Gauge Including Projector Augmented Wave Research Articles

Local versus Average Structure in LaSrAl3O7: A NMR and DFT Investigation

LaSrAl3O7 belongs to the family of M2T1(1)T2(2)O7 compounds with tetragonal melilite-like layered structure. In such compounds the local structure and properties may be very different from the average ones, mainly due to cationic disorder on the M site. In this work, solid-state 27Al NMR spectroscopy and periodic density functional theory calculations were used to highlight the differences between local and average order in the LaSrAl3O7 crystal. The 27Al isotropic chemical shifts and quadrupolar coupling constants were computed by employing the gauge including projector augmented wave (GIPAW) and PAW formalisms, respectively. An impressive linear relationship between the computed quadrupolar coupling constant CQ and the Al tetrahedra (T1, T2) distortion was observed. In particular, our calculations showed that the distortion of the T2 environment is determined by the La/Sr speciation around the apical nonbridging oxygen.

Probing silicon and aluminium chemical environments in silicate and aluminosilicate glasses by solid state NMR spectroscopy and accurate first-principles calculations

Silicon and aluminium chemical environments in silicate and aluminosilicate glasses with compositions 60SiO2·20Na2O·20CaO (CSN), 60SiO2·20Al2O3·20CaO (CAS), 78SiO2·11Al2O3·11Na2O (NAS) and 60SiO2·10Al2O3·10Na2O·20CaO (CASN) have been investigated by 27Al and 29Si solid state magic angle spinning (MAS) and multiple quantum MAS (MQMAS) nuclear magnetic resonance (NMR) experiments. To interpret the NMR data, first-principles calculations using density functional theory were performed on structural models of these glasses. These models were generated by Shell-model molecular dynamics (MD) simulations. The theoretical NMR parameters and spectra were computed using the gauge including projected augmented wave (GIPAW) method and spin-effective Hamiltonians, respectively. This synergetic computational–experimental approach offers a clear structural characterization of these glasses, particularly in terms of network polymerization, chemical disorder (i.e. Si and Al distribution in second coordination sphere) and modifier cation distributions. The relationships between the local structural environments and the 29Si and 27Al NMR parameters are highlighted, and show that: (i) the isotropic chemical shift of both 29Si and 27Al increases of about +5ppm for each Al added in the second sphere and (ii) both the 27Al and 29Si isotropic chemical shifts linearly decrease with the reduction of the average Si/Al–O–T bond angle. Conversely, 27Al and 29Si NMR parameters are much less sensitive to the connectivity with triple bridging oxygen atoms, precluding their indirect detection from 27Al and 29Si NMR.

Difference in the structures of alanine tri‐ and tetra‐peptides with antiparallel β‐sheet assessed by X‐ray diffraction, solid‐state NMR and chemical shift calculations by GIPAW

Alanine oligomers provide a key structure for silk fibers from spider and wild silkworms.We report on structural analysis of L-alanyl-L-alanyl-L-alanyl-L-alanine (Ala)4 with anti-parallel (AP) β-structures using X-ray and solid-state NMR. All of the Ala residues in the (Ala)4 are in equivalent positions, whereas for alanine trimer (Ala)3 there are two alternative locations in a unit cell as reported previously (Fawcett and Camerman, Acta Cryst., 1975, 31, 658-665). (Ala)4 with AP β-structure is more stable than AP-(Ala)3 due to formation of the stronger hydrogen bonds. The intermolecular structure of (Ala)4 is also different from polyalanine fiber structure, indicating that the interchain arrangement of AP β-structure changes with increasing alanine sequencelength. Furthermore the precise (1)H positions, which are usually inaccesible by X-ray diffraction method, are determined by high resolution (1)H solid state NMR combined with the chemical shift calculations by the gauge-including projector augmented wave method.

Refined Structure Determination of Blue-Emitting Tris(8-hydroxyquinoline) Aluminum(III) (Alq3) by the Combined Use of Cross-Polarization/Magic-Angle Spinning 13C Solid-State NMR and First-Principles Calculation

The combined use of cross-polarization/magic-angle spinning (CP/MAS) 13C NMR experiments and gauge-including projector-augmented wave (GIPAW) isotropic chemical shift calculations is an easy and useful method for the structural refinement of organic aggregates. In this study, the method is applied to an important material for organic light-emitting diodes, tris(8-hydroxyquinoline) aluminum(III) (Alq3). CP/MAS 13C NMR spectra include precise structural information of not only the conformation of the molecules but also the intermolecular packing. First, the structural refinements were performed for the Alq3 in the γ- and δ-crystalline forms employing the combined method. Second, information on intramolecular structures and intermolecular structures was distinguished by comparing GIPAW calculations for crystals under periodic boundary conditions and those for isolated molecules extracted from the crystals. It was found from the analysis that the γ-Alq3 and δ-Alq3 crystals have similar intramolecular structures both in the facial isomeric state, whereas their intermolecular packing is significantly different. Both the γ-Alq3 and δ-Alq3 crystals exhibit unusual blue emission, which is different from conventional green emission, and the origin of the difference has been debated. This investigation shows that the origin of the blue-shifted emission is the isomeric states of Alq3, not the intermolecular packing.

Multinuclear Solid‐State Magnetic Resonance as a Sensitive Probe of Structural Changes upon the Occurrence of Halogen Bonding in Co‐crystals

Although the understanding of intermolecular interactions, such as hydrogen bonding, is relatively well-developed, many additional weak interactions work both in tandem and competitively to stabilize a given crystal structure. Due to a wide array of potential applications, a substantial effort has been invested in understanding the halogen bond. Here, we explore the utility of multinuclear ((13)C, (14/15)N, (19)F, and (127)I) solid-state magnetic resonance experiments in characterizing the electronic and structural changes which take place upon the formation of five halogen-bonded co-crystalline product materials. Single-crystal X-ray diffraction (XRD) structures of three novel co-crystals which exhibit a 1:1 stoichiometry between decamethonium diiodide (i.e., [(CH3)3N(+)(CH2)10N(+)(CH3)3][2 I(-)]) and different para-dihalogen-substituted benzene moieties (i.e., p-C6X2Y4, X=Br, I; Y=H, F) are presented. (13)C and (15)N NMR experiments carried out on these and related systems validate sample purity, but also serve as indirect probes of the formation of a halogen bond in the co-crystal complexes in the solid state. Long-range changes in the electronic environment, which manifest through changes in the electric field gradient (EFG) tensor, are quantitatively measured using (14)N NMR spectroscopy, with a systematic decrease in the (14)N quadrupolar coupling constant (CQ) observed upon halogen bond formation. Attempts at (127)I solid-state NMR spectroscopy experiments are presented and variable-temperature (19)F NMR experiments are used to distinguish between dynamic and static disorder in selected product materials, which could not be conclusively established using solely XRD. Quantum chemical calculations using the gauge-including projector augmented-wave (GIPAW) or relativistic zeroth-order regular approximation (ZORA) density functional theory (DFT) approaches complement the experimental NMR measurements and provide theoretical corroboration for the changes in NMR parameters observed upon the formation of a halogen bond.

Insight into Magnesium Coordination Environments in Benzoate and Salicylate Complexes through 25Mg Solid-State NMR Spectroscopy

We report on the (25)Mg solid-state nuclear magnetic resonance (NMR) characterization of a series of magnesium complexes featuring Mg(2+) ions in organic coordination environments. Six compounds have been synthesized with benzoate and salicylate ligands, which are typically used as linkers in metal organic frameworks (MOFs). The use of ultrahigh-field solid-state NMR has revealed a relatively large range of values for the (25)Mg quadrupolar coupling constant, CQ((25)Mg), in these compounds. In contrast to some previously studied inorganic Mg(2+) complexes, the values of CQ((25)Mg) in organic Mg(2+) complexes are well rationalized by the degree of octahedral strain of the "MgO6" coordination polyhedra. (13)C and (25)Mg isotropic chemical shifts were also found to be sensitive to the binding mode of the carboxylate ligands. The experimental findings are corroborated by gauge-including projector-augmented-wave (GIPAW) density functional theory (DFT) computations, and these have allowed for an interpretation of the experimentally observed trend in the CQ((25)Mg) values and for the visualization of the EFG tensor principal components with respect to the molecular structure. These new insights may prove to be valuable for the understanding and interpretation of (25)Mg NMR data for Mg(2+) ions in organic binding environments such as those found in MOFs and protein-divalent metal binding sites.

Coupling Solid-State NMR with GIPAW ab Initio Calculations in Metal Hydrides and Borohydrides

An integrated experimental–theoretical approach for the solid-state NMR investigation of a series of hydrogen-storage materials is illustrated. Seven experimental room-temperature structures of groups I and II metal hydrides and borohydrides, namely, NaH, LiH, NaBH4, MgH2, CaH2, Ca(BH4)2, and LiBH4, were computationally optimized. Periodic lattice calculations were performed by means of the plane-wave method adopting the density functional theory (DFT) generalized gradient approximation (GGA) with the Perdew–Burke–Ernzerhof (PBE) functional as implemented in the Quantum ESPRESSO package. Projector augmented wave (PAW), including the gauge-including projected augmented-wave (GIPAW), methods for solid-state NMR calculations were used adopting both Rappe–Rabe–Kaxiras–Joannopoulos (RRKJ) ultrasoft pseudopotentials and new developed pseudopotentials. Computed GIPAW chemical shifts were critically compared with the experimental ones. A good agreement between experimental and computed multinuclear chemical shifts was obtained.

ChemInform Abstract: First‐Principles Calculation of NMR Parameters Using the Gauge Including Projector Augmented Wave Method: A Chemist′s Point of View

AbstractReview: 439 refs.

An NMR crystallography DFT-D approach to analyse the role of intermolecular hydrogen bonding and π–π interactions in driving cocrystallisation of indomethacin and nicotinamide

Density functional theory (DFT) calculations using the Perdew–Burke–Ernzerhof (PBE) exchange-correlation functional are presented for a 1 : 1 cocrystal formed by indomethacin and nicotinamide (IND-NIC) as well as for crystal structures of the individual components. DFT-D approaches which correct the DFT energy for dispersion effects, specifically the Grimme (G06) and Tkatchenko–Scheffler (TS) schemes, are investigated: for geometry optimisation starting with crystal structures determined experimentally by diffraction and allowing the atomic positions and the unit cell to vary, closest agreement with the experimental unit cell parameters is achieved with the PBE-TS approach (calculated volumes are less than 4% smaller than in experiment). Calculations of solid-state NMR chemical shifts using the GIPAW (gauge including projector augmented wave) approach are presented. Closest agreement between NMR chemical shifts calculated with variable and fixed (experimental) unit cell parameters is also observed for the PBE-TS approach: the root mean squared standard deviation difference is 0.15 ppm (1H) and 0.29 ppm (13C) for PBE-TS, as compared to 0.45 ppm (1H) and 0.68 ppm (13C) with standard PBE. Differences in 1H chemical shifts calculated for the full periodic crystal structure and for isolated molecules extracted from the geometry-optimised crystal structure are presented in conjunction with NICS (nucleus independent chemical shift) maps, so as to separately quantify intermolecular hydrogen bonding and π–π interactions. This analysis is complemented by total energy calculations, including also at the B97D/6-311+G* level of theory with basis set superposition error correction, in order to understand the interactions that drive cocrystallisation.

Structural study of calcium phosphonates: a combined synchrotron powder diffraction, solid-state NMR and first-principle calculations approach

The structures of four Ca-phosphonate phases are reported here: Ca(C6H5–PO3H)2 (1), Ca(C6H5–PO3)·2H2O (2), Ca(C4H9–PO3H)2 (3) and Ca(C4H9–PO3)·H2O (4). Structural models were obtained ab initio by using a combined synchrotron powder diffraction, solid-state nuclear magnetic resonance, and gauge including projector augmented wave (GIPAW) calculation approach. The 1H, 13C, 31P and 43Ca NMR parameters calculated from these structural models were found to be in good agreement with the experimental values, thereby indicating the high accuracy of the DFT-optimized structures. Correlations between the NMR parameters and structural features around the phosphonate were then analyzed, showing in particular the high sensitivity of the 31P asymmetry parameter ηCS and the 43Ca isotropic chemical shift to changes in local structure around the phosphonate groups and the Ca2+, respectively. Finally, the NMR data of a new mixed Na–Ca phosphonate phase, Ca1.5Na(C4H9–PO3)2, are reported.

77Se solid-state NMR of As2Se3, As4Se4 and As4Se3 crystals: a combined experimental and computational study

(77)Se NMR parameters for three prototypical crystalline compounds (As2Se3, As4Se4 and As4Se3) have been determined from solid-state NMR spectra in the framework of an investigation concerning AsxSe(1-x) glass structure understanding. Density functional NMR calculations using the gauge including projector augmented wave methodology have been performed on X-ray and optimized crystal structures for a set of selenium-based crystals. These theoretical results have been combined with the experimental data in order to achieve a precise assignment of the spectral lines. This work and the high sensitivity of solid-state NMR to local order show that the structure of As4Se3 should be reinvestigated using state-of-the-art diffraction techniques. Calculations performed on several molecules derived from the crystal structures have demonstrated the limited effect of interlayer or intermolecular interactions on the isotropic chemical shifts. These interactions are therefore not responsible for the unexpected large chemical shift difference observed between these three systems that could mostly be attributed to the presence of short rings.

Refining crystal structures with experimental 13C NMR shift tensors and lattice-including electronic structure methods

Large differences are found in the quality of crystal structures obtained from different diffraction methods. The most accurate studies identify all atomic sites, including hydrogens, while others lack even the resolution needed to locate individual atoms. The gauge including projector augmented wave method (GIPAW) provides a technique to further refine any of these structures under lattice constraints. Here, the sensitivity of solid-state NMR 13C shift tensor principal value data to GIPAW refinement is investigated. The refinement is shown to improve X-ray powder, X-ray single crystal and even neutron single crystal diffraction data. Convergence to a single structure is observed in most cases. Surprisingly, the final refined structures usually diverge from the original neutron diffraction coordinates – data typically viewed as the most accurate. To ensure that the structural changes represent improvements, three metrics are monitored comprising fit to 13C shift tensors, forces upon the atoms and changes in atomic positions relative to a reference structure. In all cases these parameters improve upon refinement suggesting that GIPAW creates structures surpassing the accuracy of single crystal neutron diffraction data. However, the influence of thermal motions remains unknown. Improvements are seen most strongly in forces and NMR fits and least in atom positions. This study evaluates reasonably accurate model structures to quantify improvements. However, structures obtained from lower resolution methods (e.g. electron diffraction) will benefit most from GIPAW refinement. In such structures the refinement has the potential to convert structures with questionable atom positions into coordinates rivaling neutron diffraction single crystal data.

NMR crystallography methods to probe complex hydrogen bonding networks: application to structure elucidation of anhydrous quercetin

Despite the simple molecular structure of quercetin, the exact conformation of the hydroxyl groups and the induced hydrogen bonding network in its anhydrous form could not be determined if starting from crystal structure models provided by X-ray powder diffraction (XRPD) alone. If instead a multi-technique approach that combines XRPD data analysis with information from 13C and 1H solid-state Nuclear Magnetic Resonance (ss-NMR) and molecular modeling is employed the ambiguities could be largely reduced. A conformational analysis was performed on the isolated molecule at the molecular mechanics (MM) level of theory, whereas quantum chemical computations of the full crystal were employed for geometry optimization and chemical shift calculation based on the Gauge Including Projector Augmented-Wave (GIPAW) method. 13C and ultra-fast MAS (60 kHz) 1H ss-NMR data were used at 11.75 T to assess the reliability of the derived structure solutions, and to obtain important insights into the relationship between the hydrogen bonding network and the induced supra-molecular architectures/crystal packing patterns. A direct comparison with the data recorded on quercetin dihydrate, of which single-crystal X-ray structure is known, proved useful for increasing the confidence level in the derived conclusions. Also, an ultra-fast MAS 1H double-quantum (DQ) excitation scheme is employed, which has the advantage of providing better resolution at long DQ excitation times compared with conventional multiple-pulse homonuclear decoupling: this may be relevant for further methodological development in NMR crystallography, especially when dealing with the effects of increased lattice disorder.

95Mo Solid-State Nuclear Magnetic Resonance Spectroscopy and Quantum Simulations: Synergetic Tools for the Study of Molybdenum Cluster Materials

The ability of (95)Mo solid-state nuclear magnetic resonance (SSNMR) spectroscopy to probe the atomic and electronic structures of inorganic molybdenum cluster materials has been demonstrated for the first time. Six cluster compounds were studied: MoBr(2), Cs(2)Mo(6)Br(14), (Bu(4)N)(2)Mo(6)Br(14), each containing the octahedral Mo(6)Br(14)(2-) cluster unit, and MoS(2)Cl(3), Mo(3)S(7)Cl(4), and MoSCl that contain metallic dimers, trimers, and tetramers, respectively. To overcome inherent difficulties due to the low sensitivity of (95)Mo SSNMR, both high-magnetic-field spectrometers and the quadrupolar Carr-Purcell Meiboom-Gill sensitivity enhancement pulse sequence under magic-angle-spinning conditions, combined with a hyperbolic-secant pulse were used. Experimental measurements as well as characterization of the (95)Mo electric field gradient and chemical shift tensors have been performed with the help of quantum-chemical calculations under periodic boundary conditions using the projector augmented-wave and the gauge-including projector augmented-wave methods, respectively. A large (95)Mo chemical shift range is measured, ∼3150 ppm, and the isotropic chemical shift of the Mo atoms is clearly correlated to their formal oxidation degree in the various clusters. Furthermore, a direct relation is evidenced between the molybdenum quadrupolar coupling constant and the bond lengths with its surrounding ligands. Our results demonstrate the efficiency of the combined use of quantum-chemical calculations and (95)Mo SSNMR experiments to study inorganic molybdenum cluster compounds.

Boronate Ligands in Materials: Determining Their Local Environment by Using a Combination of IR/Solid‐State NMR Spectroscopies and DFT Calculations

Boronic acids (R-B(OH)(2)) are a family of molecules that have found a large number of applications in materials science. In contrast, boronate anions (R-B(OH)(3)(-)) have hardly been used so far for the preparation of novel materials. Here, a new crystalline phase involving a boronate ligand is described, Ca[C(4)H(9)-B(OH)(3)](2), which is then used as a basis for the establishment of the spectroscopic signatures of boronates in the solid state. The phase was characterized by IR and multinuclear solid-state NMR spectroscopy ((1)H, (13)C, (11)B and (43)Ca), and then modeled by periodic DFT calculations. Anharmonic OH vibration frequencies were calculated as well as NMR parameters (by using the Gauge Including Projector Augmented Wave--GIPAW--method). These data allow relationships between the geometry around the OH groups in boronates and the IR and (1)H NMR spectroscopic data to be established, which will be key to the future interpretation of the spectra of more complex organic-inorganic materials containing boronate building blocks.

NMR Crystallography Comparative Studies of Chiral (1R,2S,3R,5R)-3-Amino-6,6-dimethylbicyclo[3.1.1]heptan-2-ol and Its p-Toluenesulfonamide Derivative

The crystal structure of (1R,2S,3R,5R)-3-amino-6,6-dimethyl-2-hydroxybicyclo[3.1.1]heptane 1 was determined and it is presented in reference to the structure of (1R,2S,3R,5R)-3-(p-tosylamino)-6,6-dimethyl-2-hydroxybicyclo[3.1.1]heptane 2. 1H and 13C chemical shifts parameters for both structures and for whole unit cells were calculated by using the GIPAW (gauge including projector augmented waves) method. Theoretically calculated chemical shift tensor parameters were verified by 13C CP MAS, 2D PASS, and 13C–1H FSLG HETCOR results to obtain a full structural assignment for 13C and 1H resonances in the solid-state. PISEMA MAS experiment was performed to determine the molecular dynamics of aminoalcohol 1. The comparison of two structures, obtained after all-atom positions optimization after the GIPAW calculations, revealed small conformational differences consistent with the single-crystal X-ray diffaction results.

First-Principles Calculations of Potassium Amidoborane KNH2BH3: Structure and 39K NMR Spectroscopy

We have studied the structural, electronic, and vibrational properties of potassium amidoborane (KAB, KNH2BH3) using density-functional theory (DFT) calculations. The optimized structural parameters of KAB were found to be in good agreement with the experimental data. The electronic structure calculations suggested the covalent characters of N–H, B–H, and N–B as well as the ionic character of K. Moreover, we computed the 39K NMR parameters of KAB and several K-containing materials by using the gauge-including projector augmented wave (GIPAW) approach, and found that the precise theoretical predictions and assignments of 39K NMR parameters were possible. The DFT-GIPAW calculations were successfully applied to assign the 39K MAS NMR signals of KAB to the crystallographically inequivalent K1 and K2 sites.

87Sr Solid-State NMR as a Structurally Sensitive Tool for the Investigation of Materials: Antiosteoporotic Pharmaceuticals and Bioactive Glasses

Strontium is an element of fundamental importance in biomedical science. Indeed, it has been demonstrated that Sr(2+) ions can promote bone growth and inhibit bone resorption. Thus, the oral administration of Sr-containing medications has been used clinically to prevent osteoporosis, and Sr-containing biomaterials have been developed for implant and tissue engineering applications. The bioavailability of strontium metal cations in the body and their kinetics of release from materials will depend on their local environment. It is thus crucial to be able to characterize, in detail, strontium environments in disordered phases such as bioactive glasses, to understand their structure and rationalize their properties. In this paper, we demonstrate that (87)Sr NMR spectroscopy can serve as a valuable tool of investigation. First, the implementation of high-sensitivity (87)Sr solid-state NMR experiments is presented using (87)Sr-labeled strontium malonate (with DFS (double field sweep), QCPMG (quadrupolar Carr-Purcell-Meiboom-Gill), and WURST (wideband, uniform rate, and smooth truncation) excitation). Then, it is shown that GIPAW DFT (gauge including projector augmented wave density functional theory) calculations can accurately compute (87)Sr NMR parameters. Last and most importantly, (87)Sr NMR is used for the study of a (Ca,Sr)-silicate bioactive glass of limited Sr content (only ~9 wt %). The spectrum is interpreted using structural models of the glass, which are generated through molecular dynamics (MD) simulations and relaxed by DFT, before performing GIPAW calculations of (87)Sr NMR parameters. Finally, changes in the (87)Sr NMR spectrum after immersion of the glass in simulated body fluid (SBF) are reported and discussed.

Structural Investigation of α- and β-Sodium Hexafluoroarsenate, NaAsF6, by Variable Temperature X-ray Powder Diffraction and Multinuclear Solid-State NMR, and DFT Calculations

We report the phase transition between the α- and β-phases of NaAsF6 monitored by DTA, variable temperature 19F solid-state NMR and temperature controlled X-ray powder diffraction (XRPD) as well as their crystalline structures determined from XRPD data. The structural type of β-NaAsF6 has been determined thanks to 19F and 75As solid-state NMR experiments. 19F, 23Na, and 75As NMR parameters, including 19F–75As 1J coupling, have been measured for both phases. The 19F, 23Na, and 75As solid-state NMR investigations are in full agreement with both crystalline structures from a qualitative point of view. Chemical shielding tensors have been calculated from the gauge including projector augmented wave approach. The electric field gradient tensors of 23Na and 75As have been calculated in α-NaAsF6 from the all-electrons method and the projector augmented-wave approach. Two difficulties were encountered: the libration of the rigid and regular AsF6– anions in the β-phase, highlighted by the atomic anisotropic displacement parameters for F, which leads to erroneous shortened As–F bond length, and the overestimation of the As–F bond length with the PBE functional used in the density functional theory calculations. We show that both difficulties can be overcome by full optimization and rescaling of the cell parameters of the crystalline structures. Additionally, a linear correlation is observed between experimental 23Na δiso values and calculated 23Na σiso values from previously reported data and from our own measurements and calculations.

Solid‐state 11B and 13C NMR, IR, and X‐ray crystallographic characterization of selected arylboronic acids and their catechol cyclic esters

Nine arylboronic acids, seven arylboronic catechol cyclic esters, and two trimeric arylboronic anhydrides (boroxines) are investigated using (11)B solid-state NMR spectroscopy at three different magnetic field strengths (9.4, 11.7, and 21.1 T). Through the analysis of spectra of static and magic-angle spinning samples, the (11)B electric field gradient and chemical shift tensors are determined. The effects of relaxation anisotropy and nutation field strength on the (11)B NMR line shapes are investigated. Infrared spectroscopy was also used to help identify peaks in the NMR spectra as being due to the anhydride form in some of the arylboronic acid samples. Seven new X-ray crystallographic structures are reported. Calculations of the (11)B NMR parameters are performed using cluster model and periodic gauge-including projector-augmented wave (GIPAW) density functional theory (DFT) approaches, and the results are compared with the experimental values. Carbon-13 solid-state NMR experiments and spectral simulations are applied to determine the chemical shifts of the ipso carbons of the samples. One bond indirect (13)C-(11)B spin-spin (J) coupling constants are also measured experimentally and compared with calculated values. The (11)B/(10)B isotope effect on the (13)C chemical shift of the ipso carbons of arylboronic acids and their catechol esters, as well as residual dipolar coupling, is discussed. Overall, this combined X-ray, NMR, IR, and computational study provides valuable new insights into the relationship between NMR parameters and the structure of boronic acids and esters.