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 Topotactic Phase Transformations To Obtain Solutions of the Crystal Structures of Highly Disordered Materials

A straightforward procedure is outlined for prediction of the complete three-dimensional coordinate set for a highly disordered phase. For a mother and daughter phase, where one of the pair has an “unsolvable” structure, one needs only to (a) establish the topotaxy using previously published techniques, (b) obtain the topotactic transformation matrix, φ, between the ordered and highly disordered phase, and (c) apply the transpose of φ^–1 to obtain a trial set of coordinates for refinement using the reflection data set of the highly disordered phase. For the inclusion compound [Fe­(η-C₅H₅)]­·3­(NH₂)₂CS (<b>1</b>), which contains highly disordered ferrocene molecules above 160 K (polymorph <b>1_I</b>), we found a more ordered structure at low temperature. At 135 K (polymorph <b>1_II</b>), two ferrocene moieties are present in the thiourea channel in an approximately 1:1 ratio. One is nearly orthogonal (87.0°) to the channel axis, while the other is tipped 16.2° from that direction. Using steps (a–c) outlined above, a trial structure may be obtained for <b>1_I</b>, and refinement leads to <i>R</i>₁ = 4.25%. The structure of <b>1_1</b>, containing 12-fold disordered ferrocene molecules, is similar to that found at temperatures below the phase transition, with a greater amount of the orthogonal orientation (55:45 vs 51:48), consistent with, but lower than, amounts found using solid-state NMR techniques. The low temperature polymorph is a trill, with an approximately 3:1:1 ratio of twin components. The exact alignment of the mother phase and the three daughters has been established using the methods of topotactic analysis described previously

Formation and Subsequent Reactivity of a N₂‑Stabilized Cobalt–Hydride Complex

The reduced heterobimetallic Co/Zr complex N₂Co­(^<i>i</i>Pr₂PNMes)₃Zr­(THF) (<b>1</b>) has been previously reported to react with the CO bonds of CO₂ and benzophenone to generate Zr/Co μ-oxo complexes OC-Co­(^<i>i</i>Pr₂PNMes)₂(μ-O)­Zr­(^<i>i</i>Pr₂PNMes) (<b>1-CO</b>_<b>2</b>) and Ph₂CCo­(^<i>i</i>Pr₂PNMes)₂(μ-O)­Zr­(^<i>i</i>Pr₂PNMes) (<b>1-Ph</b>_<b>2</b><b>CO</b>), respectively. Herein, we report a similar reaction of <b>1</b> with pyridine-<i>N</i>-oxide to form an analogous complex (pyridine)­Co­(^<i>i</i>Pr₂PNMes)₂(μ-O)­Zr­(^<i>i</i>Pr₂PNMes) (<b>2</b>) with a more labile ligand bound to cobalt. Much like <b>1-CO</b>_<b>2</b> and <b>1-Ph</b>_<b>2</b><b>CO</b>, compound <b>2</b> reacts with Ph₃SiH via formation of a Si–O linkage to form (N₂)­(H)­Co­(^<i>i</i>Pr₂PNMes)₃ZrOSiPh₃ (<b>5</b>). The dinitrogen ligand in <b>5</b> is weakly bound and can be readily removed in vacuo or displaced by other L-type ligands. This allows complex <b>5</b> to undergo insertion reactions with unsaturated substrates, including diphenyldiazomethane, CO₂, benzonitrile, and phenylacetylene to give hydrazonato (Ph₂CNNH)­Co­(^<i>i</i>Pr₂PNMes)_<b>3</b>ZrOSiPh₃ (<b>7</b>), formate (OC­(H)­O)­Co­(^<i>i</i>Pr₂PNMes)₃ZrOSiPh₃ (<b>8</b>), ketimide (PhHCN)­Co­(^<i>i</i>Pr₂PNMes)₃ZrOSiPh₃ (<b>9</b>), and ylide Co­(PhHCCHP^<i>i</i>Pr₂NMes)­(^<i>i</i>Pr₂PNMes)₂ZrOSiPh₃ (<b>10</b>) products, respectively. Compound <b>5</b> was also found to catalyze the isomerization of 1-hexene to internal isomers

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

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

Experimental Establishment of Mother–Daughter Orientation Relationships and Twinning Effects in Phase Transitions: A Great Legacy from Jack Gougoutas and Peggy Etter

A simple procedure, with an available program, may readily be used to establish the three-dimensional relationships between a mother and daughter phase, where mother and daughter are either two different phases of a material <i>or</i> a reactant and product in a solid-state transformation. The only requirements are that (i) the process involves a crystal-to-crystal transformation, and (ii) the experiment must be carried out without changing the alignment of the mother crystal. Application of the method supports the inferred alignment of mother and daughter phases in the published structures of two polymorphs of 4-cyanopyridinium perchlorate monohydrate <b>1</b>. A new low-temperature, monoclinic polymorph of ferrocenium tetrafluoroborate <b>2</b> is produced when the known orthorhombic polymorph is cooled from 173 to 120 K. The major features of the transformation include “conservative twinning” and a modulation of the structure along the crystallographic <i>b</i> direction upon cooling. Redetermination of the structure of the low-temperature polymorph of ferrocenium hexafluorophosphate <b>3</b> reveals that the phase change is accompanied by reproducible four-component twinning, providing a proper explanation for the previously reported, very high <i>R</i>-factor of 12.4%. Included tutorial information on the process will assist the reader in obtaining topotactic relationships, as well as in preparing figures and animations describing phase transitions or reactions

Experimental Establishment of Mother–Daughter Orientation Relationships and Twinning Effects in Phase Transitions: A Great Legacy from Jack Gougoutas and Peggy Etter

A simple procedure, with an available program, may readily be used to establish the three-dimensional relationships between a mother and daughter phase, where mother and daughter are either two different phases of a material <i>or</i> a reactant and product in a solid-state transformation. The only requirements are that (i) the process involves a crystal-to-crystal transformation, and (ii) the experiment must be carried out without changing the alignment of the mother crystal. Application of the method supports the inferred alignment of mother and daughter phases in the published structures of two polymorphs of 4-cyanopyridinium perchlorate monohydrate <b>1</b>. A new low-temperature, monoclinic polymorph of ferrocenium tetrafluoroborate <b>2</b> is produced when the known orthorhombic polymorph is cooled from 173 to 120 K. The major features of the transformation include “conservative twinning” and a modulation of the structure along the crystallographic <i>b</i> direction upon cooling. Redetermination of the structure of the low-temperature polymorph of ferrocenium hexafluorophosphate <b>3</b> reveals that the phase change is accompanied by reproducible four-component twinning, providing a proper explanation for the previously reported, very high <i>R</i>-factor of 12.4%. Included tutorial information on the process will assist the reader in obtaining topotactic relationships, as well as in preparing figures and animations describing phase transitions or reactions

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>)

Experimental Establishment of Mother–Daughter Orientation Relationships and Twinning Effects in Phase Transitions: A Great Legacy from Jack Gougoutas and Peggy Etter

A simple procedure, with an available program, may readily be used to establish the three-dimensional relationships between a mother and daughter phase, where mother and daughter are either two different phases of a material <i>or</i> a reactant and product in a solid-state transformation. The only requirements are that (i) the process involves a crystal-to-crystal transformation, and (ii) the experiment must be carried out without changing the alignment of the mother crystal. Application of the method supports the inferred alignment of mother and daughter phases in the published structures of two polymorphs of 4-cyanopyridinium perchlorate monohydrate <b>1</b>. A new low-temperature, monoclinic polymorph of ferrocenium tetrafluoroborate <b>2</b> is produced when the known orthorhombic polymorph is cooled from 173 to 120 K. The major features of the transformation include “conservative twinning” and a modulation of the structure along the crystallographic <i>b</i> direction upon cooling. Redetermination of the structure of the low-temperature polymorph of ferrocenium hexafluorophosphate <b>3</b> reveals that the phase change is accompanied by reproducible four-component twinning, providing a proper explanation for the previously reported, very high <i>R</i>-factor of 12.4%. Included tutorial information on the process will assist the reader in obtaining topotactic relationships, as well as in preparing figures and animations describing phase transitions or reactions