Conrad Goodwin

Los Alamos National Laboratory | LANL · Inorganic, Isotope and Actinide Chemistry Group (IIAC)

σ-Hydrocarbyl complexes of the form [M(η5-PC4Me4)2(μ-η1:η6-CH2Ph)2K(η6-arene)] (M = La, Ce, Pr, U, Np, Pu; arene = benzene or toluene) were synthesised in one-pot reactions from [MI3(THF)4], or [U(BH4)3(toluene)] (M = U). All complexes were examined by multinuclear (1H, 13C{1H}, 31P{1H}) NMR and UV-vis-NIR spectroscopy, as well as single-crystal X-...

Since the advent of organotransuranium chemistry six decades ago, structurally verified complexes remain restricted to π-bonded carbocycle and σ-bonded hydrocarbyl derivatives. Thus, transuranium-carbon multiple or dative bonds are yet to be reported. Here, utilizing diphosphoniomethanide precursors we report the synthesis and characterization of t...

We report the synthesis of heteroleptic dysprosium complexes of the 1,2,4-tris(trimethylsilyl)cyclopentadienyl ligand (Cp‴={C5H2(SiMe3)3-1,2,4}), and diamagnetic yttrium analogues, by salt metathesis protocols from KCp‴ and molecular lanthanoid halide or borohydride precursors: [{Ln(Cp‴)2(μ-Cl)2K}2]∞ (1-Ln; Ln = Y, Dy), [Ln(Cp‴)2(THF)(Cl)] (2-Ln; L...

Neptunium was the first actinide element to be artificially synthesized, yet, compared with its more famous neighbours uranium and plutonium, is less conspicuously studied. Most neptunium chemistry involves the neptunyl di(oxo)-motif, and transuranic compounds with one metal–ligand multiple bond are rare, being found only in extended-structure oxid...

Direct comparison of homologous molecules provides a foundation from which to elucidate both subtle and patent changes in reactivity patterns, redox processes, and bonding properties across a series of elements. While trivalent molecular U chemistry is richly developed, analogous Np or Pu research has long been hindered by synthetic routes often re...

Californium (Cf) is currently the heaviest element accessible above microgram quantities. Cf isotopes impose severe experimental challenges due to their scarcity and radiological hazards. Consequently, chemical secrets ranging from the accessibility of 5f/6d valence orbitals to engage in bonding, the role of spin–orbit coupling in electronic struct...

The interplay of bond strength and covalency are examined in AnO2Cl2(OPcy3)2 (An = Pu, U) complexes. The synthesis of trans-PuO2Cl2(OPcy3)2, 1-Pu, has been carried out and confirmed by single crystal X-ray diffraction along with UV-vis-NIR, and 31P NMR spectroscopies. Theoretical analysis finds that despite a higher calculated covalency for the Pu-...

There is significant interest in ligands that can stabilize actinide ions in oxidation states that can be exploited to chemically differentiate 5f and 4f elements. Applications range from developing large-scale...

Differential covalency in trivalent actinide versus lanthanide bonding with soft donors can aid separations. In their Research Article (DOI: 10.1002/anie.202017186), Enrique R. Batista, Andrew J. Gaunt, Ping Yang et al. compare electronic structure and bonding with isoradial Am3+ and Nd3+ using hard O‐ and soft Se‐donor ligands. The first structura...

Unterschiedliche Kovalenzen in der Bindung dreiwertiger Actinide und Lanthanide mit weichen Donoren können Stofftrennungen unterstützen. In ihrem Forschungsartikel (DOI: 10.1002/ange.202017186) vergleichen Enrique R. Batista, Andrew J. Gaunt, Ping Yang et al. die Bindung der isoradialen Am3+‐ und Nd3+‐Ionen mit harten O‐ und weichen Se‐Donor‐Ligand...

The discovery of ferrocene nearly 70 years ago marked the genesis of metallocene chemistry. Although the ferrocenium cation was discovered soon afterwards, a derivatized ferrocenium dication was only isolated in 2016 and the monoanion of ferrocene has only been observed in low-temperature electrochemical studies. Here we report the isolation of a d...

Reaction of 3 equiv of NaNR2 (R = SiMe3) with NpCl4(DME)2 in THF afforded the Np(IV) silylamide complex, [Np(NR2)3Cl] (1), in good yield. Reaction of 1 with 1.5 equiv of KC8 in THF, in the presence of 1 equiv of dibenzo-18-crown-6, resulted in formation of [{K(DB-18-C-6)(THF)}3(μ3-Cl)][Np(NR2)3Cl]2 (4), also in good yield. Complex 4 represents the...

Covalency is often considered to be an influential factor in driving An 3+ vs Ln 3+ selectivity invoked by soft donor ligands. This is intensely debated, particularly the extent to which An 3+ /Ln 3+ covalency differences prevail and manifest as the f-block is traversed, particularly the effects of periodic breaks beyond Pu. Herein, two Am complexe...

Two Am complexes, [Am{N(E=PPh2)2}3] (1‐Am, E=Se; 2‐Am, E=O) are compared to isoradial [Nd{N(E=PPh2)2}3] (1‐Nd, 2‐Nd) complexes. Covalent contributions are assessed and compared to U/La and Pu/Ce analogues. Through ab initio calculations grounded in UV‐vis‐NIR spectroscopy and single‐crystal X‐ray structures, we observe differences in f‐orbital invo...

We report two low-spin diphosphametallocenates [K(2.2.2-crypt)][M(PC 4 Me 4 ) 2 ] (M = Cr, Fe) and propose structural features that allow spin-control in 3d metallocenates.

Progress in the synthesis, design, and characterisation of single-molecule magnets (SMMs) has expanded dramatically from curiosity driven beginnings to molecules that retain magnetization above the boiling point of liquid nitrogen. This is in no small part due to the increasingly collaborative nature of this research where synthetic targets are gui...

An approach to obtaining substantial amounts of data from a hazardous starting material that can only be obtained and handled in small quantities is demonstrated by the investigation of a single small-scale reaction of cyclooctatetraene, C8H8, with a solution obtained from the reduction of Cp'3Pu (Cp' = C5H4SiMe3) with potassium graphite. This one...

The introduction of (N2)3-• radicals into multinuclear lanthanide molecular magnets raised hysteresis temperatures by stimulating strong exchange coupling between spin centers. Radical ligands with larger donor atoms could promote more efficient magnetic coupling between lanthanides to provide superior magnetic properties. Here, we show that heavy...

The recent discovery of single-ion magnets with magnetic hysteresis above liquid-nitrogen temperatures placed these compounds among the best candidates to realize high-density storage devices. Starting from a prototypical dysprosocenium molecule, showing hysteresis up to 60 K, we derive here a general recipe to design high-blocking-temperature rare...

The fluid synergy between experimentalists and theoreticians has, for decades, led to a deeper understanding of the processes that govern single‐molecule magnets. This approach has allowed for the establishment of proven design criteria for the control of magnetic properties through molecular architecture and the development of new magnetic measure...

A dinuclear dysprosocenium dication has been synthesised that is bound together by weak interactions between {Dy(Cp*)2}+ fragments and neutral NEt3AlMe3 molecules. The axiality of the Dy3+ crystal fields are perturbed...

A dinuclear dysprosocenium dication has been synthesised that is bound together by weak interactions between {Dy(Cp*)₂}⁺ fragments and neutral NEt₃AlMe₃ molecules. The axiality of the Dy³⁺ crystal fields are perturbed by these equatorial interactions but a relatively large effective barrier to...

Here, we report a first series of in-plane thorium(IV), uranium(IV), and neptunium(IV) expanded porphyrin complexes. These actinide (An) complexes were synthesized using a hexa-aza porphyrin analogue, termed dipyriamethyrin, and the non-aqueous An(IV) precursors: ThCl4(DME)2, UCl4, and NpCl4(DME)2 under conditions of in situ sodium bis(trimethylsil...

Low coordinate metal complexes can exhibit superlative physicochemical properties, but this chemistry is challenging for the lanthanides (Ln) due to their tendency to maximize electrostatic contacts in predominantly ionic bonding regimes. Although a handful of Ln2+ complexes with only two monodentate ligands have been isolated, examples in the most...

Organometallic americium synthetic chemistry has been dormant for decades. Now, E. R. Batista, W. J. Evans, A. J. Gaunt, S. A. Kozimor, P. Yang et al. report the crystallographically characterized complex [Am(C5Me4H)3], featuring the first quantitative measurement of Am−C molecular bonding interactions. In their Communication (DOI: 10.1002/anie.201...

The proposal that paramagnetic transition metal complexes could be used as qubits for quantum information processing (QIP) requires that the molecules retain the spin information for a sufficient length of time to allow computation and error correction. Therefore, understanding how the electron spin-lattice relaxation time (T1) and phase memory tim...

Metallorganische Americium‐Synthesechemie wurde über Jahrzehnte kaum beachtet. Nun berichten E. R. Batista, W. J. Evans, A. J. Gaunt, S. A. Kozimor, P. Yang et al. über den kristallographisch charakterisierten Komplex [Am(C5Me4H)3], inklusive der ersten quantitativen Bestimmung molekularer Am‐C‐Wechselwirkungen. In ihrer Zuschrift (DOI: 10.1002/ang...

Captain Americium: Die erste strukturelle Charakterisierung einer molekularen Am-C-Wechselwirkung wurde mit Standard-Charakterisierungstechniken der synthetischen Chemie, einschließlich ¹H-NMR- und UV/Vis/NIR-Spektroskopie in Lösung, durchgeführt. Theoretische Modelle der elektronischen Struktur sind in ausgezeichneter Übereinstimmung mit den exper...

We report the small‐scale synthesis, isolated yield, single‐crystal X‐ray structure, 1H NMR solution spectroscopy /solid‐state UV/Vis‐nIR spectroscopy, and density functional theory (DFT)/ab initio wave function theory calculations on an Am3+ organometallic complex, [Am(C5Me4H)3] (1). This constitutes the first quantitative data on Am−C bonding in...

We report magnetic hysteresis studies of three Dy(III) single-molecule magnets (SMMs). The three compounds are [Dy(tBuO)Cl(THF)5][BPh4] (1), [K(18-crown-6-ether)(THF)2][Dy(BIPM)2] (2, BIPM = C{PPh2NSiMe3}2), and [Dy(Cpttt)2][B(C6F5)4] (3), chosen as they have large energy barriers to magnetisation reversal of 665, 565, and 1223 cm-1, respectively....

p>Synthesis of bent, formally two-coordinate lanthanide(III) cations. Characterization by multinuclear NMR, EPR, UV/Vis/NIR and ATR-IR spectroscopy, single crystal XRD, magnetic measurements, elemental analysis and ab initio calculations. </p

As the dysprosocenium complex [Dy(Cpttt)2][B(C6F5)4] (Cpttt = C5H2tBu3‐1,2,4, 1‐Dy) exhibits magnetic hysteresis at 60 K, similar lanthanide (Ln) complexes have been targeted in order to provide insights into this remarkable property. We recently reported homologous [Ln(Cpttt)2][B(C6F5)4] (1‐Ln) for all the heavier Ln from Gd‐Lu; herein, we extend...

Using electron spins within molecules for quantum information processing (QIP) was first proposed by Leuenberger and Loss (1), who showed how the Grover algorithm could be mapped onto a Mn12 cage (2). Since then several groups have examined two-level (S = ½) molecular spin systems as possible qubits (3-12). There has also been a report of the imple...

A series of heavy lanthanide metallocenium cations [Ln(Cpttt)2]+ (Ln = Y, Gd, Dy, Ho, Er, Tm, Yb, Lu; Cpttt = C5H2tBu3-1,2,4) were recently prepared by halide abstraction of [Ln(Cpttt)2(Cl)], but...

Alkali metal amides are vital reagents in synthetic chemistry and the bis(silyl)amide {N(SiMe3)2} (N′′) is one of the most widely-utilized examples. Given that N′′ has provided landmark complexes, we have investigated synthetic routes to lithium and sodium bis(silyl)amides with increased steric bulk to analyse the effects of R-group substitution on...

Addition of various oxidants to the near-linear Sm(II) complex [Sm(N††)2] (1), where N†† is the bulky bis(triisopropylsilyl)amide ligand {N(SiiPr3)2}, afforded a family of heteroleptic three-coordinate Sm(III) halide complexes, [Sm(N††)2(X)] (X = F, 2-F; Cl, 2-Cl; Br, 2-Br; I, 2-I). In addition, the trinuclear cluster [{Sm(N††)}3(μ2-I)3(μ3-I)2] (3)...

Herein we investigate salt metathesis reactions of the bulky bis(silyl)amide potassium salts [K{N(SiMe2tBu)2}]n, [K{N(SiMe2tBu)(SiiPr3)}]n, [K{N(SiiPr3)2}]n and [K{N(SiPh3)2}]n (1) with AeI2 (Ae = Mg, Ca, Sr) in efforts to synthesise rare homoleptic 2-coordinate complexes. Recrystallization of 1 from THF provided structural authentication of the so...

The bis(silyl)amide {N(SiMe3)2} (N′′) has supported spectacular actinide (An) chemistry for over 40 years, yet surprisingly there are only a handful of An complexes containing larger bis(silyl)amides, e.g. [U(N**)3] [N** = {N(SiMe2tBu)2}, 1]. Herein we report the structural characterization of the UIII complexes [U(N**)2(μ-I)]2 (2), [U(N†′)2(μ-I)]2...

p>Energy barriers to magnetisation reversal (U_eff) in single-molecule magnets (SMMs) have vastly increased recently, but only for the dysprosocenium SMM [Dy(Cp^ttt)₂][B(C₆F₅)₄] (Cp^ttt = C₅H₂^tBu₃-1,2,4) has this translated into a c...

Since the origin of 60 K magnetic hysteresis in the dysprosocenium complex [Dy(Cpttt)2][B(C6F5)4] (Cpttt = C5H2tBu3-1,2,4, 1-Dy) remains mysterious, we envisaged that analysis of a series of [Ln(Cpttt)2]+ (Ln = lanthanide) cations could shed light on these properties. Herein we report the synthesis and physical characterization of a family of isola...

Lanthanides have been investigated extensively for potential applications in quantum information processing and high-density data storage at the molecular and atomic scale. Experimental achievements include reading and manipulating single nuclear spins, exploiting atomic clock transitions for robust qubits and, most recently, magnetic data storage...

In recent work we have reported the synthesis and physical properties of near-linear Ln(II) (Ln = lanthanide) complexes utilizing the bulky bis(silylamide) {N(Si(i)Pr3)2}. Herein, we synthesize trigonal-planar Ln(II) complexes by employing a smaller bis(silylamide), {N(Si(t)BuMe2)2} (N**), to study the effects of this relatively rare Ln geometry/ox...

Following our report of the first near-linear lanthanide (Ln) complex, [Sm(N(††))2] (1), herein we present the synthesis of [Ln(N(††))2] [N(††) = {N(Si(i)Pr3)2}; Ln = Eu (2), Tm (3), Yb (4)], thus achieving approximate uniaxial geometries for a series of "traditional" Ln(II) ions. Experimental evidence, together with calculations performed on a mod...

The preparation of silylamide Hauser base (R2NMgX; X = halide) and amido-Grignard (R2NMgR) complexes from simple Grignard reagents using [K{N(SiMe2 tBu)2}]n, [K{N(SiMe2 tBu)(Sii Pr3)}]n and [K{N(Sii Pr3)2}]n, and their parent silylamines, was explored. Both salt metathesis and protonolysis routes proved ineffective with allylmagnesium chloride as a...

The lithium silylamides [Li(μ3-NHSiMe2But)]6 (1) and [Li(μ-NHSiPri3)(THF)]2 (2) were reacted with ClSiMe3, ClSiMe2But, or ClSiPri3 to prepare a series of secondary silylamines by salt metathesis reactions. These were deprotonated with KH to afford the group 1 transfer agents [K{μ-N(SiMe2But)(SiMe3)}(C7H8)]2 (3), [{K[μ-N(SiPri3)(SiMe3)]}2]∞ (4), [{K...

We report the first near-linear 4f-block compound and show that this novel structure, if implemented with dysprosium(III), would have unprecedented single molecule magnet (SMM) properties with an energy barrier, Ueff, for reorientation of magnetization of 1800 cm-1.

We report the synthesis and characterization of the uranium(III) triamide complex [UIII(N**)3] [1, N**=N(SiMe2tBu)2−]. Surprisingly, complex 1 exhibits a trigonal planar geometry in the solid state, which is unprecedented for three-coordinate actinide complexes that have exclusively adopted trigonal pyramidal geometries to date. The characterizatio...