[ReO(N2O2)X] complexes: "4 + 1"?

[ReO(ppme)X] (where ppme(2-) is 2,5-diazo-N,N'-dimethylhexyl-1,6-bis(phenylphosphinate), X = Br0.3Cl0.7) has been synthesized via a substitution reaction and structurally characterized. The coordination geometry is a distorted octahedron and one phosphinate coordinates cis and the other trans to the oxo O atom. This coordination mode is conserved in all [ReOppmeX] complexes synthesized in this study. [ReO(ppme)Cl] has been prepared by a reduction/complexation reaction from [NH4][ReO4]. [ReO(ppme)Cl] reacts with thiocyanate and benzene thiolate forming [ReO(ppme)X] (X = (-)NCS, (-)SC6H5), but the one-pot synthesis of the respective ternary thiolate complexes from perrhenate was not successful. The reduction/complexation reaction of a thiol, H2ppmeCl4, and perrhenate resulted in the formation of [H3ppme][ReO(SR)4], the reaction of which with [ReO(ppme)Cl] does not lead to [ReO(ppme)SR] in high yields.

Insulin-enhancing vanadium(III) complexes.

Simple, high-yield, large-scale syntheses of the V(III) complexes tris(maltolato)vanadium(III), V(ma)3, tris(ethylmaltolato)vanadium(III), V(ema)3, tris(kojato)vanadium(III) monohydrate, V(koj)3-H2O, and tris(1,2-dimethyl-3-hydroxy-4-pyridinonato)vanadium(III) dodecahydrate, V(dpp)3-12H2O, are described; the characterization of these complexes by various methods and, in the case of V(dpp)3-12H2O, by an X-ray crystal structure determination, is reported. The ability of these complexes to normalize glucose levels in the STZ-diabetic rat model has been examined and compared with that of the benchmark compound BMOV (bis(maltolato)oxovanadium(IV)), an established insulin-enhancing agent.

Lanthanide chemistry with (bis[[bis(carboxymethyl)amino]methyl]phosphinate: what does an extra phosphinate group do to EDTA?

H5XT (bis[[bis(carboxymethyl)amino]methyl]phosphinic acid) is an EDTA(4-)-like ligand containing an extra phosphinate group. [Co(II)(XT)]3-, [Co(III)(XT)]2-, and a series of [Ln(XT)]2- complexes have been prepared. The phosphinate group is not coordinated in the Co complexes but is bound in the lanthanide complexes. Solid state and solution behaviors of Ln-XT species are consistent: both monoprotonated and nonprotonated species have been found. Protonation of the metal complex does not lead to dissociation of a carboxylate; rather, the proton distributes around the molecular ion. The pM values of Ln-XT are comparable to those of Ln-EDTA but are higher than those of Ln-TMDTA. The inclusion of a phosphinate eases the selectivity of an EDTA-type ligand for late lanthanides.

Superelectrophilic tetrakis(carbonyl)palladium(II)- and -platinum(II) undecafluorodiantimonate(V), [Pd(CO)4][Sb(2)F(11)]2 and [Pt(CO)4][Sb(2)F(11)]2: syntheses, physical and spectroscopic properties, their crystal, molecular, and extended structures, and density functional calculations: an experimental, computational, and comparative study .

The salts [M(CO)(4)][Sb(2)F(11)](2), M = Pd, Pt, are prepared by reductive carbonylation of Pd[Pd(SO(3)F)(6)], Pt(SO(3)F)(4) or PtF(6) in liquid SbF(5), or HF-SbF(5). The resulting moisture-sensitive, colorless solids are thermally stable up to 140 degrees C (M = Pd) or 200 degrees C (M = Pt). Their thermal decompositions are studied by differential scanning calorimetry (DSC). Single crystals of both salts are suitable for an X-ray diffraction study at 180 K. Both isostructural salts crystallize in the monoclinic space group P2(1)/c (No. 14). The unit cell volume of [Pt(CO)(4)][Sb(2)F(11)](2) is smaller than that of [Pd(CO)(4)][Sb(2)F(11)](2) by about 0.4%. The cations [M(CO)(4)](2+), M = Pd, Pt, are square planar with only very slight angular and out-of-plane deviations from D(4)(h)() symmetry. The interatomic distances and bond angles for both cations are essentially identical. The [Sb(2)F(11)](-) anions in [M(CO)(4)][Sb(2)F(11)](2,) M = Pd, Pt, are not symmetry-related, and both pairs differ in their Sb-F-Sb bridge angles and their dihedral angles. There are in each salt four to five secondary interionic C- -F contacts per CO group. Of these, two contacts per CO group are significantly shorter than the sum of the van der Waals radii by 0.58 - 0.37 A. In addition, structural, and spectroscopic details of recently synthesized [Rh(CO)(4)][Al(2)Cl(7)] are reported. The cations [Rh(CO)(4)](+) and [M(CO)(4)](2+), M = Pd, Pt, are characterized by IR and Raman spectroscopy. Of the 16 vibrational modes (13 observable, 3 inactive) 10 (Pd, Pt) or 9 (Rh), respectively, are found experimentally. The vibrational assignments are supported by DFT calculations, which provide in addition to band positions also intensities of IR bands and Raman signals as well as internal force constants for the cations. (13)C NMR measurements complete the characterization of the square planar metal carbonyl cations. The extensive characterization of [M(CO)(4)][Sb(2)F(11)](2), M = Pd, Pt, reported here, allows a comparison to linear and octahedral [M(CO)(n)()][Sb(2)F(11)](2) salts [M = Hg (n = 2); Fe, Ru, Os (n = 6)] and their derivatives, which permit a deeper understanding of M-CO bonding in the solid state for superelectrophilic cations with [Sb(2)F(11)](-) or [SbF(6)](-) as anions.

Reaction of [P(2)N(2)]Ta==CH(2)(Me) with ethylene: synthesis of [P(2)N(2)]Ta(C(2)H(4))Et, a neutral species with a beta-agostic ethyl group in equilibrium with an alpha-agostic ethyl group ([P(2)N(2)] = PhP(CH(2)SiMe(2)CH(2))(2)PPh).

The photolysis of [P(2)N(2)]TaMe(3) ([P(2)N(2)] = PhP(CH(2)SiMe(2)NSiMe(2)CH(2))(2)PPh) produces [P(2)N(2)]Ta=CH(2)(Me) as the major product. The thermally unstable methylidene complex decomposes in solution in the absence of trapping agents to unidentified products. However, in the presence of ethylene [P(2)N(2)]Ta=CH(2)(Me) is slowly converted to [P(2)N(2)]Ta(C(2)H(4))Et, with [P(2)N(2)]Ta(C(2)H(4))Me observed as a minor product. A mechanistic study suggests that the formation of [P(2)N(2)]Ta(C(2)H(4))Et results from the trapping of [P(2)N(2)]TaEt, formed by the migratory insertion of the methylene moiety into the tantalum-methyl bond. The minor product, [P(2)N(2)]Ta(C(2)H(4))Me, forms from the decomposition of a tantalacyclobutane resulting from the addition of ethylene to [P(2)N(2)]Ta=CH(2)(Me) and is accompanied by the production of an equivalent of propylene. Pure [P(2)N(2)]Ta(C(2)H(4))Et can be synthesized by hydrogenation of [P(2)N(2)]TaMe(3) in the presence of PMe(3), followed by the reaction of ethylene with the resulting trihydride. Crystallographic and NMR data indicate the presence of a beta-agostic interaction between the ethyl group and tantalum center in [P(2)N(2)]Ta(C(2)H(4))Et. Partially deuterated analogues of [P(2)N(2)]Ta(C(2)H(4))Et show a large isotopic perturbation of resonance for both the beta-protons and the alpha-protons of the ethyl group, indicative of an equilibrium between a beta-agostic and an alpha-agostic interaction for the ethyl group in solution. An EXSY spectrum demonstrates that an additional fluxional process occurs that exchanges all of the (1)H environments of the ethyl and ethylene ligands. The mechanism of this exchange is believed to involve the direct transfer of the beta-agostic hydrogen atom from the ethyl group to the ethylene ligand, via the so-called beta-hydrogen transfer process.

Synthesis of 14-oxa-1,4,8,11-tetraazabicyclo[9.5.3]nonadecane(L1) and a spectroscopic and structural study of [Ni(L1)(ClO4)](ClO4) and of the macrobicyclic precursor diamide complex, [Ni(HL2)](ClO4); chloride substitution kinetics of the corresponding [Ni(III)(L1)]3+ species.

The pentadentate ligand 14-oxa-1,4,8,11-tetraazabicyclo[9.5.3]nonadecane (L1) has been synthesized by the high dilution cyclization of 1-oxa-4,8-diazacyclododecane ([10]aneN(2)O) (1) with 1,3-bis(alpha-chloroacetamido)propane (2) and subsequent reduction of the diamide intermediate. The structure [Ni(L1)(ClO(4))](ClO(4)) (P2(1)/c (no. 14), a = 8.608(3), b = 16.618(3), c = 14.924(4) A, beta = 91.53(3) degrees converged at R = 0.050 (R(w) = 0.046) for 307 parameters using 2702 reflections with I > 2sigma(I). For the nickel(II) complex of the (monodeprotonated) precursor diamide ligand 14-oxa-1,4,8,11-tetraazabicyclo[9.5.3]nonadecane-3,9-dione (H(2)L2), [Ni(HL2)](ClO(4)) (Pbca (no. 61), a = 15.1590(3), b = 13.235(2), c = 18.0195(6) A), the structure converged at R = 0.045 (R(w) = 0.038) for 265 parameters using 1703 reflections with I > 3sigma(I). In the reduced system, the cyclam-based ligand adopts a trans-III configuration. The [Ni(L1)(ClO(4))](2+) ion is pseudooctahedral with the Ni-O(ether) 2.094(3) A distance shorter than the Ni-O(perchlorate) 2.252(4) A. The nickel(II) and nickel(III) complexes are six-coordinate in solution. Oxidation of [Ni(L1)(OH(2))](2+) with K(2)S(2)O(8) in aqueous media yielded an axial d(7) Ni(III) species (g( perpendicular) = 2.159 and g( perpendicular) = 2.024 at 77 K). The [Ni(L1)(solv)](2+) ion in CH(3)CN showed two redox waves, Ni(II/I) (an irreversible cathodic peak, E(p,c) = -1.53 V) and Ni(III/II) (E(1/2) = 0.85 V (reversible)) vs Ag/Ag(+). The complex [Ni(HL2)](ClO(4)) displays square-planar geometry with monodeprotonation of the ligand. The ether oxygen is not coordinated. Ni-O(3) = 2.651(6) A and Ni-O(3a) = 2.451(12) A, respectively. The Ni(III/II) oxidation at E(1/2) = 0.24 V (quasi-reversible) vs Ag/Ag(+) is considerably lower than the saturated system. The kinetics of Cl(-) substitution at [Ni(L1)(solv)](3+) are pH dependent. Detachment of the ether oxygen atom is proposed, with insertion of a protonated water molecule which deprotonates at a pK(a) more acidic than in the corresponding cyclam complex. Mechanistic implications are discussed.

2-pyrrolylthiones as monoanionic bidentate N,S-chelators: synthesis and molecular structure of 2-pyrrolylthionato complexes of nickel(II), cobalt(III), and mercury(II).

The metal-chelating ability of 2-pyrrolylthiones is described. The readily available ligands di-2-pyrrolyl thione (6), 2-thioacetylpyrrole (10), and 2-thiobenzoylpyrrole (11) constitute examples of monoanionic ligands with N,S-donor atom sets, although di-2-pyrrolyl thione (6) could theoretically also achieve chelation through an N,N-donor set. A square planar Ni(II) complex, 14, an octahedral Co(III) complex, 18, and a tetrahedral Hg(II) complex, 17, with the di-2-pyrrolyl thionato chelate have been prepared, and their structures have been characterized by 1H NMR, UV-vis, MS, IR, elemental analysis, and single-crystal X-ray diffraction. Crystal data for 14: C18H14N4NiS2.0.28H2O, trigonal, R3, a = 18.467(1) A, b = 18.467(1) A, c = 26.404(2) A, V = 7797(1) A3; Z = 18, R = 3.2%. Crystal data for 18-mer: C27H21CoN6S3.C3H6O (acetone), monoclinic, P21/n, a = 9.569(1) A, b = 23.152(1) A, c = 13.659(1) A, beta = 100.882(8) degrees, V = 2971.6(5) A3, Z = 4, R = 4.3%. Crystal data for 17: C18H14HgN4S2, triclinic, P1, a = 8.443(2), b = 14.278(1) A, c = 7.445(1) A, alpha = 90.561(9) degrees, beta = 97.64(1) degrees, gamma = 104.250(9) degrees, V = 861.3(2) A3, Z = 2, R = 4.2%. The bond lengths and angles of these metal complexes are comparable to those of known N,S-chelates. A comparison of the structural parameters of the ligand in the metal complexes with those for the free ligand 6 demonstrates the preorganization of the free ligand for complexation and demonstrates the spectator role of the noncoordinating pyrrolic unit. Chelation of Ni(II) by 2-thioacetylpyrrole (10) and 2-thiobenzoylpyrrole (11) to provide complexes 12 and 13 with structures analogous to complex 14 is also described.

Seven-coordinate [ReVON4X2]+ complexes (X = O and Cl).

The oxorhenium(V) complexes with ligands containing N4 (H2pmen) and N4O2 (H2bbpen, H2Clbbpen, and H2bped) donor atom sets have been synthesized. X-ray crystallographic analyses of the [ReO(H2pmen)Cl2]+, [ReO(bbpen)]+, and [ReO(bped)]+ complexes showed that all three cations share a rare seven-coordinate structure with a distorted pentagonal bipyramidal geometry, which represents a novel and potentially general structural motif in ReV = O complexes. 1H NMR spectroscopy shows that the structures of the complexes are retained in the solution.

Homotrinuclear lanthanide(III) arrays: assembly of and conversion from mononuclear and dinuclear units.

The reactions of potentially hexadentate H2bbpen (N,N'-bis(2-hydroxybenzyl)-N,N'-bis(2-pyridylmethyl)-ethylenediamine, H2L1), H2(Cl)bbpen (N,N'-bis(5-chloro-2-hydroxybenzyl)-N,N'-bis(2-pyridylmethyl)ethylenediamine, H2L2), and H2(Br)bbpen (N,N'-bis(5-bromo-2-hydroxybenzyl)-N,N'-bis(2-pyridylmethyl)ethylenediamine, H2L3) with Ln(III) ions in the presence of a base in methanol resulted in three types of complexes: neutral mononuclear ([LnL(NO3)]), monocationic dinuclear ([Ln2L2(NO3)]+), and monocationic trinuclear ([Ln3L2(X)n(CH3OH)]+), where X = bridging (CH3COO-) and bidentate ligands (NO3-, CH3COO-, ClO4-) and n is 4. The formation of a complex depends on the base (hydroxide or acetate) and the size of the respective Ln(III) ion. All complexes were characterized by infrared spectroscopy, mass spectrometry, and elemental analyses; in some cases, X-ray diffraction studies were also performed. The structures of the neutral mononuclear [Yb(L1)(NO3)], dinuclear [Pr2(L1)2(NO3)(H2O)]NO3.CH3OH and [Gd2(L1)2(NO3)]NO3.CH3OH.3H2O, and trinuclear [Gd3(L3)2(CH3COO)4(CH3OH)]ClO4.5CH3OH and [Sm3(L1)2(CH3COO)2(NO3)2(CH3OH)]NO3.CH3OH.3.65H2O were solved by X-ray crystallography. The [LnL(NO3)] or [Ln2L2(NO3)]+ complexes could be converted to [Ln3L2(X)n(CH3OH)]+ complexes by the addition of 1 equiv of a Ln(III) salt and 2-3 equiv of sodium acetate in methanol. The trinuclear complexes were found to be the most stable of the three types, which was evident from the presence of the intact monocationic high molecular weight parent peaks ([Ln3L2(X)n]+) in the mass spectra of all the trinuclear complexes and from the ease of conversion from the mononuclear or dinuclear to the trinuclear species. The incompatibility of the ligand denticity with the coordination requirements of the Ln(III) ions was proven to be a useful tool in the construction of multinuclear Ln(III) metal ion arrays.

Coaggregation of paramagnetic d- and f-block metal ions with a podand-framework amine phenol ligand.

This report covers initial studies in the coaggregation of nickel (Ni2+) and lanthanide (Ln3+) metal ions to form complexes with interesting structural and magnetic properties. The tripodal amine phenol ligand H3tam (1,1,1-tris(((2-hydroxybenzyl)amino)methyl)ethane) is shown to be particularly accommodating with respect to the geometric constraints of both transition and lanthanide metal ions, forming isolable complexes with both of these ion types. In the solid-state structure of [Ni(H2tam)(CH3CN)]PF6.2.5CH3CN.0.5CH3OH (1), the Ni(II) center has a distorted octahedral geometry, with an N3O2 donor set from the [H2tam]- ligand and a coordinated solvent (acetonitrile) occupying the sixth site. The reaction of stoichiometric amounts of H3tam with the Ni(II) ion in the presence of lanthanide(III) ions provides [LnNi2(tam)2]+ cationic complexes which contain coaggregated metal ions. These complexes are isolable and have been characterized by a variety of analytical techniques, with mass spectrometry proving to be particularly diagnostic. The solid-state structures of [LaNi2(tam)2(CH3OH)1/2(CH3CH2OH)1/2(H2O)]ClO4.0.5CH3OH.0.5CH3CH2OH.4H2O (2), [DyNi2(tam)2(CH3OH)(H2O)]ClO4.CH3OH. H2O(6), and [YbNi2(tam)2(H2O)]ClO4.2.58H2O(9) have been determined. Each complex contains two octahedral Ni(II) ions, each of which is encapsulated by the ligand tam3- in an N3O3 coordination sphere; each [Ni(tam)]-unit caps the lanthanide(III) ion via bridging phenoxy oxygen donor atoms. In 2, La3+ is eight-coordinated, while in 6, Dy(III) is seven- (to "weakly eight-") coordinated, and Yb(III) in 9 has a six-coordination environment. The complexes are symmetrically different, 2 possessing C2 symmetry and 6 and 9 having C1 symmetry. Magnetic studies of 2, 6, and 9 indicate that antiferromagnetic exchange coupling between the Ni(II) and Ln(III) ions increases with decreasing ionic radius of Ln(III).

The synthesis and the molecular structure of hexakis(carbonyl)hexafluoroantimonato(V)tungsten(II) undecafluorodiantimonate(V), [W(CO)6(FSbF5)][Sb2F11].

The reaction of tungsten hexacarbonyl, W(CO)6, with antimony(V) fluoride, SbF5, in the conjugate Brønsted-Lewis superacid HF-SbF5 at 40 degrees C produces quantitatively the salt [W(CO)6(FSbF5)][Sb2F11] as the main product. The observed 2e- oxidation without any loss of CO is unprecedented. The cation [W(CO)6(FSbF5)]+ is seven coordinated with a distorted C2v capped trigonal prismatic structure. [W(CO)6(FSbF5)][Sb2F11] crystallizes in the monoclinic space group P21 (No. 4). a = 8.2051(12) A, b = 16.511(3) A, c = 8.1432(2) A, beta = 111.5967(6) degrees, V = 1025.8(2) A3, Z = 2. Number of reflections measured = 9112, unique 4410. Residuals on F, I > 3 sigma (I): R (Rw) = 0.023 (0.023). In the [W(CO)6(FSbF5)]+ cation the FSbF5 group is very tightly coordinated to tungsten with the bridging fluorine nearly equidistant from W and Sb. The details of the molecular structure are compared to those to polymeric [[Mo(CO)4]2(cis-mu-F2SbF4)3]x[Sb2F11]x reported by us very recently.

Syntheses, molecular structures, and vibrational spectra of chloropentacarbonylrhodium(III) and -iridium(III) undecafluorodiantimonate(V), [Rh(CO)5Cl][Sb2F11]2 and [Ir(CO)5Cl][Sb2F11]2: an experimental and density functional study.

The reactions of either bis(mu-chloro)tetracarbonyldirhodium(I), [Rh(CO)2(mu-Cl)]2, or chlorotricarbonyliridium(I), [Ir(CO)3Cl]n, in the conjugate Brønsted-Lewis superacid HF-SbF5 and in a CO atmosphere, produce [Rh(CO)5Cl][Sb2F11]2 or [Ir(CO)5Cl][Sb2F11]2, respectively. In these oxidative carbonylation reactions, antimony(V) fluoride functions as an oxidizing agent. The reduced product is identified as 6SbF3.5SbF5. [Rh(CO)5Cl][Sb2F11]2 is obtained in the form of single crystals. Crystal data: monoclinic, space group P2(1) (No. 4); a = 9.721(1), b = 12.602(1), c = 10.538(1) A; beta = 106.51(1) degrees; V = 1237.7(2) A3; Z = 2; T = 300 K; R1 [I > 3 sigma (I)] = 0.0367, wR2 = 0.0739. Single crystals of [Ir(CO)5Cl][Sb2F11]2 are produced in small amounts from a solution of mer-Ir(CO)3(SO3F)3 in magic acid, HSO3F-SbF5. The possible source of chlorine will be discussed. Crystal data for [Ir-(CO)5Cl][Sb2F11]2: monoclinic, space group P2(1) (No. 4); a = 9.686(2), b = 12.585(2), c = 10.499(2) A; beta = 106.59(2) degrees; V = 1226.5(4) A3; Z = 2; T = 294 K; R1[I > 3 sigma (I)] = 0.032, Rw = 0.031. The bond lengths and bond angles are nearly identical in the two isostructural salts; however, the cell volume of [Ir(CO)5Cl][Sb2F11]2 is slightly smaller than that of [Rh(CO)5Cl][Sb2F11]2. The cations (point group C4v) feature unusually long M-C bonds (M = Rh, Ir) and correspondingly short CO bonds, as well as high CO stretching wavenumbers and high CO stretching force constants. The [Sb2F11]- anions are not symmetry related, and their dihedral and bridge angles differ slightly in both salts. There are significant interionic contacts in [Ir(CO)5Cl][Sb2F11]2 exclusively of the C-F type (about 2 for each C atom of the five carbonyl groups) resulting in extended structures. The vibrational spectra for both [M(CO)5Cl]2+ cations (M = Rh, Ir) are assigned with the help of density functional calculations, which also provide intensities for IR and Raman bands. While [Rh(CO)5Cl]2+ is the first cationic carbonyl derivative of Rh(III), the vibrational and structural parameters for [Ir(CO)5Cl]2+ are compared to data for [Ir(CO)6]3+ and mer-Ir(CO)3(SO3F)3.