表面活性剂浓度的增加先增加后降低. 含催化剂的水相循环使用 4 次后, 催化活性和区域选择性没有明显下降. Catalysis system composed of RhCl(CO)(TPPTS) 2 -TPPTS and a cationic surfactant showed good catalytic activity for dicyclopentadiene hydroformylation

Arylglyoxylrhodium Complexes, Their Thermolysis, and Attempted Generation by Carbonylation of an Aroylrhodium Complex

Reactions of ArCOCOCl (Ar = p-ClC6H4, Ph) with Rh(acac)(CO)2 proceeded readily to afford dimeric arylglyoxyl rhodium complexes [Rh(μ-Cl)(acac)(CO)(COCOAr)]2. [Rh(μ-Cl)(acac)(CO){COCO(p-ClC6H4)}]2 was characterized by X-ray diffraction. Thermolysis of the products showed that [Rh(μ-Cl)(acac)(CO){COCO(p-ClC6H4)}]2 was more stable than [Rh(μ-Cl)(acac)(CO)(COCOPh)]2. The reaction of p-CH3OC6H4COCOCl with Rh(acac)(CO)2 did not form a similar dimeric complex as final product, but gave p-CH3OC6H4COCl as major product, showing thermal instability of corresponding arylglyoxyl and aroyl rhodium complexes. The reaction of C6F5COCOCl did not form a simlar dimeric complex either, but a mononuclear complex RhCl(acac)(COCOC6F5)(CO)2 was generated as a transient intermediate, which was readily transformed to a furanone arising from reductive elimination of the acac ligand and C6F5COCO moiety followed by cyclization. In the thermolysis of [Rh(μ-Cl)(acac)(CO)(COCOAr)]2, only ArCOCl and Rh(acac)(CO)2 were formed, and any ArCORh species could not be detected during the thermolysis process. However, the reaction of Rh(acac)(CO)2 with PhCOCl formed RhCl(acac)(CO)2(COPh), albeit only to a small extent, suggesting that the reaction is not thermodynamically favored. The reaction of RhCl(CO)(PMe3)2 with p-ClC6H4COCOCl also proceeded cleanly to furnish p-ClC6H4COCORhCl2(CO)(PMe3)2. Thermolysis of the complex formed p-ClC6H4CORhCl2(CO)(PMe3)2, indicating slow reductive elimination of ClC6H4COCl as compared with the ArCORh species, generated in the thermolysis of [Rh(μ-Cl)(acac)(CO)(COCOAr)]2. Treatment of ClC6H4CORhCl2(CO)(PMe3)2 with carbon monoxide generates p-ClC6H4COCORhCl2(CO)(PMe3)2, although the yield was low.

ChemInform Abstract: Coordination Chemistry of a New Tetratertiary Phosphine Ligand.

The synthesis and characterization of the new tetratertiary phosphine 2,3-bis[(diphenylphosphino)methyl]-1,4-bis(diphenylphosphino)butane (5) is reported. Oxidation of 5 with t-BuOOH or S[sub 8] yields the tetraphosphoryl and tetrathiophosphoryl derivatives 6 and 7, respectively. The molecular structure of 6 was confirmed by X-ray crystallography. Crystals of 6 are triclinic. The complexes [CH(CH[sub 2]PPh[sub 2])[sub 2]ML[sub n]][sub 2] have been prepared for ML[sub n] = PdCl[sub 2], PdBr[sub 2], PdI[sub 2], NiCl[sub 2], PtCl[sub 2], Cr(CO)[sub 4], Mo(CO)[sub 4], W(CO)[sub 4], and Fe(CO)[sub 3], in which 5 coordinates in a bis(bidentate) manner to two metals with the formation of two six-membered chelate rings. This coordination mode was confirmed by single-crystal X-ray diffraction studies on the complexes [CH(CH[sub 2]PPh[sub 2])[sub 2]ML[sub n]][sub 2] for ML[sub n] = PdCl[sub 2] and NiCl[sub 2]. Crystals of [CH(CH[sub 2]PPh[sub 2])[sub 2]PdCl[sub 2]][sub 2] are monoclinic. Crystals of [CH(CH[sub 2]PPh[sub 2])[sub 2]NiCl[sub 2]][sub 2] are triclinic. The monometallic complex (Ph[sub 2]P(O)CH[sub 2])[sub 2]CHCH(CH[sub 2]PPh[sub 2])[sub 2]PdCl[sub 2] was also synthesized. Crystals of this complex are orthorhombic. The monometallic complexes (5-P,P[prime],P[double prime])Mo(CO)[sub 3] were prepared in which 5 exhibits a tridentate (P,P[prime]P[double prime]) coordination mode and where the fourth P of 5 can have a lone pair or be bondedmore » to O or S in addition to two phenyl groups. The monometallic complex (5)RhCl was also prepared, but [sup 31]P NMR spectroscopy indicated a complicated solution behavior for this complex. Similarly, attempted syntheses of monometallic complexes of Ni(II) and Pd(II) yielded mixtures which also exhibit complex behavior in solution as shown by [sup 31]P NMR spectroscopy.« less