Some ruthenium complexes containing cyanocarbon ligands: syntheses, structures and extent of electronic communication in binuclear systems

The preparation of several ruthenium complexes containing cyanocarbon anions is reported. Deprotonation (KOBu^t) of [Ru(NCCH₂CN)(PPh₃)₂Cp]PF₆ (1) gives Ru{NCCH(CN)}(PPh₃)₂Cp (2), which adds a second [Ru(PPh₃)₂Cp]⁺ unit to give [{Ru(PPh₃)₂Cp}₂(μ-NCCHCN)]⁺ (3). Attempted deprotonation of the latter to give the μ-NCCCN complex was unsuccessful. Similar chemistry with tricyanomethanide anion gives Ru{NCC(CN)₂}(PPh₃)₂Cp (4) and [{Ru(PPh₃)₂Cp}₂{μ-NCC(CN)CN}]PF₆ (5), and with pentacyanopropenide, Ru{NCC(CN)C(CN)C(CN)₂}(PPh₃)₂Cp (6) and [{Ru(PPh₃)₂Cp}₂{μ-NCC(CN)C(CN)C(CN)CN}]PF₆ (7). The Ru(dppe)Cp* analogues of 6 and 7 (8 and 9) were also prepared. Thermolysis of 6 (refluxing toluene, 12 h) results in loss of PPh₃ and formation of the binuclear cyclic complex {Ru(PPh₃)Cp[μ-NC{C(CN)C(CN)₂}CN]}₂ (10). The solid-state structures of 2-4 and 8-10 have been determined and the nature of the isomers shown to be present in solutions of the binuclear cations 7 and 9 by NMR studies has been probed using Hartree-Fock and density functional theory.     

Cyclopentadienyl ruthenium alkynyldithiocarboxylate complexes

Treatment of the ruthenium chloride, CpRu(PPh₃)₂Cl, with the alkynyldithiocarboxylate anions, , in refluxing THF affords the chelate complexes CpRu(PPh₃)(κ²S,S-S₂CCCR) (1) (R = Bu^t (a), Buⁿ (b), Ph (c), SiMe₃ (d)) in high yield. The room temperature reaction of the solvated species, [CpRu(PPh₃)₂(NCPh)]⁺, with the alkynyldithiocarboxylate anions, , produces the chelate complexes 1 and the mono-coordinated complexes CpRu(PPh₃)₂(κS-S₂CCCR) (2). Complexes 2 are converted to 1 in solution so that they were characterized spectroscopically.     

Half-sandwich trihydrido ruthenium complexes

This paper reports facile preparation of half-sandwich trihydrido complexes of ruthenium based on the reactions of the readily available precursors [Cp(R₃P)Ru(NCCH₃)₂][PF₆] with LiAlH₄. The target complexes were characterized by spectroscopic methods and X-ray structure analysis of .     

Syntheses,characterization, and structures of three ruthenium complexes containing two monodentate dppm ligands

Three cis-Ru(dppm)₂XY complexes (XY?=?C₂O₄, 1; X?=?Cl, Y?=?N₃, 2; X?=?Y?=?N₃, 3) were prepared by reactions of cis-Ru(dppm)₂Cl₂ with (NH₄)₂C₂O₄, a mixture of NaN₃ and NaPF₆, and only NaN₃, respectively, while 3 could also be obtained from further reaction of 2 with NaN₃ undergoing a facile chloride abstraction. All complexes have been characterized by IR, NMR, UV–vis, and luminescence spectroscopic analyses as well as X-ray diffraction studies. Of these structures, 1 shows oxalate coordinates to Ru as a chelating ligand, while 2 displays Ru and azide linear, and 3 gives two azide groups cis to each other, which are different from two substituting ligands commonly lying in trans positions in Ru(P–P)₂ complexes by using cis-Ru(dppm)₂Cl₂ as a precursor.     

Reactions of cyano(alkynyl)ethenes with some alkynyl- and diynyl-ruthenium complexes

Reactions of Ru(CCPh)(PPh₃)₂Cp with (NC)₂CCR¹R² (R¹ = H, R² = CCSiPrⁱ₃8; R¹ = R² = CCPh 9) have given η³-butadienyl complexes Ru{η³-C[C(CN)₂]CPhCR¹R²}(PPh₃)Cp (11, 12), respectively, by formal [2 + 2]-cycloaddition of the alkynyl and alkene, followed by ring-opening of the resulting cyclobutenyl (not detected) and displacement of a PPh₃ ligand. Deprotection (tbaf) of 11 and subsequent reactions with RuCl(dppe)Cp and AuCl(PPh₃) afforded binuclear derivatives Ru{η³-C[C(CN)₂]CPhCHCC[ML_n]}(PPh₃)Cp [ML_n = Ru(dppe)Cp 19, Au(PPh₃) 20]. Reactions between 8 and Ru(CCCCR)(PP)Cp [PP = (PPh₃)₂, R = Ph, SiMe₃, SiPrⁱ₃; PP = dppe, R = Ph] gave η¹-dienynyl complexes Ru{CCC[C(CN)₂]CRCH[CC(SiPrⁱ₃)]}(PP)Cp (15-18), respectively, in reactions not involving phosphine ligand displacement. The phthalodinitrile C₆H(CCSiMe₃)(CN)₂(NH₂)(SiMe₃) 10 was obtained serendipitously from (Me₃SiCC)₂CO and CH₂(CN)₂, as shown by an XRD structure determination. The XRD structures of precursor 7 and adducts 11, 12 and 17 are also reported.     

Some benzimidazole amide complexes of ruthenium(II)

The synthesis and characterisation of ruthenium(II) complexes with 2-amidobenzimidazoles are reported. The complexes RuCl₂(DMSO)₄ and RuCl₂(PPh₃) react with 2-(acetamido)benzimidazole (AB) and 2-(benzamido)benzimidazole (BB) it acetone to give products of the type [Ru(L)₂(N−O)₂]Cl₂ [L=DMSO, PPh₃, N−O=AB, BB). The displacement reactions are faster in the case of methyl (AB) than phenyl (BB) substituted ligands. The ligands are bifunctional chelating agents coordinating through the tertiary nitrogen of benzimidazole ring and amide oxygen. The complexes are characterised based on their elemental analysis, conductivity data, infrared,¹H and³¹P nmr spectra. Acis-geometry is proposed for all the complexes reported.     

p-Cymene ruthenium thioether complexes

Thioethers PhC₂H₄SMe, PhC₃H₆SⁱPr and MeSAllyl form substitutionally labile monomeric adducts (p-cymene)RuCl₂(SRR′) (2a-c) upon treatment with the {(p-cymene)RuCl₂}₂ dimer (p-cymene = η⁶-MeC₆H₄ⁱPr-1,4). Pure adducts were obtained by crystallization from CH₂Cl₂/Et₂O, and 2a,c as well as the bis(thioether) complex (3) were studied by X-ray crystallography. The trichloro bridged diruthenium complex is formed as a byproduct in the preparation of 3 and was also crystallographically characterized. In solution, pure samples 2a-c equilibrate with free thioether and the dimeric starting complex 1. The amount of 1 present in these mixtures increases with increasing bulk of the thioether substituents. Attempts to thermally replace the cymene ligand by the dangling arene substituent of the thioether ligand of 2a,b failed. Complexes 2a-c as well as the dimethylsufide derivative 2d were studied by cyclic voltammetry and display a close to reversible (2a,c,d) or partially reversible (2b) oxidation near +0.85 V and an irreversible reduction at rather negative potential. New peaks observed after oxidation and reduction point to dissociation of the thioether ligand as the main decomposition pathway of the associated radical cations and anions.     

Some complexes containing carbon chains end-capped with tungsten or ruthenium groups and tricobalt carbonyl clusters

The Pd(0)/Cu(I)-catalysed reactions between Co₃(μ₃-CBr) (CO)₉ and W(CCCCH)(CO)₃Cp gives the C₅ complex {Cp(OC)₃W}CCCCC{Co₃(CO)₉} (2). Similarly, Co₃(μ₃-CBr)(μ-dppm)(CO)₇ and W(CCCCH)(CO)₃Cp or Ru(CCCCH)(dppe)Cp* give {Cp(OC)₃W}CCCCC{Co₃(μ-dppm)(CO)₇} and {Cp*(dppe)Ru}CCCCC{Co₃(μ-dppmn)(CO)₇} (5). An attempt to prepare a C₃ analogue from Ru(CCH)(PPh₃)₂Cp and Co₃(μ₃-CBr)(CO)₉ gave instead the acyl derivative {Cp(Ph₃P)₂Ru}CCC(O)C{Co₃(CO)₈(PPh₃)} (7). The X-ray structures of 2, 5 and 7 are reported: the C₅ chains in 2 and 5 have an essentially unperturbed -CC-CC-C formulation.     

Hydrosilylation of alkynes catalyzed by ruthenium carbene complexes

Hydrosilylation of terminal alkynes with a variety of silanes catalyzed by Cl₂(PCy₃)₂RuCHPh (1) affords mainly the Z-isomer via trans addition in excellent yields. The presence of a hydroxyl group in close proximity to the triple bond was observed to exert a strong directing effect, resulting in the highly selective formation of the α-isomer. Intramolecular hydrosilylation of a homopropargylic silyl ether was demonstrated to give the cis addition product.     

Synthesis of chiral chelating N-heterocyclic carbene complexes of ruthenium

The first 9-membered chiral chelating bidentate imidazol-2-ylidene ruthenium (II) benzylidene complexes based on a cyclopentane backbone were synthesised and characterised via NMR and HRMS.     

Preparation of hydride complexes of ruthenium with bidentate phosphite ligands

Hydride complex RuH₂(PFFP)₂ (1) [PFFP = (CF₃CH₂O)₂PN(CH₃)N(CH₃)P(OCH₂CF₃)₂] was prepared by allowing the compound RuCl₄(bpy) · H₂O (bpy = 1,2-bipyridine) to react first with the phosphite PFFP and then with NaBH₄. Chloro-complex RuCl₂(PFFP)₂ (2) was also prepared, either by reacting RuCl₄(bpy) · H₂O with PFFP and zinc dust or by substituting triphenylphosphine with PFFP in the precursor complex RuCl₂(PPh₃)₃. Hydride derivative RuH₂(POOP)₂ (3) (POOP = Ph₂POCH₂CH₂OPPh₂) was prepared by reacting compound RuCl₃(AsPh₃)₂(CH₃OH) first with the phosphite POOP and then with NaBH₄. Depending on experimental conditions, treatment of carbonylated solutions of RuCl₃ · 3H₂O with POOP yields either the cis- or trans-RuCl₂(CO)(PHPh₂)(POOP) (4) derivative. Reaction of both cis- and trans-4 with LiAlH₄ in thf affords dihydride complex RuH₂(CO)(PHPh₂)(POOP) (5). Chloro-complex all-trans-RuCl₂(CO)₂(PPh₂OMe)₂ (6) was obtained by reacting carbonylated solutions of RuCl₃ · 3H₂O in methanol with POOP. Treatment of chloro-complex 6 with NaBH₄ in ethanol yielded hydride derivative all-trans-RuH₂(CO)₂(PPh₂OMe)₂ (7). The complexes were characterised spectroscopically and the X-ray crystal structures of complexes 1, 3, cis-4 and 6 were determined.     

Reactions of metalloalkynes VII. Protonation of ruthenium ethyne-1,2-diyl complexes

The acid–base chemistry of some ruthenium ethyne-1,2-diyl complexes, [{Ru(CO)₂(η-C₅H₄R)}₂(μ₂-CC)] (R=H, Me) has been investigated. Initial protonation of [{Ru(CO)₂{η-C₅H₄R}}₂(μ₂-CC)] gave the unexpected complex cation, crystallised as the BF₄ salt, [{Ru(CO)₂(η-C₅H₄R}}₃(μ₃-CC)][BF₄] (R=Me structurally characterised). This synthesis proved to be unreliable but subsequent, careful protonation experiments gave excellent yields of the protonated ethyne-1,2-diyl complexes, [{Ru(CO)₂{η-C₅H₄R)}₂(μ₂-η¹:η²-CCH)](BF₄) (R=Me structurally characterised) which could be deprotonated in high yield to return the starting ethyne-1,2-diyl complexes.     

Reaction of ruthenium complexes containing heterocyclic thiazine–thione ligand

Treatment of the ruthenium complex [Ru]---

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(3, [Ru]=Cp(dppe)Ru) containing a heterocyclic [1,3]-thiazine-4-thione six-membered-ring ligand with various organic halides results in alkylation at the thione sulfur terminus of the ligand to yield [Ru]---

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][X] (4a, R=CN, X=I; 4b, R=Ph, X=Br; 4c, R=CH=CH₂, X=I, 4d, R=p-C₆H₄CF₃, X=Br). Similarly the reaction of 3 with HgCl₂ at room temperature affords [Ru]---

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][Cl] (5). Transformation of 5 to the cationic vinylidene complex {[Ru]=C=C(Ph)C(O)NHPh}₂[Hg₂Cl₆] (6) readily occurred in the air. The structures of 4c and 6 are determined by single crystal X-ray diffraction analysis.     

The synthesis and reactivity of some indenyl and bis-indenyl ruthenium carbonyl complexes

The reaction of [Ru₃(CO)₁₂] (1), with indene in refluxing xylene affords [{(η⁵-C₉H₇)Ru(CO)₂}₂] (2), in high yield. An analogous reaction of 1 with 2-phenylindene affords the expected dinuclear complex [{(η⁵-C₉H₆Ph)Ru(CO)₂}₂] (5), and a heptaruthenium cluster [(C₉H₄Ph)Ru₇(μ-H)(μ-CO)₂(CO)₁₆] (6). The indenyl ligand in compound 6 exhibits a novel bonding mode in which the benzenoid ring is μ₄,η¹:η¹:η²:η² bound to the cluster. Refluxing 1 with bis-indenyl methane affords the dinuclear complex [Ru₂(CO)₄{μ-(η⁵-C₉H₆)₂CH₂}] (7), which reacts with iodine via Ru-Ru bond cleavage to give [Ru₂I₂(CO)₄{(η⁵-C₉H₆)₂CH₂}] (8).     

Monothiolate ruthenium alkylidene complexes with tricyclic fluorinated N-heterocyclic carbene ligands

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Grubbs and Hoveyda-type ruthenium complexes bearing a cyclic bent-allene

Stable cyclic bent-allene 1 displaces the chelating ether linkage of the Hoveyda-Grubbs-type ruthenium complex 2 bearing triphenylphosphine. The resulting complex 3 features an unusual cis-arrangement of the phosphine and the cyclic bent-allene, while retaining a distorted square pyramidal geometry around the ruthenium center. Monitoring by ³¹P NMR spectroscopy the reaction of cyclic bent-allene 1 with the indenylidene bis(triphenylphosphine)ruthenium dichloride complex 4 allowed for the observation of dissociated triphenylphosphine, and the formation of a ruthenium complex featuring 1 and triphenylphosphine in the desired trans-configuration. However, continued reaction times saw the disappearance of this complex, and after workup complex 5 featuring a cis-arrangement was isolated.     

Some organometallic chemistry of ruthenium(II)

Stoichiometric and catalytic reaction of Ru(II) phosphine complexes with alkynes, olefins, and enynes are described. The hydride complex RuCl(CO)H(PPh₃)₃ (1) reacts with the double bond of a cis-enyne whereas it reacts with triple bonds of trans-enynes. Metathesis of vinyl silanes with olefins are catalyzed by 1 where β-Si elimination is the key step. Dimerizations of ^tBu- and Me₃Si-substituted acetylanes into the corresponding butatrienes are catalyzed by Ru(II) active species as studied by isolation of the intermediates. A model reaction for the crucial step of the catalytic cycle, formation of a Ru vinylidene complex from acetylene, has been fully simulated by ab initio-MO calculations.     

Ruthenium titanocene and ruthenium titanium half-sandwich bimetallic complexes in catalytic cyclopropanation

The reaction of the phosphine functionalised titanium half-sandwich complexes 7, 9 and 10 with the binuclear complex [(p-cymene)RuCl₂]₂ allowed the access to three new early-late bimetallic complexes (p-cymene)[(μ-η⁵:η¹-C₅H₄(CH₂)_nPR₂)TiX₃]RuCl₂ (11-13). The structure of 11 (n = 0, X = Cl) has been confirmed by X-ray diffraction. The ruthenium titanium half-sandwich bimetallic complexes so formed and the ruthenium titanocene analogues 4-6 catalyse the addition of ethyl diazoacetate to styrene with high selectivity toward cyclopropanation versus metathesis contrary to the monometallic complexes (p-cymene)RuCl₂PR₃.     

Direct Aminophosphonylation of aldehydes catalyzed by cyclopentadienyl ruthenium(II) complexes

This work reports a novel method for the direct aminophosphonylation of aldehydes catalyzed by cyclopentadienyl ruthenium(II) complexes. The system HP(O)(OEt)₂/[CpRu(PPh₃)₂Cl] was very efficient for the aminophosphonylation of aldehydes with primary and secondary amines, producing the corresponding α-aminophosphonates in good to excellent yields. This novel method has several advantages including the use of a small amount of catalyst (0.5?mol%), high chemoselectivity, solvent-free conditions and application of the catalyst [CpRu(PPh₃)₂Cl] for at least 12 cycles with excellent activity.