Half-sandwich binuclear carbaborane compounds: Closo-carbaboranes as good σ-donar ligands

The synthesis of half-sandwich binuclear transition-metal complexes containing the Cab^C,C chelate ligands (Cab^C,C = C₂B₁₀H₁₀ (1)) is described. 1Li₂ was reacted with chloride-bridged dimers [Cp∗RhCl(μ-Cl)]₂ (Cp∗ = η⁵-C₅(CH₃)₅), [Cp′RhCl(μ-Cl)]₂ (Cp′ = η⁵-1,3-^tBu₂C₅H₃), [Cp∗IrCl(μ-Cl)]₂ and [(p-cymene)RuCl(μ-Cl)]₂ to give half-sandwich binuclear complexes [Cp∗Rh(μ-Cl)]₂(Cab^C,C) (2), [Cp′Rh(μ-Cl)]₂(Cab^C,C) [3),[Cp∗Ir(μ-Cl)]₂(Cab^C,C) (4) and [(p-cymene)Ru(μ-Cl)]₂(Cab^C,C) (5), respectively. Addition reactions of the ruthenium complex 5 with air gave [(p-cymene)₂Ru₂(μ-OH)(μ-Cl)](Cab^C,C) (6), rhodium complex 2 with LiSPh gave [Cp∗Rh(μ-SPh)]₂(Cab^C,C) (7). The complexes were characterized by IR, NMR spectroscopy and elemental analysis. In addition, X-ray structure analysis were performed on complexes 2-7 where the potential C,C-chelate ligand was found to coordinate in a bidentate mode as a bridge.     

Insertion of nitrene and chalcogenolate groups into the Ir-C σ bond in a cyclometalated iridium(III) complex

Treatment of [Cp∗Ir(ppy)Cl] (Cp∗ = η⁵-C₅Me₅, ppyH = 2-(2-pyridyl)phenyl) with Ag(OTf) (OTf⁻ = triflate) in MeOH and MeCN gave the solvento complexes [Cp∗Ir(ppy)(solv)][OTf] (solv = MeOH (1) and MeCN (2)). Complex 1 is capable of catalyzing oxidation and azirdination of styrene with PhIO and PhINTs (Ts = tosyl), respectively. Treatment of 2 with a stoichiometric amount of PhINTs resulted in the insertion of the NTs group into the Ir-C(ppy) bond and formation of [Cp∗Ir(η²-ppy-NTs)(MeCN)][OTf] (3). Treatment of 1 with R₂E₂ afforded [Cp∗Ir(ppy)(η¹-R₂E₂)][OTf] (E = S (4), Se (5), Te (6)). Reactions of 4 and 5 with Ag(OTf) resulted in cleavage of the E-E bond and insertion of an ER group into the Ir-C(ppy) bond. The crystal structures of complexes 2-6 and [Cp∗Ir(η²-ppy-S-p-tol)(H₂O)][OTf]₂ have been determined.     

Mono and dinuclear half-sandwich platinum group metal complexes bearing pyrazolyl-pyrimidine ligands: Syntheses and structural studies

Reactions of 0.5 eq. of the dinuclear complexes [(η⁶-arene)Ru(μ-Cl)Cl]₂ (arene = η⁶-C₆H₆, η⁶-p-ⁱPrC₆H₄Me) and [(Cp∗)M(μ-Cl)Cl]₂ (M = Rh, Ir; Cp∗ = η⁵-C₅Me₅) with 4,6-disubstituted pyrazolyl-pyrimidine ligands (L) viz. 4,6-bis(pyrazolyl)pyrimidine (L1), 4,6-bis(3-methyl-pyrazolyl)pyrimidine (L2), 4,6-bis(3,5-dimethyl-pyrazolyl)pyrimidine (L3) lead to the formation of the cationic mononuclear complexes [(η⁶-C₆H₆)Ru(L)Cl]⁺ (L = L1, 1; L2, 2; L3, 3), [(η⁶-p-ⁱPrC₆H₄Me)Ru(L)Cl]⁺ (L = L1, 4; L2, 5; L3, 6), [(Cp∗)Rh(L)Cl]⁺ (L = L1, 7; L2, 8; L3, 9) and [(Cp∗)Ir(L)Cl]⁺ (L = L1, 10; L2, 11; L3, 12), while reactions with 1.0 eq. of the dinuclear complexes [(η⁶-arene)Ru(μ-Cl)Cl]₂ and [(Cp∗)M(μ-Cl)Cl]₂ give rise to the dicationic dinuclear complexes [{(η⁶-C₆H₆)RuCl}₂(L)]²⁺ (L = L1, 13; L2, 14; L3, 15), [{(η⁶-p-ⁱPrC₆H₄Me)RuCl}₂(L)]²⁺ (L = L1, 16; L2, 17; L3, 18), [{(Cp∗)RhCl}₂(L)]²⁺ (L = L1, 19; L2, 20; L3, 21) and [{(Cp∗)IrCl}₂(L)]²⁺ (L = L1 22; L2, 23; L3 24). The molecular structures of [3]PF₆, [6]PF₆, [7]PF₆ and [18](PF₆)₂ have been established by single crystal X-ray structure analysis.     

Synthesis and characterization of scandium complexes with reduced ligands: Crystal structures of Cp∗ScI2, [Cp∗ScI(bpy)]2, and [Cp∗ScCl(bpy)]2

The synthesis and characterization of complexes containing a Cp∗Sc(R₂bpy) (Cp∗ = pentamethylcyclopentadienyl, bpy = 4,4′-R,R-2,2′-bipyridine, R = H, Me) motif are described. Cp∗ScI₂ (1) was prepared from Cp∗Sc(acac)₂ (acac = acetylacetonate) and AlI₃ (2 equiv) in pentane. Compound 1 reacted with bipyridine and 4,4′-dimethyl-2,2′-bipyridine (dmb) in benzene to yield Cp∗ScI₂(bpy) (3) and Cp∗ScI₂(dmb) (4), respectively. Compound 3 was reduced by alkali metal reductants such as Na/Hg, NaK₂, and K in aromatic solvents to yield [Cp∗ScI(bpy)]₂ (5). The chloride analog of 5, [Cp∗ScCl(bpy)]₂ (7), was prepared from Cp∗ScCl₂ by salt metathesis with Li₂(dme)₂bpy (6) (dme = dimethoxyethane) in toluene. Compounds 1, 5, and 7 have been structurally characterized. Analysis of the bond distances of the bipyridine ligands in 5 and 7, together with infrared and UV/vis spectroscopic data, suggest that the bipyridine ligands in these molecules exist as radical anions. The bipyridine ligands in 5 and 7 are arranged co-facially and are in close proximity (?3.30 Å), suggesting the presence of a π-π interaction.     

Interligand H?Si interactions in tungsten silyl trihydride complexes

The dichloride complex Cp∗(Am)WCl₂ (1, Am = [(iPrN)₂CMe]⁻) reacted with the primary silanes PhSiH₃, (p-tolyl)SiH₃, (3,5-xylyl)SiH₃, and (C₆F₅)SiH₃ to produce the W(VI) (silyl)trihydrides Cp∗(Am)W(H)₃(SiHPhCl) (2), Cp∗(Am)W(H)₃(SiHTolylCl) (3), Cp∗(Am)W(H)₃(SiHXylylCl) (4), and Cp∗(Am)W(H)₃[SiH(C₆F₅)Cl] (5). In an analogous manner, 1 reacted with PhSiH₂Cl to give Cp∗(Am)W(H)₃(SiPhCl₂) (6). Complex 6 can alternatively be quantitatively produced from the reaction of 2 with Ph₃CCl. NMR spectroscopic studies and X-ray crystallography reveal an interligand H?Si interaction between one W-H and the chlorosilyl group, which is further supported by DFT calculations.     

Synthesis and characterization of half-sandwich Rh, Ir complexes containing mono-thiolate-ortho-carborane ligand

Two binuclear complexes [Cp^∗M(Cl)Carb^S]₂ (Cp^∗ = η⁵-C₅Me₅, M = Rh (1a), Carb^S = SC₂(H)B₁₀H₁₀, Ir (1b)) were synthesized by the reaction of LiCarb^S with the dimeric metal complexes [Cp^∗MCl(μ-Cl)]₂ (M = Rh, Ir). Four mononuclear complexes Cp^∗M(Cl)(L)Carb^S (L = BuⁿPPh₂, M = Rh (2a), Ir (2b); L = PPh₃, M = Rh (4a), Ir (4b)) were synthesized by reactions of 1a or 1b with L (L = BuⁿPPh₂ (2); PPh₃ (4)) in moderate yields, respectively. Complexes 3a, 3b, 5a, 5b were obtained by treatment of 2a, 2b, 4a, 4b with AgPF₆ in high yields, respectively. All of these compounds were fully characterized by IR, NMR, and elemental analysis, and the crystal structures of 1a, 1b, 2a, 2b, 4a, 4b were also confirmed by X-ray crystallography. Their structures showed 3a, 3b and 5a, 5b could be expected as good candidates for heterolytic dihydrogen activation. Preliminary experiments on the dihydrogen activation driven by these half-sandwich Rh, Ir complexes were done under mild conditions.     

Synthesis and characterization of binuclear μ-oxo and μ-telluro molybdenum(V) complexes, [CpMo(O)(μ-Te)]2

Pyrolysis of an in-situ generated intermediate, produced in the reaction of [Cp^∗MoCl₄], 1, (Cp^∗ = η⁵-C₅Me₅) with [LiBH₄·THF], with an excess of difuryl ditelluride in toluene at 90 °C yielded syn and anti isomers of [Cp^∗Mo(O)(μ-Te)]₂ (2, 3) and [Cp^∗₂Mo₂O₂(μ-O)(μ-Te)] (4, 5). In a similar fashion, dibenzyl diselenide yielded syn and anti isomers of [Cp^∗Mo(O)(μ-Se)]₂ (6, 7), along with the known nido-[(Cp^∗Mo)₂B₄H₈Se₂]. Note that in parallel with 2-7, [(Cp^∗Mo)₂B₅H₉] was isolated as the major product in both cases. Compounds 2-7 have been isolated in modest yield as orange to brown crystalline solids. All the new compounds have been characterized in solution by mass, IR, ¹H, ¹³C, ⁷⁷Se and ¹²⁵Te NMR spectroscopy, and the structural types were unequivocally established by crystallographic analysis of 2-4 and 7.     

Metallacarboranes and triple-decker complexes with the (C4Me4)Pt fragment

Complex Cp∗PtCl₂ (Cp∗ = η-C₄Me₄) reacts with the carborane anions [7,8-C₂B₉H₁₁]²⁻ and [9-SMe₂-7,8-C₂B₉H₁₀]⁻ giving platinacarboranes Cp∗Pt(η-7,8-C₂B₉H₁₁) (1) and [Cp∗Pt(η-9-SMe₂-7,8-C₂B₉H₁₀)]⁺ (2), respectively. Reactions of the [Cp∗Pt]²⁺ fragment (as a labile nitromethane solvate) with the sandwich compounds Cp∗Fe(η-C₅H₃Me₂BMe) and Cp∗Rh(η⁵-C₄H₄BPh) afford the triple-decker cations [Cp∗Pt(μ-η:η-C₅H₃Me₂BMe)FeCp∗]²⁺ (3) and [Cp∗Pt(μ-η⁵:η⁵-C₄H₄BPh)RhCp∗]²⁺ (4) with bridging boratabenzene and borole ligands. The structures of 1 and 3(CF₃SO₃)₂ were determined by X-ray diffraction.     

Crystal structures of (azido)(pentamethylcyclopentadienyl)iridium(III) complexes containing various types of bidentate ligands

Several (azido)iridium(III) complexes having a pentamethylcyclopentadienyl (Cp∗) group, [Cp∗Ir(N₃)₂(Ph₂Ppy-κP)] (1: Ph₂Ppy = 2-diphenylphosphinopyridine), [Cp∗Ir(N₃)(Ph₂Ppy-κP,κN)]CF₃SO₃ (2), [Cp∗Ir(N₃)(dmpm)]PF₆ (3: dmpm = bis(dimethylphosphino)methane), [Cp∗Ir(N₃)(Ph₂Pqn)]PF₆·$·$CH₃OH (4·$·$CH₃OH: Ph₂Pqn = 8-diphenylphosphinoquinoline), and [Cp∗Ir(N₃)(pybim)] (5: Hpybim = 2-(2-pyridyl)benzimidazole) have been prepared and their crystal structures have been analyzed by X-ray diffraction. In complex 1, the Ph₂Ppy ligand is only coordinated via the P atom (-κP), while in 2 it acts as a bidentate ligand through the P and N atoms (-κP,κN) to form a four-membered chelate ring. Comparing the structural parameters of the chelate ring in 2 with those of a similar five-membered chelate ring formed by Ph₂Pqn in 4, it became apparent that the angular distortion in the Ph₂Ppy-κP,κN ring was remarkable, although the Ir–P and Ir–N bonds in the Ph₂Ppy-κP,κN ring were not elongated very much from the corresponding bonds in the Ph₂Pqn-κP,κN ring. In the pybim complex 5, the five-membered chelate ring was coplanar with the pyridine and benzimidazolyl rings. With the related (azido)iridium(III) complexes analyzed previously, comparison of the structural parameters of the Ir–N₃ moiety in [Cp∗Ir^III(N₃)(L–L′)]^+/0 complexes reveals an anomalous feature of the 2,2′-bipyridyl (bpy) complex, [Cp∗Ir(N₃)(bpy)]PF₆.     

Synthesis, X-ray structures, and syndiospecific polymerization behavior of styrene of new (pentamethylcyclopentadientyl) titanatranes containing modified tetradentate triethanolamine ligands

A series of monomeric pentamethylcyclopentadienyltitanatranes, [n = 0, 1; n = 1, 2; n = 2, 3], were synthesized by the reaction of Cp∗TiCl₃ with corresponding triethanolamines such as (HOCH₂CH₂)_nN(CH₂CMe₂OH)_{3 − n} (n = 0, L1H₃; n = 1, L2H₃; n = 2, L3H₃), which varied by the number of CMe₂ groups adjacent to an OH functionality from 3 (L1H₃) to 2 (L2H₃) to 1 (L3H₃), in the presence of NEt₃. All complexes were characterized by elemental analysis and solution ¹H and ¹³C{¹H} NMR spectroscopy. Moreover, their solid state structures, which are slightly distorted three-legged piano stool geometry, have been confirmed by single crystal X-ray diffraction analysis. On activation with methylaluminoxane (MAO), these complexes showed good catalytic activity for the polymerization of styrene producing syndiotactic polystyrene (SPS) with high molecular weights. Compounds 1 and 2 bearing more than two pairs of methyl substituents on the side arms of triethanolamines showed the enhanced catalytic activities as the polymerization temperature went up from 50 °C to 110 °C, whereas less bulky complexes 3 and Cp∗Ti(OCH₂CH₂)₃N (4) gave the decreased activities as polymerization temperature rose. Unlike 3 and 4, complexes 1 and 2 in the presence of MAO as a cocatalyst gave SPS with controlled bimodal molecular weight distribution. Bimodal properties were much distinct at low polymerization temperature.     

Aqueous organometallic chemistry. 3. Catalytic hydride transfer reactions with ketones and aldehydes using [Cp∗Rh(bpy)(H2O)](OTf)2 as the precatalyst and sodium formate as the hydride source: Kinetic and activation parameters, and the significance of steric and electronic effects

The reaction of a precatalyst, [Cp∗Rh(bpy)(H₂O)](OTf)₂ (1), with sodium formate provided the hydride complex, [Cp∗Rh(bpy)(H)]⁺ (2), in situ, at pH 7.0, which was then evaluated in an aqueous, catalytic hydride transfer process with water soluble substrates that encompass 2-pentanone (3), cyclohexanone (4), acetophenone (5), propionaldehyde (6), benzaldehyde (7), and p-methoxybenzaldehyde (8). The initial rates, r_i, of appearance of the reduction product alcohols at 23 °C provided a relative rate scale: 8 > 7 ≈ 6 > 5 > 4 > 3, while the effect of concentration of substrate, precatalyst, and sodium formate on r_i, using 7 as an example, implicates [Cp∗Rh(bpy)(H)]⁺ formation as the rate-limiting step. The experimental kinetic rate expression was found to be: d[alcohol]/dt = k_cat[1][HCO₂Na]; substrate being pseudo zero order in water. The steric effects were also analyzed and appeared to be of less importance intra both the ketone and aldehyde series, but an inter series comparison appeared to show that the aldehydes had less of a steric effect on the initial rate, i.e., 7 > 4 by a factor of 3.6, while the aldehyde series appeared to have some moderate electronic influence on rates, presumably via electron donation to increase binding to the Cp∗Rh metal ion center, in accordance with these proposed concerted binding/hydride transfer reactions. A proposed catalytic cycle will also be presented.     

Ruthenium piano-stool complexes containing mono- or bidentate pyrrolidinylalkylphosphines and their reactions with small molecules

Ruthenium piano-stool complexes incorporating the new bidentate aminoalkylphosphine ligand 1,2-bis(dipyrrolidin-1-ylphosphino)ethane (dpyrpe, I) or its monodentate counterpart bis(pyrrolidin-1-yl)methylphosphine (pyr₂PMe, II) have been prepared, [(C₅R₅)RuCl(PP)] (R = Me and PP = dpyrpe, 1; R = Me and PP = (pyr₂PMe)₂, 2; R = H and PP = dpyrpe, 3). Complexes 2 and 3 have been characterized by X-ray crystallography. Complexes 1 and 2 react with NaBAr₄^f in the presence of ligand L to yield [Cp^∗Ru(L)(dpyrpe-κ²P)][BAr^f₄] (L = MeCN, 4a; CO, 4b; N₂, 4c) and [Cp^∗Ru(L)(pyr₂PMe)₂][BAr₄^f] (L = MeCN, 5a; CO, 5b; N₂, 5c). Complex 4a was crystallographically characterized. The CO complexes 4b and 5b were examined using IR spectroscopy in an attempt to establish the electron-donating capabilities of I and II. Complex 1 oxidatively adds H₂ in the presence of NaBAr₄^f to yield the Ru(IV) dihydride [Cp^∗RuH₂(dpyrpe-κ²P)][BAr₄^f], 7.     

Trimetallic complexes containing 1,1′-Rc′(CC)2 units [Rc′ = ruthenocene-1,1′-diyl, Ru(η-C5H4-)2]

Reactions between 1,1′-(Me₃SiCC)₂Rc′ [Rc′ = ruthenocen-1,1′-diyl, Ru(η-C₅H₄-)₂] and RuCl(PP)Cp′ in the presence of KF gave 1,1′-{Cp(PP)RuCC}₂Rc′ [Cp′ = Cp, PP = PPh₃1, P(m-tol)₃2, dppe 3, dppf 4; Cp′ = Cp^∗, PP = dppe 5]. Compounds 1 and 2 react with tcne to give two diastereomers a/b of the allylic (vinylcarbene) complexes 6 and 7, while methylation of 5 gave the bis-vinylidene [1,1′-{Cp^∗(dppe)RuCCMe}₂Rc′](BPh₄)₂ (8). The X-ray structures of 4, 6b and 8 have been determined. Cyclic voltammograms indicate that there is some electronic communication between the ruthenium end-groups through the Rc′ centre.     

Syntheses of new Mo(II) and W(II) mono(hydrosulfido) complexes and their conversion into di- and tetranuclear sulfido-bridged heterobimetallic complexes

Treatment of [Cp′MH(CO)₃] (M = Mo, W; Cp′ = η⁵-C₅H₅ (Cp), η⁵-C₅Me₅ (Cp*)) with 1/8 equiv of S₈ in THF, followed by the reaction with dppe under UV irradiation, gave new mono(hydrosulfido) complexes [Cp′M(SH)(CO)(dppe)] (Cp′ = Cp: M = Mo (5), W (6); Cp′ = Cp*: M = Mo (7), W (8); dppe = Ph₂PCH₂CH₂PPh₂). When 5 and 6 dissolved in THF were allowed to react with [RhCl(PPh₃)₃] in the presence of base, heterodinuclear complexes with bridging S and dppe ligands [CpM(CO)(μ-S)(μ-dppe)Rh(PPh₃)] (M = Mo (9), W(10)) were obtained. Semi-bridging feature of the CO ligands were also demonstrated. Upon standing in CH₂Cl₂ solutions, 9 and 10 were converted further to the dimerization products [(CpM)₂{Rh(dppe)}₂(μ₂-CO)₂(μ₃-S)₂] (M = Mo (13), W). Detailed structures of mononuclear 7 and 8, dinuclear 9 and tetranuclear 13 have been determined by the X-ray diffraction.     

Synthesis and structures of dialkyl zirconium complexes with an [OSSO]-type bis(phenolate) ligand bearing a trans-1,2-cyclooctanediylbis(thio) unit

Dimethyl and bis[(trimethylsilyl)methyl] zirconium complexes ([OSSO]ZrR₂) [4, R = Me; 5, R = CH₂SiMe₃] having [OSSO]-type bis(phenolato) ligand 1 based on the trans-1,2-cyclooctanediylbis(thio) core have been synthesized by the reactions of the corresponding dichloro zirconium complex 3 with 2 equiv. of MeMgBr and Me₃SiCH₂MgCl, respectively, in Et₂O/toluene at −78 °C. The molecular structures of these complexes 3-5 were characterized by NMR spectroscopy, elemental analyses, and X-ray crystallography. ¹H and ¹³C NMR data of complexes 3-5 exhibited that they took the C₂-symmetry in solution in the NMR time scale. In the crystal structures of 3-5, each zirconium center lies at the center of a distorted octahedral coordination sphere with cis sulfur atoms and trans oxygen atoms, which adopts a cis-α [(Λ^∗,S^∗,S^∗)] configuration.     

Chalcogen-capped ruthenium carbonyl clusters derived from diphosphazane mono- and dichalcogenides of the type X2P(E)N(R)PX2 and X2P(E)N(R)P(E)X2 (E = S or Se)

Reactions of Ru₃(CO)₁₂ with diphosphazane monoselenides Ph₂PN(R)P(Se)Ph₂ [R = (S)-∗CHMePh (L⁴), R = CHMe₂ (L⁵)] yield mainly the selenium bicapped tetraruthenium clusters [Ru₄(μ₄-Se)₂(μ-CO)(CO)₈{μ-P,P-Ph₂PN(R)PPh₂}] (1, 3). The selenium monocapped triruthenium cluster [Ru₃(μ₃-Se)(μ_sb-CO)(CO)₇{κ²-P,P-Ph₂PN((S)-∗CHMePh)PPh₂}] (2) is obtained only in the case of L⁴. An analogous reaction of the diphosphazane monosulfide (PhO)₂PN(Me)P(S)(OPh)₂ (L⁶) that bears a strong π-acceptor phosphorus shows a different reactivity pattern to yield the triruthenium clusters, [Ru₃(μ₃-S)(μ₃-CO)(CO)₇{μ-P,P-(PhO)₂PN(Me)P(OPh)₂}] (9) (single sulfur transfer product) and [Ru₃(μ₃-S)₂(CO)₅{κ²-P,P-(PhO)₂PN(Me)P(OPh)₂}{μ-P,P-(PhO)₂PN(Me)P(OPh)₂}] (10) (double sulfur transfer product). The reactions of diphosphazane dichalcogenides with Ru₃(CO)₁₂ yield the chalcogen bicapped tetraruthenium clusters [Ru₄(μ₄-E)₂(μ-CO)(CO)₈{μ-P,P-Ph₂PN(R)PPh₂}] [R = (S)-∗CHMePh, E = S (6); R = CHMe₂, E = S (7); R = CHMe₂, E = Se (3)]. Such a tetraruthenium cluster [Ru₄(μ₄-S)₂(μ- CO)(CO)₈{μ-P,P-(PhO)₂PN(Me)P(OPh)₂}] (11) is also obtained in small quantities during crystallization of cluster 9. The dynamic behavior of cluster 10 in solution is probed by NMR studies. The structural data for clusters 7, 9, 10 and 11 are compared and discussed.     

Half-sandwich Ru(II), Ir(III) and Rh(III) complexes with bridging or chelating N-heterocyclic bis-carbene ligand: Synthesis and characterization

N-heterocyclic bis-carbene ligand (bis-NHC) which was derived from 1,1′-diisopropyl-3,3′-ethylenediimidazolium dibromide (L·2HBr) via silver carbene transfer method, reacted with [(η⁶-p-cymene)RuCl₂]₂ and [Cp^∗MCl₂]₂ (Cp^∗ = η⁵-C₅Me_5, M = Ir, Rh) respectively, afforded complexes [(η⁶-p-cymene)RuCl₂]₂(L) (1), [Cp^∗IrCl₂]₂(L) (2) and [Cp^∗RhCl(L)][Cp^∗RhCl₃] (3). When [Cp^∗IrCl₂]₂ was treated with 2 equiv AgOTf at first, and then reacted with bis-NHC ligand, [Cp^∗IrCl(L)]OTf (4) was obtained. The molecular structures of complexes 1-4 were determined by X-ray single crystal analysis, showing that 1 and 2 adopted bridging coordination mode, 3 and 4 adopted chelating coordination mode. All of these complexes were characterized by ¹H, ¹³C NMR spectroscopy and element analysis.     

Nucleophilic properties of Ru(CCH)(dppe)Cp∗: Synthesis and structure of Ru{c-CCArC(O)C(O)O}(dppe)Cp∗ [Ar = 2,4-(NO2)2C6H3]

The complex Ru{c-CCArC(O)C(O)O}(dppe)Cp∗ [Ar = 2,4-(NO₂)₂C₆H₃] 2, containing a dihydrofuran-3,4-dione ligand, was obtained from a reaction between the strong nucleophile Ru(CCH)(dppe)Cp∗ 1 and bis(2,4-dinitrophenyl) oxalate. The X-ray determined molecular structure of 2 is reported, together with a plausible route for its formation.     

Synthesis and characterization of half-sandwich iridium complexes containing 2,6(7)-bis(4-pyridyl)-1,4,5,8-tetrathiafulvalene and ancillary ortho-carborane-1,2-dichalcogenolato ligands

The binuclear half-sandwich iridium complexes {Cp^∗IrCl₂}₂(μ-2,6(7)-bis(4-pyridyl)-1,4,5,8-tetrathiafulvalene) (3) and {Cp^∗Ir[E₂C₂(B₁₀H₁₀)]}₂(μ-2,6(7)-bis(4-pyridyl)-1,4,5,8-tetrathiafulvalene) (E = S(5a), Se(5b)) were prepared from the reaction of [Cp^∗IrCl(μ-Cl)]₂ or the “pseudo-aromatic” half-sandwich iridium complex Cp^∗Ir[E₂C₂(B₁₀H₁₀)] (E = S(4a), Se(4b)) with a tetrathiafulvalene (TTF) derivative 2,6-bis(4-pyridyl)-1,4,5,8-tetrathiafulvalene (2) at room temperature. The complexes (3, 5a and 5b) have been fully characterized by IR and NMR spectroscopy, as well as elemental analysis. And the molecular structures of 2 and 5a were established through X-ray crystallography. It is interesting that infinite tunnels are created by repeating ‘buckled bowl’ molecules of 5a.     

Catalytic hydrogenation of CO and CN bonds via heterolysis of H2 mediated by metal-sulfur bonds of rhodium and iridium thiolate complexes

Coordinatively unsaturated rhodium and iridium complexes having a bulky thiolate, [Cp∗M(PMe₃)(SDmp)](BAr^F₄) (1a: M = Rh; 1b: M = Ir; Dmp = 2,6-(mesityl)₂C₆H₃, Ar^F = 3,5-(CF₃)₂C₆H₃), catalyzed the hydrogenation of benzaldehyde, N-benzylideneaniline, and cyclohexanone, under 1 atm of H₂ at low temperatures. In these catalytic reactions, the M-H/S-H complexes [Cp∗M(PMe₃)(H)(HSDmp)](BAr^F₄) (2a: M = Rh; 2b: M = Ir) generated via H₂ heterolysis by 1a or 1b were suggested to transfer both M-H hydride and S-H proton to substrates. The catalytic reactions were terminated by the dissociation of H-SDmp from the metal centers of 2a and 2b that occurs at ambient temperature under H₂ atmosphere.