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1. Solid-state ¹¹ B NMR studies of coinage metal complexes containing a phosphine substituted diboraanthracene ligand

   https://doi.org/10.1039/d1dt02981a  

   Huynh, Winn ; Taylor, Jordan W. ; Harman, W. Hill ; Conley, Matthew P. ( October 2021 , Dalton Transactions)

   Transition metal interactions with Lewis acids (M → Z linkages) are fundamentally interesting and practically important. The most common Z-type ligands contain boron, which contains an NMR active 11 B nucleus. We measured solid-state 11 B{ 1 H} NMR spectra of copper, silver, and gold complexes containing a phosphine substituted 9,10-diboraanthracene ligand (B 2 P 2 ) that contain planar boron centers and weak M → BR 3 linkages ([(B 2 P 2 )M][BAr F 4 ] (M = Cu (1), Ag (2), Au (3)) characterized by large quadrupolar coupling ( C Q ) values (4.4–4.7 MHz) and large span ( Ω ) values (93–139 ppm). However, the solid-state 11 B{ 1 H} NMR spectrum of K[Au(B 2 P 2 )] − (4), which contains tetrahedral borons, is narrow and characterized by small C Q and Ω values. DFT analysis of 1–4 shows that C Q and Ω are expected to be large for planar boron environments and small for tetrahedral boron, and that the presence of a M → BR 3 linkage relates to the reduction in C Q and 11 B NMR shielding properties. Thus solid-state 11 B NMR spectroscopy contains valuable information about M → BR 3more »linkages in complexes containing the B 2 P 2 ligand.« less
2. Peculiarities of crystal structures and photophysical properties of Ga ^III /Ln ^III metallacrowns with a non-planar [12-MC-4] core

   https://doi.org/10.1039/c9qi01647c  

   Nguyen, Tu N. ; Eliseeva, Svetlana V. ; Chow, Chun Y. ; Kampf, Jeff W. ; Petoud, Stéphane ; Pecoraro, Vincent L. ( March 2020 , Inorganic Chemistry Frontiers)

   A new series of gallium( iii )/lanthanide( iii ) metallacrown (MC) complexes ( Ln-1 ) was synthesized by the direct reaction of salicylhydroxamic acid (H 3 shi) with Ga III and Ln III nitrates in a CH 3 OH/pyridine mixture. X-ray single crystal analysis revealed two types of structures depending on whether the nitrate counterion coordinate or not to the Ln III : [LnGa 4 (shi) 4 (H 2 shi) 2 (py) 4 (NO 3 )](py) 2 (Ln = Gd III , Tb III , Dy III , Ho III ) and [LnGa 4 (shi) 4 (H 2 shi) 2 (py) 5 ](NO 3 )(py) (Ln = Er III , Tm III , Yb III ). The representative Tb-1 and Yb-1 MCs consist of a Tb/YbGa 4 core with four [Ga III –N–O] repeating units forming a non-planar ring that coordinates the central Ln III through the oxygen atoms of the four shi 3− groups. Two H 2 shi − groups bridge the Ln III to the Ga III ring ions. The Yb III in Yb-1 is eight-coordinated while the ligation of the nine-coordinated Tb III in Tb-1 is completed by one chelating nitrate ion. Ln-1 complexes in the solidmore »state showed characteristic sharp f–f transitions in the visible (Tb, Dy) and near-infrared (Dy, Ho, Er, Yb) spectral ranges upon excitation into the ligand-centered electronic levels at 350 nm. Observed luminescence lifetimes and absolute quantum yields were collected and discussed. For Yb-1 , luminescence data were also acquired in CH 3 OH and CD 3 OD solutions and a more extensive analysis of photophysical properties was performed. This work demonstrates that while obtaining highly luminescent lanthanide( iii ) MCs via a direct synthesis is feasible, many factors such as molar absorptivities, triplet state energies, non-radiative deactivations through vibronic coupling with overtones of O–H, N–H, and C–H oscillators and crystal packing will strongly contribute to the luminescent properties and should be carefully considered.« less
3. Coinage metal metallacycles involving a fluorinated 3,5-diarylpyrazolate

   https://doi.org/10.1039/d0nj03744c  

   Lakhi, Jaspreet S. ; Patterson, Monika R. ; Dias, H. V. ( September 2020 , New Journal of Chemistry)

   Copper( i ) and silver( i ) pyrazolate complexes {[3,5-(3,5-(CF 3 ) 2 Ph) 2 Pz]Cu} 3 and {[3,5-(3,5-(CF 3 ) 2 Ph) 2 Pz]Ag} 3 have been synthesized using the fluorinated 3,5-(diaryl)pyrazole 3,5-(3,5-(CF 3 ) 2 Ph) 2 PzH and copper( i ) oxide and silver( i ) oxide, respectively. The gold( i ) analog was obtained from a reaction between Au(THT)Cl and [3,5-(3,5-(CF 3 ) 2 Ph) 2 Pz]H/NaH. The X-ray crystal structures show that the coinage metal complexes {[3,5-(3,5-(CF 3 ) 2 Ph) 2 Pz]M} 3 (M = Cu, Ag, Au) are trinuclear in the solid state. They feature distorted nine-membered M 3 N 6 metallacyclic cores. The M–N distances follow Cu < Au < Ag, which is the trend expected from covalent radii of the corresponding coinage metal ions. The 3,5-(3,5-(CF 3 ) 2 Ph) 2 PzH forms hydrogen bonded trimers in the solid state that are further organized by π-stacking between aryl rings. Solid samples of {[3,5-(3,5-(CF 3 ) 2 Ph) 2 Pz]M} 3 display blue photoluminescence. The copper complex {[3,5-(3,5-(CF 3 ) 2 Ph) 2 Pz]Cu} 3 is an excellent catalyst for mediating azide–alkyne cycloaddition chemistry.
4. Conformational control through co-operative nonconventional C—H...N hydrogen bonds

   https://doi.org/10.1107/S2053229621007427  

   Bosch, Eric ; Bowling, Nathan P. ; Oburn, Shalisa M. ( August 2021 , Acta Crystallographica Section C Structural Chemistry)

   We report the design, synthesis, and crystal structure of a conjugated aryleneethynyl molecule, 2-(2-{4,5-dimethoxy-2-[2-(2,3,4-trifluorophenyl)ethynyl]phenyl}ethynyl)-6-[2-(pyridin-2-yl)ethynyl]pyridine, C 30 H 17 F 3 N 2 O 2 , that adopts a planar rhombus conformation in the solid state. The molecule crystallizes in the space group P -1, with Z = 2, and features two intramolecular sp 2 -C—H...N hydrogen bonds that co-operatively hold the arylethynyl molecule in a rhombus conformation. The H atoms are activated towards hydrogen bonding since they are situated on a trifluorophenyl ring and the H...N distances are 2.470 (16) and 2.646 (16) Å, with C—H...N angles of 161.7 (2) and 164.7 (2)°, respectively. Molecular electrostatic potential calculations support the formation of C—H...N hydrogen bonds to the trifluorophenyl moiety. Hirshfeld surface analysis identifies a self-complementary C—H...O dimeric interaction between adjacent 1,2-dimethoxybenzene segments that is shown to be common in structures containing that moiety.
5. Crystal structure of N , N -diisopropyl-4-methylbenzenesulfonamide

   https://doi.org/10.1107/S2056989020007185  

   Stenfors, Brock A. ; Staples, Richard J. ; Biros, Shannon M. ; Ngassa, Felix N. ( July 2020 , Acta Crystallographica Section E Crystallographic Communications)

   The synthesis of the title compound, C 13 H 21 NO 2 S, is reported here along with its crystal structure. This compound crystallizes with two molecules in the asymmetric unit. The sulfonamide functional group of this structure features S=O bond lengths ranging from 1.433 (3) to 1.439 (3) Å, S—C bond lengths of 1.777 (3) and 1.773 (4) Å, and S—N bond lengths of 1.622 (3) and 1.624 (3) Å. When viewing the molecules down the S—N bond, the isopropyl groups are gauche to the aromatic ring. On each molecule, two methyl hydrogen atoms of one isopropyl group are engaged in intramolecular C—H...O hydrogen bonds with a nearby sulfonamide oxygen atom. Intermolecular C—H...O hydrogen bonds and C—H...π interactions link molecules of the title compound in the solid state.