Activation and Coordination of Ammonia at [Cp*Ir(H)2]: NMR and Matrix Isolation Studies

¹H NMR exchange spectroscopy of a reaction mixture of [Cp*Ir(H)₄] ( 1 ; Cp*=1,2,3,4,5‐pentamethylcyclopentadienyl) and ammonia suggests an exchange of hydrogen atoms between the hydrido ligands and ammonia. Treatment of 1 with ND₃ led to an H/D exchange between ND₃ and the hydrido ligands of 1 . Subsequent studies showed that photolysis of 1 isolated in frozen argon matrices leads to the formation of the iridium compounds [Cp*Ir(H)₂] ( 2 ) and [Cp*Ir(H)₃] ( 4 ), as it was confirmed by IR spectroscopy. In the presence of water the aqua complex [Cp*Ir(H)₂(OH₂)] ( 3 ) was generated simultaneously. Accordingly, photolysis of 1 in an argon matrix doped with ammonia gave rise to the ammine complex [Cp*Ir(H)₂(NH₃)] ( 5 ). IR assignments were supported by calculations of the gas‐phase IR spectra of 1 – 5 by DFT methods.     

Mono(sulfido)-bridged mixed-valence nitrosyl complex: protonation and oxidative addition of iodine across the Ir(II)-Ir(0) bond

Treatment of [Cp*IrH(SH)(PMe3)] (Cp* = eta5-C5Me5) with [IrCl2(NO)(PPh3)2] in the presence of triethylamine yielded the sulfido-bridged Ir(II)Ir0 complex [Cp*Ir(PMe3)(mu-S)Ir(NO)(PPh3)], which further reacted with I2 and triflic acid to give the diiodo complex [Cp*Ir(PMe3)(mu-I)(mu-S)IrI(NO)(PPh3)] and the hydrido complex [Cp*Ir(PMe3)(mu-H)(mu-S)Ir(NO)(PPh3)][OSO2CF3], respectively.     

Construction of trinuclear iridium clusters through ancillary ortho-carborane-1,2-diselenolato ligands, with simultaneous iridium-induced B-H activation

The reaction of the 16-electron "pseudo-aromatic" complex Cp*Ir[Se2C2(B10H10)] (1, Cp* = eta5-C5Me5) with [Ir(cod)(micro-OC2H5)]2 leads to the trinuclear iridium complexes {(cod)Ir[Se2C2(B10H8)(OC2H5)]}Ir{[Se2C2(B10H10)]IrCp*} (2), {(cod)Ir[Se2C2(B10H8)(OC2H5)]}Ir{[Se2C2(B10H9)]IrCp*} (3), {Cp*Ir[Se2C2(B10H9)]}{IrSe(2)[C2(B10H9)(OC2H5)]}{[Se2C2(B10H10)] IrCp*} (4) and one mononuclear complex Cp*Ir[Se2C2(B10H8)(OC2H5)(2)] (5). The reactivity of 2 was investigated and revealed that transformation from 2 to 3 occurred thermally in solution. The transoid complex 2 (with the carborane diselenolato units in trans position) can be converted in nearly 90% yield to the cisoid complex 3. In complexes 2, 3, two diselenolato carborane ligands bridge the Ir(3) core, which consists of Ir-Ir metal bonds. Compared with transoid 2, the cisoid 3 contains two iridium-boron bonds. Complex 4 consists of three different coordination environment carborane ligands (Ir-B(cluster): {Cp*Ir[Se2C2(B10H9)]}, O-B(cluster): {[Se2C2(B10H9)](OC2H5)}, and intact carborane: {Cp*Ir[Se2C2 (B10H10)]}) without the presence of a metal-metal bond. Analogous reaction of 1 with [Ir(cod)(micro-OCH(3))](2) results in formation of the trinuclear complex {Cp*Ir[Se2C2(B10H9)]}{IrSe(2)[C2(B10H9)(OCH3)]}{[Se2C2(B10H10)]IrCp*} (6) and mononuclear complex Cp*Ir[Se2C2(B10H8)(OCH3)(2)] (7). The structures of 2, 3, 4, 5, 6 and 7 have been determined by crystallographic studies.     

Synthesis and characterization of heterometallic clusters (Ir2Rh, Ir2W, Rh3) Containing 1,2-dicarba-closo-dodecaborane(12)-1,2-dithiolate chelate ligands, [(B10H10)C2S2]2-

The 16-electron half-sandwich complex [Cp*Ir[S2C2(B10H10)]] (Cp* = eta5-C5Me5) (1a) reacts with [[Rh(cod)(mu-Cl)]2] (cod = cycloocta-1,5-diene, C8H12) in different molar ratios to give three products, [[Cp*Ir[S2C2(B10H9)]]Rh(cod)] (2), trans-[[Cp*Ir[S2C2(B10H9)]]Rh[[S2C2(B10H10)]IrCp*]] (3), and [Rh2(cod)2[(mu-SH)(mu-SC)(CH)(B10H10)]] (4). Complex 3 contains an Ir2Rh backbone with two different Ir-Rh bonds (3.003(3) and 2.685(3) angstroms). The dinuclear complex 2 reacts with the mononuclear 16-electron complex 1a to give 3 in refluxing toluene. Reaction of 1a with [W(CO)3(py)3] (py = C5H5N) in the presence of BF3.EtO2 leads to the trinuclear cluster [[Cp*Ir[S2C2(B10H10)]]2W(CO)2] (5) together with [[Cp*Ir(CO)[S2C2(B10H10)]]W(CO)5] (6), and [Cp*Ir(CO)[S2C2(B10H10)]] (7). Analogous reactions of [Cp*Rh[S2C2(B10H10)]] (1 b) with [[Rh(cod)(mu-Cl)]2] were investigated and two complexes cis-[[Cp*Rh[S2C2(B10H10)]]2Rh] (8) and trans-[[Cp*Rh[S2C2(B10H10)]]2Rh] (9) were obtained. In refluxing THF solution, the cisoid 8 is converted in more than 95 % yield to the transoid 9. All new complexes 2-9 were characterized by NMR spectroscopy (1H, 11B NMR) and X-ray diffraction structural analyses are reported for complexes 2-5, 8, and 9.     

Preparation and structure of mono- and binuclear half-sandwich iridium, ruthenium, and rhodium carbene complexes containing 1,2-dichalcogenolao 1,2-dicarba-closo-dodecaboranes

The synthesis of half-sandwich transition metal complexes containing both 1,2-dichalcogenolato-1,2-dicarba-closo-docecaborane (Cab(E,E)) [Cab(E,E)=E(2)C(2)(B(10)H(10)); E = S, Se] and N-heterocyclic carbene (NHC) ligands is described. Addition of mono-NHC ligand to the 16e half-sandwich dichalcogenolato carborane complexes [Cp*Rh(Cab(E,E))], [Cp*Ir(Cab(S,S))], [(p-cymene)Ru(Cab(S,S))] (Cp* = pentamethylcyclopentadienyl) gives corresponding mononuclear 18e dithiolate complexes of the type [LM(Cab(E,E))(NHC)]: [Cp*M(Cab(S,S))(1-ethenyl-3-methylimidazolin-2-ylidene)] (M = Ir (2), Rh (3)), [Cp*Rh(Cab(E,E))(3-methyl-1-picolyimidazolin-2-ylidene)] [E = S (6), Se (7)], [(p-cymene)Ru(Cab(S,S))(NHC)] [NHC = 1-ethenyl-3-methylimidazolin-2-ylidene (4), 3-methyl-1-picolyimidazolin-2-ylidene (8)], whereas bis-NHC give centrosymmetric binuclear complexes [{Cp*M(Cab(S,S))}(2)(1,1'-dimethyl-3,3'-methylene(imidazolin-2-ylidene))] [M = Rh (10), Ir (11)]. The complexes were characterized by IR, NMR spectroscopy and elemental analysis. In addition, X-ray structure analyses were performed on complexes 2-4, 6, 8, 10 and 11.     

pH-selective synthesis and structures of alkynyl, acyl, and ketonyl intermediates in anti-Markovnikov and Markovnikov hydrations of a terminal alkyne with a water-soluble iridium aqua complex in water

Chemoselective synthesis and isolation of alkynyl [Cp*Ir(III)(bpy)CCPh]+ (2, Cp* = eta5-C5Me5, bpy = 2,2'-bipyridine), acyl [Cp*Ir(III)(bpy)C(O)CH2Ph]+ (3), and ketonyl [Cp*Ir(III)(bpy)CH2C(O)Ph]+ (4) intermediates in anti-Markovnikov and Markovnikov hydration of phenylacetylene in water have been achieved by changing the pH of the solution of a water-soluble aqua complex [Cp*Ir(III)(bpy)(H2O)]2+ (1) used as the same starting complex. The alkynyl complex [2]2.SO4 was synthesized at pH 8 in the reaction of 1.SO4 with H2O at 25 degrees C, and was isolated as a yellow powder of 2.X (X = CF3SO3 or PF6) by exchanging the counteranion at pH 8. The acyl complex [3]2.SO4 was synthesized by changing the pH of the aqueous solution of [2]2.SO4 from 8 to 1 at 25 degrees C, and was isolated as a red powder of 3.PF6 by exchanging the counteranion at pH 1. The hydration of phenylacetylene with 1.SO4 at pH 4 at 25 degrees C gave a mixture of [2]2.SO4 and [4]2.SO4. After the counteranion was exchanged from SO4(2-) to CF3SO3-, the ketonyl complex 4.CF3SO3 was separated from the mixture of 2.CF3SO3 and 4.CF3SO3 because of the difference in solubility at pH 4 in water. The structures of 2-4 were established by IR with 13C-labeled phenylacetylene (Ph12C13CH), electrospray ionization mass spectrometry (ESI-MS), and NMR studies including 1H, 13C, distortionless enhancement by polarization transfer (DEPT), and correlation spectroscopy (COSY) experiments. The structures of 2.PF6 and 3.PF6 were unequivocally determined by X-ray analysis. Protonation of 3 and 4 gave an aldehyde (phenylacetaldehyde) and a ketone (acetophenone), respectively. Mechanism of the pH-selective anti-Markovnikov vs Markovnikov hydration has been discussed based on the effect of pH on the formation of 2-4. The origins of the alkynyl, acyl, and ketonyl ligands of 2-4 were determined by isotopic labeling experiments with D2O and H2(18)O.     

Synthesis, reactivity, spectroscopic characterization, X-ray structures, PGSE, and NOE NMR studies of (eta5-C5Me5)-rhodium and -iridium derivatives containing bis(pyrazolyl)alkane ligands

Rhodium(III) and iridium(III) complexes containing bis(pyrazolyl)methane ligands (pz = pyrazole, L' in general; specifically, L1 = H2C(pz)2, L2 = H2C(pzMe2)2, L3 = H2C(pz4Me)2, L4 = Me2C(pz)2), have been prepared in a study exploring the reactivity of these ligands toward [Cp*MCl(mu-Cl)]2 dimers (M = Rh, Ir; Cp* = pentamethylcyclopentadienyl). When the reaction was carried out in acetone solution, complexes of the type [Cp*M(L')Cl]Cl were obtained. However, when L1 and L2 ligands have been employed with excess [Cp*MCl(mu-Cl)]2, the formation of [Cp*M(L')Cl][Cp*MCl3] species has been observed. PGSE NMR measurements have been carried out for these complexes, in which the counterion is a cyclopentadienyl metal complex, in CD2Cl2 as a function of the concentration. The hydrodynamic radius (rH) and, consequently, the hydrodynamic volume (VH) of all the species have been determined from the measured translational self-diffusion coefficients (Dt), indicating the predominance of ion pairs in solution. NOE measurements and X-ray single-crystal studies suggest that the [Cp*MCl3]- approaches the cation, orienting the three Cl-legs of the "piano-stool" toward the CH2 moieties of the bis(pyrazolyl)methane ligands. The reaction of 1 equiv of [Cp*M(L')Cl]Cl or [Cp*M(L')Cl][Cp*MCl3] with 1 equiv of AgX (X = ClO4 or CF3SO3) in CH2Cl2 allows the generation of [Cp*M(L')Cl]X, whereas the reaction of 1 equiv of [Cp*M(L')Cl] with 2 equiv of AgX yields the dicationic complexes [Cp*M(L')(H2O)][X]2, where single water molecules are directly bonded to the metal atoms. The solid-state structures of a number of complexes were confirmed by X-ray crystallographic studies. The reaction of [Cp*Ir(L')(H2O)][X]2 with ammonium formate in water or acetone solution allows the generation of the hydride species [Cp*Ir(L')H][X].     

C-H activation on a diphosphine and hydrido-bridged diiridium complex: generation and detection of an active IrII-IrII species [(Cp*Ir)2(micro-dmpm)(micro-H)]+

Reaction of [Cp*Ir(micro-H)](2) (5) (Cp* = eta(5)-C(5)Me(5)) with bis(dimethylphosphino)methane (dmpm) gives a new neutral diiridium complex [(Cp*Ir)(2)(micro-dmpm)(micro-H)(2)] (3). Treatment of 3 with methyl triflate at -30 degrees C results in the formation of [(Cp*Ir)(H)(micro-dmpm)(micro-H)(Me)(IrCp*)][OTf] (6). Warming a solution of above 0 degrees C brings about predominant generation of 32e(-) Ir(II)-Ir(II) species [(Cp*Ir)(micro-dmpm)(micro-H)(IrCp*)][OTf] (7). Further heating of the solution of 7 up to 30 degrees C for 14 h leads to quantitative formation of a new complex [(Cp*Ir)(H)(micro-Me(2)PCH(2)PMeCH(2))(micro-H)(IrCp*)][OTf] (8), which is formed by intramolecular oxidative addition of the methyl C-H bond of the dmpm ligand. Intermolecular C-H bond activation reactions with 7 are also examined. Reactions of 7 with aromatic molecules (benzene, toluene, furan, and pyridine) at room temperature result in the smooth sp(2) C-H activation to give [(Cp*Ir)(H)(micro-dmpm)(micro-H)(Ar)(IrCp*)][OTf] (Ar = Ph (9); Ar = m-Tol (10a) or p-Tol (10b); Ar = 2-Fur (11)) and [(Cp*Ir)(H)(micro-dmpm)(micro-C(5)H(4)N)(H)(IrCp*)][OTf] (12), respectively. Complex also reacts with cyclopentene at 0 degrees C to give [(Cp*Ir)(H)(micro-dmpm)(micro-H)(1-cyclopentenyl)(IrCp*)][OTf] (13). Structures of 3, 8 and 12 have been confirmed by X-ray analysis.     

Inter- and intramolecular activation of aromatic C-H bonds by diphosphine and hydrido-bridged dinuclear iridium complexes

Reactions of [(Cp*Ir)2(mu-dmpm)(mu-H)2]2+ (1) with NaOtBu in aromatic solvent at room temperature give [(Cp*Ir)(H)(mu-dmpm)(mu-H)(Cp*Ir)(Ar)]+ [Ar = Ph (3), p-Tol (4a), m-Tol (4b), 2-furanyl (5a), 3-furanyl (5b)] via intermolecular aromatic C-H activation. Treatment of [(Cp*Ir)2(mu-dppm)(mu-H)2]2+ (2) with base (Et2NH) results in intramolecular C-H activation of the phenyl group in the dppm ligand to give [(Cp*Ir)(H){mu-PPh(C6H4)CH2PPh2}(mu-H)(Cp*Ir)]+ (6). The structures of 3, 5a, and 6 have been determined by X-ray diffraction methods.     

Proton-induced lewis acidity of unsaturated iridium amides

Oxidation of Cp*Ir((rac-TsDPEN)H (DPEN = H2NCHPhCHPhNTs) with Cp2FePF6 or Ph3CPF6 in MeCN solution generates [Cp*Ir(TsDPEN)(NCMe)]PF6 ([1H(NCMe)]PF6) together with H2 and Ph3CH, respectively. Labeling studies revealed that the Ir-H was abstracted. The formation of a transient electrophilic species is implicated by the formation of a cyclometalated derivative. The labile species [1H(NCMe)]+ was also obtained by protonation of the diamido derivative Cp*Ir(TsDPEN-H) (1) in MeCN solution (BArF4- = B(C6H3-3,5-(CF3)2)4-). The unsaturated, "naked" cation [1H]BArF4 can be prepared by protonation of 1 with H(OEt2)2BArF4 in CH2Cl2 solution or by thermal elimination of MeCN from [1H(NCMe)]+. Crystallographic analysis confirms the structure of this 16e cation in [1H]BArF4. The formally unsaturated species 1 and [1H]BArF4 have strongly contrasting Lewis acidities, with the cation binding PPh3, CO, and NH3. 1 does not measurably bind these same ligands. [1H]BArF4 is reactive toward H2, at least in the absence of inhibiting donor ligands such as MeCN. [1H]BArF4 (CH2Cl2 solutions) catalyzes the addition of H2 to 1 by proton transfer from an apparent dihydrogen complex. This work demonstrates that the protonation activates the Lewis acidity of unsaturated Ir(III) amides, giving rise to novel organometallic Lewis acids.     

Silylenediamido [(CH3)2Si(NTs)2(2-); Ts = p-CH3C6H4SO2] complexes of iridium: synthesis, structures and facile Si-N bond cleavage

The N,N'-bis(sulfonyl)diaminosilane TsdmsinH(2) (TsdmsinH(2) = (CH(3))(2)Si(NHTs)(2), Ts = p-CH(3)C(6)H(4)SO(2)) reacted with [Cp*IrCl(2)](2) (Cp* = eta(5)-C(5)(CH(3))(5)) in the presence of a base to give the coordinatively unsaturated (silylenediamido)iridium complex [Cp*Ir(Tsdmsin)] (2), which was further converted to the 18e adducts [Cp*Ir(Tsdmsin)L] (L = P(C(6)H(5))(3) (3a), P(OC(2)H(5))(3), CO); the reactions of 2 and 3a with water led to the formation of the imido-bridged dinuclear complex [Cp*Ir(micro(2)-NTs)(2)IrCp*] and the bis(amido) complex [Cp*Ir(NHTs)(2){P(C(6)H(5))(3)}], respectively.     

Sulfur-bridged early-late heterobimetallics synthesized by incorporation of titanium,vanadium, and molybdenum into bis(hydrosulfido) templates of group 9 metals

Reactions of the bis(hydrosulfido) complexes [Cp*Rh(SH)(2)(PMe(3))] (1a; Cp* = eta(5)-C(5)Me(5)) with [CpTiCl(3)] (Cp = eta(5)-C(5)H(5)) and [TiCl(4)(thf)(2)] in the presence of triethylamine led to the formation of the sulfido-bridged titanium-rhodium complexes [Cp*Rh(PMe(3))(micro(2)-S)(2)TiClCp] (2a) and [Cp*Rh(PMe(3))(micro2-S)(2)TiCl(2)] (3a), respectively. Complex 3a and its iridium analogue 3b were further converted into the bis(acetylacetonato) complexes [Cp*M(PMe(3))(micro(2)-S)(2)Ti(acac)(2)] (4a, M = Rh; 4b, M = Ir) upon treatment with acetylacetone. The hydrosulfido complexes 1a and [Cp*Ir(SH)(2)(PMe(3))] (1b) also reacted with [VCl(3)(thf)(3)] and [Mo(CO)(4)(nbd)] (nbd = 2,5-norbornadiene) to afford the cationic sulfido-bridged VM2 complexes [(Cp*M(PMe(3))(micro2-S)(2))2V](+) (5a(+), M = Rh; 5b(+), M = Ir) and the hydrosulfido-bridged MoM complexes [Cp*M(PMe(3))(micro2-SH)(2)Mo(CO)(4)] (6a, M = Rh; 6b, M = Ir), respectively.     

含半夹心结构铑的1,1'-二硫(硒、碲)二茂铁化合物

以半夹心结构铑的化合物Cp*Rh(CN^tBu)Cl2(1)(Cp*=η^5-C5Me5)与Fe(C5H4ELi)2.2THF反应,合成出异双核二茂铁化合物Cp*Rh(CN^tBu)(EC5H4)2Fe[E=S(2),Se(3),Te(4)]。通过AgBF4氧化2和3得到二茂铁离子型化合物[Cp*Rh(CN^tBu)(EC5H4)2Fe]BF4[E=S(5),Se(6)]。采用元素分析、红外光谱、^1H和13CNMR谱以及EI-MS表征了所合成的化合物。     

Approaches to trinuclear half-sandwich carbene complexes containing 1,2-dicarba-closo-dodecaboranes

The synthesis of trinuclear half-sandwich iridium and rhodium complexes containing both N-heterocyclic carbene (NHC) and 1,2-dicarba-closo-dodecaborane ligands is described. Complexes {Cp*M[E2C2(B10H10)]}3(L) (Cp*=pentamethylcyclopentadienyl; L=tris(2-(3-methylimidazol-2-ylidene)ethyl)amine; M=Ir (), Rh (); E=S (), Se ()) were obtained from the reactions of Cp*M[E2C2(B10H10)] (M=Ir (), Rh ()) with a silver-NHC precursor or from the reactions of [Cp*MCl2]3(L) (M=Ir (), Rh ()) with Li2E2C2(B10H10) (E=S, Se). The complexes were characterized by IR, NMR spectroscopy, elemental analysis. In addition, X-ray structure analyses were performed on complexes and .     

Pentamethylcyclopentadienyl-iridium(III) complexes with pyridylamino ligands: synthesis and applications as asymmetric catalysts for Diels-Alder reactions

Reaction of the dimer [(Cp*IrCl)2(P-Cl)2] with chiral pyridylamino ligands (pyam, L1-L5) in the presence of NaSbF6 gave complexes [Cp*IrCl(pyam)][SbF6] 1-5 as diastereomeric mixtures, which have been fully characterised, including the X-ray molecular structure determination of the complexes (S(Ir),R(N),R(C))-[Cp*IrClL1][SbF6] 1a and (R(Ir),S(N),S(C))-[Cp*IrClL5][SbF6] 5a. Treatment of these cations with AgSbF6 affords the corresponding aqua species [Cp*Ir(pyam)(H2O)][SbF6]2 6-10 which have been also fully characterised. The molecular structure of the complex (S(Ir),R(N),R(C))-[Cp*IrL,(H2O)][SbF6]2 6 has been determined by X-ray diffractometric methods. The aqua complexes [Cp*Ir(pyam)(H2O)][SbF6]2 (6, pyam = L2 (7), L3 (8)) evolve to the cyclometallated species [Cp*Ir{kappa3(N,N',C)-(R)-(C6H4)CH(CH3)NHCH2C5NH4}][SbF6] (11), [Cp*Ir{kappa3(N,N',C)-(R)-(C10H6)CH(CH3)-NHCH2C5NH4)}][SbF6] (12), and [Cp*Ir{kappa3(N,N',C)-(R)-(C10H6)CH(CH3)NHCH2C9NH6)}][SbF6] (13) respectively, via intramolecular activation of an ortho C-H aryl bond. Complexes 6-10 are enantioselective catalysts for the Diels-Alder reaction between methacrolein and cyclopentadiene. Reaction occurs rapidly at room temperature with good exo : endo selectivity (from 81 : 19 to 98 : 2) and moderate enantioselectivity (up to 72%). The involved intermediate Lewis acid-dienophile compounds [Cp*Ir(pyam)(methacrolein)][SbF]2 (pyam = L4 (14), L5 (15)) have been isolated and characterised.     

Half-sandwich iridium complexes for homogeneous water-oxidation catalysis

Iridium half-sandwich complexes of the types Cp*Ir(N-C)X, [Cp*Ir(N-N)X]X, and [CpIr(N-N)X]X are catalyst precursors for the homogeneous oxidation of water to dioxygen. Kinetic studies with cerium(IV) ammonium nitrate as primary oxidant show that oxygen evolution is rapid and continues over many hours. In addition, [Cp*Ir(H(2)O)(3)]SO(4) and [(Cp*Ir)(2)(μ-OH)(3)]OH can show even higher turnover frequencies (up to 20 min(-1) at pH 0.89). Aqueous electrochemical studies on the cationic complexes having chelate ligands show catalytic oxidation at pH > 7; conversely, at low pH, there are no oxidation waves up to 1.5 V vs NHE for the complexes. H(2)(18)O isotope incorporation studies demonstrate that water is the source of oxygen atoms during cerium(IV)-driven catalysis. DFT calculations and kinetic experiments, including kinetic-isotope-effect studies, suggest a mechanism for homogeneous iridium-catalyzed water oxidation and contribute to the determination of the rate-determining step. The kinetic experiments also help distinguish the active homogeneous catalyst from heterogeneous nanoparticulate iridium dioxide.     

Syntheses and structures of half-sandwich iridium(III) and rhodium(III) complexes with organochalcogen (S, Se) ligands bearing N-methylimidazole and their use as catalysts for norbornene polymerization

The organochalcogen ligands derived from 3-methyl-imidazole-2-thione/selone groups, Mbit, Mbis, Ebit and Ebis [Mbit = 1,1'-methylenebis(3-methyl-imidazole-2-thione); Mbis = 1,1'-methylenebis(3-methyl-imidazole-2-selone), Ebit = 1,1'-(1,2-ethanediyl)bis(3-methyl-imidazole-2-thione), Ebis = 1,1'-(1,2-ethanediyl)bis(3-methyl-imidazole-2-selone)] have been synthesized and characterized. Reactions of [Cp*Ir(micro-Cl)Cl]2 and [Cp*Rh(micro-Cl)Cl]2 (Cp* = eta5-pentamethylcyclopentadienyl) with Mbit, Mbis, Ebit and Ebis result in the formation of the complexes [Cp*Ir(Mbit)Cl]Cl 1a x Cl), [Cp*Ir(Mbis)Cl]Cl (3a x Cl), [Cp*Ir(Ebit)Cl]Cl (1b x Cl), [Cp*Ir(Ebis)Cl]Cl (2a x Cl), [Cp*Rh(Mbit)Cl]Cl (2b x Cl), Cp*Rh(Mbis)Cl][Cp*RhCl(3)] (3b x[Cp*RhCl(3)]), [Cp*Rh(Ebit)Cl]Cl (4a x Cl) and [Cp*Rh(Ebis)Cl]Cl (4b x Cl), respectively. All compounds have been characterized by elemental analysis, NMR and IR spectra. The molecular structures of 1b, 2b, 3a, 3b and 4a have been determined by X-ray crystallography. After activation with methylaluminoxane (MAO), the iridium complexes exhibit moderate activities for the vinyl polymerization of norbornene.     

半夹心结构有机金属铱和铑化合物[Cp*M(TmMe)]Cl(M=Ir，Rh；TmMe=三(2-巯基-1-甲基咪唑)硼酸根)的合成与表征

三齿配体三(2-巯基-1-甲基咪唑)硼酸盐[TmMe]K与含有半夹心结构金属铱和铑化合物[Cp*Ir(μ-Cl)Cl]2和[Cp*Rh(μ-Cl)Cl]2反应形成具有18电子结构的配合物[Cp*Ir(TmMe)]Cl(1)和[Cp*Rh(TmMe)]Cl(2).所有的化合物都经过IR,NMR和EA表征,并通过X-射线衍射单晶结构分析测定了配合物2的分子结构.     

Syntheses and skeletal transformations of NCNH- and NCN-bridged tetrairidium(III) cages

The diiridium complex [Cp*IrCl2]2 (Cp* = eta5-C5Me5) reacts with 2 equiv of Na(NCNH) at room temperature to afford the 16-membered macrocyclic tetrairidium complex [Cp*IrCl(mu2-NCNH-N,N')]4 (1a). Treatment of 1a with 4 equiv of triethylamine at room temperature leads to the formation of the "C3-elongated cubane-like" tetrairidium complex [Cp*Ir(mu3-NCN-N,N,N')3(IrCp*)3(mu3-NCN-N,N,N)] (2) as the major product, which is further converted into the cubane-type complex [Cp*Ir(mu3-NCN-N,N,N)]4 (3) on refluxing in p-xylene. The molecular structures of [Cp*IrI(mu3-NCNH-N,N')]4.C7H8 (1b.C7H8), 2.0.5C7H8, and 3 have been determined by X-ray analyses.     

Synthesis and reactivity of the monomeric late-transition-metal parent amido complex [Ir(Cp*)(PMe3)(Ph)(NH2)

The late-transition-metal parent amido compound [Ir(Cp*)(PMe3)(Ph)(NH2)] (2) has been synthesized by deprotonation of the corresponding ammine complex [Ir(Cp*)(PMe3)(Ph)(NH3)][OTf] (6) with KN(SiMe3)2. An X-ray structure determination has ascertained its monomeric nature. Proton-transfer studies indicate that 2 can successfully deprotonate p-nitrophenylacetonitrile, aniline, and phenol. Crystallographic analysis has revealed that the ion pair [Ir(Cp*)(PMe3)(Ph)(NH3)][OPh] (8) exists as a hydrogen-bonded dimer in the solid state. Reactions of 2 with isocyanates and carbodiimides lead to overall insertion of the heterocumulenes into the N--H bond of the Ir-bonded amido group, demonstrating the ability of 2 to act as an efficient nucleophile. Intriguing reactivity is observed when amide 2 reacts with CO or 2,6-dimethylphenyl isocyanide. eta4-Tetramethylfulvene complexes [Ir(eta4-C5Me4CH2)(PMe3)(Ph)(L)] (L=CO (15), CNC6H3-2,6-(CH3)2 (16)) are formed in solution through displacement of the amido group by the incoming ligand followed by deprotonation of a methyl group on the Cp* ring and liberation of ammonia. Conclusive evidence for the presence of the Ir-bonded eta4-tetramethylfulvene moiety in the solid state has been provided by an X-ray diffraction study of complex 16.