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High quality epitaxial thin films of the quasi-one dimensional conductor K0.3MoO3 have been successfully grown on SrTiO3(100), SrTiO3(110), and SrTiO3(510) substrates via pulsed laser deposition.

Guest Editors Linda H. Doerrer and Rasika Dias introduce the spotlight collection: “Fluorinated ligands and their effects on physical properties and chemical reactivity”.

The achievement of atomic control over the organic-inorganic interface is key to engineering electronic and spintronic properties of molecular devices. We leverage insights from inorganic chemistry to create hard-soft acid-base (HSAB) theory-derived design principles for incorporation of single molecules onto metal electrodes. A single molecule circuit is assembled via a bond between an organic backbone and an under-coordinated metal atom of the electrode surface, typically Au. Here, we study molecular composition factors affecting the junction assembly of coordination complexes containing transition metals atoms on Au electrodes. We employ hetero- and homobimetallic lantern complexes and systematically change the coordination environment to vary the character of the intramolecular bonds relative to the electrode-molecule interaction. We observe that trends in the robustness and chemical selectivity of single molecule junctions formed with a range of linkers correlate with HSAB principles, which have traditionally been used to guide atomic arrangements in the synthesis of coordination complexes. We find that this similarity between the intermolecular electrode-molecule bonding in a molecular circuit and the intramolecular bonds within a coordination complex has implications for the design of metal-containing complexes compatible with electrical measurements on metal electrodes. Our results here show that HSAB principles determine which intramolecular interactions can be compromised by inter molecule-electrode coordination; in particular on Au electrodes, soft-soft metal-ligand bonding is vulnerable to competition from soft-soft Au-linker bonding in the junction. Neutral donor-acceptor intramolecular bonds can be tuned by the Lewis acidity of the transition metal ion, suggesting future synthetic routes toward incorporation of transition metal atoms into molecular junctions for increased functionality of single molecule devices.

A new template condensation reaction has been discovered in a mixture of Pt(II), thiobenzamide, and base. Four complexes of the general form [Pt(ctaPhR)2], R = CH3 (1a), H (1b), F (1c), Cl (1d), cta = condensed thioamide, have been prepared under similar conditions and thoroughly characterized by 1H NMR and UV-vis-NIR spectroscopy, (spectro)electrochemistry, elemental analysis, and single-crystal X-ray diffraction. The ligand is redox active and can be reduced from the initial monoanion to a dianionic and then trianionic state. Chemical reduction of 1a with [Cp2Co] yielded [Cp2Co]2[Pt(ctaPhCH3)2], [Cp2Co]2[1a], which has been similarly characterized with the addition of EPR spectroscopy and SQUID magnetization. The singly reduced form containing [1a]1-, (nBu4N)[Pt(ctaPhCH3)2], has been generated in situ and characterized by UV-vis and EPR spectroscopies. DFT studies of 1b, [1b]1-, and [1b]2- confirm the location of additional electrons in exclusively ligand-based orbitals. A detailed analysis of this redox-active ligand, with emphasis on the characteristics that favor noninnocent behavior in six-membered chelate rings, is included.

The synthesis and characterization of a series of Sn(II) and Sn(IV) complexes supported by the highly electron-withdrawing dianionic perfluoropinacolate (pinF) ligand are reported herein. Three analogs of [SnIV(pinF)3]2− with NEt3H+ (1), K+ (2), and {K(18C6)}+ (3) counter cations and two analogs of [SnII(pinF)2]2− with K+ (4) and {K(15C5)2}+ (5) counter cations were prepared and characterized by standard analytical methods, single-crystal X-ray diffraction, and 119Sn Mossbauer and NMR spectroscopies. The six-coordinate SnIV(pinF) complexes display 119Sn NMR resonances and 119Sn Mossbauer spectra similar to SnO2 (cassiterite). In contrast, the four-coordinate SnII(pinF) complexes, featuring a stereochemically-active lone pair, possess low 119Sn NMR chemical shifts and relatively high quadrupolar splitting. Furthermore, the Sn(II) complexes are unreactive towards both Lewis bases (pyridine, NEt3) and acids (BX3, Et3NH+). Calculations confirm that the Sn(II) lone pair is localized within the 5s orbital and reveal that the Sn 5px LUMO is energetically inaccessible, which effectively abates reactivity.

High quality epitaxial thin films of the quasi-one dimensional conductor K

A new series of heterobimetallic lantern complexes, [PtM(SAc)4(pySMe)] (M = Mn (1), Fe (2), Co (3), Ni (4), Zn (5)), as well as additions to the previously reported series, [PtM(SAc)4(pyNH2)] (M = Mn (6), Fe (7)), have been synthesized and thoroughly characterized. Notably, compounds 1 and 6 are the first crystallographically characterized, neutral Pt-Mn containing lantern complexes. Compounds 2 and 7 are the first examples of Pt-Fe containing lantern complexes with a pyridine based axial ligand. These newly synthesized complexes have been characterized by single-crystal X-ray diffraction and UV–vis (1–7), 1H and 13C NMR spectroscopies (5), and solution magnetic susceptibility (1–4 and 6–7) and analyzed in comparison to our previously reported lantern families. Compounds 2–4 are isomorphous and contain two crystallographically independent dimers with the same staggered conformations. One dimer has a typical Pt⋯Pt metallophilic interaction ranging from 3.2198(6) to 3.2913(6) A while the other has a much longer contact ranging from 3.3212(6) to 3.4533(6) A. These latter contacts suggest metallophilic interactions that are the longest reported to date in any system. Solid state variable-temperature magnetic susceptibility studies suggest antiferromagnetic coupling between the 3d metal centers in the two lantern complexes of the dimeric forms of 2, 3, and 4.

A Cu(I) fully fluorinated O-donor monodentate alkoxide complex, K[Cu(OC4F9)2], was previously shown to form a trinuclear copper–dioxygen species with a {Cu3(μ3-O)2} core, TOC4F9, upon reactivity with O2 at low temperature. Herein is reported a significantly expanded kinetic and mechanistic study of TOC4F9 formation using stopped-flow spectroscopy. The TOC4F9 complex performs catalytic oxidase conversion of hydroquinone (H2Q) to benzoquinone (Q). TOC4F9 also demonstrated hydroxylation of 2,4-di-tert-butylphenolate (DBP) to catecholate, making TOC4F9 the first trinuclear species to perform tyrosinase (both monooxygenase and oxidase) chemistry. Resonance Raman spectra were also obtained for TOC4F9, to our knowledge, the first such spectra for any T species. The mechanism and substrate reactivity of TOC4F9 are compared to those of its bidentate counterpart, TpinF, formed from K[Cu(pinF)(PR3)]. The monodentate derivative has both faster initial formation and more diverse substrate reactivity.

Investigation of Cu–O2 oxidation reactivity is important in biological and anthropogenic chemistry. Zeolites are one of the most promising Cu/O based oxidation catalysts for development of industrial-scale CH4 to CH3OH conversion. Their oxidation mechanisms are not well understood, however, highlighting the importance of the investigation of molecular Cu(I)–O2 reactivity with O-donor complexes. Herein, we give an overview of the synthesis, structural properties, and O2 reactivity of three different series of O-donor fluorinated Cu(I) alkoxides: K[Cu(OR)2], [(Ph3P)Cu(μ-OR)2Cu(PPh3)], and K[(R3P)Cu(pinF)], in which OR = fluorinated monodentate alkoxide ligands and pinF = perfluoropinacolate. This breadth allowed for the exploration of the influence of the denticity of the ligand, coordination number, the presence of phosphine, and K⋯F/O interactions on their O2 reactivity. K⋯F/O interactions were required to activate O2 in the monodentate-ligand-only family, whereas these connections did not affect O2 activation in the bidentate complexes, potentially due to the presence of phosphine. Both families formed trisanionic, trinuclear cores of the form {Cu3(μ3-O)2}3−. Intramolecular and intermolecular substrate oxidation were also explored and found to be influenced by the fluorinated ligand. Namely, {Cu3(μ3-O)2}3− from K[Cu(OR)2] could perform both monooxygenase reactivity and oxidase catalysis, whereas those from K[(R3P)Cu(pinF)] could only perform oxidase catalysis.

A new air-stable catalyst for the oxidative dehydrogenation of benzylic alcohols under ambient conditions has been developed. The synthesis and characterization of this compound and the related monomeric and dimeric V(IV)- and V(V)-pinF (pinF = perfluoropinacolate) complexes are reported herein. Monomeric V(IV) complex (Me4N)2[V(O)(pinF)2] (1) and dimeric (μ-O)2-bridged V(V) complex (Me4N)2[V2(O)2(μ-O)2(pinF)2] (3a) are prepared in water under ambient conditions. Monomeric V(V) complex (Me4N)[V(O)(pinF)2] (2) may be generated via chemical oxidation of 1 under an inert atmosphere, but dimerizes to 3a upon exposure to air. Complexes 1 and 2 display a perfectly reversible VIV/V couple at 20 mV (vs Ag/AgNO3), whereas a quasi-reversible VIV/V couple at -865 mV is found for 3a. Stoichiometric reactions of 3a with both fluorenol and TEMPOH result in the formation of (Me4N)2[V2(O)2(μ-OH)2(pinF)2] (4a), which contains two V(IV) centers that display antiferromagnetic coupling. In order to structurally characterize the dinuclear anion of 4a, {K(18C6)}+ countercations were employed, which formed stabilizing K···O interactions between the counterion and each terminal oxo moiety and H-bonding between the oxygen atoms of the crown ether and μ-OH bridges of the dimer, resulting in {K(18C6)}2[V2(O)2(μ-OH)2(pinF)2] (4b). The formal storage of H2 in 4a is reversible and proton-coupled electron transfer (PCET) from crystals of 4a regenerates 3a upon exposure to air over the course of several days. Furthermore, the reaction of 3a (2%) under ambient conditions with excess fluorenol, cinnamyl alcohol, or benzyl alcohol resulted in the selective formation of fluorenone (82% conversion), cinnamaldehyde (40%), or benzaldehyde (7%), respectively, reproducing oxidative alcohol dehydrogenation (OAD) chemistry known for VOx surfaces and demonstrating, in air, the thermodynamically challenging selective oxidation of alcohols to aldehydes/ketones.

The synthesis and characterization of a series of Sn(ii) and Sn(iv) complexes supported by the highly electron-withdrawing dianionic perfluoropinacolate (pin

The new PtVO(SOCR)4 lantern complexes, 1 (R = CH3) and 2 (R = Ph) behave as neutral O-donor ligands to Ln(OR)3 with Ln = Ce, Nd. Four heterotrimetallic complexes with linear {LnOVPt} units were prepared: [Ln(ODtbp)3{PtVO(SOCR)4}] (Ln = Ce, 3Ce (R = CH3), 4Ce (R = Ph); Nd, 3Nd (R = CH3), 4Nd (R = Ph); ODtbp = 2,6-ditertbutylphenolate). Magnetic characterization confirms slow magnetic relaxation behaviour and suggests antiferromagnetic coupling across {Ln-O[double bond, length as m-dash]V} in all four complexes, with variations tunable as a function of Ln and R.

Four groups of rare-earth complexes, comprising 11 new compounds, with fluorinated O-donor ligands ([K(THF)6][Ln(OC4F9)4(THF)2] (1-Ln; Ln = Ce, Nd), [K](THF)x[Ln(OC4F9)4(THF)y] (2-Ln; Ln = Eu, Gd, Dy), [K(THF)2][Ln(pinF)2(THF)3] (3-Ln; Ln = Ce, Nd), and [K(THF)2][Ln(pinF)2(THF)2] (4-Ln; Ln = Eu, Gd, Dy, Y) have been synthesized and characterized. Single-crystal X-ray diffraction data were collected for all compounds except 2-Ln. Species 1-Ln, 3-Ln, and 4-Ln are uncommon examples of six-coordinate (Eu, Gd, Dy, and Y) and seven-coordinate (Ce and Nd) LnIII centers in all-O-donor environments. Species 1-Ln, 2-Ln, 3-Ln, and 4-Ln are all luminescent (except where Ln = Gd and Y), with the solid-state emission of 1-Ce being exceptionally blue-shifted for a Ce complex. The emission spectra of the six Nd, Eu, and Dy complexes do not show large differences based on the ligand and are generally consistent with the well-known free-ion spectra. Time-dependent density functional theory results show that 1-Ce and 3-Ce undergo allowed 5f → 4d excitations, consistent with luminescence lifetime measurements in the nanosecond range. Eu-containing 2-Eu and 4-Eu, however, were found to have luminescence lifetimes in the millisecond range, indicating phosphorescence rather than fluorescence. The performance of a pair of multireference models for prediction of the Ln = Nd, Eu, and Dy absorption spectra was assessed. It was found that spectroscopy-oriented configuration interaction as applied to a simplified model in which the free-ion lanthanide was embedded in ligand-centered Lowdin point charges performed as well (Nd) or better (Eu and Dy) than canonical NEVPT2 calculations, when the ligand orbitals were included in the treatment.

A tutorial review of Cu in biology for advanced undergraduates and new graduate students is presented. An overview of the use of Cu by different classes of organisms is given, focusing on the two major functions of Cu in current understanding: electron transfer and substrate oxidation. Structural data from the Protein Data Bank and Enzyme Commission numbers are used as organizing principles. Selected structural and reactivity examples are given throughout, and the newest areas of research are introduced at the end.

Oxidation of distorted square-planar perfluoropinacolate Co compound [CoII(pinF)2]2−, 1, to [CoIII(pinF)2]1−, 2, is reported. Rigidly square-planar 2 has an intermediate-spin, S = 1, ground state and very large zero-field splitting (ZFS) with D = 67.2 cm−1; |E| = 18.0 cm−1, (E/D = 0.27), g⊥ = 2.10, g‖ = 2.25 and χTIP = 1950 × 10−6 cm3 mol−1. This Co(III) species, 2, reacts with ROS to oxidise two (pinF)2− ligands to form tetrahedral [CoII(Hpfa)4]2−, 3.

A pair of thiocarboxylate lantern complexes, [PtNi(SAc)4(L)] (L = pyCN (2), HpipCN (3)) and three new {N,S} chelated mercaptopyridine lantern complexes [PtNi(mpyS)4(L)] (L = H2O (4), MeCN (5), pyCN (6)) have been synthesized and characterized by SCXRD, 1H NMR and UV–vis spectroscopies, as well as elemental analysis and RT solution magnetization. A detailed structural comparison was made of the {O,S} and {N,S} donor systems that demonstrates that the stronger field mercaptopyridine ligand decreases the Pt (donor) – M (acceptor) character within the lantern, reducing the Pt(II) Lewis acidity and therefore preventing the formation of intermolecular interactions in Ni(II) complexes 4–6. An unexpected pentameric species [Pt(PtNi(mpyS)4(Cl))2] (7) was also formed, albeit in very low quantities, that showed the importance of the choice of Ni(II) starting material. Additionally, the development of an improved air- and water-stable synthesis for the formation of the homoleptic, [Pt2(pyS)4], is reported.

Superparamagnetic nanoparticles with a high initial magnetic susceptibility χo are of great interest in a wide variety of chemical, biomedical, electronic, and subsurface energy applications. In order to achieve the theoretically predicted increase in χo with the cube of the magnetic diameter, new synthetic techniques are needed to control the crystal structure, particularly for magnetite nanoparticles larger than 10 nm. Aqueous magnetite dispersions (Fe3O4) with a χo of 3.3 (dimensionless SI units) at 1.9 vol %, over 3- to 5-fold greater than those reported previously, were produced in a one-pot synthesis at 210 °C and ambient pressure via thermal decomposition of Fe(II) acetate in triethylene glycol (TEG). The rapid nucleation and focused growth with an unusually high precursor-to-solvent molar ratio of 1:12 led to primary particles with a volume average diameter of 16 nm and low polydispersity according to TEM. The morphology was a mixture of stoichiometric and substoichiometric magnetite according to ...

CuI complexes of the form K[(R3P)Cu(pinF)], in which (pinF)2− is the bidentate, oxygen-donating ligand perfluoropinacolate, were synthesized and characterized. Low-temperature oxygenation of the K[(R3P)Cu(pinF)(PR3)] species resulted in a trisanionic bis(μ3-oxo) trinuclear copper(II,II,III) core characterized by UV/Vis spectroscopy (λmax [nm] = 330, 535, 630), cryospray-ionization mass spectrometry, and X-band electron paramagnetic resonance spectroscopy (derivative resonance at 3300 G, Δms=2 at 1500 G). The kinetic behavior of the trimeric {Cu3O2} species was quantified by stopped-flow spectroscopy and the associated electronic structures were investigated by DFT calculations. An asymmetric {Cu3O2} species, AsTpinF, which bears a structure similar to multicopper oxidases, forms prior to full formation of the symmetric trinuclear core, SyTpinF. The trimer catalytically oxidizes para-hydroquinone to benzoquinone (a form of oxidase chemistry).

Four new quasi-1D Ni2-lantern chain complexes of the form [Ni2(SOCR)4(L)]∞ (R = Ph, L = DABCO (1); R = Ph, L = pyz (2); R = CH3, L = DABCO (3); R = CH3, L = pyz (4)) were prepared from the reaction of [Ni2(SOCR)4(EtOH)], R = CH3 or Ph, with the N,N'-donor bridging ligands pyrazine (pyz) or 1,4-diazabicyclo[2.2.2]octane (DABCO). Reaction of [Ni2(tba)4(EtOH)], (tba = thiobenzoate) with the mono-N donor ligand quinuclidine (quin) gave the discrete Ni2-lantern complex [Ni2(tba)4(quin)] (5), whereas reaction with pyridine led to fragmentation of the lantern and formation of the known [Ni(tba)2(py)2] (6). Single-crystal X-ray diffraction reveals 2-4 to be 1D chain complexes comprising DABCO or pyz ligands which bridge the Ni2-lantern units. Complex 5 forms dimers through two equivalent NiS interactions. The Ni-Ni distances within the Ni2-lanterns are 2.5316(18)-2.595(2) A for the 1D chain complexes 2-4, and 2.5746(4) A in the dimeric complex 5, respectively. Comparing the solid state magnetism of 5 to precursor [Ni2(tba)4(EtOH)] demonstrates a change in coupling upon change of capping ligand. Meanwhile, chains 1-4 exhibit magnetic properties consistent with an S = 1 system, due to a mixed valent system where the two Ni centers differ in spin state, while 5 possesses two S = 1 Ni(ii) centers. DFT calculations confirm low-spin S = 0 {NiS4} and high-spin S = 1 {NiO4} centers in each lantern. Fits to the magnetic susceptibility data of the chains suggest a weak antiferromagnetic mean field interaction is present that is largely 1-D in nature, though neither pyrazine nor DABCO promote significant magnetic interaction between neighboring Ni2-lanterns.

Exploitation of HSAB preferences allows for high-yield, one-pot syntheses of lanthanide complexes chelated by two Pd or Pt metalloligands, [MII(SAc)4]2− (SAc− = thioacetate, M = Pd, Pt). The resulting complexes with 8 oxygen donors surrounding the lanthanides can be isolated in crystallographically tetragonal environments as either [NEt4]+ (space group: P4/mcc) or [PPh4]+ (space group: P4/n) salts. In the case of M = Pt, the complete series of lanthanide complexes has been structurally characterized as the [NEt4]+ salts (except for Ln = Pm), while the [PPh4]+ salts have been structurally characterized for Ln = Gd–Er, Y. For M = Pd, selected lanthanide complexes have been structurally characterized as both salts. The only significant structural difference between salts of the two counter ions is the resulting twist angle connecting tetragonal prismatic and tetragonal anti-prismatic configurations, with the [PPh4]+ salts approaching ideal D4d symmetry very closely (φ = 44.52–44.61°) while the [NEt4]+ salts exhibit intermediate twist angles in the interval φ = 17.28–27.41°, the twist increasing as the complete 4f series is traversed. Static magnetic properties for the latter half of the lanthanide series are found to agree well in the high temperature limit with the expected Curie behavior. Perpendicular and parallel mode EPR spectroscopy on randomly oriented powder samples and single crystals of the Gd complexes with respectively Pd- and Pt-based metalloligands demonstrate the nature of the platinum metal to strongly affect the spectra. Consistent parametrization of all of the EPR spectra reveals the main difference to stem from a large difference in the magnitude of the leading axial term, B02, this being almost four times larger for the Pt-based complexes as compared to the Pd analogues, indicating a direct Pt(5dz2)–Ln interaction and an arguable coordination number of 10 rather than 8. The parametrization of the EPR spectra also confirms that off-diagonal operators are associated with non-zero parameters for the [NEt4]+ salts, while only contributing minimally for the [PPh4]+ salts in which lanthanide coordination approximates D4d point group symmetry closely.

A Cu(i) fully fluorinated O-donor monodentate alkoxide complex, K[Cu(OC4F9)2], was previously shown to form a trinuclear copper-dioxygen species with a {Cu3(μ3-O)2} core, TOC4F9, upon reactivity with O2 at low temperature. Herein is reported a significantly expanded kinetic and mechanistic study of TOC4F9 formation using stopped-flow spectroscopy. The TOC4F9 complex performs catalytic oxidase conversion of hydroquinone (H2Q) to benzoquinone (Q). TOC4F9 also demonstrated hydroxylation of 2,4-di-tert-butylphenolate (DBP) to catecholate, making TOC4F9 the first trinuclear species to perform tyrosinase (both monooxygenase and oxidase) chemistry. Resonance Raman spectra were also obtained for TOC4F9, to our knowledge, the first such spectra for any T species. The mechanism and substrate reactivity of TOC4F9 are compared to those of its bidentate counterpart, TpinF, formed from K[Cu(pinF)(PR3)]. The monodentate derivative has both faster initial formation and more diverse substrate reactivity.

Investigation of Cu-O2 oxidation reactivity is important in biological and anthropogenic chemistry. Zeolites are one of the most promising Cu/O based oxidation catalysts for development of industrial-scale CH4 to CH3OH conversion. Their oxidation mechanisms are not well understood, however, highlighting the importance of the investigation of molecular Cu(i)-O2 reactivity with O-donor complexes. Herein, we give an overview of the synthesis, structural properties, and O2 reactivity of three different series of O-donor fluorinated Cu(i) alkoxides: K[Cu(OR)2], [(Ph3P)Cu(μ-OR)2Cu(PPh3)], and K[(R3P)Cu(pinF)], in which OR = fluorinated monodentate alkoxide ligands and pinF = perfluoropinacolate. This breadth allowed for the exploration of the influence of the denticity of the ligand, coordination number, the presence of phosphine, and KF/O interactions on their O2 reactivity. KF/O interactions were required to activate O2 in the monodentate-ligand-only family, whereas these connections did not affect O2 activation in the bidentate complexes, potentially due to the presence of phosphine. Both families formed trisanionic, trinuclear cores of the form {Cu3(μ3-O)2}3-. Intramolecular and intermolecular substrate oxidation were also explored and found to be influenced by the fluorinated ligand. Namely, {Cu3(μ3-O)2}3- from K[Cu(OR)2] could perform both monooxygenase reactivity and oxidase catalysis, whereas those from K[(R3P)Cu(pinF)] could only perform oxidase catalysis.

A trio of dimeric copper(I) complexes of the formula [(Ph3P)Cu(μ-X)2Cu(PPh3)] (X = OC6F5, 1, OC4F9, 2, OCPh(CF3)2, 3) were prepared and characterized by X-ray crystallography, elemental analysis, and NMR spectroscopy (1H, 13C, 19F, 31P), as was the monomeric [(cy3P)Cu(OC4F9)] (cy = cyclohexyl, 4). Solution conductivity studies demonstrate that all three new dinuclear compounds, as well as the known [(Ph3P)Cu(μ-OC4H9)2Cu(PPh3)], 2-H, are neutral species in solution and do not rearrange into ion pairs. The fold angle (β) varies among these four dimers and the Cu(I)⋯Cu(I) distance in the structure of 2, 2.8315(5) A, is cuprophilic. The Cu(I)⋯Cu(I) distances for 1, 2-H, and 3 are 3.0533(5), 2.890(2), and 3.0169(6) A respectively. Density functional theory (DFT) calculations were performed on 1, 2, 3, and 2-H, as well as the hypothetical 1-H, and several related models. Five PMe3 models, 1(Me), 1-H(Me), 2(Me), 2-H(Me), and 3(Me) were also studied as well as five monomers [(Me3P)CuX] 1-mon, 1-H(mon), 2-mon, 2-H(mon), and 3-mon to understand the electronic reasons for folding in this group of compounds. A Natural Energy Decomposition Analysis (NEDA) indicates that electrostatic stabilizations are the dominant factor governing the strength of interaction between monomeric fragments in 1(Me)–3(Me). NBO analysis reveals that 1(Me) and 1-H(Me) do not display any cuprophilic interactions. The folding angle observed in 2(Me), 2-H(Me), and 3(Me), which is correlated with an increased delocalization from the oxygen 2pz lone pairs, brings the metal centers into sufficient propinquity to have weak Cu⋯Cu orbital interactions. Weak luminescence behavior at room-temperature is also consistent with these assignments.

The synthesis, structure, and electronic properties of several series of late first-row transition metal complexes stabilized by highly-fluorinated alkoxide and aryloxide (ORF) ligands, including partially fluorinated OAr’ (3,5-OC6H3(CF3)2)− and fully fluorinated OArF (OC6F5)−, perfluoro-tbutoxide (OC4F9)−, and perfluoropinacolate, denoted as pinF, ({OC(CF3)2}2)2− are described herein. Compared to their protio counterparts, the powerful electron-withdrawing nature of these fluorinated ligands makes them considerably less basic and some syntheses may be conveniently carried out in aqueous media when the metal redox chemistry is compliant. Additionally, the decreased propensity of these ligands to form bridging complexes reduces the number of dimeric or polymeric extended structures, leading to monomeric systems whose corresponding protio analogs may not be synthetically achieved. As pseudo-halogens, these ligands have been found to be electronically similar to fluoride (F−), and in several cases, spectroscopic characterization of their corresponding metal complexes has revealed high-spin electronic configurations, justifying their description as medium field ligands. Furthermore, interactions between O/F atoms on the ligand and counter-cations such as K+ and Tl+ play a key structural role, influencing the solubility and solid-state nuclearity or geometry of the complexes.

A series of heteroleptic mixed phosphine/alkoxide 3d complexes was designed to evaluate PPh3 as a protecting group, stabilizing the metal coordination sphere prior to O2 exposure, but oxidatively dissociating in the presence of O2 to allow facile O2 reduction by low coordinate metal centers. Complexes of the form [(Ph3P)2M(OC4F9)2] (M = Fe (1), Co (2), Ni (3), Zn (4)) and [(Ph3P)2M(pinF)] (M = Co (8), Ni (9), Zn (10) were prepared, along with related complexes with non-reactive l -donors, [(DME)Fe(OC4F9)2] (5) and [(Ph3PO)2M(OC4F9)2] (M = Fe (6), Ni (7)). Complexes were characterized by UV–vis and NMR spectroscopies, elemental analysis, and single-crystal X-ray diffraction for 1, 3, 6, 7, 8, 9, and 10. The electronic structure of 3 is particularly notable, with ~D4h geometry at room temperature and ~Td at low temperature, as determined by temperature dependent UV–vis and NMR (1H, 31P) spectroscopies. Complexes (M = Fe, Co, Ni) were screened for O2 reactivity to assess the efficacy of PPh3 as a protecting group. Dimeric [Fe2(μ2-O)(OPPh3)2(OC4F9)4] (13) was isolated after O2 reactivity with 1 and characterized as described above. Related Fe complexes 5 and 6 were each combined with O2 to generate intermediate species capable of both stoichiometric oxidase of hydroquinone to benzoquinone and sub-stoichiometric oxygen atom transfer of thioanisole (PhSMe) to methyl phenyl sulfoxide. Fluorinated alkoxide ligand choice influenced O2 reactivity in CoII complexes, as reactivity was only seen in the less sterically hindering pinF–containing complex 8. In the NiII complexes, on the other hand, the particular fluorinated ligand was not a factor in O2 reduction, as 3 and 9 exhibited similar reactivity. Related dimeric compounds [Co2(pinF)2(THF)4)] (11) and [Zn2(pinF)2(THF)2)] (12) were also isolated and characterized.

The lanthanide elements are prevalent in modern electronics, contrast agents, and phosphors. Precursors for luminescent materials frequently use fluorinated ligands to promote volatility for chemical vapor deposition methods. In molecular complexes, fluorination is also a commonly used technique to reduce energy loss during luminescence, and the oxophilicity of the lanthanide ions makes fluorinated alkoxides an attractive tool for the design of luminescent lanthanide complexes. Herein, the structural and photophysical properties of lanthanide complexes ligated by fluorinated alkoxides have been reviewed. Selected examples of several categories are presented in detail, including carboxylates, chelating and non-chelating ligands, and systems with up to three metal centers. Potential areas for further investigation are highlighted.

Oxidation of distorted square-planar perfluoropinacolate Co compound [CoII(pinF)2]2-, 1, to [CoIII(pinF)2]1-, 2, is reported. Rigidly square-planar 2 has an intermediate-spin, S = 1, ground state and very large zero-field splitting (ZFS) with D = 67.2 cm-1; |E| = 18.0 cm-1, (E/D = 0.27), g⊥ = 2.10, g‖ = 2.25 and χTIP = 1950 × 10-6 cm3 mol-1. This Co(iii) species, 2, reacts with ROS to oxidise two (pinF)2- ligands to form tetrahedral [CoII(Hpfa)4]2-, 3.

ConspectusAs the scale of microelectronic circuit devices approaches the atomic limit, the study of molecular-based wires and magnets has become more prevalent. Compounds with quasi-1D geometries have been investigated for their electronic conductivity and magnetic properties with potential use as nanoscale circuit components and information storage devices. To increase the number of compositionally tailored molecular systems available to study, we have taken a building-block, bottom-up approach to the development of improved electronic structure and magnetic properties of quasi-1D arrays. Over the past decade, a large family of asymmetric complexes that can assemble into extended arrays has resulted.Lantern (or paddle-wheel) complexes with conventional {O, O} donor carboxylates are legion, but by the use of monothiocarboxylate ligands and hard–soft Lewis acid–base principles, dozens of new lantern complexes of the form [PtM(SOCR)4(L)] (M = Mg, Ca, Cr, Mn, Fe, Co, Ni, Zn; R = Ph (tba = thiobenzoate), CH3 ...

Total control over the electronic spin relaxation in molecular nanomagnets is the ultimate goal in the design of new molecules with evermore realizable applications in spin-based devices. For single-ion lanthanide systems, with strong spin-orbit coupling, the potential applications are linked to the energetic structure of the crystal field levels and quantum tunneling within the ground state. Structural engineering of the timescale of these tunneling events via appropriate design of crystal fields represents a fundamental challenge for the synthetic chemist, since tunnel splittings are expected to be suppressed by crystal field environments with sufficiently high-order symmetry. Here, we report the long missing study of the effect of a non-linear (C4) to pseudo-linear (D4d) change in crystal field symmetry in an otherwise chemically unaltered dysprosium complex. From a purely experimental study of crystal field levels and electronic spin dynamics at milliKelvin temperatures, we demonstrate the ensuing threefold reduction of the tunnel splitting., M.A.S., U.B.H., K.L., and J.Be. acknowledge financial support from the Danish Research Councils for Independent Research (12-125226). M.A.S., U.B.H., M.R, and K.L. acknowledge DANSCATT for financial support for the neutron scattering experiments. For the experiments conducted at FRM II, this project has received funding from the European Union’s 7th Framework Programme for research, technological development and demonstration under the NMI3-II Grant number 283883. M.A.S. thanks the Oticon Foundation (16-2669), and the Augustinus Foundation (16-2917) for financial support in relation to a research stay at Institut für Physikalische Chemie, Universität Stuttgart, Germany. M.P. and J.v.S. thank the DFG for funding (SL104/5-1). K.S.P. thanks the Danish Research Council for Independent Research for a DFF-Sapere Aude Research Talent grant (4090-00201). E.B., A.A, and, J.Ba. acknowledge the financial support of Spanish MINECO project MAT2017-83468-R. M.J. acknowledges the Swiss National Science Foundation.

We present a detailed study of the microstructure and electronic structure of β-NaxV2O5 (x ≈ 0.33) polycrystalline films, combining film growth, X-ray spectroscopies, and first-principles calculations. High-quality crystalline and stoichiometric V2O5 and β-Na0.33V2O5 films were grown by a sol–gel process, spin-coating, and rapid thermal annealing. The V2O5 film, which exhibits a rough surface, is preferentially oriented in the (001) direction perpendicular to the surface, whereas the b-axis of β-Na0.33V2O5 is oriented in the substrate plane. The β-Na0.33V2O5 film consists of a nested layered structure composed of single-crystalline rods of a few hundred nanometers in diameter and a few micrometers in length. Photoemission and X-ray absorption measurements of β-Na0.33V2O5 confirm the Na incorporation and the presence of mixed V5+ and V4+ species and weakly occupied V 3d states. At the V L-edge, X-ray absorption and resonant inelastic X-ray measurements suggest a larger crystal field for β-Na0.33V2O5 compar...

Seven new homoleptic complexes of the form A2[M(pin(F))2] have been synthesized with the dodecafluoropinacolate (pin(F))(2-) ligand, namely (Me4N)2[Fe(pin(F))2], 1; (Me4N)2[Co(pin(F))2], 2; ((n)Bu4N)2[Co(pin(F))2], 3; {K(DME)2}2[Ni(pin(F))2], 4; (Me4N)2[Ni(pin(F))2], 5; {K(DME)2}2[Cu(pin(F))2], 7; and (Me4N)2[Cu(pin(F))2], 8. In addition, the previously reported complexes K2[Cu(pin(F))2], 6, and K2[Zn(pin(F))2], 9, are characterized in much greater detail in this work. These nine compounds have been characterized by UV-vis spectroscopy, cyclic voltammetry, elemental analysis, and for paramagnetic compounds, Evans method magnetic susceptibility. Single-crystal X-ray crystallographic data were obtained for all complexes except 5. The crystallographic data show a square-planar geometry about the metal center in all Fe (1), Ni (4), and Cu (6, 7, 8) complexes independent of countercation. The Co species exhibit square-planar (3) or distorted square-planar geometries (2), and the Zn species (9) is tetrahedral. No evidence for solvent binding to any Cu or Zn complex was observed. Solvent binding in Ni can be tuned by the countercation, whereas in Co only strongly donating Lewis solvents bind independent of the countercation. Indirect evidence (diffuse reflectance spectra and conductivity data) suggest that 5 is not a square-planar compound, unlike 4 or the literature K2[Ni(pin(F))2]. Cyclic voltammetry studies reveal reversible redox couples for Ni(III)/Ni(II) in 5 and for Cu(III)/Cu(II) in 8 but quasi-reversible couples for the Fe(III)/Fe(II) couple in 1 and the Co(III)/Co(II) couple in 2. Perfluorination of the pinacolate ligand results in an increase in the central C-C bond length due to steric clashes between CF3 groups, relative to perhydropinacolate complexes. Both types of pinacolate complexes exhibit O-C-C-O torsion angles around 40°. Together, these data demonstrate that perfluorination of the pinacolate ligand makes possible highly unusual and coordinatively unsaturated high-spin metal centers with ready thermodynamic access to rare oxidation states such as Ni(III) and Cu(III).

A trio of Pt-based heterobimetallic lantern complexes of the form [(py)PtM(SAc)4(py)] (M = Co, 1; Ni, 2; Zn, 3) with unusual octahedral coordination of Pt(II) was prepared from a reaction of [PtM(SAc)4] with excess pyridine. These dipyridine lantern complexes could be converted to monopyridine derivatives with gentle heat to give the series [PtM(SAc)4(py)] (M = Co, 4; Ni, 5; Zn, 6). An additional family of the form [PtM(SAc)4(pyNH2)] (M = Co, 7; Ni, 8; Zn, 9) was synthesized from reaction of [PtM(SAc)4(OH2)] or [PtM(SAc)4] with 4-aminopyridine. Dimethylsulfoxide and N,N-dimethylformamide were also determined to react with [PtM(SAc)4] (M = Co, Ni), respectively, to give [PtCo(SAc)4(DMSO)](DMSO), 10, and [PtNi(SAc)4(DMF)](DMF), 11. Structural and magnetic data for these compounds and those for two other previously published families, [PtM(tba)4(OH2)] and [PtM(SAc)4(L)], L = OH2, pyNO2, are used to divide the structures among three distinct categories based on Pt···Pt and Pt···S distances. In general, the weaker donors H2O and pyNO2 seem to favor metallophilicity and antiferromagnetic coupling between 3d metal centers. When Pt···S interactions are favored over Pt···Pt ones, no coupling is observed and the pKa of the pyridine donor correlates with the interlantern S···S distance. UV-vis-NIR electronic and (1)H NMR spectra provide complementary characterization as well.

The monomeric and dimeric Zn(II) aryloxide complexes {K(18C6)}2[Zn(OArF)4], 1a, {K(18C6)}[KZn(OArF)4], 1b, {K(18C6)}2[Zn(OAr′)4], 2a, {K(18C6)}2[Zn2(OArF)6], 3, including a heterobimetallic Zn–Tl complex [Tl2Zn(OArF)4], 4, and the first homoleptic, mononuclear Zn(II) alkoxide complex {K(18C6)}[Zn(OCPhMeF2)3], have been prepared and characterized by 1H, 13C{1H}, 19F NMR spectroscopy as well as single crystal X-ray diffraction, including one alternative crystal structure {K(18C6)}2[Zn(OAr′)4]·toluene, 2b, from different recrystallization conditions. A detailed structural comparison to other Zn aryloxide and alkoxide complexes in the literature is presented which shows the same general pattern of increased Zn–O bond lengths with fluorinated ligands compared to very similar structures in non-fluorinated analogs. Compound 4 also exhibits Tl⋯arene bonding in the solid state.

The paramagnetic trigonal-planar copper complexes {K(18C6)}[CuII(OC(CH3)(CF3)2)3] (2) and K[CuII(OC(C6H5)(CF3)2)3] (3) have been prepared and characterized, including X-ray crystallography, in 61% and 3% yields, respectively. The latter complex does not form preferentially, because CuBr2 and KOC(C6H5)(CF3)2)3 also form the diamagnetic complexes {K(18C6)}[K2{CuI(OC(C6H5)(CF3)2)2}3] (4) and {K(18C6)}[CuIII(OC(C6H4)(CF3)2)2] (5). These species were characterized by X-ray crystallography, UV–vis spectroscopy, 1H, 13C{1H}, and 19F{1H} NMR spectroscopy, and elemental analysis. The unique organocuprate Cu(III) species with {O2C2} coordination was formed by ortho metalation of two phenyl rings, resulting in trans-{O2C2} coordination of Cu(III), and is stable at room temperature in the solid state and in dark solutions of THF.

A series of Pt-based heterobimetallic lantern complexes of the form [PtM(SAc)4(OH2)] (M = Co, 1; Ni, 2; Zn, 3) were prepared using a facile, single-step procedure. These hydrated species were reacted with 3-nitropyridine (3-NO2py) to prepare three additional lantern complexes, [PtM(SAc)4(3-NO2py)] (M = Co, 4; Ni, 5; Zn, 6), or alternatively dried in vacuo to the dehydrated species [PtM(SAc)4] (M = Co, 7; Ni, 8; Zn, 9). The Co- and Ni-containing species exhibit Pt-M bonding in solution and the solid state. In the structurally characterized compounds 1-6, the lantern units form dimers in the solid state via a short Pt···Pt metallophilic interaction. Antiferromagnetic coupling between 3d metal ions in the solid state through noncovalent metallophilic interactions was observed for all the paramagnetic lantern complexes prepared, with J-coupling values of -12.7 cm(-1) (1), -50.8 cm(-1) (2), -6.0 cm(-1) (4), and -12.6 cm(-1) (5). The Zn complexes 3 and 6 also form solid-state dimers, indicating that the formation of short Pt···Pt interactions in these complexes is not predicated on the presence of a paramagnetic 3d metal ion. These contacts and the resultant antiferromagnetic coupling are also not unique to heterobimetallic lantern complexes with axially coordinated H2O or the previously reported thiobenzoate supporting ligand.

Seven E[Cu(OR)2] copper(I) complexes (E = K(+), {K(18C6)}(+) (18C6 = [18]crown-6), or Ph4P(+); R = C4F9, CPhMe(F)2, and CMeMe(F)2) have been prepared and their reactivity with O2 studied. The K[Cu(OR)2] species react with O2 in a copper-concentration-dependent manner such that 2:1 and 3:1 Cu/O2 adducts are observed manometrically at -78 °C. Analogous reactivity with O2 is not observed with the {K(18C6)}(+) or Ph4P(+) derivatives. Solution conductivity data demonstrate that these K[Cu(OR)2] complexes do not behave as 1:1 electrolytes in solution. The K(+) ions induce aggregation of multiple [Cu(OR)2](-) units through K⋅⋅⋅F/O interactions and thereby effect irreversible O2 reduction by multiple Cu centers. Bond valence analyses for the potassium cations confirm the dominance of the fluorine interactions in the coordination spheres of K(+) ions. Intramolecular hydroxylation of ligand aryl and alkyl C-H bonds is observed. Nucleophilic reactivity with CO2 is observed for the oxygenated Cu complexes and a Cu(II) carbonate has been isolated and characterized.

Five structures of two monometallic cobalt aryloxide compounds and two bimetallic cobalt-thallium compounds with bridging fluorinated aryloxide ligands (OC 6 F 5 = OAr F , OC 6 H 3 (CF 3 ) 2 = OAr′) are presented with magnetic susceptibility and spectroscopic characterization data. The monometallic compounds, [Co(OAr F ) 2 (DME)] 2 , 1 , and [Co(OAr′) 2 (DME)] 2 , 2 , are prepared by metathesis reactions between two equivalents of TlOAr and one of CoI 2 . The heterobimetallic compounds [Tl 2 Co(OAr F ) 4 ]·2 toluene, 3a , and [Tl 2 Co(OAr′) 4 ] 2 ·2 toluene, 4 , were prepared with a 4:1 ratio of the thallium aryloxide to CoI 2 . An unsolvated form of [Tl 2 Co(OAr F ) 4 ], 3b , was also structurally characterized. Magnetic susceptibility studies revealed that 3b is a simple, isolated high-spin Co II with Curie–Weiss behavior. Dimeric compounds 1 and 2 are also high-spin Co II but exhibit antiferromagnetic coupling, via superexchange through two μ 2 -OAr F ligands, as supported by DFT calculations. Compound 4 exhibits ferromagnetic behavior which is ascribed to the presence of μ 3 -OAr ligands, instead of μ 2 -OAr groups.

Cu

Pt-based heterobimetallic lantern complexes of the form [PtM(SOCR)4(L)] have been shown previously to form intermolecular metallophilic interactions and engage in antiferromagnetic coupling between lanterns having M atoms with open shell configurations. In order to understand better the influence of the carboxylate bridge and terminal ligand on the electronic structure, as well as the metal-metal interactions within each lantern unit, a series of diamagnetic lantern complexes, [PtMg(SAc)4(OH2)] (1), [PtMg(tba)4(OH2)] (2), [PtCa(tba)4(OH2)] (3), [PtZn(tba)4(OH2)] (4), and a mononuclear control (Ph4P)2[Pt(SAc)4] (5) have been synthesized. Crystallographic data show close Pt-M contacts enforced by the lantern structure in each dinuclear case. 195Pt-NMR spectroscopy of 1-4, (Ph4P)2[Pt(SAc)4] (5), and several previously reported lanterns revealed a strong chemical shift dependence on the identity of the second metal (M), mild influence by the thiocarboxylate ligand (SOCR; R = CH3 (thioacetate, SAc), C6H5 (thiobenzoate, tba)), and modest influence from the terminal ligand (L). Fluorescence spectroscopy has provided evidence for a Pt···Zn metallophilic interaction in [PtZn(SAc)4(OH2)], and computational studies demonstrate significant dative character. In all of 1-4, the short Pt-M distances suggest that metal-only Lewis donor (Pt)-Lewis acceptor (M) interactions could be present. DFT and NBO calculations, however, show that only the Zn examples have appreciable covalent character, whereas the Mg and Ca complexes are much more ionic.

A series of heterobimetallic lantern complexes with the central unit {PtM(SAc)4(NCS)} have been prepared and thoroughly characterized. The {Na(15C5)}[PtM(SAc)4(NCS)] series, 1 (Co), 2 (Ni), 3 (Zn), are discrete compounds in the solid state, whereas the {Na(12C4)2)}[PtM(SAc)4(NCS)] series, 4 (Co), 5 (Ni), 6 (Zn), and 7 (Mn), are ion-separated species. Compound 7 is the first {PtMn} lantern of any bridging ligand (carboxylate, amide, etc.). Monomeric 1-7 have M(2+), necessitating counter cations that have been prepared as {(15C5)Na}(+) and {(12C4)2Na}(+) variants, none of which form extended structures. In contrast, neutral [PtCr(tba)4(NCS)]∞ 8 forms a coordination polymer of {PtCr}(+) units linked by (NCS)(-) in a zigzag chain. All eight compounds have been thoroughly characterized and analyzed in comparison to a previously reported family of compounds. Crystal structures are presented for compounds 1-6 and 8, and solution magnetic susceptibility measurements are presented for compounds 1, 2, 4, 5, and 7. Further structural analysis of dimerized {PtM} units reinforces the empirical observation that greater charge density along the Pt-M vector leads to more Pt···Pt interactions in the solid state. Four structural classes, one new, of {MPt}···{PtM} units are presented. Solid state magnetic characterization of 8 reveals a ferromagnetic interaction in the {PtCr(NCS)} chain between the Cr centers of J/kB = 1.7(4) K.

The ansa-rhenocene compound [Re{(η-C5H4)CMe2(η-C5H4)}Cl] 1 has been prepared by reaction of ReCl5 with [K2(C5H4)CMe2(C5H4)]. X-Ray crystallography shows the molecular structure to be unsymmetrical, with the angle defined by the Re-bridgehead carbon vector and the chlorine atom found to be 170.4°. A density functional study compares the electronic structure of [Re{(η-C5H4)CH2(η-C5H4)}Cl] with [Re{(η-C5H5)2Cl] and shows that for the ansa-bridged species, the chlorine binds less effectively in the central position. The calculated structure of [Re{(η-C5H4)CH2(η-C5H4)}Cl] is also found to be unsymmetrical.

The new compounds [Nb{(eta-C5H4)X(eta-C5H4)}Cl-2] (X = CEt2 1a, C(C5H10) 1b, C2Me4 1c), [Nb{(eta-(C5H3Bu)-Bu-t)C2Me4(eta-(C5H3Bu)-Bu-t)}Cl-2] 1d, [Nb{(eta-C5H4)X(eta-C5H4)}(eta(2)-BH4)] (X = CEt2 2a*, C(C5H10) 2b, C2Me4 2c*, SiMe2 2e*), [Nb((eta-(C5H3Bu)-Bu-t)C2Me4(eta-(C5H3Bu)-Bu-t)}(eta(2)-BH4)] (2d*), [Nb{(eta-C5H4)X(eta-C5H4)}(eta(2)-BD4)] (X = C2Me4 3c, CMe2 4), and [V{(eta-C5H4)C2Me4(eta-C5H4)}(eta(2)-BH4)} (5*) have been prepared. The asterisk indicates the crystal structure has been determined. The hydrogen scrambling processes in the tetrahydroborate complexes 2a-e, 3c, 4, 5, and [Nb{(eta-C5H4)CMe2(eta-C5H4)}(eta(2)-BH4)] have been studied. The free energy barrier Delta G(double dagger) to bridge-terminal hydrogen exchange is considerably reduced when the bridging unit imposes significant structural changes in the metallocene.

Two series of homoleptic phenolate complexes with fluorinated aryloxide ligands A2[M(OAr)4] with M = Co2+ or Cu 2+, OAr- = (OC6F5)- (OArF) or {3,5-OC6H3(CF3) 2}- (OAr′), A+ = K (18-crown-6) +, Tl+, Ph4P+, Et3HN +, or Me4N+ have been synthesized. Two related complexes with nonfluorinated phenoxide ligands have been synthesized and studied in comparison to the fluorinated aryloxides demonstrating the dramatic structural changes effected by modification of OPh to OArF. The compounds {K(18-crown-6)}2[Cu(OArF)4], 1a; {K(18-crown-6)}2[Cu(OAr′)4], 1b; [Tl 2Cu(OArF)4], 2a; [Tl2Cu(OAr′) 4], 2b; (Ph4P)2[Cu(OArF) 4], 3; (nBu4N)2[Cu(OAr F)4], 4; (HEt3N)2[Cu(OAr F)4], 5; {K(18-crown-6)}2[Cu 2(μ2-OC6H5)2(OC 6H5)4], 6; {K(18-crown-6)} 2[Co(OArF)4], 7a; {K(18-crown-6)} 2[Co(OAr′)4], 7b; [Tl2Co(OAr F)4], 8a; [Tl2Co(OAr′)4], 8b; (Me4N)2[Co(OArF)4], 9; [Cp 2Co]2[Co(OAr′)4], 10; and {K(18-crown-6)}2[Co2(μ2-OC6H 5)2(OC6H5)4], 11, have been characterized with UV-vis and multinuclear NMR spectroscopy and solution magnetic moment studies. Cyclic voltammetry was used to study 1a, 1b, 7a, and 7b, X-ray crystallography was used to characterize 1b, 3, 4, 5, 6, 7a, 7b; 10, and 11. The related [MX4]2- compound (Ph 4P)2[Co(OArF)2Cl2], 12, has also been synthesized and characterized spectroscopically, as well as with conductivity and single-crystal X-ray diffraction. Use of fluorinated aryloxides permits synthesis and isolation of the mononuclear, homoleptic phenolate anions in good yield without oligomerized side products. The reaction conditions that result in homoleptic 1a and 7a with OArF upon changing the ligand to OPh result in μ2-OPh bridging phenoxides and the dimeric complexes 6 and 11. The [M(OArF)4]2- and [M(OAr′)4]2- anions in 1a, 1b, 3, 4, 5, 7a, 7b, 9, and 10 demonstrate that stable, isolable homoleptic phenolate anions do not need to be coordinatively or sterically saturated and can be achieved by increasing the electronegativity of the ligand.