Cyclic Trinuclear Gold(I) Clusters with N,N and Unusual C,C Mixed-Ligand Bridges.

Three crystalline trinuclear gold(I) clusters, [Aufy] (1), [Aufy] (2), and [Auy] (3), where f = N,N'-bis(2,6-dimethylphenyl)methanimidamidate and y = dimethylendiphenylphosphinate, exhibit bridges from the N,N-formamidinate and/or from the ylide anion ligand whose P-methylene groups chelate in an unusual fashion, where the chelate CPC unit is perpendicular to the trigonal plane of the metal atoms. Assemblies 1 and 2 are the first gold(I) trinuclear clusters featuring mixed-ligand bridges from different N,N and C,C donors; 3 is a previously unknown homoleptic ylide anion cyclic trinuclear assembly. Formamidinate bridges in 1 and 2 connect gold(I) atoms at aurophilic distances of 3.

Exploring the Intricacies of Weak Interactions in Metal-Metal Bonds Using an Unsymmetrical Carbonyl Precursor and a Triple-Bonded W2(6+) Paddlewheel.

Stepwise reaction of W(CO)6 with tetramethylated bicyclic guanidinate ligands, characterized by a central C(N)3 unit joining two fused six-membered rings with CH2CMe2CH2 units spanning two of the nitrogen atoms, allowed isolation of W2(μ-CO)2(μ-TMhpp)2(η(2)-TMhpp)2, 1, a precursor of W2(TMhpp)4Cl2 ( J. Am. Chem.

Multinuclear copper(I) and silver(I) amidinate complexes: synthesis, luminescence, and CS2 insertion reactivity.

Dinuclear Cu(I) and Ag(I) complexes, Cu2[(2,6-Me2C6H3N)2C(H)]2, 1, Ag2[(2,6-Me2C6H3N)2C(H)]2, 2, Cu2[2,6-(i)Pr2C6H3N)2C(H)]2, 3, and Ag2[(2,6-(i)Pr2C6H3N)2C(H)]2, 4, were synthesized from reactions of [Cu(NCCH3)4][PF6] with Na[(2,6-R2C6H3N)2C(H)] and AgO2CCH3 with [Et3NH][(2,6-R2C6H3N2C(H)], R = Me, (i)Pr. Carbon disulfide was observed to insert into the metal-nitrogen bonds of 1 to produce Cu4[CS2(2,6-Me2C6H3NC(H)═NC6H3Me2)]4, 5, with a Cu4S8 core, which represents a rare transformation of dinuclear to tetranuclear species. Insertion is also observed with 2 and CS2, with the product likely being polymeric, 6.

Manipulating magnetism: Ru₂⁵⁺ paddlewheels devoid of axial interactions.

Variable-temperature magnetic and structural data of two pairs of diruthenium isomers, one pair having an axial ligand and the formula Ru2(DArF)4Cl (where DArF is the anion of a diarylformamidine isomer and Ar = p-anisyl or m-anisyl) and the other one being essentially identical but devoid of axial ligands and having the formula [Ru2(DArF)4]BF4, show that the axial ligand has a significant effect on the electronic structure of the diruthenium unit. Variable temperature crystallographic and magnetic data as well as density functional theory calculations unequivocally demonstrate the occurrence of π interactions between the p orbitals of the chlorine ligand and the π* orbitals in the Ru2(5+) units. The magnetic and structural data are consistent with the existence of combined ligand σ/metal σ and ligand pπ/metal-dπ interactions.

A strong metal-to-metal interaction in an edge-sharing bioctahedral compound that leads to a very short tungsten-tungsten double bond.

An ionic edge-sharing bioctahedral (ESBO) species has been prepared having a tetramethylated bicyclic guanidinate with two fused six-membered rings characterized by a fairly flat N-C(N)-N skeleton and abbreviated as TMhpp. The anion has two W(IV) atoms bridged by two oxo groups; the metal atoms are also spanned by two bridging guanidinate ligands, and each has two monodentate chlorine atoms. The complex formulated as (H2TMhpp)2[W(μ-O)(μ-TMhpp)Cl2]2 has the shortest W-W distance (2.

Solubilizing the most easily ionized molecules and generating powerful reducing agents.

Two very soluble compounds having W2(bicyclic guanidinate)4 paddlewheel structures show record low ionization energies (onsets at 3.4 to 3.5 eV) and very negative oxidation potentials in THF (-1.

Direct evidence from electron paramagnetic resonance for additional configurations in uncommon paddlewheel Re2(7+) units surrounded by an unsymmetrical bicyclic guanidinate.

Three rare compounds have been synthesized and structurally characterized; these species have paddlewheel structures and Re(2)(7+) cores surrounded by four bicyclic guanidinates and two axial ligands along the Re-Re axis. Each possesses a formal bond order of 3.5 and a σ(2)π(4)δ(1) electronic configuration that entails the presence of one unpaired electron for each compound.

An uncommon highly oxidized multiple bonded Re2(8+) species.

A long-sought metal-metal bonded species with an M(2)(8+) core has been structurally characterized. The diamagnetic compound {[Re(2)(hpp)(3)(OH)(O(3)SCF(3))](2)(μ-O)(2)}(O(3)SCF(3))(2), 2, has two σ(2)π(4) electron-poor triple-bonded Re(2)(8+) units embraced by three bicyclic guanidinate ligands (hpp) and axial OH and triflate groups; the two dimetal units are held together by bridging oxo-groups.

Synthesis and structure of a dinuclear gold(II) complex with terminal fluoride ligands.

The potential for reductive elimination of fluorine from dinuclear gold(II) for catalysis has prompted our efforts to synthesize a dinuclear gold(II) fluoride complex. This has been achieved with bis(2,6-dimethylphenyl)formamidinate bridging ligands. In order to obtain this product, it was necessary first to synthesize the corresponding dinuclear gold(II) nitrate, which reacts readily with KF in a metathesis reaction.

Tuning the electrochemistry of Re2(6+) species with divergent bicyclic guanidinate ligands and by modification of axial π interactions.

Four Re(2)(6+) paddlewheel compounds with equatorial bicyclic guanidinate ligands and two monodentate anions in axial positions show a large change in the metal-metal distance that depends on the bite angle of the ligands and whether there are pi interactions between the dimetal unit and the axial ligands. These processes are accompanied by significant changes in the redox behavior. The two pairs of compounds that have been synthesized are Re(2)(tbn)(4)Cl(2), 1, and Re(2)(tbn)(4)(SO(3)CF(3))(2), 2, as well as Re(2)(tbo)(4)Cl(2), 3, and Re(2)(tbo)(4)(SO(3)CF(3))(2), 4, where tbn is the anion of a bicyclic guanidinate with six- and five-membered rings (1,5,7-triazabicyclo[4.

Halide and nitrite recognizing hexanuclear metallacycle copper(II) pyrazolates.

Halide-centered hexanuclear, anionic copper(II) pyrazolate complexes [trans-Cu(6)((3,5-CF(3))(2)pz)(6)(OH)(6)X](-), X = Cl, Br, I are isolated in a good yield from the redox reaction of the trinuclear copper(I) pyrazolate complex [μ-Cu(3)((3,5-CF(3))(2)pz)(3)] with a halide source such as PPh(3)AuCl or [Bu(4)N]X, X = Cl, Br, or I, in air. X-ray structures of the anion-centered hexanuclear complexes show that the six copper atoms are bridged by bis(3,5-trifluoromethyl)pyrazolate and hydroxyl ligands above and below the six copper atom plane. The anions are located at the center of the cavity and weakly bound to the six copper atoms in a μ(6)-arrangement, Cu-X = ~3.

Large changes in electronic structures of Ru2(6+) species caused by the variations of the bite angle of guanidinate ligands: tuning magnetic behavior.

Syntheses and characterization of two Ru(2)(6+) paddlewheel compounds having very different magnetic behavior are reported. The compounds Ru(2)(tbn)(4)Cl(2), 1, and Ru(2)(tbo)(4)Cl(2), 2 (where tbn = the anion of 1,5,7-triazabicyclo[4.3.

A short, unsupported CuI...CuI interaction, 2.65 A, in a dinuclear guanidine chloride complex.

The reaction of CuCl with the neutral guanidine Hhpp ligand (1,3,4,6,7,8-hexahydropyrimido[1,2-a]pyrimidine) yields two crystalline polymorphs of the neutral dimer, bis(1,3,4,6,7,8-hexahydropyrimido[1,2-a]pyrimidine) dichloro-di-copper(I) with the shortest distance known for a bridging unsupported copper(I)-copper(I) interaction.

Proof by EPR spectroscopy that the unpaired electron in an Os(2)(7+) species is in a delta* metal-based molecular orbital.

Variable temperature structural and EPR studies are reported on the paddlewheel compound [Os(2)(hpp)(4)Cl(2)]PF(6), 1, (hpp = the anion of the bicyclic guanidine 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine) that contains a rare M(2)(7+) species, with the goal of determining whether the unpaired electron resides in a metal- or ligand-based molecular orbital. Crystallographic studies show that the Os-Os distance in 1 remains essentially unchanged from 213 to 30 K, which is consistent with no changes in electronic structure in this range of temperature. It is noteworthy that the metal-metal distance in 1 is about 0.

A monomeric gold(I) carbanion complex with an uncoordinated thioether: [2-(methylsulfanyl)phenyl](triphenylphosphine)gold(I).

The title compound, [Au(C7H7S)(C18H15P)], is conformationally chiral and crystallizes from benzene-hexane as individually enantiopure crystals. This mononuclear compound has the Au(I) atom linearly bound to a triphenylphosphine P atom and to a phenyl C atom of a 2-(methylsulfanyl)phenyl group. The angle at the Au(I) atom is 175.

The neutral cluster amminehexa-mu(2)-chlorido-mu(4)-oxido-tris(1,4,6-triazabicyclo[3.3.0]oct-4-ene)tetracopper(II).

The title compound, [Cu(4)Cl(6)O(C(5)H(9)N(3))(3)(NH(3))], is a neutral conformationally chiral cluster which crystallizes under the conditions described in this paper as a racemic conglomerate. It contains four Cu(II) atoms in a tetrahedral coordination with a central O atom lying on a crystallographic threefold axis. Six chloride anions bridge the four Cu(II) atoms.

Further study of the reaction of Fe2+ with CN-: synthesis and characterization of cis and trans [FeII,III(CN)4L2]n- complexes.

The reaction of Fe2+ with CN-, which was first performed in 1704, has been used to synthesize a new series of basic [FeII,III(CN)4L2]n- complexes, where L is a monodentate ligand. trans-Na2[FeII(CN)4(DMSO)2] and cis-[NEt4]2[FeII(CN)4(pyridine)2] are synthesized by the direct reaction of FeCl2 with 4 equiv of CN- in DMSO or pyridine. Air oxidation of the latter compound gives cis-[NEt4][FeIII(CN)4(pyridine)2].