243 research outputs found
Unexpected C-F activation during redox transmetallation with silver N,N '-bis(2,6-difluorophenyl)formamidinate
The trivalent lanthanoid formamidinates, [Yb-2(DFForm)(4)F-2(py)(2)]center dot CH3CN (1) (DFForm=N,N'-bis(2,6-difluorophenyl)formamidinate), and [La-6(DFForm)(8)F8O(CH3CN)(2)].6CH(3)CN (2) have been prepared from redox transmetallation (RT) reactions employing lanthanoid metals and silver formamidinate (AgDFForm) in CH3CN. C-F activation was observed in both reactions. The structure of 1 is a fluorine bridged dimer with two seven-coordinate ytterbium metal ions. Surprisingly the lanthanum complex is a trivalent cage with an unexpected central oxygen atom. [La-6(DFForm)(8)F8O(CH3CN)(2)].6CH(3)CN (2) formed a 15 membered ring cage of six La atoms, eight F and one O at the centre. There are three different La3+ ions in 2 with two different coordination numbers. All the La atoms are coordinated by four bridging fluorides and the central oxygen
PromptTTS: Controllable Text-to-Speech with Text Descriptions
Using a text description as prompt to guide the generation of text or images
(e.g., GPT-3 or DALLE-2) has drawn wide attention recently. Beyond text and
image generation, in this work, we explore the possibility of utilizing text
descriptions to guide speech synthesis. Thus, we develop a text-to-speech (TTS)
system (dubbed as PromptTTS) that takes a prompt with both style and content
descriptions as input to synthesize the corresponding speech. Specifically,
PromptTTS consists of a style encoder and a content encoder to extract the
corresponding representations from the prompt, and a speech decoder to
synthesize speech according to the extracted style and content representations.
Compared with previous works in controllable TTS that require users to have
acoustic knowledge to understand style factors such as prosody and pitch,
PromptTTS is more user-friendly since text descriptions are a more natural way
to express speech style (e.g., ''A lady whispers to her friend slowly''). Given
that there is no TTS dataset with prompts, to benchmark the task of PromptTTS,
we construct and release a dataset containing prompts with style and content
information and the corresponding speech. Experiments show that PromptTTS can
generate speech with precise style control and high speech quality. Audio
samples and our dataset are publicly available.Comment: Submitted to ICASSP 202
Reinvestigation of Reactions of HgPh<inf>2</inf> with Eu and Yb Metal and the Synthesis of a Europium(II) Bis(tetraphenylborate) â€
Europium bis(tetraphenylborate) [Eu(thf)7][BPh4]2⋅thf containing a fully solvated [Eu(thf)7]2+ cation, was synthesized by protolysis of “EuPh2” (from Eu and HgPh2) with Et3NHBPh4, and the structure was determined by single-crystal X-ray diffraction. Efforts to characterize the putative “Ph2Ln” (Ln = Eu, Yb) reagents led to the synthesis of a mixed-valence complex, [(thf)3YbII(μ-Ph)3YbIII(Ph)2(thf)]⋅2thf, resulting from the reaction of Yb metal with HgPh2 at a low temperature. This mixed-valence YbII/YbIII compound was studied by 171Yb-NMR spectroscopy and single-crystal X-ray diffraction, and the oxidation states of the Yb atoms were assigned
Syntheses, Structures, and Corrosion Inhibition of Various Alkali Metal Carboxylate Complexes
Complexes of the alkali metals Li-Cs with 3-thiophenecarboxylate (3tpc), 2-methyl-3-furoate (2m3fur), 3-furoate (3fur), 4-hydroxycinnamate (4hocin), and 4-hydroxybenzoate (4hob) ions were prepared via neutralisation reactions, and the structures of [Li2(3tpc)2]n (1Li); [K2(3tpc)2]n (1K); [Rb(3tpc)(H2O)]n (1Rb); [Cs{H(3tpc)2}]n (1Cs); [Li2(2m3fur)2(H2O)3] (2Li); [K2(2m3fur)2(H2O)]n (2K); [Li(3fur)]n(3Li); [K(4hocin](H2O)3]n (4K); [Rb{H(4hocin)2}]n.nH2O (4Rb); [Cs(4hocin)(H2O)]n (4Cs); [Li(4hob)]n (5Li); [K(4hob)(H2O)3]n (5K); [Rb(4hob)(H2O)]n (5Rb); and [Cs(4hob)(H2O)]n (5Cs) were determined via X-ray crystallography. Bulk products were also characterised via XPD, IR, and TGA measurements. No sodium derivatives could be obtained as crystallographically suitable single crystals. All were obtained as coordination polymers with a wide variety of carboxylate-binding modes, except for dinuclear 2Li. Under conditions that normally gave coordinated carboxylate ions, the ligation of hydrogen dicarboxylate ions was observed in 1Cs and 4Rb, with short H-bonds and short O…O distances associated with the acidic hydrogen. The alkali-metal carboxylates showed corrosion inhibitor properties inferior to those of the corresponding rare-earth carboxylates
Bromobenzene Transforms Lanthanoid Pseudo-Grignard Chemistry
Divalent lanthanoid pseudo-Grignard reagents PhLnBr (Ln=Sm, Eu and Yb) can be easily prepared by the oxidative addition of bromobenzene (PhBr) to lanthanoid metals in tetrahydrofuran (THF). PhLnBr reacts with bulky N,N′-bis(2,6-di-isopropylphenyl)formamidine (DippFormH) to generate LnII complexes, namely [Ln(DippForm)Br(thf)3]2⋅6thf (1; Sm, 2; Eu), and [Yb(DippForm)Br(thf)2]2⋅2thf (3; Yb). Samarium and europium (in 1 and 2) are seven coordinate, whereas ytterbium (in 3) is six coordinate, and all are bromine-bridged dimers. When PhLnBr reacts with 3,5-diphenylpyrazole (Ph2pzH), both divalent (5; [Eu(Ph2pz)2(thf)4]) and trivalent (4 a; [Sm(Ph2pz)3(thf)3]⋅3thf, 4 b; [Sm(Ph2pz)3(dme)2]⋅dme) complexes are obtained. In the monomeric compounds 4(a,b), samarium is nine coordinate but europium is eight coordinate in 5. The use of PhLnBr in this work transforms the outcomes from earlier reactions of PhLnI
Furnishing Sound Event Detection with Language Model Abilities
Recently, the ability of language models (LMs) has attracted increasing
attention in visual cross-modality. In this paper, we further explore the
generation capacity of LMs for sound event detection (SED), beyond the visual
domain. Specifically, we propose an elegant method that aligns audio features
and text features to accomplish sound event classification and temporal
location. The framework consists of an acoustic encoder, a contrastive module
that align the corresponding representations of the text and audio, and a
decoupled language decoder that generates temporal and event sequences from the
audio characteristic. Compared with conventional works that require complicated
processing and barely utilize limited audio features, our model is more concise
and comprehensive since language model directly leverage its semantic
capabilities to generate the sequences. We investigate different decoupling
modules to demonstrate the effectiveness for timestamps capture and event
classification. Evaluation results show that the proposed method achieves
accurate sequences of sound event detection.Comment: 8 pages,2 figures,published to AAA
New Interventions by silicone grease in synthesis
In redox-transmetallation protolysis (RTP) reactions in tetrahydrofuran (thf) between excess scandium or cerium metal, Hg(C6F5)(2) and 3,5-dimethylpyrazole (Me(2)pzH) in silicone greased Schlenk flasks, formation of the 3,5-dimethyl-1-pyrazolyl(dimethyl)siloxide (Me(2)pzSiMe(2)O) ligand was observed. Thus the former reaction gave [Sc-2(Me(2)pz)(4)(Me(2)pzSiMe(2)O)(2)] 1 in good yield, whilst the latter gave a mixture of [Ce4O(Me(2)pz)(9)(Me(2)pzSiMe(2)O)(2)] 2 a, [Ce4O(Me(2)pz)(11)] 2 b, both mixed oxidation state species, and the Ce-IV complex [Ce(Me(2)pz)(4)(Me(2)pzH)] 2 c
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