The effect on oligomerization of increased steric bulk in dimethylindium(III) chalcogenolates (Me(2)InER') (E = O, S, Se) has been examined. The facile reaction of Me(3)In with a series of phenols, thiophenols and selenophenols afforded the compounds [Me(2)InO(C(6)H(5))](2) (1), [Me(2)InO(2,6-Me(2)C(6)H(3))](2) (2), Me(2)InO(2,4,6-tBu(3)C(6)H(3)) (3), [Me(2)InS(C(6)H(5))](infinity) (4), [Me(2)InS(2,4,6-tBu(3)C(6)H(3))](infinity) (6), [Me(2)InSe(C(6)H(5))](2) (7), [Me(2)InSe(2,4,6-Me(3)C(6)H(3))](infinity) (8) and [Me(2)InSe(2,4,6-tBu(3)C(6)H(3))](infinity) (9). All compounds have been characterized by elemental analysis, melting point, FT-IR, FT-Raman, solution NMR, and X-ray crystallography. The structures of 1-2 are dimeric via short intermolecular In-O interactions, yielding a symmetric In(2)O(2) unit and a distorted tetrahedral C(2)O(2) bonding environment for indium. Increasing steric bulk in 3 results in the isolation of a monomeric species, exhibiting a distorted trigonal planar C(2)O bonding environment for indium. In contrast to 1, the thiolate analogue 4 exhibits a polymeric structure via mu(2)-SPh groups and a distorted tetrahedral C(2)S(2) bonding environment for indium. Increasing steric bulk resulted in the formation of a chain of weakly coordinated monomers via intermolecular In...S interactions in [Me(2)InS(2,4,6-tBu(3)C(6)H(2))](infinity) (6). Although 7 shows a dimeric species similar to 1, the 2,4,6-trimethyl substituted selenolate analogue 8 exhibits a polymeric structure, while the -Se-2,4,6-tBu(3)C(6)H(3) analogue (9) showing a similar structure to 6. Comparison to previously reported structures of diorganoindium chalcogenolates demonstrates the importance of the methyl substituents on indium in facilitating the isolation of higher (non-dimeric) oligomers. Theoretical calculations demonstrate the significance of altering the R and R' groups and E on the degree of oligomerization in [R(2)InER'](n) species.
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Isostructural Dy(III) and Er(III) complexes [L12Ln(H2O)5][I]3·L12·(CH2Cl2) (Ln = Dy (1), Er (3)) and [L22Ln(H2O)5][I]3·L22·(CH2Cl2)2 (Ln = Dy (2), Er (4)), with distorted pentagonal bipyramidal geometry (D5h) around the central metal were synthesized by utilizing two bulky phosphonamide ligands, adamantyl phosphonamide, (Ad)P(O)(NHiPr)2 (L1) and carbazolyl phosphoramide (Cz)P(O)(NHiPr)2 (L2). The resultant complexes were investigated for their magnetic properties in order to elucidate the impact of modification of the coordinating P-O bond environment either by increasing steric bulk and/or introduction of a third P-N bond at the central phosphorus atom. Magnetic studies revealed substantial energy barriers (Ueff) of 640 K and 560 K for Dy compounds 1 and 2, respectively, rendering them as some of the best-performing air-stable SIMs amongst the class of SIMs with D5h symmetry.
View Article and Find Full Text PDFJ Am Chem Soc
December 2024
Department of Chemistry, Indiana University, 800 East Kirkwood Ave., Bloomington, Indiana 47405, United States.
The synthesis and isolation of TerP═GaTer and TerP═InTer (Ter = 2,6-Dipp-CH; Dipp = 2,6-diisopropylphenyl) is reported. These compounds feature unsupported P═Ga and P═In double bonds and two-coordinate triel element centers. Key to the stabilization of such compounds is the steric bulk of the terphenyl substituents, which serve to shield the highly reactive P═E bonds (E = Ga, In) and prevent further aggregation.
View Article and Find Full Text PDFChem Sci
December 2024
Department of Chemistry, Columbia University New York NY 10027 USA
We report the synthesis and characterization of octahedral UiO-66 nanocrystals ( = 17-25 nm) terminated with amine, oleate, and octadecylphosphonate ligands. Acetate capped UiO-66 nanocrystals were dispersed in toluene using oleic acid and oleylamine. Ligand exchange with octadecylphosphonic acid produces ammonium octadecylphosphonate terminated nanocrystals with coverages of 2.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
December 2024
Wuhan University of Technology, State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, CHINA.
Angew Chem Int Ed Engl
December 2024
Department of Chemistry, Zhejiang University, Hangzhou, 310027, China.
Control over stereochemistry in poly(vinyl ether)s leads to a notable change in their physical properties, yet remains a grand challenge. Here, we demonstrate the bulk stereoselective cationic polymerization of vinyl ethers using ZrCl coordinated with a spirocyclic phosphoric acid (SPA). The widely variable substituents in SPAs exert a profound impact on the stereochemical and activity outcome of the polymerization: the % m of poly(vinyl ether)s linearly increases with the Hammett substituent constant (σ) of SPAs; the catalytic activity increases with the σ; the large steric hindrance groups lead to decreased polymerization activity.
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