Anhydrides of real and hypothetical [hydroxy(R-O)iodo]benzenes.

The anhydrides of [hydroxy(methanesulfonato-O)]iodobenzene (HMIB) and [hydroxy(toluenesulfonato-O)]iodobenzene (HTIB) were prepared by drying acetonitrile solutions of the compounds. The anhydrides of the hypothetical compounds [hydroxy(chloroacetato)-O]iodobenzene and [hydroxy(iodoacetato)-O]iodobenzene were obtained from aqueous solutions. Crystallographic structures were obtained for the anhydrides, except that of HTIB. The electron-domain geometries of the I atoms vis-a-vis secondary I...O bonds were explored. The presence of delocalized bonding in groupings of O and I atoms was suggested. A linear relationship between the C-I-O angles and the I-O bond orders was observed.

Multimodal study of secondary interactions in Cp*Ir complexes of imidazolylphosphines bearing an NH group.

Hydrogen bonding phenomena are explored using a combination of X-ray diffraction, NMR and IR spectroscopy, and DFT calculations. Three imidazolylphosphines R(2)PImH (ImH = imidazol-2-yl, R = t-butyl, i-propyl, phenyl, 1a-1c) and control phosphine (i-Pr)(2)PhP (1d) lacking an imidazole were used to make a series of complexes of the form Cp*Ir(L(1))(L(2))(phosphine). In addition, in order to suppress intermolecular interactions with either imidazole nitrogen, 1e, a di(isopropyl)imidazolyl analogue of 1b was made along with its doubly (15)N-labeled isotopomer to explore bonding interactions at each imidazole nitrogen. A modest enhancement of transfer hydrogenation rate was seen when an imidazolylphosphine ligand 1b was used. Dichloro complexes (L(1) = L(2) = Cl, 2a-2c,2e) showed intramolecular hydrogen bonding as revealed by four X-ray structures and various NMR and IR data. Significantly, hydride chloride complexes [L(1) = H, L(2) = Cl, 3a-3c and 3e-((15)N)(2)] showed stronger hydrogen bonding to chloride than hydride, though the solid-state structure of 3b evinced intramolecular Ir-H...H-N bonding reinforced by intermolecular N...H-N bonding between unhindered imidazoles. These results are compared to literature examples, which show variations in preferred hydrogen bonding to hydride, halide, CO, and NO ligands. Surprising differences were seen between the dichloro complex 2b with isopropyl groups on phosphorus, which appeared to exist as a mixture of two conformers, and related complex 2a with tert-butyl groups on phosphorus, which exists in chlorinated solvents as a mixture of conformer 2a-endo and chelate 5a-Cl, the product of ionization of one chloride ligand. This difference became apparent only through a series of experiments, especially (15)N chemical shift data from 2D (1)H-(15)N correlation. The results highlight the difficulty of characterizing hemilabile, bifunctional complexes and the importance of innocent ligand substituents in determining structure and dynamics.

Reversible Ligand Pairing and Sorting Processes Leading to Heteroligated Palladium(II) Complexes with Hemilabile Ligands.

Halide-induced ligand pairing and sorting processes have been observed in the context of Pd(II) complexes with hemilabile P,S and P,O ligands. Mixing of the ligands Ph2PCH2CH2SMe (7) and Ph2PCH2CH2SPh (8) with a Pd(II) precursor in CH2Cl2 results in a mixture of [(7)2ClPd]Cl, [(8)2Cl2Pd], and [(7)(8)ClPd]Cl complexes at 20 °C. This equilibrium can be driven toward the heteroligated structure [(7)(8)ClPd]Cl by (1) cooling the mixture or (2) precipitation with hexanes, leading to the exclusive formation of semiopen heteroligated complex cis-[κ 2-(7)-κ 1-(8)ClPd]Cl (9a), as confirmed by a single-crystal X-ray diffraction study and solid state CPMAS 31P{1H} NMR spectroscopy. Dissolution of 9a in CH2Cl2 leads to the original mixture of complexes, which illustrates the reversible nature of this ligand pairing and sorting process. Similar processes occur when a combination of P,S and P,O ligands is used. The semiopen heteroligated complexes can be chemically manipulated in a reversible fashion to form closed complexes, allowing for control of the relative position and flexibility between neighboring substituents in these "tweezer"-like structures. Control experiments suggest these ligand sorting and pairing processes occur via a halide-induced ligand rearrangement (HILR) reaction.

Platinum-catalyzed enantioselective tandem alkylation/arylation of primary phosphines. Asymmetric synthesis of P-stereogenic 1-phosphaacenaphthenes.

Enantioselective tandem alkylation/arylation of primary phosphines with 1-bromo-8-chloromethylnaphthalene catalyzed by Pt(DuPhos) complexes gave P-stereogenic 1-phosphaacenaphthenes (AcePhos) in up to 74% ee. Diastereoselective formation of four P-C bonds in one pot with bis(primary) phosphines gave C2-symmetric diphosphines, including the o-phenylene derivative DuAcePhos, for which the rac isomer was formed with high enantioselectivity. These reactions, which appear to proceed via an unusual metal-mediated nucleophilic aromatic substitution pathway, yield a new class of heterocycles with potential applications in asymmetric catalysis.

Structure activity relationships of 5-, 6-, and 7-methyl-substituted azepan-3-one cathepsin K inhibitors.

The syntheses, in vitro characterizations, and rat and monkey in vivo pharmacokinetic profiles of a series of 5-, 6-, and 7-methyl-substituted azepanone-based cathepsin K inhibitors are described. Depending on the particular regiochemical substitution and stereochemical configuration, methyl-substituted azepanones were identified that had widely varied cathepsin K inhibitory potency as well as pharmacokinetic properties compared to the 4S-parent azepanone analogue, 1 (human cathepsin K, K(i,app) = 0.16 nM, rat oral bioavailability = 42%, rat in vivo clearance = 49.2 mL/min/kg). Of particular note, the 4S-7-cis-methylazepanone analogue, 10, had a K(i,app) = 0.041 nM vs human cathepsin K and 89% oral bioavailability and an in vivo clearance rate of 19.5 mL/min/kg in the rat. Hypotheses that rationalize some of the observed characteristics of these closely related analogues have been made using X-ray crystallography and conformational analysis. These examples demonstrate the potential for modulation of pharmacological properties of cathepsin inhibitors by substituting the azepanone core. The high potency for inhibition of cathepsin K coupled with the favorable rat and monkey pharmacokinetic characteristics of compound 10, also known as SB-462795 or relacatib, has made it the subject of considerable in vivo evaluation for safety and efficacy as an inhibitor of excessive bone resorption in rat, monkey, and human studies, which will be reported elsewhere.

Coordination copolymerization of severely encumbered isoalkenes with ethylene: enhanced enchainment mediated by binuclear catalysts and cocatalysts.

This contribution describes the implementation of the binuclear organotitanium "constrained geometry catalysts" (CGCs), (mu-CH(2)CH(2)-3,3'){(eta(5)-indenyl)[1-Me(2)Si((t)()BuN)](TiMe(2))}(2)[EBICGC(TiMe(2))(2); Ti(2)] and (mu-CH(2)-3,3'){(eta(5)-indenyl)[1-Me(2)Si((t)BuN)](TiMe(2))}(2)[MBICGC(TiMe(2))(2); C1-Ti(2)], in combination with the bifunctional bisborane activator 1,4-(C(6)F(5))(2)BC(6)F(4)B(C(6)F(5))(2) (BN(2)) in ethylene + olefin copolymerization processes. Specifically examined are the classically poorly responsive 1,1-disubstituted comonomers, methylenecyclopentane (C), methylenecyclohexane (D), 1,1,2-trisubstituted 2-methyl-2-butene (E), and isobutene (F). For the first three comonomers, this represents the first report of their incorporation into a polyethylene backbone via a coordination polymerization process. C and D are incorporated via a ring-unopened pathway, and E is incorporated via a novel pathway involving 2-methyl-1-butene enchainment in the copolymer backbone. In ethylene copolymerization, Ti(2) + BN(2) enchains approximately 2.5 times more C, approximately 2.5 times more D, and approximately 2.3 times more E than the mononuclear catalyst analogue [1-Me(2)Si(3-ethylindenyl)((t)BuN)]TiMe(2) (Ti(1)) + B(C(6)F(5))(3) (BN) under identical polymerization conditions. Polar solvents are found to weaken the catalyst-cocatalyst ion pairing, thus influencing the comonomer enchainment selectivity.

The coordination chemistry of the hydrotris(3-diphenylmethylpyrazol-1-yl)borate (Tp(CHPh2)) ligand.

The new ligand, hydrotris[3-(diphenylmethyl)pyrazol-1-yl]borate, Tp(CHPh2), has been synthesized and its coordination chemistry was compared with that of the analogous Tp(iPr). The new ligand was converted to a variety of complexes, such as M[Tp(CHPh2)]X (M = Co, Ni, Zn; X = Cl, NCO, NCS), Pd[Tp(CHPh2)][eta3-methallyl], Co[Tp(CHPh2)](acac), and Co[Tp(CHPh2)](scorpionate ligand). Compounds Tl[Tp(CHPh2)], 1, Co[Tp(CHPh2)]Cl, 2, Co[Tp(CHPh2)](NCS)(DMF), 3, Ni[Tp(CHPh2)](NCS)(DMF)2, 4, Co[Tp(CHPh2)](acac), 5, Co[Tp(CHPh2)][Ph2Bp], 6, Co[Tp(CHPh2)][Bp(Ph)], 7, Co[Tp(CHPh2)][Tp], 8, and (Ni[Tp(CHPh2)])2[C2O4](H2O)2, 9, were structurally characterized.

Catalyst/cocatalyst nuclearity effects in single-site olefin polymerization. Significantly enhanced 1-octene and isobutene comonomer enchainment in ethylene polymerizations mediated by binuclear catalysts and cocatalysts.

This Communication describes the implementation of a new binuclear homometallic organotitanium "constrained geometry catalyst" (CGC), (mu-CH2CH2-3,3'){ (eta5-indenyl )[1-Me2Si (tBuN)](TiMe2)}2[EBICGC(TiMe2)2; Ti2], together with the bifunctional activators (Ph3C+)2[1,4-(C6F5)3BC6F4B(C6F5)3]2- (B2) and new bisborane 1,4-(C6F5)2BC6F4B(C6F5)2 (BN2) in ethylene + alpha-olefin copolymerization processes. Specifically examined are the comonomers 1-octene and poorly responsive isobutene. Large increases in comonomer enchainment efficiency into the polyethylene microstructure are observed versus the corresponding mononuclear catalyst [1-Me2Si(3-ethylindenyl)(tBuN)]TiMe2 (Ti1) + Ph3C+B(C6F5)4- (B1) or B(C6F5)3 (BN) under identical polymerization conditions. In ethylene + 1-octene copolymerization, 11 times more 1-octene incorporation is observed for Ti2 + B2 vs Ti1 + B1. In ethylene + isobutene copolymerization, 5 times more isobutene incorporation is observed for Ti2 + BN2 vs Ti1 + BN.

Synthesis and characterization of volatile, fluorine-free beta-ketoiminate lanthanide MOCVD precursors and their implementation in low-temperature growth of epitaxial CeO(2) buffer layers for superconducting electronics.

A new class of volatile, low-melting, fluorine-free lanthanide metal-organic chemical vapor deposition (MOCVD) precursors has been developed. The neutral, monomeric Ce, Nd, Gd, and Er complexes are coordinatively saturated by a versatile, multidentate ether-functionalized beta-ketoiminato ligand series, the melting point and volatility characteristics of which can be tuned by altering the alkyl substituents on the keto, imino, and ether sites of the ligand. Direct comparison with conventional lanthanide beta-diketonate complexes reveals that the present precursor class is a superior choice for lanthanide oxide MOCVD. Epitaxial CeO(2) buffer layer films can be grown on (001) YSZ substrates by MOCVD at significantly lower temperatures (450-650 degrees C) than previously possible by using one of the newly developed cerium beta-ketoiminate precursors. Films deposited at 540 degrees C have good out-of-plane (Deltaomega = 0.85 degrees ) and in-plane (Deltaphi = 1.65 degrees ) alignment and smooth surfaces (rms roughness approximately 4.3 A). The film growth rate decreases and the films tend to be smoother as the deposition temperature is increased. High-quality yttrium barium copper oxide (YBCO) films grown on these CeO(2) buffer layers by pulsed organometallic molecular beam epitaxy exhibit very good electrical transport properties (T(c) = 86.5 K, J(c) = 1.08 x 10(6) A/cm(2) at 77.4 K).

A new route to coordination complexes of nitroxyl (HN=O) via insertion reactions of nitrosonium triflate with transition-metal hydrides.

Nitrosonium triflate reacts with cold methylene chloride solutions of mer,trans-ReH(CO)3(PPh3)2 (1) with 1,1-insertion of NO+ into the Re-H bond to give the orange nitroxyl complex [mer,trans-Re(NH=O)(CO)3(PPh3)2][SO3CF3] (3) in 86% isolated yield. Use of [NO][PF6] or [NO][BF4] gives analogous insertion products at low temperature, which decompose on warning to ambient temperature to the fluoride complex mer,trans-ReF(CO)3(PPh3)2 (4). A related 1,1-insertion is observed in the reaction of 1 with [PhN2][PF6] in acetone that affords the yellow-orange phenyldiazene salt [mer,trans-Re(NH=NPh)(CO)3(PPh3)2][PF6] (2), which has been characterized by X-ray crystallographic methods. The methyl derivative mer,trans-Re(CH3)(CO)3(PPh3)2 (5) also undergoes a 1,1-insertion reaction with [NO][SO3CF3] to give the nitrosomethane adduct [mer,trans-Re{N(CH3)=O}(CO)3(PPh3)2][SO3CF3] (6) as red crystals in 75% yield. The nitroxyl complex [cis,trans-OsBr(NH=O)(CO)2(PPh3)2][SO3CF3] (8) can be similarly prepared as orange crystals in 52% yield by reaction of cis,trans-OsHBr(CO)2(PPh3)2 (7) with [NO][SO3CF3] in cold methylene chloride solution.

Catalyst/cocatalyst nuclearity effects in single-site polymerization. Enhanced polyethylene branching and alpha-olefin comonomer enchainment in polymerizations mediated by binuclear catalysts and cocatalysts via a new enchainment pathway.

The binuclear "constrained geometry catalyst" (CGC) (mu-CH2CH2-3,3'){(eta5-indenyl )[1-Me2Si(tBuN)](ZrMe2)}2 [EBICGC(ZrMe2)2; Zr2] and the trityl bisborate dianion (Ph3C+)2[1,4-(C6F5)3BC6F4B(C6F5)3]2- (B2) have been synthesized to serve as new types of multicenter homogeneous olefin polymerization catalysts and cocatalysts, respectively. Additionally, the complex [1-Me2Si(3-ethylindenyl)(tBuN)]ZrMe2 (Zr1) was synthesized as a mononuclear control. For the bimetallic catalyst or bisborate cocatalyst, high effective local active site concentrations and catalyst center-catalyst center cooperative effects are evidenced by bringing the catalytic centers together via either covalent or electrostatic bonding. For ethylene homopolymerization at constant conversion, the branch content of the polyolefin products (primarily ethyl branches) is dramatically increased as catalyst or cocatalyst nuclearity is increased. Moreover, catalyst and cocatalyst nuclearity effects are approximately additive. Compared to the catalyst derived from monometallic Zr1 and monofunctional Ph3C+B(C6F5)4- (B1), the active catalyst derived from bimetallic Zr2 and bifunctional B2 produces approximately 11 times more ethyl branches in ethylene homopolymerization via a process which is predominantly intradimer in character. Moreover, approximately 3 times more 1-hexene incorporation in ethylene + 1-hexene copolymerization and approximately 4 times more 1-pentene incorporation in ethylene + 1-pentene copolymerization are observed for Zr2 + B2 versus Zr1 + B1.

Coordination chemistry of novel scorpionate ligands based on 3-cyclohexylpyrazole and 3-cyclohexyl-4-bromopyrazole.

The ligands [hydrotris(3-cyclohexylpyrazol-1-yl)borate, [Tp(Cy)](-), tetrakis(3-cyclohexylpyrazol-1-yl)borate, [pz(o)Tp(Cy)](-), and hydrotris(3-cyclohexyl-4-bromopyrazol-1-yl)borate, [Tp(Cy,4Br)](-) were synthesized and characterized as their Tl(I) derivatives. They were converted to a variety of tetrahedral LMX and octahedral LML' complexes, as well as to the dinuclear nickel carbonate complex [Ni(Tp(Cy))](2)(CO(3)), 4, and the compound Ni[Tp(Cy,4Br)][pz(Cy,4Br)](3)(H)(2), 5. The structures of Co[Tp(Cy)]Cl, 1, Co[Tp(Cy,4Br)]Cl, 2, Co[Tp(Cy,4Br)]NCS, 3, [Ni(Tp(Cy))](2)(CO(3)), 4, Ni[Tp(Cy,4Br)][pz(Cy,4Br)](3)(H)(2), 5, and Mo[Tp(Cy)](CO)(2)(eta(3)-methallyl), 6, were determined by X-ray crystallography. The structures of paramagnetic heteroleptic complexes Co[Tp(Cy)][Tp], Co[Tp(Cy)][Tp], Co[Tp(Cy,4Br)][Tp], and Co[Tp(Cy,4Br)][Tp] were established by NMR. The homoleptic compounds Co[Tp(Cy)](2) and Co[Tp(Cy,4Br)](2) rearrange thermally to Co[Tp(Cy)](2) and to Co[Tp((Cy,4Br))](2), respectively, containing one 5-cyclohexyl group/ligand.

Syntheses and solid state structures of tris(pyrazolyl)methane complexes of sodium, potassium, calcium, and strontium: comparison of structures with analogous complexes of lead(II).

The reaction of NaI with 2 equiv of HC(pz)(3) or HC(3,5-Me(2)pz)(3) (pz = pyrazolyl ring) leads to the formation of [[HC(pz)(3)](2)Na](I) (1) and [[HC(3,5-Me(2)pz)(3)](2)Na](I) (2), respectively. Both compounds have trigonally distorted octahedral arrangements about the sodium. A similar reaction of KPF(6) with HC(3,5-Me(2)pz)(3) results in the formation of [[HC(3,5-Me(2)pz)(3)](2)K](PF(6)) (3), a complex also shown crystallographically to have a trigonally distorted octahedral arrangement about the potassium, which is an unusually low coordination number for this large metal ion. The complex [[HC(pz)(3)](2)Sr](BF(4))(2) (4) forms in the reaction of Sr(acac)(2) (acac = acetylacetonate) with HBF(4).Et(2)O followed by 2 equiv of HC(pz)(3). The structure is highly distorted, showing kappa(3) bonding of both tris(pyrazolyl)methane ligands and, in addition, interactions with the metal from three fluorine atoms from the BF(4)(-) counterions. The symmetrical structure of 1 and the nine-coordinate structure of 4 are both very different from the distorted, six-coordinate structure [[HC(pz)(3)](2)Pb](BF(4))(2), indicating that for this compound the lone pair on lead(II) is influencing the structure. The reaction of M(acac)(2) (M = Sr, Ca) with H[B[3,5-(CF(3))(2)C(6)H(3)](4)] followed by 2 equiv of HC(pz)(3) produces [[HC(pz)(3)](2)(Hacac)Sr][B[3,5-(CF(3))(2)C(6)H(3)](4)](2) (5) (when the reaction is done in CH(2)Cl(2)), [[HC(pz)(3)](2)(Me(2)CO)(2)Sr][B[3,5-(CF(3))(2)C(6)H(3)](4)](2) (6) (when the reaction is done in acetone), and [[HC(pz)(3)](2)(Hacac)Ca][B[3,5-(CF(3))(2)C(6)H(3)](4)](2)(7), respectively. The structures of all three complexes show a distorted eight-coordinate arrangement of the ligands about the metal. Crystal data: 1 is orthorhombic, Pnma, a = 16.931(1), b = 22.368(3), c = 7.937(2) A, alpha = 90, beta = 90, gamma = 90 degrees, Z = 4; 2 is trigonal, R3, a = 10.7483(8), b = 10.7483(8), c = 35.395(4) A, alpha = 90, beta = 90, gamma = 120 degrees, Z = 3; 3 is monoclinic, P2(1)/c, a = 9.144(4), b = 13.377(6), c = 15.988(7) A, alpha = 90, beta = 92.291(10), gamma = 90 degrees, Z = 2; 4 is hexagonal, P6(5), a = 9.42530(10), b = 9.42530(10), c = 55.3713(5) A, alpha = 90, beta = 90, gamma = 120 degrees, Z = 6; 5 is monoclinic, P2/n, a = 14.1601(3), b = 13.1756(3), c = 27.1826(6) A, alpha = 90, beta = 90.1744(7), gamma = 90 degrees, Z = 2; 6 is monoclinic, P2/n, a = 14.2709(7), b = 13.2646(7), c = 27.4189(13) A, alpha = 90, beta = 90.3850(10), gamma = 90 degrees, Z = 2; 7 is monoclinic, P2/n, a = 14.2388(2), b = 13.1919(2), c = 26.7879(3) A, alpha = 90, beta = 90.0650(8), gamma = 90 degrees, Z = 2.

Tris[(alkylthio)methyl]silanes: Syntheses and Structures of Chromium, Molybdenum, and Tungsten Complexes with a Tripodal Thioether Ligand.

The first member of a new family of tripodal thioether ligands, the methyltris[(alkylthio)methyl]silanes MeSi(CH(2)SR)(3) (R = Me), has been synthesized and characterized. Reactivity studies lead to the isolation of the complete series of group 6 metal carbonyl derivatives {eta(3)-MeSi(CH(2)SMe)(3)}M(CO)(3) (M = Cr, Mo, W), whose structures have been determined by single-crystal X-ray diffraction. The three complexes are isomorphous and display distorted octahedral structures with face-capping tridentate thioether ligands. {eta(3)-MeSi(CH(2)SMe)(3)}Cr(CO)(3) is monoclinic, P2(1)/c, a = 8.1658(2) Å, b = 15.0563(2) Å, c = 26.5791(3) Å, beta = 90.3653(6) degrees, V = 3267.74(8) Å(3), Z = 8. {eta(3)-MeSi(CH(2)SMe)(3)}Mo(CO)(3) is monoclinic, P2(1)/c, a = 8.34630(6) Å, b = 15.2747(2) Å, c = 27.1865(4) Å, beta = 90.8987(9) degrees, V = 3465.44(10) Å(3), Z = 8. {eta(3)-MeSi(CH(2)SMe)(3)}W(CO)(3) is monoclinic, P2(1)/c, a = 8.1582(2) Å, b = 14.9903(2) Å, c = 26.7268(4) Å, beta = 90.6568(8) degrees, V = 3268.30(9) Å(3), Z = 8.

Synthesis, Structure, and Molecular Orbital Studies of Yttrium, Erbium, and Lutetium Complexes Bearing eta(2)-Pyrazolato Ligands: Development of a New Class of Precursors for Doping Semiconductors.

Treatment of yttrium metal with bis(pentafluorophenyl)mercury (1.5 equiv), 3,5-di-tert-butylpyrazole (3 equiv), and pyridine (2 equiv) in toluene at ambient temperature for 120 h afforded tris(3,5-di-tert-butylpyrazolato)bis(pyridine)yttrium(III) (33%). In an analogous procedure, the reaction of erbium metal with 3,5-dialkylpyrazole (alkyl = methyl or tert-butyl), bis(pentafluorophenyl)mercury, and a neutral nitrogen donor (4-tert-butylpyridine, pyridine, n-butylimidazole, or 3,5-di-tert-butylpyrazole) yielded tris(3,5-di-tert-butylpyrazolato)bis(4-tert-butylpyridine)erbium(III) (63%), tris(3,5-di-tert-butylpyrazolato)bis(pyridine)erbium(III) (88%), tris(3,5-di-tert-butylpyrazolato)bis(n-butylimidazole)erbium(III) (48%), tris(3,5-dimethylpyrazolato)bis(4-tert-butylpyridine)erbium(III) (50%), and tris(3,5-di-tert-butylpyrazolato)(3,5-di-tert-butylpyrazole)erbium(III) (59%), respectively. Treatment of tris(cyclopentadienyl)lutetium(III) or tris(cyclopentadienyl)erbium(III) with 3,5-di-tert-butylpyrazole (3 equiv) and 4-tert-butylpyridine (2 equiv) in toluene at ambient temperature for 24 h afforded tris(3,5-di-tert-butylpyrazolato)bis(4-tert-butylpyridine)lutetium(III) (83%) and tris(3,5-di-tert-butylpyrazolato)bis(4-tert-butylpyridine)erbium(III) (41%), respectively. The X-ray crystal structures of all new complexes were determined. The X-ray structure analyses revealed seven- and eight-coordinate lanthanide complexes with all-nitrogen coordination spheres and eta(2)-pyrazolato ligands. Molecular orbital calculations were carried out on dichloro(pyrazolato)diammineyttrium(III). The calculations demonstrate that eta(2)-bonding of the pyrazolato ligand is favored over the eta(1)-bonding mode and give insight into the bonding between yttrium and the pyrazolato ligands. Complexes bearing 3,5-di-tert-butylpyrazolato ligands can be obtained in a high state of purity and sublime without decomposition (150 degrees C, 0.1 mmHg). Application of these complexes as source compounds for chemical vapor deposition processes is discussed.

One-Dimensional Copper(I) Coordination Polymers Based on a Tridentate Thioether Ligand.

The one-dimensional copper(I) coordination polymers Cu(3){MeSi(CH(2)SMe)(3)}(2)X(3) (X = Cl, Br) and [{MeSi(CH(2)SMe)(3)}Cu(NCMe)]Y (Y = OSO(2)CF(3), BF(4), PF(6)) were readily obtained in very good to excellent yields (80-95%) by reacting CuX or [Cu(NCMe)(4)]Y, respectively, with the tridentate thioether ligand MeSi(CH(2)SMe)(3) in acetonitrile. The new complexes were characterized by a combination of analytical and spectroscopic techniques, including electrospray ionization mass spectrometry and, for the bromo and hexafluorophosphate derivatives, single-crystal X-ray diffraction. Both complexes exhibit one-dimensional chain structures with approximately tetrahedral copper centers and bridging unidentate/bidentate thioether ligands.

Adducts of Titanium Tetrachloride with Alkylselenium Compounds: Molecular Precursors to Titanium Diselenide Films.

Treatment of titanium tetrachloride (2 equiv) with dimethyl diselenide or diethyl diselenide (1 equiv) in hexane at 0 degrees C, followed by crystallization at -20 degrees C, afforded (TiCl(4))(2)(Se(2)(CH(3))(2)) (78%) and (TiCl(4))(2)(Se(2)(CH(2)CH(3))(2)) (63%), respectively, as red and orange crystalline solids. (TiCl(4))(2)(Se(2)(CH(2)CH(3))(2)) is stable in solution and in the solid state at 23 degrees C, but (TiCl(4))(2)(Se(2)(CH(3))(2)) decomposes to TiCl(4)(Se(CH(3))(2))(2), gray selenium, and other products upon standing in hexane solution, in the solid state, or upon sublimation at 250 degrees C. Treatment of titanium tetrachloride with 2 equiv of dimethyl selenide or diethyl selenide in hexane at ambient temperature afforded a spectroscopically pure brick red solid of TiCl(4)(Se(CH(3))(2))(2) (96%) or TiCl(4)(Se(CH(2)CH(3))(2))(2) (96%), respectively. X-ray crystal structures of (TiCl(4))(2)(Se(2)(CH(2)CH(3))(2)), TiCl(4)(Se(CH(3))(2))(2), and TiCl(4)(Se(CH(2)CH(3))(2))(2) were determined to establish solid state nuclearities. (TiCl(4))(2)(Se(2)(CH(2)CH(3))(2)) crystallizes in the hexagonal space group P3(1)21 with a = 12.106(1) Å, c = 10.786(1) Å, V = 1368.8(4) Å(3), and Z = 3. TiCl(4)(Se(CH(3))(2))(2) crystallizes in the monoclinic space group P2(1)/n with a = 8.175(1) Å, b = 13.051(1) Å, c = 16.871(3) Å, beta = 102.675(8) degrees, V = 1756.3(2) Å(3), and Z = 4. TiCl(4)(Se(CH(2)CH(3))(2))(2) crystallizes in the monoclinic space group P2(1)/n with a = 6.404(4) Å, b = 16.376(7) Å, c = 13.058(8) Å, beta = 101.45(4) degrees, V = 1342(1) Å(3), and Z = 4. TiCl(4)(Se(CH(3))(2))(2) and TiCl(4)(Se(CH(2)CH(3))(2))(2) were evaluated as precursors to titanium diselenide films. TiCl(4)(Se(CH(3))(2))(2) was not a good precursor, but TiCl(4)(Se(CH(2)CH(3))(2))(2) afforded rose-bronze colored titanium diselenide films at substrate temperatures of 500-600 degrees C. The films were characterized by X-ray powder diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy. Surprisingly, titanium diselenide films prepared from TiCl(4)(Se(CH(2)CH(3))(2))(2) are moisture sensitive and are apparently hydrolyzed by ambient moisture to titanium dioxide and hydrogen selenide. The relevance of the coordination chemistry to the development of precursors to titanium diselenide films is discussed.