Penerapan Model Pembelajaran Atraktif Berbasis Multiple Intelligences Tentang Pemantulan Cahaya pada Cermin

Penelitian ini bertujuan untuk mengetahui efektivitas penerapan model pembelajaran atraktif berbasis multiple intelligences dalam meremediasi miskonsepsi siswa tentang pemantulan cahaya pada cermin. Pada penelitian ini digunakan bentuk pre-eksperimental design dengan rancangan one group pretest-post test design. Alat pengumpulan data berupa tes pilihan ganda dengan reasoning. Hasil validitas sebesar 4,08 dan reliabilitas 0,537. Siswa dibagi menjadi lima kelompok kecerdasan, yaitu kelompok linguistic intelligence, mathematical-logical intelligence, visual-spatial intelligence, bodily-khinestetic intelligence, dan musical intelligence. Siswa membahas konsep fisika sesuai kelompok kecerdasannya dalam bentuk pembuatan pantun-puisi, teka-teki silang, menggambar kreatif, drama, dan mengarang lirik lagu. Efektivitas penerapan model pembelajaran multiple intelligences menggunakan persamaan effect size. Ditemukan bahwa skor effect size masing-masing kelompok berkategori tinggi sebesar 5,76; 3,76; 4,60; 1,70; dan 1,34. Penerapan model pembelajaran atraktif berbasis multiple intelligences efektif dalam meremediasi miskonsepsi siswa. Penelitian ini diharapkan dapat digunakan pada materi fisika dan sekolah lainnya

Use of a Bidentate Ligand Featuring an <i>N</i>‑Heterocyclic Phosphenium Cation (NHP⁺) to Systematically Explore the Bonding of NHP⁺ Ligands with Nickel

A novel bidentate ligand featuring an <i>N</i>-heterocyclic phosphenium cation (NHP⁺) linked to a phosphine side arm is used to explore the coordination chemistry of NHP⁺ ligands with nickel. Direct P–Cl bond cleavage from a chlorophosphine precursor [PP]-Cl (<b>1</b>) by Ni­(COD)₂ affords the asymmetric bimetallic complex [Cl₂Ni­(μ-PP)₂Ni] (<b>2</b>) via a nonoxidative process. Abstraction of the halide with either NaBPh₄ or K­[B­(C₆F₅)₄] prior to metal coordination to form the free phosphenium ligand [PP]⁺ <i>in situ</i>, followed by coordination to Ni­(COD)₂, afforded the halide-free Ni⁰ complexes [(PP)­Ni­(COD)] [B­(C₆F₅)₄] (<b>4</b>) and [(PP)­Ni­(COD)]­[BPh₄] (<b>5</b>). Chloride abstraction from <b>1</b> is problematic in the presence of a PF₆^– counterion, however, as evident by the formation of [(PP)­Ni­(PP-F)]­[PF₆] (<b>3</b>). The COD ligand in <b>5</b> can be readily displaced with PMe₃ or PPh₃ to afford [(PP)­NiL₂]­[BPh₄] (L = PMe₃ (<b>6</b>), PPh₃ (<b>7</b>)). Complexes <b>2</b>–<b>7</b> feature planar geometries about the NHP⁺ phosphorus atom and unusually short Ni–P distances, indicative of multiple bonding resulting from both P → Ni σ donation and Ni → P π backbonding. This bonding description is supported by theoretical studies using natural bond orbital analysis

Noninnocent Behavior of Bidentate Amidophosphido [NP]^2– Ligands upon Coordination to Copper

The synthesis and preliminary coordination chemistry of two new redox-active bidentate ligands containing amido and phosphido donors are described. Treatment of the [^RNP]^2– (R = Ph, 2,4,6-trimethylphenyl) ligands with CuCl₂ and PMe₃ results in a dimeric copper­(I) P–P coupled product via ligand oxidation. The intermediate of this reaction is proposed to involve a ligand radical generated via oxidation of the [^RNP]^2– ligand by copper­(II), and the existence of such an intermediate is probed using computational methods. Significant radical character on the phosphorus atoms of the alleged [^RNP]^•–/copper­(I) intermediate leads to P–P radical coupling

Cobalt N‑Heterocyclic Phosphenium Complexes Stabilized by a Chelating Framework: Synthesis and Redox Properties

Two cobalt complexes containing coordinated N-heterocyclic phosphenium (NHP⁺) ligands are synthesized using a bidentate NHP⁺/phosphine chelating ligand, <b>[PP]</b>^<b>+</b>. Treatment of Na­[Co­(CO)₄] with the chlorophosphine precursor [PP]Cl (<b>1</b>) affords [PP]­Co­(CO)₂ (<b>2</b>), which features a planar geometry at the NHP⁺ phosphorus center and a short Co–P distance [1.9922(4) Å] indicative of a CoP double bond. The more electron-rich complex [PP]­Co­(PMe₃)₂ (<b>3</b>), which is synthesized in a one-pot reduction procedure with <b>1</b>, CoCl₂, PMe₃, and KC₈, has an even shorter Co–P bond [1.9455(6) Å] owing to stronger metal-to-phosphorus back-donation. The redox properties of <b>2</b> and <b>3</b> were explored using cyclic voltammetry, and oxidation of <b>3</b> was achieved to afford [[PP]­Co­(PMe₃)₂]⁺ (<b>4</b>). The electron paramagnetic resonance spectrum of complex <b>4</b> features hyperfine coupling to both ⁵⁹Co and ³¹P, suggesting strong delocalization of the unpaired electron density in this complex. Density functional theory calculations are used to further explore the bonding and redox behavior of complexes <b>2</b>–<b>4</b>, shedding light on the potential for redox noninnocent behavior of NHP⁺ ligands

Synthesis, Structure, and Reactivity of an Anionic Zr–Oxo Relevant to CO₂ Reduction by a Zr/Co Heterobimetallic Complex

Oxidative addition of CO₂ to the reduced Zr/Co complex (THF)­Zr­(MesNP^<i>i</i>Pr₂)₃Co (<b>1</b>) followed by one-electron reduction leads to formation of an unusual terminal Zr–oxo anion [<b>2]­[Na­(THF)</b>_<b>3</b><b>]</b> in low yield. To facilitate further study of this compound, an alternative high-yielding synthetic route has been devised. First, <b>1</b> is treated with CO to form (THF)­Zr­(MesNP^<i>i</i>Pr₂)₃Co­(CO) (<b>3</b>); then, addition of H₂O to <b>3</b> leads to the Zr–hydroxide complex (HO)­Zr­(MesNP^<i>i</i>Pr₂)₃Co­(CO) (<b>4</b>). Deprotonation of <b>4</b> with Li­(N­(SiMe₃)₂) leads to the anionic Zr–oxo species <b>[2]­[Li­(THF)</b>_<b>3</b><b>]</b> or <b>[2]­[Li­(12-c-4)]</b> in the absence or presence of 12-crown-4, respectively. The coordination sphere of the Li⁺ countercation is shown to lead to interesting structural differences between these two species. The anionic oxo fragment in complex <b>[2]­[Li­(12-c-4)]</b> reacts with electrophiles such as MeOTf and Me₃SiOTf to generate (MeO)­Zr­(MesNP^<i>i</i>Pr₂)₃Co­(CO) (<b>5</b>) and (Me₃SiO)­Zr­(MesNP^<i>i</i>Pr₂)₃Co­(CO) (<b>6</b>), respectively, and addition of acetic anhydride generates (AcO)­Zr­(MesNP^<i>i</i>Pr₂)₃Co­(CO) (<b>7</b>). Complex <b>[2]­[Li­(12-c-4)]</b> is also shown to bind CO₂ to form a monoanionic Zr–carbonate, [(12-crown-4)­Li]­[(κ²-CO₃)­Zr­(MesNP^<i>i</i>Pr₂)₃Co­(CO)] (<b>[8]­[Li­(12-c-4)]</b>). A more stable version of this compound <b>[8]­[K­(18-c-6)]</b> is formed when a K⁺ counteranion and 18-crown-6 are used. Binding of CO₂ to <b>[2]­[Li­(12-c-4)]</b> is shown to be reversible using isotopic labeling studies. In an effort to address methods by which these CO₂-derived products could be turned over in a catalytic cycle, it is shown that the Zr–OMe bond in <b>5</b> can be cleaved using H⁺ and the CO ligand can be released from Co under photolytic conditions in the presence of I₂

Interaction and Activation of Carbon–Heteroatom π Bonds with a Zr/Co Heterobimetallic Complex

Single-electron transfer from the Zr^IVCo^–I heterobimetallic complex (THF)­Zr­(MesNP^<i>i</i>Pr₂)₃Co-N₂ (<b>1</b>) to benzophenone was previously shown to result in the isobenzopinacol product [(Ph₂CO)­Zr­(MesNP^<i>i</i>Pr₂)₃Co-N₂]₂ (<b>4</b>) via coupling of two ketyl radicals. Thermolysis of <b>4</b> led to cleavage of the CO bond to generate a Zr/Co μ-oxo species featuring an unusual terminal CoCPh₂ carbene linkage (<b>3</b>). In this work monomeric ketyl radical complexes have been synthesized, and the reactivity of these compounds has been explored. The electronic preference for the formation of a ketyl radical complex or a coordination complex has been investigated computationally. Furthermore, thione substrates were allowed to react with <b>1</b>, generating new complexes that bind the thione to the Co rather than undergoing single-electron transfer (<b>12</b>,<b> 14</b>). The preference of thiones to coordinate to Co can be overridden if the Co is ligated by CO, in which case a thioketyl radical complex forms (<b>13</b>) analogous to <b>4</b>. The reaction between <b>1</b> and imines resulted in N–H bond activation, affording a μ-methyleneamido Co–H complex (<b>16</b>) that can undergo cyclometalation and loss of H₂ (<b>15</b>)

Lewis Acid Catalysis with Cationic Dinuclear Gold(II,II) and Gold(III,III) Phosphorus Ylide Complexes

The dinuclear gold­(II,II) and gold­(III,III) complexes [Au₂(μ-PY)₂(MeCN)₂]­OTf₂ (<b>2-OTf</b>_<b>2</b>) and [Au₂(μ-PY)₂(μ-CH₂)­(MeCN)₂]­OTf₂ (<b>3-OTf</b>_<b>2</b>) (PY = [(CH₂)₂PPh₂]⁻) have been synthesized and evaluated as Lewis acid catalysts for Mukaiyama addition and alkyne hydroamination reactions. <b>2-OTf</b>_<b>2</b> and <b>3-OTf</b>_<b>2</b> provide similar or improved catalytic activity for these reactions compared to the commonly used gold­(I) Lewis acids Ph₃PAuOTf and IPrAuOTf. The versatile Lewis acidity of <b>2-OTf</b>_<b>2</b> was further demonstrated by its superior performance in a cascade reaction involving intramolecular hydroamination followed by intermolecular conjugate addition to generate a 2,3-substituted indole

Stoichiometric CO Bond Oxidative Addition of Benzophenone by a Discrete Radical Intermediate To Form a Cobalt(I) Carbene

Single electron transfer from the Zr^IIICo⁰ heterobimetallic complex (THF)­Zr­(MesNP^<i>i</i>Pr₂)₃Co–N₂ (<b>1</b>) to benzophenone was previously shown to result in the isobenzopinacol product [(Ph₂CO)­Zr­(MesNP^<i>i</i>Pr₂)₃Co–N₂]₂ (<b>2</b>) via coupling of two ketyl radicals. In this work, thermolysis of <b>2</b> in an attempt to favor a monomeric ketyl radical species unexpectedly led to cleavage of the C–O bond to generate a Zr/Co μ-oxo species featuring an unusual terminal CoCPh₂ carbene linkage, (η²-MesNP^<i>i</i>Pr₂)­Zr­(μ-O)­(MesNP^<i>i</i>Pr₂)₂CoCPh₂ (<b>3</b>). This complex was characterized structurally and spectroscopically, and its electronic structure is discussed in the context of density functional theory calculations. Complex <b>3</b> was also shown to be active toward carbene group transfer (cyclopropanation), and silane addition to <b>3</b> leads to PhSiH₂O–Zr­(MesNP^<i>i</i>Pr₂)₃Co–N₂ (<b>5</b>) via a proposed Co–alkyl bond homolysis route

Cobalt N‑Heterocyclic Phosphenium Complexes Stabilized by a Chelating Framework: Synthesis and Redox Properties

Two cobalt complexes containing coordinated N-heterocyclic phosphenium (NHP⁺) ligands are synthesized using a bidentate NHP⁺/phosphine chelating ligand, <b>[PP]</b>^<b>+</b>. Treatment of Na­[Co­(CO)₄] with the chlorophosphine precursor [PP]Cl (<b>1</b>) affords [PP]­Co­(CO)₂ (<b>2</b>), which features a planar geometry at the NHP⁺ phosphorus center and a short Co–P distance [1.9922(4) Å] indicative of a CoP double bond. The more electron-rich complex [PP]­Co­(PMe₃)₂ (<b>3</b>), which is synthesized in a one-pot reduction procedure with <b>1</b>, CoCl₂, PMe₃, and KC₈, has an even shorter Co–P bond [1.9455(6) Å] owing to stronger metal-to-phosphorus back-donation. The redox properties of <b>2</b> and <b>3</b> were explored using cyclic voltammetry, and oxidation of <b>3</b> was achieved to afford [[PP]­Co­(PMe₃)₂]⁺ (<b>4</b>). The electron paramagnetic resonance spectrum of complex <b>4</b> features hyperfine coupling to both ⁵⁹Co and ³¹P, suggesting strong delocalization of the unpaired electron density in this complex. Density functional theory calculations are used to further explore the bonding and redox behavior of complexes <b>2</b>–<b>4</b>, shedding light on the potential for redox noninnocent behavior of NHP⁺ ligands

Stoichiometric CO Bond Oxidative Addition of Benzophenone by a Discrete Radical Intermediate To Form a Cobalt(I) Carbene

Single electron transfer from the Zr^IIICo⁰ heterobimetallic complex (THF)­Zr­(MesNP^<i>i</i>Pr₂)₃Co–N₂ (<b>1</b>) to benzophenone was previously shown to result in the isobenzopinacol product [(Ph₂CO)­Zr­(MesNP^<i>i</i>Pr₂)₃Co–N₂]₂ (<b>2</b>) via coupling of two ketyl radicals. In this work, thermolysis of <b>2</b> in an attempt to favor a monomeric ketyl radical species unexpectedly led to cleavage of the C–O bond to generate a Zr/Co μ-oxo species featuring an unusual terminal CoCPh₂ carbene linkage, (η²-MesNP^<i>i</i>Pr₂)­Zr­(μ-O)­(MesNP^<i>i</i>Pr₂)₂CoCPh₂ (<b>3</b>). This complex was characterized structurally and spectroscopically, and its electronic structure is discussed in the context of density functional theory calculations. Complex <b>3</b> was also shown to be active toward carbene group transfer (cyclopropanation), and silane addition to <b>3</b> leads to PhSiH₂O–Zr­(MesNP^<i>i</i>Pr₂)₃Co–N₂ (<b>5</b>) via a proposed Co–alkyl bond homolysis route