Two Novel Acentric Borate Fluorides: M₃B₆O₁₁F₂ (M = Sr, Ba)

Two novel, noncentrosymmetric borate fluorides, Sr₃B₆O₁₁F₂ and Ba₃B₆O₁₁F₂, have been synthesized hydrothermally and their structures determined. The compounds are isostructural, crystallizing in space group <i>P</i>2₁, having lattice parameters of <i>a</i> = 6.4093 (13) Å, <i>b</i> = 8.2898 (17) Å, <i>c</i> = 9.3656 (19) Å, and β = 101.51 (3)° for Sr₃B₆O₁₁F₂ and <i>a</i> = 6.5572 (13) Å, <i>b</i> = 8.5107 (17) Å, <i>c</i> = 9.6726 (19) Å, and β = 101.21 (3)° for Ba₃B₆O₁₁F₂. The structure consists of a complex triple-ring borate framework having aligned triangular [BO₃] groups that impart polarity. Fluorine atoms are bound only to the alkaline-earth metals and are not part of the borate framework, resulting in a vastly different structure from those of the hydrated borates Sr₃B₆O₁₁(OH)₂ and Ba₃B₆O₁₁(OH)₂ with similar formulas. The title compounds are transparent to nearly 200 nm, making them potentially useful for deep-ultraviolet nonlinear-optical applications

Two Novel Acentric Borate Fluorides: M₃B₆O₁₁F₂ (M = Sr, Ba)

Two novel, noncentrosymmetric borate fluorides, Sr₃B₆O₁₁F₂ and Ba₃B₆O₁₁F₂, have been synthesized hydrothermally and their structures determined. The compounds are isostructural, crystallizing in space group <i>P</i>2₁, having lattice parameters of <i>a</i> = 6.4093 (13) Å, <i>b</i> = 8.2898 (17) Å, <i>c</i> = 9.3656 (19) Å, and β = 101.51 (3)° for Sr₃B₆O₁₁F₂ and <i>a</i> = 6.5572 (13) Å, <i>b</i> = 8.5107 (17) Å, <i>c</i> = 9.6726 (19) Å, and β = 101.21 (3)° for Ba₃B₆O₁₁F₂. The structure consists of a complex triple-ring borate framework having aligned triangular [BO₃] groups that impart polarity. Fluorine atoms are bound only to the alkaline-earth metals and are not part of the borate framework, resulting in a vastly different structure from those of the hydrated borates Sr₃B₆O₁₁(OH)₂ and Ba₃B₆O₁₁(OH)₂ with similar formulas. The title compounds are transparent to nearly 200 nm, making them potentially useful for deep-ultraviolet nonlinear-optical applications

Two Novel Acentric Borate Fluorides: M₃B₆O₁₁F₂ (M = Sr, Ba)

Two novel, noncentrosymmetric borate fluorides, Sr₃B₆O₁₁F₂ and Ba₃B₆O₁₁F₂, have been synthesized hydrothermally and their structures determined. The compounds are isostructural, crystallizing in space group <i>P</i>2₁, having lattice parameters of <i>a</i> = 6.4093 (13) Å, <i>b</i> = 8.2898 (17) Å, <i>c</i> = 9.3656 (19) Å, and β = 101.51 (3)° for Sr₃B₆O₁₁F₂ and <i>a</i> = 6.5572 (13) Å, <i>b</i> = 8.5107 (17) Å, <i>c</i> = 9.6726 (19) Å, and β = 101.21 (3)° for Ba₃B₆O₁₁F₂. The structure consists of a complex triple-ring borate framework having aligned triangular [BO₃] groups that impart polarity. Fluorine atoms are bound only to the alkaline-earth metals and are not part of the borate framework, resulting in a vastly different structure from those of the hydrated borates Sr₃B₆O₁₁(OH)₂ and Ba₃B₆O₁₁(OH)₂ with similar formulas. The title compounds are transparent to nearly 200 nm, making them potentially useful for deep-ultraviolet nonlinear-optical applications

Two Novel Acentric Borate Fluorides: M₃B₆O₁₁F₂ (M = Sr, Ba)

Two novel, noncentrosymmetric borate fluorides, Sr₃B₆O₁₁F₂ and Ba₃B₆O₁₁F₂, have been synthesized hydrothermally and their structures determined. The compounds are isostructural, crystallizing in space group <i>P</i>2₁, having lattice parameters of <i>a</i> = 6.4093 (13) Å, <i>b</i> = 8.2898 (17) Å, <i>c</i> = 9.3656 (19) Å, and β = 101.51 (3)° for Sr₃B₆O₁₁F₂ and <i>a</i> = 6.5572 (13) Å, <i>b</i> = 8.5107 (17) Å, <i>c</i> = 9.6726 (19) Å, and β = 101.21 (3)° for Ba₃B₆O₁₁F₂. The structure consists of a complex triple-ring borate framework having aligned triangular [BO₃] groups that impart polarity. Fluorine atoms are bound only to the alkaline-earth metals and are not part of the borate framework, resulting in a vastly different structure from those of the hydrated borates Sr₃B₆O₁₁(OH)₂ and Ba₃B₆O₁₁(OH)₂ with similar formulas. The title compounds are transparent to nearly 200 nm, making them potentially useful for deep-ultraviolet nonlinear-optical applications

Two Novel Acentric Borate Fluorides: M₃B₆O₁₁F₂ (M = Sr, Ba)

Two novel, noncentrosymmetric borate fluorides, Sr₃B₆O₁₁F₂ and Ba₃B₆O₁₁F₂, have been synthesized hydrothermally and their structures determined. The compounds are isostructural, crystallizing in space group <i>P</i>2₁, having lattice parameters of <i>a</i> = 6.4093 (13) Å, <i>b</i> = 8.2898 (17) Å, <i>c</i> = 9.3656 (19) Å, and β = 101.51 (3)° for Sr₃B₆O₁₁F₂ and <i>a</i> = 6.5572 (13) Å, <i>b</i> = 8.5107 (17) Å, <i>c</i> = 9.6726 (19) Å, and β = 101.21 (3)° for Ba₃B₆O₁₁F₂. The structure consists of a complex triple-ring borate framework having aligned triangular [BO₃] groups that impart polarity. Fluorine atoms are bound only to the alkaline-earth metals and are not part of the borate framework, resulting in a vastly different structure from those of the hydrated borates Sr₃B₆O₁₁(OH)₂ and Ba₃B₆O₁₁(OH)₂ with similar formulas. The title compounds are transparent to nearly 200 nm, making them potentially useful for deep-ultraviolet nonlinear-optical applications

Synthesis and Spectroscopy of New Plutonium(III) and -(IV) Molybdates: Comparisons of Electronic Characteristics

Synthesis of a plutonium­(III) molybdate bromide, PuMoO₄Br­(H₂O), has been accomplished using hydrothermal techniques in an inert-atmosphere glovebox. The compound is green in color, which is in stark contrast to the typical blue color of plutonium­(III) complexes. The unusual color arises from the broad charge transfer (CT) spanning from approximately 300 to 500 nm in the UV–vis–near-IR spectra. Repeating the synthesis with an increase in the reaction temperature results in the formation of a plutonium­(IV) molybdate, Pu₃Mo₆O₂₄(H₂O)₂, which also has a broad CT band and red-shifted f–f transitions. Performing an analogous reaction with neodymium produced a completely different product, [Nd­(H₂O)₃]­[NdMo₁₂O₄₂]·2H₂O, which is built of Silverton-type polyoxometallate clusters

Synthesis and Spectroscopy of New Plutonium(III) and -(IV) Molybdates: Comparisons of Electronic Characteristics

Synthesis of a plutonium­(III) molybdate bromide, PuMoO₄Br­(H₂O), has been accomplished using hydrothermal techniques in an inert-atmosphere glovebox. The compound is green in color, which is in stark contrast to the typical blue color of plutonium­(III) complexes. The unusual color arises from the broad charge transfer (CT) spanning from approximately 300 to 500 nm in the UV–vis–near-IR spectra. Repeating the synthesis with an increase in the reaction temperature results in the formation of a plutonium­(IV) molybdate, Pu₃Mo₆O₂₄(H₂O)₂, which also has a broad CT band and red-shifted f–f transitions. Performing an analogous reaction with neodymium produced a completely different product, [Nd­(H₂O)₃]­[NdMo₁₂O₄₂]·2H₂O, which is built of Silverton-type polyoxometallate clusters

Covalency-Driven Dimerization of Plutonium(IV) in a Hydroxamate Complex

The reaction of formohydroxamic acid [NH­(OH)­CHO, FHA] with Pu^III should result in stabilization of the trivalent oxidation state. However, slow oxidation to Pu^IV occurs, which leads to formation of the dimeric plutonium­(IV) formohydroxamate complex Pu₂(FHA)₈. In addition to being reductants, hydroxamates are also strong π-donor ligands. Here we show that formation of the Pu₂(FHA)₈ dimer occurs via covalency between the 5f orbitals on plutonium and the π* orbitals of FHA^– anions, which gives rise to a broad and intense ligand-to-metal charge-transfer feature. Time-dependent density functional theory calculations corroborate this assignment

Covalency-Driven Dimerization of Plutonium(IV) in a Hydroxamate Complex

The reaction of formohydroxamic acid [NH­(OH)­CHO, FHA] with Pu^III should result in stabilization of the trivalent oxidation state. However, slow oxidation to Pu^IV occurs, which leads to formation of the dimeric plutonium­(IV) formohydroxamate complex Pu₂(FHA)₈. In addition to being reductants, hydroxamates are also strong π-donor ligands. Here we show that formation of the Pu₂(FHA)₈ dimer occurs via covalency between the 5f orbitals on plutonium and the π* orbitals of FHA^– anions, which gives rise to a broad and intense ligand-to-metal charge-transfer feature. Time-dependent density functional theory calculations corroborate this assignment

Spontaneous Partitioning of Californium from Curium: Curious Cases from the Crystallization of Curium Coordination Complexes

The reaction of ²⁴⁸CmCl₃ with excess 2,6-pyridinedicarboxylic acid (DPA) under mild solvothermal conditions results in crystallization of the tris-chelate complex Cm­(HDPA)₃·H₂O. Approximately half of the curium remains in solution at the end of this process, and evaporation of the mother liquor results in crystallization of the bis-chelate complex [Cm­(HDPA)­(H₂DPA)­(H₂O)₂Cl]­Cl·2H₂O. ²⁴⁸Cm is the daughter of the α decay of ²⁵²Cf and is extracted in high purity from this parent. However, trace amounts of ^249,250,251Cf are still present in all samples of ²⁴⁸Cm. During the crystallization of Cm­(HDPA)₃·H₂O and [Cm­(HDPA)­(H₂DPA)­(H₂O)₂Cl]­Cl·2H₂O, californium­(III) spontaneously separates itself from the curium complexes and is found doped within crystals of DPA in the form of Cf­(HDPA)₃. These results add to the growing body of evidence that the chemistry of californium is fundamentally different from that of earlier actinides