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Selected highlights of the recent literature on solid-state NMR of some of the lesser studied nuclei are provided. The roles of ultrahigh magnetic fields, radiofrequency pulse sequences, dynamic nuclear polarization, isotopic enrichment, and nuclear quadrupole resonance in opening up the periodic table to in-depth study are discussed. [ABSTRACT FROM AUTHOR]

Calcium is an important component of materials, metalloproteins, minerals, glasses, and small inorganic and organic complexes. However, NMR spectroscopy of the quadrupolar 43Ca nuclide remains difficult primarily due to its low natural abundance and low resonance frequency. In this Perspective, experimental challenges and recent successes in the field are highlighted, with a focus on solid-state 43Ca NMR spectroscopy. Solution 43Ca NMR studies of calcium-binding biomolecules are also presented. The structural insights afforded from quadrupolar and chemical shift parameters are examined. For example: isotropic chemical shifts have been shown to correlate with the mean Ca–O distance and also with calcium coordination number; quadrupolar coupling constants and chemical shift tensor spans have been shown to be useful probes of polymorphism; and, distance measurements involving 43Ca have been recently demonstrated. Lastly, challenges and opportunities for the future are considered. [ABSTRACT FROM AUTHOR]

Matere bonds (MaB) to rhenium in a set of organic perrhenates are probed via185/187Re solid-state NMR in applied magnetic fields of up to 35.2 T, and via185/187Re NQR. 185/187Re quadrupolar couplings distinguish between MaB samples and control samples, and their precise values are governed by shear strain of the ReO4− anions. [ABSTRACT FROM AUTHOR]

The first example of a binary cocrystal, comprised of SnPh3Cl and PPh3, whose components are organized via short and directional tetrel bonds (TtB) between tin and phosphorus, is described. DFT elucidates, for the first time, the factors influencing the strength of TtBs involving heavy pnictogens. A CSD survey reveals that such TtBs are also present and determinative in single component molecular systems, highlighting their significant potential as tuneable structure-directing elements. [ABSTRACT FROM AUTHOR]

Group 16 chalcogen atoms may exhibit Lewis acidic σ-holes which are able to form attractive supramolecular interactions with Lewis bases via chalcogen bonds (ChB). Interest in ChB is increasing rapidly; however, the potential for anion binding has not been fully explored. Herein we report on the application of chemically robust and stable benzylic selenocynates (1 and 2) for halide ion recognition in the solid state and in solution. Single crystal X-ray structural analysis of various cocrystals reveals structurally important Se…X− (X = Cl, Br, I) chalcogen bonds. Changes in the 13C and 77Se chemical shifts via NMR spectroscopy show how halide ion recognition influences the local electronic environment of the selenium atoms in solution. Deviations of the interaction from the extension of the C–Se covalent bond are quantified and assessed with the aid of computational chemistry. [ABSTRACT FROM AUTHOR]

The crystal structures of two sodium diphosphates (Na4P2O7 and Na3HP2O7·H2O) that were solved using diffraction methods are refined with the use of 23Na and 31P NMR data in conjunction with projector-augmented-wave density functional theory (DFT) calculations. The sodium cations' NMR parameters are shown to be particularly well suited for the investigation of crystalline structures as they are largely dictated by the crystalline network instead of local directional bonding interactions. High-resolution spin-diffusion 23Na correlation spectra were acquired with the use of double rotation (DOR) and the spin diffusion build-up curves were modeled with the use of the rate matrix method. The availability of dipolar-based information from these measurements is important in validating the assignment of the resonances prior to performing structural refinements using the 23Na EFG tensor parameters. The NMR-refined structures of Na4P2O7 and Na3HP2O7·H2O are then cross-validated with the use of diffraction and magnetic shielding tensor information and are compared to the pure DFT and X-ray diffraction structures. A new crystal structure of Na3HP2O7·9H2O is solved using single-crystal X-ray diffraction and is compared to the refined crystal structures of Na3HP2O7·H2O. The combination of methods used in this work ensures consistency of the final structures with all available data. [ABSTRACT FROM AUTHOR]

2-Iodoethynylpyridine and 2-iodoethynyl-1-methyl-imidazole self-assemble under halogen-bonding control into discrete macrocycles, viz. supramolecular triangles. [ABSTRACT FROM AUTHOR]

Halogen bonding has been shown to be a versatile interaction for crystal engineering purposes, with characteristics that parallel those of hydrogen bonding. Here, we explore the potential of a new halogen bond donor, 3-iodoethynylbenzoic acid (1), which is functionalized with both halogen bond donor and hydrogen bond donor groups. We explore its crystal engineering potential by cocrystallizing it with a series of nitrogen-containing heterocycles, namely 2,3,5,6-tetramethylpyrazine, 1,4-diazabicyclo[2.2.2]octane, piperazine, and hexamethylenetetramine. In total, we report six new single-crystal X-ray diffraction structures, including those of 1 and five of its halogen-bonded cocrystals. The halogen-bonded cocrystals are further investigated using 13C magic-angle spinning solid-state NMR spectroscopy and the observed changes in chemical shifts are attributed to particular structural or crystallographic features. The 13C chemical shift of the ethynyl carbon bonded to the aromatic ring consistently decreased by several ppm upon halogen bond formation while that of the ethynyl carbon bonded to iodine increased. Furthermore, we show that these cocrystals are also readily prepared by mechanochemical ball milling, allowing for the rapid screening of cocrystal formation based on this halogen bond donor. [ABSTRACT FROM AUTHOR]

In situ31P solid-state NMR studies of halogen bond formation between triphenylphosphine oxide and para-diiodotetrafluorobenzene provide insights into the cocrystallisation process and provide an estimate of the activation energy. The effects of temperature, magic-angle spinning speed, and initially added liquid on the reaction rate and mechanism have been investigated. [ABSTRACT FROM AUTHOR]

Studies of three related CdII systems (a discrete [CdII2] unit, a one-dimensional [CdII2]n coordination polymer and a CdII-based MOF) all derived from the ligand 2,4,6-tris(2-pyrimidyl)-1,3,5-triazine, reveal an exceptionally rare example of 113Cd–113Cd J coupling in the polymer that is detectable by solid-state NMR (2JCd–Cd = ∼65 Hz). [ABSTRACT FROM AUTHOR]

An overview of the role of solid-state nuclear magnetic resonance (SSNMR) spectroscopy in the field of crystal engineering is provided. NMR methodologies often provide insights into the structure and dynamics of solid materials which would otherwise be unavailable by X-ray diffraction. More generally, NMR crystallographic structure solutions or refinement approaches seek to incorporate available data from all sources, including the results of density functional theory calculations and diffraction data. This Highlight article discusses the state of the field through a recapitulation of relevant theory and selected applications from the literature. Specific topics covered include NMR structure refinement, polymorph identification and differentiation, non-covalent interactions, and the role of dynamics. [ABSTRACT FROM AUTHOR]

We report the preparation and characterisation of a cocrystal of triphenylphosphine with 1,3,5-trifluoro-2,4,6-triiodobenzene. The structure features a rare example of phosphorus acting as a halogen bond acceptor. [ABSTRACT FROM AUTHOR]

2D polymeric water–chloride/bromide sheets comprising a unique pentagon-like dichloride/dibromide-trihydrate cluster in the solid state have been observed as [Co(bpca)2]+ (bpca = bis(2-pyrimidylcarbonyl)amidate anion) counterions. Both compounds were obtained by the reaction of 2,4,6-tris(2-pyrimidyl)-1,3,5-triazine (TPymT) with CoX2 (X = Cl, Br) in water. Solid-state multinuclear magnetic resonance spectroscopy and XRD provide insight into the structures. [ABSTRACT FROM AUTHOR]

Halogen bonds constitute an important and topical class of non-covalent interaction. We report a combined X-ray diffraction, multinuclear (77Se, 31P, 13C) solid-state magnetic resonance, and computational study of a series of crystalline triphenylphosphine selenide-iodoperfluorobenzene complexes which feature P=Se⋯I-C halogen bonds. Selenium-77 chemical shifts increase due to halogen bonding with iodine and correlate with the P=Se distance, which in turn correlates with the strength of the halogen bond. (77Se, 31P) coupling constants increase in magnitude as the halogen bond weakens. This observation is understood a natural localized molecular orbital (NLMO) DFT approach which shows that contributions from the selenium lone pair orbital tend to dominate both the magnitude and trends in (77Se, 31P), with the selenium-phosphorus bonding orbital being the second largest contributor. This work suggests that couplings measured NMR spectroscopy may play an important role in the characterization of halogen bonds, in clear analogy with their role in the characterization of hydrogen bonds. [ABSTRACT FROM AUTHOR]

Reaction of 2,4,6-tris(2-pyrimidyl)-1,3,5-triazine (TPymT) with Pb(NO3)2 in aqueous medium leads to the formation of a mixture of two pseudopolymorphs, {[Pb2(TPymT)(H2O)(NO3)4]·H2O}n, 1 and [Pb2(TPymT)(NO3)4]n, 2, where TPymT molecules are coordinated with two PbII ions in a bridging bis-terpyridine fashion. We demonstrate that fast evaporation of the solvent leads exclusively to the formation of 1, while 2 was formed upon slow evaporation. The two pseudopolymorphs can be interconverted by dissolving in water upon heating and controlling the evaporation rate. [ABSTRACT FROM AUTHOR]