Various forms of linear dipyridyls in discrete rectangles, dinuclear rods, and one-dimensional networks containing (eta5-pentamethylcyclopentadienyl)rhodium(III)

[Cp*Rh(eta1-NO3)(eta2-NO3)] (1) reacted with pyrazine (pyz) to give a dinuclear complex [Cp*Rh(eta1-NO3)(mu-pyz)(0.5)]2.CH2Cl2(3.CH2Cl2). Tetranuclear rectangles of the type [Cp*Rh(eta1,mu-X)(mu-L)(0.5)]4(OTf)4(4a: X = N3, L = bpy; 4b: X = N3, L = bpe; 4c: X = NCO, L = bpy) were prepared from [Cp*Rh(H2O)3](OTf)2 (2), a pseudo-halide (Me3SiN3 or Me3SiNCO), and a linear dipyridyl [4,4'-bipyridine (bpy) or trans-1,2-bis(4-pyridyl)ethylene (bpe)] by self-assembly through one-pot synthesis at room temperature. Treating complex with NH4SCN and dipyridyl led to the formation of dinuclear rods, [Cp*Rh(eta1-SCN)3]2(LH2) (5a: L = bpy; 5b: L = bpe), in which two Cp*Rh(eta1-SCN)3 units are connected by the diprotonated dipyridyl (LH2(2+)) through N(+)-H...N hydrogen bonds. Reactions of complex 2 with 1-(trimethylsilyl)imidazole (TMSIm) and dipyridyl (bpy or bpe) also produced another family of dinuclear rods [Cp*Rh(ImH)3]2.L (6a: L = bpy; 6b: L = bpe). Treating 1 and 2 with TMSIm and NH4SCN (in the absence of dipyridyl) generated a 1-D chain [Cp*Rh(ImH)3](NO3)2 (7) and a 1-D helix [Cp*Rh(eta1-SCN)2(eta1-SHCN)].H2O (8.H2O), respectively. The structures of complexes 3.CH2Cl2, 4a.H2O, 4c.2H2O, 5b, 6a, 7 and 8.H2O were determined by X-ray diffraction.     

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.     

Turning on red and near-infrared phosphorescence in octahedral complexes with metalated quinones

We report the synthesis of π-bonded ruthenium, rhodium, and iridium o-benzoquinones [Cp*M(o-C(6)H(4)O(2))](n) [M = Ru (2), n = 1-; Rh (3), n = 0; Ir (4), n = 0] following a novel synthetic procedure. Compounds 2-4 were fully characterized by spectroscopic methods and used as chelating organometallic linkers, "OM-linkers", toward luminophore bricks such as Ru(bpy)(2)(2+), Rh(ppy)(2)(+), and Ir(ppy)(2)(+) (bpy = 2,2'-bipyridine; ppy = 2-phenylpyridine) for the design of a novel family of octahedral bimetallic complexes of the general formula [(L-L)(2)M(OM-linkers)][X](m) (X = counteranion; m = 0, 1, 2) whose luminescent properties depend on the choice of the OM-linker and the luminophore brick. Thus, dinuclear assemblies such as [(bpy)(2)Ru(2)][OTf] (5-OTf), [(bpy)(2)Ru(2)][Δ-TRISPHAT] (5-ΔT) {TRISPHAT = tris[tetrachlorobenzene-1,2-bis(olato)]phosphate}, [(bpy)(2)Ru(3)][OTf](2) (6-OTf), [(bpy)(2)Ru(4)][OTf](2) (7-OTf), [(bpy)(2)Ru(4)][Δ-TRISPHAT](2) (7-ΔT), [(ppy)(2)Rh(2)] (8), [(ppy)(2)Rh(3)][OTf] (9-OTf), [(ppy)(2)Rh(4)][OTf] (10-OTf), [(ppy)(2)Rh(4)][Δ-TRISPHAT] (10-ΔT), [(ppy)(2)Ir(2)] (11), [(ppy)(2)Ir(3)][OTf] (12-OTf), [(ppy)(2)Ir(4)][OTf] (13-OTf), and [(ppy)(2)Ir(4)][Δ-TRISPHAT] (13-ΔT) were prepared and fully characterized. The X-ray molecular structures of three of them, i.e., 5-OTf, 8, and 11, were determined. The structures displayed a main feature: for instance, the two oxygen centers of the OM-linker [Cp*Ru(o-C(6)H(4)O(2))](-) (2) chelate the octahedral chromophore metal center, whether it be ruthenium, rhodium, or iridium. Further, the carbocycle of the OM-linker 2 adopts a η(4)-quinone form but with some catecholate contribution due to metal coordination. All of these binuclear assemblies showed a wide absorption window that tailed into the near-IR (NIR) region, in particular in the case of the binuclear ruthenium complex 5-OTf with the anionic OM-linker 2. The latter feature is no doubt related to the effect of the OM-linker, which lights up the luminescence in these homo- and heterobinuclear compounds, while no effect has been observed on the UV-visible and emission properties because of the counteranion, whether it be triflate (OTf) or Δ-TRISPHAT. At low temperature, all of these compounds become luminescent; remarkably, the o-quinonoid linkers [Cp*M(o-C(6)H(4)O(2))](n) (2-4) turn on red and NIR phosphorescence in the binuclear octahedral species 5-7. This trend was even more observable when the ruthenium OM-linker 2 was employed. These assemblies hold promise as NIR luminescent materials, in contrast to those made from organic 1,2-dioxolene ligands that conversely are not emissive.     

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.     

Synthesis, structures, and properties of group 9- and group 10-group 6 heterodinuclear nitrosyl complexes

The reaction of the group 9 bis(hydrosulfido) complexes [Cp*M(SH)2(PMe3)] (M=Rh, Ir; Cp*=eta(5)-C 5Me5) with the group 6 nitrosyl complexes [Cp*M'Cl2(NO)] (M'=Mo, W) in the presence of NEt3 affords a series of bis(sulfido)-bridged early-late heterobimetallic (ELHB) complexes [Cp*M(PMe3)(mu-S)2M'(NO)Cp*] (2a, M=Rh, M'=Mo; 2b, M=Rh, M'=W; 3a, M=Ir, M'=Mo; 3b, M=Ir, M'=W). Similar reactions of the group 10 bis(hydrosulfido) complexes [M(SH)2(dppe)] (M=Pd, Pt; dppe=Ph 2P(CH2) 2PPh2), [Pt(SH)2(dppp)] (dppp=Ph2P(CH2) 3PPh2), and [M(SH)2(dpmb)] (dpmb=o-C6H4(CH2PPh2)2) give the group 10-group 6 ELHB complexes [(dppe)M(mu-S)2M'(NO)Cp*] (M=Pd, Pt; M'=Mo, W), [(dppp)Pt(mu-S)2M'(NO)Cp*] (6a, M'=Mo; 6b, M'=W), and [(dpmb)M(mu-S)2M'(NO)Cp*] (M=Pd, Pt; M'=Mo, W), respectively. Cyclic voltammetric measurements reveal that these ELHB complexes undergo reversible one-electron oxidation at the group 6 metal center, which is consistent with isolation of the single-electron oxidation products [Cp*M(PMe3)(mu-S)2M'(NO)Cp*][PF6] (M=Rh, Ir; M'=Mo, W). Upon treatment of 2b and 3b with ROTf (R=Me, Et; OTf=OSO 2CF 3), the O atom of the terminal nitrosyl ligand is readily alkylated to form the alkoxyimido complexes such as [Cp*Rh(PMe3)(mu-S)2W(NOMe)Cp*][OTf]. In contrast, methylation of the Rh-, Ir-, and Pt-Mo complexes 2a, 3a, and 6a results in S-methylation, giving the methanethiolato complexes [Cp*M(PMe3)(mu-SMe)(mu-S)Mo(NO)Cp*][BPh 4] (M=Rh, Ir) and [(dppp)Pt(mu-SMe)(mu-S)Mo(NO)Cp*][OTf], respectively. The Pt-W complex 6b undergoes either S- or O-methylation to form a mixture of [(dppp)Pt(mu-SMe)(mu-S)W(NO)Cp*][OTf] and [(dppp)Pt(mu-S) 2W(NOMe)Cp*][OTf]. These observations indicate that O-alkylation and one-electron oxidation of the dinuclear nitrosyl complexes are facilitated by a common effect, i.e., donation of electrons from the group 9 or 10 metal center, where the group 9 metals behave as the more effective electron donor.     

Azido- or hydroxyl-capped half-cubanes containing Cp*Rh fragments: [Cp*3Rh3(mu-X)3(mu3-X)]2+ (X-=OH- or N3-)

Treatment of [Cp*Rh(H(2)O)(3)](OTf)(2) (1) with Me(3)SiNH-t-Bu in acetone gave a hydroxyl-capped half-cubane [Cp*(3)Rh(3)(mu-OH)(3)(mu(3)-OH)](OTf)(3)(t-BuNH(3)) (2). Slow diffusion of Me(3)SiN(3) in diethyl ether into compound in acetone produced an azido-capped half-cubane [Cp*(3)Rh(3)(mu-N(3))(3)(mu(3)-N(3))](OTf)(2) (3). On the other hand, treating 1 with Me(3)SiN(3) in acetone gave an azido-bridged, dinuclear rhodium(III) complex [Cp*Rh(mu-N(3))(OH(2))](2)(OTf)(2) (4). Complexes 2 and 3 represent the first azido- or hydroxyl-capped, incomplete cubane-type Rh clusters. Under appropriate conditions, complexes 2 and 3 could be converted to complex 4. The structures of all products were determined by X-ray diffraction.     

Synthesis, reactivity and applications of zinc-zinc bonded complexes

The discovery of decamethyldizincocene [Zn(2)(η(5)-Cp*)(2)] (Cp* = C(5)Me(5)), the first complex containing a covalent zinc-zinc bond, by Carmona in 2004 initiated the search for this remarkable class of compounds. Low-valent organozinc complexes can either be formed by ligand substitution reactions of [Zn(2)(η(5)-Cp*)(2)] or by reductive coupling reactions of Zn(ii) compounds. To the best of our knowledge, until now 25 low-valent Zn-Zn bonded molecular compounds stabilized by a variety of sterically demanding, very often chelating, organic ligands have been synthesized and characterized. There are two major reaction pathways of [Zn(2)(η(5)-Cp*)(2)]: it can either react with cleavage of the Zn-Zn bond or by ligand substitution. In addition, upon reaction with late transition metal complexes, [Zn(2)(η(5)-Cp*)(2)] was found to form novel intermetallic complexes with Cp*Zn and Cp*Zn(2) acting as unusual one-electron donor ligands. Very recently, the potential capability of [Zn(2)(η(5)-Cp*)(2)] to serve as a suitable catalyst in hydroamination reactions was demonstrated. Finally, the recent work on Cd-Cd bonded coordination compounds is reviewed.     

Coordination solids derived from Cp*M(CN)3- (M = Rh,Ir)

Solutions of Rh2(OAc)4 and Et4N[Cp*Ir(CN)3] react to afford crystals of the one-dimensional coordination solid [Et4N[Cp*Ir(CN)3][Rh2(OAc)4]]. This reaction is reversed by coordinating solvents such as MeCN. The structure of the polymer consists of helical anionic chains containing Rh2(OAc)4 units linked via two of the three CN ligands of Cp*Ir(CN)3-. Use of the more Lewis acidic Rh2(O2CCF3)4 in place of Rh2(OAc)4 gave purple [(Et4N)2[Cp*Ir(CN)3]2[Rh2(O2CCF3)4]3], whose insolubility is attributed to stronger Rh-NC bonds as well as the presence of cross-linking. The species [[Cp*Rh(CN)3][Ni(en)n](PF6)] (n = 2, 3) crystallized from an aqueous solution of Et4N[Cp*Rh(CN)3] and [Ni(en)3](PF6)2; [[Cp*Rh(CN)3][Ni(en)2](PF6)] consists of helical chains based on cis-Ni(en)(2)2+ units. Aqueous solutions of Et4N[Cp*Ir(CN)3] and AgNO3 afforded the colorless solid Ag-[Cp*Ir(CN)3]. Recrystallization of this polymer from pyridine gave the hemipyridine adduct [Ag[Ag(py)][Cp*Ir(CN)3]2]. The 13C cross-polarization magic-angle spinning NMR spectrum of the pyridine derivative reveals two distinct Cp* groups, while in the pyridine-free precursor, the Cp*'s appear equivalent. The solid-state structure of [Ag[Ag(py)][Cp*Ir(CN)3]2] reveals a three-dimensional coordination polymer consisting of chains of Cp*Ir(CN)3- units linked to alternating Ag+ and Ag(py)+ units. The network structure arises by the linking of these helices through the third cyanide group on each Ir center.     

Regioselective Reduction of NAD+ Models with [Cp*Rh(bpy)H]+: Structure–Activity Relationships and Mechanistic Aspects in the Formation of the 1,4-NADH Derivatives

The hydride transfer mechanism of the NAD⁺ model compound 1 to its 1,4-NADH derivative 3 [Eq. (1)] is proposed to be a consequence of the critical role of the carbonyl group of the amide to coordinate to the ring-slipped η⁵- to η³-Cp*Rh metal center of the catalyst [Cp*Rh(bpy)H]⁺, prepared in situ from 2 , while a steric effect of a substituent in the 3 position, for example, C(O)NEt₂, was found to totally inhibit this regioselective reduction. bpy=2,2′-bipyridine, Cp*=C₅Me₅, OTf=trifluoromethanesulfanate.     

Cubane-type heterometallic sulfido clusters: incorporation of two metal fragments into a dinuclear ReS(mu-S)2ReS core affording bimetallic M2Re2(mu 3-S)4 clusters (M = Ru,Pt, Cu) or trimetallic MM'Re2(mu 3-S)4 clusters via incomplete cubane-type MRe2(mu 3-S)(mu 2-S)3 intermediates (M = Ru,Rh, Ir; M' = Mo,W, Pd,Ru, Rh)

Reactions of a dirhenium tetra(sulfido) complex [PPh(4)](2)[ReS(L)(mu-S)(2)ReS(L)] (L = S(2)C(2)(SiMe(3))(2)) with a series of group 8-11 metal complexes in MeCN at room temperature afforded either the cubane-type clusters [M(2)(ReL)(2)(mu(3)-S)(4)] (M = CpRu (2), PtMe(3), Cu(PPh(3)) (4); Cp = eta(5)-C(5)Me(5)) or the incomplete cubane-type clusters [M(ReL)(2)(mu(3)-S)(mu(2)-S)(3)] (M = (eta(6)-C(6)HMe(5))Ru (5), CpRh (6), CpIr (7)), depending on the nature of the metal complexes added. It has also been disclosed that the latter incomplete cubane-type clusters can serve as the good precursors to the trimetallic cubane-type clusters still poorly precedented. Thus, treatment of 5-7 with a range of metal complexes in THF at room temperature resulted in the formation of novel trimetallic cubane-type clusters, including the neutral clusters [[(eta(6)-C(6)HMe(5))Ru][W(CO)(3)](ReL)(2)(mu(3)-S)(4)], [(CpM)[W(CO)(3)](ReL)(2)(mu(3)-S)(4)] (M = Rh, Ir), [(Cp*Ir)[Mo(CO)(3)](ReL)(2)(mu(3)-S)(4)], [[(eta(6)-C(6)HMe(5))Ru][Pd(PPh(3))](ReL)(2)(mu(3)-S)(4)], and [(Cp*Ir)[Pd(PPh(3))](ReL)(2)(mu(3)-S)(4)] (13) along with the cationic clusters [(Cp*Ir)(CpRu)(ReL)(2)(mu(3)-S)(4)][PF(6)] (14) and [(Cp*Ir)[Rh(cod)](ReL)(2)(mu(3)-S)(4)][PF(6)] (cod = 1,5-cyclooctadiene). The X-ray analyses have been carried out for 2, 4, 7, 13, and the SbF(6) analogue of 14 (14') to confirm their bimetallic cubane-type, bimetallic incomplete cubane-type, or trimetallic cubane-type structures. Fluxional behavior of the incomplete cubane-type and trimetallic cubane-type clusters in solutions has been demonstrated by the variable-temperature (1)H NMR studies, which is ascribable to both the metal-metal bond migration in the cluster cores and the pseudorotation of the dithiolene ligand bonded to the square pyramidal Re centers, where the temperatures at which these processes proceed have been found to depend upon the nature of the metal centers included in the cluster cores.     

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 of mononuclear and dinuclear Rh hydrotris(pyrazolyl)borato complexes containing arenethiolato ligands and conversion of the mononuclear complexes into dinuclear Rh-Rh and Rh-Ir complexes with bridging arenethiolato ligands

Reactions of [Tp*Rh(coe)(MeCN)](; Tp*= HB(3,5-dimethylpyrazol-1-yl)(3); coe = cyclooctene) with one equiv. of the organic disulfides, PhSSPh, TolSSTol (Tol = 4-MeC(6)H(4)), PySSPy (Py = 2-pyridyl), and tetraethylthiuram disulfide in THF at room temperature afforded the mononuclear Rh(III) complexes [Tp*Rh(SPh)(2)(MeCN)](3a), [Tp*Rh(STol)(2)(MeCN)](3b), [Tp*Rh(eta(2)-SPy)(eta(1)-SPy)](6), and [Tp*Rh(eta(2)-S(2)CNEt(2))(eta(1)-S(2)CNEt(2))](7), respectively, via the oxidative addition of the organic disulfides to the Rh(I) center in 1. For the Tp analogue [TpRh(coe)(MeCN)](2, Tp = HB(pyrazol-1-yl)(3)), the reaction with TolSSTol proceeded similarly to give the bis(thiolato) complex [TpRh(STol)(2)(MeCN)](4) as a major product but the dinuclear complex [[TpRh(STol)](2)(micro-STol)(2)](5) was also obtained in low yield. Complex 3 was treated further with the Rh(III) or Ir(III) complexes [(Cp*MCl)(2)(micro-Cl)(2)](Cp*=eta(5)-C(5)Me(5)) in THF at room temperature, yielding the thiolato-bridged dinuclear complexes [Tp*RhCl(micro-SPh)(2)MCp*Cl](8a: M = Rh, 8b: M = Ir). Dirhodium complex [TpRhCl(micro-STol)(2)RhCp*Cl](9) was obtained similarly from 4 and [(Cp*RhCl)(2)(micro-Cl)(2)]. Anion metathesis of 8a proceeds only at the Rh atom with the Cp* ligand to yield [Tp*RhCl(micro-SPh)(2)RhCp*(MeCN)][PF(6)](10), when treated with excess KPF(6) in CH(2)Cl(2)-MeCN. The X-ray analyses have been undertaken to determine the detailed structures of 3b, 4, 5, 6, 7, 8a, 9, and 10.     

Synthetic, structural, spectroscopic, and electrochemical studies of mixed sandwich Rh(III) and Ir(III) complexes involving Cp* and tridentate macrocycles

The syntheses, structures, spectroscopy, and electrochemistry for six Ir(III) and Rh(III) mixed sandwich mononuclear complexes involving tridentate macrocycles and pentamethylcyclopentadienide (Cp*) are reported. The complexes are readily prepared by direct ligand substitution reactions from the dichloro bridged binuclear complexes, [{M(Cp*)(Cl)₂}₂]. All complexes have the general formula [M(L)(Cp*)]X₂ (M = Ir(III) or Rh(III), L = macrocycle, or Cl⁻) and exhibit a distorted octahedral structure involving three donor atoms from the macrocycle and the facially coordinating carbocyclic Cp* ligand. The complex cations include: [Rh(η⁵ -Cp*)(9S3)]²⁺ (1), [Rh(η⁵-Cp*)(9N3)]²⁺ (2), [Rh(η⁵-Cp*)(10S3)]²⁺ (3), [Ir(η⁵-Cp*)(9S3)]²⁺ (4), [Ir(η⁵-Cp*)(9N3)]²⁺ (5), and [Ir(η⁵-Cp*)(10S3)]²⁺ (6), where 9S3 = 1,4,7-trithiacyclononane, 9N3 = 1,4,7-triazacyclononane, and 10S3 = 1,4,7-trithiacyclodecane. The structures for all six complexes are supported by ¹H and ¹³C{¹H} NMR spectroscopy, and five complexes are also characterized by single-crystal X-ray crystallography (complexes 1-5). The ¹H NMR splittings between the two sets of methylene protons for both the Rh(III) and Ir(III) 9S3 complexes are much larger (0.4 vs. 0.2 ppm) compared to those in the two 9N3 complexes. Similarly, the ¹³C{¹H} NMR spectra in all four thioether complexes show that the ring carbons in the Cp* ligand are shifted by over 10 ppm downfield compared to the azacrown complexes. The electrochemistry of the complexes is surprisingly invariable and is dominated by a single irreversible metal-centered reduction near −1.2 V vs. Fc/Fc⁺.     

Homoleptic hexa and penta gallylene coordinated complexes of molybdenum and rhodium

The reactions of molybdenum(0) and rhodium(I) olefin containing starting materials with the carbenoid group 13 metal ligator ligand GaR (R = Cp*, DDP; Cp* = pentamethylcyclopentadienyl, DDP = HC(CMeNC(6)H(3)-2,6-(i)Pr(2))(2)) were investigated and compared. Treatment of [Mo(η(4)-butadiene)(3)] with GaCp* under hydrogen atmosphere at 100 °C yields the homoleptic, hexa coordinated, and sterically crowded complex [Mo(GaCp*)(6)] (1) in good yields ≥50%. Compound 1 exhibits an unusual and high coordinated octahedral [MoGa(6)] core. Similarly, [Rh(GaCp*)(5)][CF(3)SO(3)] (2) and [Rh(GaCp*)(5)][BAr(F)] (3) (BAr(F) = B{C(6)H(3)(CF(3))(2)}(4)) are prepared by the reaction of GaCp* with the rhodium(I) compound [Rh(coe)(2)(CF(3)SO(3))](2) (coe = cyclooctene) and subsequent anion exchange in case of 3. Compound 2 features a trigonal bipyramidal [RhGa(5)] unit. In contrast, reaction of excess Ga(DDP) with [Rh(coe)(2)(CF(3)SO(3))](2) does not result in a high coordinated homoleptic complex but instead yields [(coe)(toluene)Rh{Ga(DDP)}(CF(3)SO(3))] (4). The common feature of 2 and 4 in the solid state structure is the presence of short CF(3)SO(2)O···Ga contacts involving the GaCp* or rather the Ga(DDP) ligand. Compounds 1, 2, and 4 have been fully characterized by single crystal X-ray diffraction, variable temperature (1)H and (13)C NMR spectroscopy, IR spectroscopy, mass spectrometry, as well as elemental analysis.     

Bis-imine-cyclometalated macrocycles: synthesis, characterization and observation of solution behaviour

A novel class of cyclometalated macrocycles [(Cp*Ir)(2)(R-N=C-C(6)H(2)-C=N-R)(2)](2)(pyrazine)(2)·(OTf)(4) [R = Ph (4a), p-MeOC(6)H(4) (4b), p-MeC(6)H(4) (4c), p-ClC(6)H(4) (4d), Me (4e)]; [(Cp*Rh)(2)(R-N=C-C(6)H(2)-C=N-R)(2)](2)(pyrazine)(2)·(OTf)(4) [R = Ph (4a'), p-MeOC(6)H(4) (4b'), p-MeC(6)H(4) (4c')] and [(Cp*Ir)(2)(R-C=N-C(6)H(4)-N=C-R)(2)](2)(pyrazine)(2)·(OTf)(4) [R = Ph (5a), p-MeOC(6)H(4) (5b)] was stepwise constructed through the double-site C-H activation of aromatic bis-imine substrates. The structures of binuclear complexes and tetranuclear macrocycles were confirmed by single-crystal X-ray diffraction. Isomers were found both in binuclear species and macrocyclic complexes. Flexible substrates led to the existence of isomers for binuclear species, yet gave no isomers after macrocyclic constructions; rigid ones, in contrast, led to isomers only for macrocyclic species. The isomers of tetranuclear macrocycles were thermodynamically stable to reversible transformation on a scale of days. Robust bonding and a certain degree of rigidity were invoked to explain the existence of isomers. This is the first example, to our knowledge, in which coordinated macrocycles containing half-sandwich Cp*M (M = Ir, Rh) fragments have been constructed, without a dynamic reversible process.     

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.     

Organotitanium Fluorides as Matrices for Trapping Molecular ZnF(2) and MeZnF

Trapped as molecular solids, the transition metal fluorides ZnF(2) and MeZnF-the latter isolated for the first time-exist as adducts in [(Cp*TiF(3))(8)(ZnF(2))(3)] (1) and [(Cp*TiF(3))(4)(MeZnF)(2)] (2), respectively. Compounds 1 and 2 were obtained in reactions of [Cp*TiF(3)] (Cp*=C(5)Me(5)) with ZnMe(2) and Me(3)SnF in various molar ratios. The single-crystal structure of 1 is shown here; the unlabeled circles are F atoms.     

Redox-switched complexation/decomplexation of K(+) and Cs(+) by molecular cyanometalate boxes

The reaction of [N(PPh(3))(2)][CpCo(CN)(3)] and [Cb*Co(NCMe)(3)]PF(6) (Cb* = C(4)Me(4)) in the presence of K(+) afforded {K subset[CpCo(CN)(3)](4)[Cb*Co](4)}PF(6), [KCo(8)]PF(6). IR, NMR, ESI-MS indicate that [KCo(8)]PF(6) is a high-symmetry molecular box containing a potassium ion at its interior. The analogous heterometallic cage {K subset[Cp*Rh(CN)(3)](4)[Cb*Co](4)}PF(6) ([KRh(4)Co(4)]PF(6)) was prepared similarly via the condensation of K[Cp*Rh(CN)(3)] and [Cb*Co(NCMe)(3)]PF(6). Crystallographic analysis confirmed the structure of [KCo(8)]PF(6). The cyanide ligands are ordered, implying that no Co-CN bonds are broken upon cage formation and ion complexation. Eight Co-CN-Co edges of the box bow inward toward the encapsulated K(+), and the remaining four mu-CN ligands bow outward. MeCN solutions of [KCo(8)](+) and [KRh(4)Co(4)](+) were found to undergo ion exchange with Cs(+) to give [CsCo(8)](+) and [CsRh(4)Co(4)](+), both in quantitative yields. Labeling experiments involving [(MeC5H4)Co(CN)(3)]- demonstrated that Cs(+)-for-K(+) ion exchange is accompanied by significant fragmentation. Ion exchange of NH(4+) with [KCo(8)](+) proceeds to completion in THF solution, but in MeCN solution, the exclusive products were [Cb*Co(NCMe)(3)]PF(6) and the poorly soluble salt NH(4)CpCo(CN)(3). The lability of the NH(4+)-containing cage was also indicated by the rapid exchange of the acidic protons in [NH(4)Co(8)](+). Oxidation of [MCo(8)](+) with 4 equiv of FcPF(6) produced paramagnetic (S = 4/2) [Co(8)](4+), releasing Cs(+) or K(+). The oxidation-induced dissociation of M(+) from the cages is chemically reversed by treatment of [Co(8)](4+) and CsOTf with 4 equiv of Cp(2)Co. Cation recognition by [Co(8)] and [Rh(4)Co(4)] cages was investigated. Electrochemical measurements indicated that E(1/2)(Cs(+))--E(1/2)(K(+)) approximately 0.08 V for [MCo(8)](+).     

Condensed tantalaborane clusters: synthesis and structures of [(Cp*Ta)2B5H7{Fe(CO)3}2] and [(Cp*Ta)2B5H9{Fe(CO)3}4

The reaction of [(Cp*Ta)(2)B(4)H(9)(μ-BH(4))] (1; Cp* = η(5)-C(5)Me(5)) with [Fe(2)(CO)(9)] in hexane yielded [(Cp*Ta)(2)B(5)H(7){Fe(CO)(3)}(2)] (2) and [(Cp*Ta)(2)B(5)H(9){Fe(CO)(3)}(4)] (3) in moderate yield. Cluster 2 represents the first example of a bicapped pentagonal-bipyramidal metallaborane with a deformed equatorial plane, and 3 can be described as a fused cluster in which two pentagonal-bipyramidal units are fused through a common 3-vertex triangular face. Compounds 2 and 3 have been characterized by mass spectrometry and IR, (1)H, (11)B, and (13)C NMR spectroscopy, and the geometric structures were unequivocally established by crystallographic analysis.     

Synthesis and reactivity of Ir(I) and Ir(III) complexes with MeNH2, Me2C=NR (R = H, Me), C,N-C6H4{C(Me)=N(Me)}-2, and N,N'-RN=C(Me)CH2C(Me2)NHR (R = H, Me) ligands

Complexes [Ir(Cp*)Cl(n)(NH2Me)(3-n)]X(m) (n = 2, m = 0 (1), n = 1, m = 1, X = Cl (2a), n = 0, m = 2, X = OTf (3)) are obtained by reacting [Ir(Cp*)Cl(mu-Cl)]2 with MeNH2 (1:2 or 1:8) or with [Ag(NH2Me)2]OTf (1:4), respectively. Complex 2b (n = 1, m = 1, X = ClO 4) is obtained from 2a and NaClO4 x H2O. The reaction of 3 with MeC(O)Ph at 80 degrees C gives [Ir(Cp*){C,N-C6H4{C(Me)=N(Me)}-2}(NH2Me)]OTf (4), which in turn reacts with RNC to give [Ir(Cp*){C,N-C6H4{C(Me)=N(Me)}-2}(CNR)]OTf (R = (t)Bu (5), Xy (6)). [Ir(mu-Cl)(COD)]2 reacts with [Ag{N(R)=CMe2}2]X (1:2) to give [Ir{N(R)=CMe2}2(COD)]X (R = H, X = ClO4 (7); R = Me, X = OTf (8)). Complexes [Ir(CO)2(NH=CMe2)2]ClO4 (9) and [IrCl{N(R)=CMe2}(COD)] (R = H (10), Me (11)) are obtained from the appropriate [Ir{N(R)=CMe2}2(COD)]X and CO or Me4NCl, respectively. [Ir(Cp*)Cl(mu-Cl)]2 reacts with [Au(NH=CMe2)(PPh3)]ClO4 (1:2) to give [Ir(Cp*)(mu-Cl)(NH=CMe2)]2(ClO4)2 (12) which in turn reacts with PPh 3 or Me4NCl (1:2) to give [Ir(Cp*)Cl(NH=CMe2)(PPh3)]ClO4 (13) or [Ir(Cp*)Cl2(NH=CMe2)] (14), respectively. Complex 14 hydrolyzes in a CH2Cl2/Et2O solution to give [Ir(Cp*)Cl2(NH3)] (15). The reaction of [Ir(Cp*)Cl(mu-Cl)]2 with [Ag(NH=CMe2)2]ClO4 (1:4) gives [Ir(Cp*)(NH=CMe2)3](ClO4)2 (16a), which reacts with PPNCl (PPN = Ph3=P=N=PPh3) under different reaction conditions to give [Ir(Cp*)(NH=CMe2)3]XY (X = Cl, Y = ClO4 (16b); X = Y = Cl (16c)). Equimolar amounts of 14 and 16a react to give [Ir(Cp*)Cl(NH=CMe2)2]ClO4 (17), which in turn reacts with PPNCl to give [Ir(Cp*)Cl(H-imam)]Cl (R-imam = N,N'-N(R)=C(Me)CH2C(Me)2NHR (18a)]. Complexes [Ir(Cp*)Cl(R-imam)]ClO4 (R = H (18b), Me (19)) are obtained from 18a and AgClO4 or by refluxing 2b in acetone for 7 h, respectively. They react with AgClO4 and the appropriate neutral ligand or with [Ag(NH=CMe2)2]ClO4 to give [Ir(Cp*)(R-imam)L](ClO4)2 (R = H, L = (t)BuNC (20), XyNC (21); R = Me, L = MeCN (22)) or [Ir(Cp*)(H-imam)(NH=CMe2)](ClO4)2 (23a), respectively. The later reacts with PPNCl to give [Ir(Cp*)(H-imam)(NH=CMe2)]Cl(ClO4) (23b). The reaction of 22 with XyNC gives [Ir(Cp*)(Me-imam)(CNXy)](ClO4)2 (24). The structures of complexes 15, 16c and 18b have been solved by X-ray diffraction methods.