Gauge-including Atomic Orbitals Research Articles

Synthesis, experimental, theoretical characterization and biological activities of 4-ethyl-5-(2-hydroxyphenyl)-2H-1,2,4-triazole-3(4H)-thione

This work presents the characterization of 4-ethyl-5-(2-hydroxyphenyl)-2H-1,2,4-triazole-3(4H)-thione (III) by quantum chemical calculations and spectral techniques. The molecular geometry, vibrational frequencies and gauge including atomic orbital (GIAO) 1H and 13C NMR chemical shift values of III in the ground state have been calculated using the density functional method (B3LYP) with the 6-31G(d) basis set. The calculated results show that the optimized geometry can well reproduce the crystal structure, and the theoretical vibrational frequencies and chemical shift values show good agreement with experimental values. To determine conformational flexibility, the molecular energy profile of the title compound was obtained by DFT calculations with respect to the selected torsion angle, which was varied from −180° to +180° in steps of 10°. The energetic behavior of III in solvent media was examined using the B3LYP method with the 6-31G(d) basis set by applying the Onsager and the polarizable continuum model (PCM). The predicted nonlinear optical properties of III are greater than ones of urea. In addition, DFT calculations of molecular electrostatic potentials and frontier molecular orbitals of III were carried out at the B3LYP/6-31G(d) level of theory. The title compound was screened for antibacterial, antifungal and antioxidant activities.

Magnetic Shielding in and around Benzene and Cyclobutadiene: A Source of Information about Aromaticity, Antiaromaticity, and Chemical Bonding

A detailed picture of the variations in the isotropic shielding σ(iso)(r) in and around the classical examples of aromatic and antiaromatic systems, benzene and square cyclobutadiene, in terms of isosurfaces and contour plots, is obtained by calculating σ(iso)(r) values at fine regular three-dimensional 7 × 7 × 7 Å grids of points with a spacing of 0.05 Å, using π space complete-active-space self-consistent field (CASSCF) wave functions constructed from gauge-including atomic orbitals (GIAOs). The results demonstrate that the σ(iso)(r) values can be used not only to distinguish between aromatic and antiaromatic systems but also to characterize chemical bonds and investigate the extents to which these bonds are affected by the aromatic or antiaromatic nature of the molecule in which they reside. The strong bonding interactions within the benzene ring are highlighted by the fact that the carbon-carbon and carbon-hydrogen bonds are wrapped up within a doughnut-shaped region of increased shielding, which is especially high along the carbon-carbon bonds, with protrusions marking the carbon-hydrogen bonds. The antiaromatic destabilization in square cyclobutadiene is seen as the consequence of the presence of a markedly deshielded dumbbell-shaped region in the center of the molecule, which disrupts the connections between the shielded regions outlining individual carbon-carbon bonds, decreases the shielding within these regions, and displaces them to off-bond locations outside the ring. The well-known deshielding of aromatic protons and increased shielding of antiaromatic protons are shown to be accompanied by analogous shielding differences along the whole lengths of the carbon-hydrogen bonds, as a result of which the carbon-hydrogen bonds should become slightly weaker in aromatic systems as opposed to the corresponding bonds in antiaromatic systems.

A combined experimental and quantum chemical (DFT and AIM) study on molecular structure, spectroscopic properties, NBO and multiple interaction analysis in a novel ethyl 4-[2-(carbamoyl)hydrazinylidene]-3,5-dimethyl-1H-pyrrole-2-carboxylate and its dimer

In the present paper, a new ethyl 4-[2-(carbamoyl)hydrazinylidene]-3,5-dimethyl-1H-pyrrole-2-carboxylate (3) has been synthesized and characterized by 1H NMR, UV–Visible, FT-IR and Mass spectroscopy. The formation of the compound and its properties have also been evaluated by quantum chemical calculations using density functional theory (DFT), B3LYP functional and 6-31G(d,p) as basis set. The calculated thermodynamic parameters show that the formation of (3) is an exothermic and spontaneous reaction at room temperature. 1H NMR chemical shifts are calculated using gauge including atomic orbitals (GIAO) approach in DMSO-d6 as solvent. Time dependent density functional theory (TD-DFT) is used to calculate the energy (E), oscillator strength (f) and wavelength absorption maxima (λmax) of various electronic transitions and their nature within the molecule. NBO analysis is carried out to investigate the stabilization energy of various intra and intermolecular interactions in molecular system. The vibrational analysis indicates the formation of dimer in the solid state by intermolecular heteronuclear hydrogen bonding (NH⋯O) and the binding energy of dimer is calculated to be 10.40kcal/mol, using DFT calculations. Topological parameters at bond critical points (BCP) are calculated to analyze the strength and nature of various types of intra and intermolecular interactions in dimer by Bader’s ‘Atoms in molecules’ AIM theory in detail. The local reactivity descriptors such as Fukui functions (fk+,fk-), local softnesses (sk+,sk-) and electrophilicity indices (ωk+,ωk-) analyses are performed to determine the reactive sites within molecule.

Aluminum alkoxide complexes from highly substituted 3,4-epoxy alcohols: An NMR and computational study

The organoaluminum mediated epoxide ring opening of epoxy alcohols is a key step in the oxirane-based approach for polypropionate synthesis. However, this reaction has shown unanticipated regioselectivities when applied to 2-methyl-3,4-epoxy alcohols. In order to gain mechanistic insight into the factors controlling the epoxide ring opening process, diastereomeric 2-methyl-3,4-epoxy alcohols were reacted with triethylaluminum in order to identify the aluminum complexes formed by these systems. Different epoxide–aluminum complexes were calculated using ab initio HF/[13s7p/11s5p] and B3PW91/6-31G** gauge-including atomic orbital (GIAO) methods and compared to the experimental NMR data. The calculated and experimental data correlates with the aluminum dimer complex (TIPSOCH2CH(OAlEt2)CH(CH)3CHCH(O)(AlEt3))2 (VIII) for the systems favoring the nucleophilic attack at the external C4 epoxide carbon, while an unusual trialuminum species TIPSOCH2CH(OAlEt2)CH(CH)3CHCH(O)(AlEt3)2 (X) is consistent with the systems favoring the internal C3 attack. The 27Al NMR data established the tetracoordinated nature of the aluminum metal in all alkoxy aluminum intermediates, while the 13C NMR data provided insight into the aluminum-oxygen coordination. The formation of the complexes was dictated by the stereochemical disposition of the substituents. These complexes are different from the generally accepted bidentate intermediates proposed for 2,3-epoxy alcohols and simpler 3,4-epoxy alcohols. Copyright © 2012 John Wiley & Sons, Ltd.

Molecular structure and spectroscopic analysis of 1,4-Bis(1-methyl-2-benzimidazolyl)benzene; XRD, FT-IR, dispersive-Raman, NMR and DFT studies

This study reports the structural characterization of a bis-benzimidazole derivative, 1,4-Bis(1-methyl-2-benzimidazolyl)benzene (BMBB), by using spectroscopic and quantum chemical methods. The BMBB molecule was synthesized under microwave conditions and was characterized by using single-crystal X-ray diffraction, FT-IR, dispersive Raman and NMR spectroscopies. The potential energy surface scan study was carried out for the conformation of the theoretical structure. Quantum chemical calculations of relative energies, molecular geometry, vibrational wavenumbers, frontier molecular orbitals, atomic charges and gauge including atomic orbital (GIAO) 1H and 13C-NMR chemical shifts of the compound were carried out by using density functional method (DFT) at B3LYP/6-311++G(d,p) theory level. The complete assignments of the vibrational modes were performed with DFT calculations combined with scaled quantum mechanics force field (SQMFF) methodology. A satisfactory consistency between the experimental and theoretical findings was obtained. On account of the relative energies, population analysis and XRD results, the most stable conformational form of the molecule was also determined.

Spectroscopy studies, X-ray diffraction and DFT, HF calculations of 4-allyl-5-(thiophen-2-ylmethyl)-2H-1,2,4-triazol-3(4H)-one

In this work, 4-allyl-5-(thiophen-2-ylmethyl)-2H-1,2,4-triazol-3(4H)-one has been synthesized and characterized by using FT-IR, 1H NMR, UV–vis spectra and XRD (X-ray single crystal determination) experimentally and using B3LYP/6-31G(d), HF/6-31G(d) methods theoretically. The structure of compound is stabilized by two intermolecular hydrogen bonds and by intermolecular CH⋯π interaction. The molecular geometry, vibrational frequencies and Gauge Including Atomic Orbital (GIAO) 1H chemical shift values of the title compound in the ground state have been calculated using the density functional (B3LYP) and HF method with the 6-31G(d) basis set. The calculated results show that the optimized geometry parameters, the theoretical vibrational frequencies and chemical shift values show good agreement with experimental values. In addition, Mulliken atomic charges of the title compound were calculated and discussed. Besides HOMO–LUMO energy gap, molecular electrostatic potential map and electronic absorption spectra were performed at B3LYP/6-31G(d) level of theory and transition states were also mentioned.

Synthesis, antihistaminic action and theoretical studies of (4-methoxybenzyl)(1,4,5,6-tetrahydropirimidin-2-yl)amine hydroiodide

In this study, (4-methoxybenzyl)(1,4,5,6-tetrahydropyrimidin-2-yl)amine hydroiodide (2) was synthesized by reaction of 2-methylmercapto-1,4,5,6-tetrahydropyrimidine hydroiodide (1) and 4-methoxybenzylamine. The synthesized compound was tested for its in vitro H1-antihistaminic activity on guinea pig trachea. A promising bronchorelaxant effect of 2 was observed in histamine-contracted guinea pig tracheal chain via H1 receptor antagonism. In addition, the molecular geometry and gauge including atomic orbital (GIAO) 1H chemical shift values of the title compound in the ground state were calculated using the density functional method (DFT/UB3LYP) and Hartree–Fock (HF) approach using 6–311G+(d), 6–311G+(d,p), LANL2DZ, DGDZVP, and DGDZVP2 basis sets and compared with the experimental data. According to the experimental and theoretical results, HF/6–311G+(d) showed a better fit to experimental values in evaluating 1H-nuclear magnetic resonance (NMR) chemical shift values. Theoretical studies supported our findings, revealing the N12 atom as the most nucleophilic. In addition, other structures of the compound such as the aromatic ring and OCH3 group increased this property.

Density Functional Theory Study on Conformers of Benzoylcholine Chloride

The optimized molecular structures and vibrational frequencies and also gauge including atomic orbital (GIAO)1H and13C NMR shift values of benzoylcholine chloride [(2-benzoyloxyethyl) trimethyl ammonium chloride] have been calculated using density functional theory (B3LYP) method with 6-31++G(d) basis set. The comparison of the experimental and calculated infrared (IR), Raman, and nuclear magnetic resonance (NMR) spectra has indicated that the experimental spectra are formed from the superposition of the spectra of two lowest energy conformers of the compound. So, it was concluded that the compound simultaneously exists in two optimized conformers in the ground state. Also the natural bond orbital (NBO) analysis has supported the simultaneous exiting of two conformers in the ground state. The calculated optimized geometric parameters (bond lengths and bond angles) and vibrational frequencies for both the lowest energy conformers were seen to be in a well agreement with the corresponding experimental data.

An approach to evaluation of 19F‐NMR chemical shifts via basis functions analysis in fluorinated small compounds

AbstractAn extensive GIAO (gauge‐including atomic orbital) calculation has been made within Hartree‐Fock (HF), density functional theory (DFT) and second‐order Møller−Plesset perturbation theory (MP2), in conjunction with selected basis sets for the prediction of 19F chemical shift values of 26 different F nuclei in small fluorine‐containing molecules. The effect of four factors, namely, electron correlation treatment, triple‐ξ valence shell, diffuse function and polarization function were assessed using a systematic comparison of the results. Based on types of series, the optimized wave functions were proposed for different molecules. An additional comparison of the principal components of the shift tensor has been used as a supplementary study to confirm the validity of the results. For the series of molecules studied, the diffuse function is the most effective factor used in this applied model and the presence of polarization function is important to minimize the difference between theoretical and experimental values. By including the electron correlation treatment, DFT approach with large basis sets provides the most reliable results. In addition, two 24 factorial designs were considered to assess the reliability of applied scheme for selection the most efficient basis function and the results were discussed in this procedure. © 2012 Wiley Periodicals, Inc. Concepts Magn Reson Part A 40A: 192–204, 2012.

N-cyclohexyl-2-[5-(4-pyridyl)-4-(p-tolyl)-4H-1,2,4-triazol-3-ylsulfanyl]-acetamide dihydrate: Synthesis, experimental, theoretical characterization and biological activities

The triazol compound N-cyclohexyl-2-[5-(4-pyridyl)-4-(p-tolyl)-4H-1,2,4-triazol-3-ylsulfanyl]-acetamide dihydrate has been synthesized and characterized by 1H NMR, 13C NMR, IR, and X-ray single-crystal determination. The molecular geometry, vibrational frequencies and gauge including atomic orbital (GIAO) 1H and 13C NMR chemical shift values of III in the ground state have been calculated using the density functional method (B3LYP) with the 6-31G(d) basis set. The calculated results show that the optimized geometry can well reproduce the crystal structure, and the theoretical vibrational frequencies and chemical shift values show good agreement with experimental values. The energetic behavior of III in solvent media was examined using the B3LYP method with the 6-31G(d) basis set by applying the Onsager and the polarizable continuum model (PCM). The predicted nonlinear optical properties of III are greater than ones of urea. In addition, DFT calculations of molecular electrostatic potentials, frontier molecular orbitals and thermodynamic properties of III were carried out at the B3LYP/6-31G(d) level of theory. The title compound was screened for antibacterial, antifungal and antioxidant activities.

FT-IR, FT-Raman, NMR studies and ab initio-HF, DFT-B3LYP vibrational analysis of 4-chloro-2-fluoroaniline

The Fourier transform infrared (FT-IR) and Fourier transform Raman (FT-Raman) spectra of 4-chloro-2-fluoroaniline (CFA) have been recorded and analyzed. The equilibrium geometry, bonding features and harmonic vibrational frequencies have been investigated with the help of ab initio and density functional theory (DFT) methods. The assignments of the vibrational spectra have been carried out with the help of normal coordinate analysis (NCA) following the scaled quantum mechanical force field methodology. The 1H and 13C nuclear magnetic resonance (NMR) chemical shifts of the molecule are calculated by the Gauge including atomic orbital (GIAO) method. The first order hyperpolarizability (β0) of this novel molecular system and related properties (β, α0 and Δα) of CFA are calculated using B3LYP/6-311++G(d,p) and HF/6-311++G(d,p) methods on the finite-field approach. The calculated results also show that the CFA molecule might have microscopic nonlinear optical (NLO) behavior with non-zero values. Stability of the molecule arising from hyper conjugative interactions, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. The result confirms the occurrence of intramolecular charge transfer (ICT) within the molecule. The HOMO–LUMO energies UV–vis spectral analysis and MEP are performed by B3LYP/6-311++G(d,p) approach. A detailed interpretation of the infrared and Raman spectra of CFA is also reported based on total energy distribution (TED). The difference between the observed and scaled wave number values of the most of the fundamentals is very small.

6-Phenyl-3-(4-pyridyl)-1,2,4-triazolo-[3,4-b][1,3,4]thiadiazole: Synthesis, experimental, theoretical characterization and biological activities

The molecular geometry, vibrational frequencies, and gauge including atomic orbital (GIAO) 1H and 13C NMR chemical shift values of the title compound in the ground state have been calculated using the Hartree–Fock (HF) and density functional theory (DFT) methods with 6-31G(d) basis sets, and compared with the experimental data. The calculated results show that the optimized geometries can well reproduce the crystal structural parameters and the theoretical vibrational frequencies, and 1H and 13C NMR chemical shift values show good agreement with experimental data. To determine conformational flexibility, molecular energy profile of the title compound was obtained by HF/6-31G(d) and (DFT/B3LYP) calculations with respect to selected degree of torsional freedom, which was varied from −180° to +180° in steps of 10°. The energetic behavior of the title compound in solvent media was examined using the B3LYP method with the 6-31G(d) basis set by applying the Onsager and the polarizable continuum model (PCM). The results obtained with these methods reveal that the PCM method provided more stable structure than Onsager’s method. The title compound has been tested in vitro for biological effects.

Application of the Multi-standard Methodology for Calculating 1H NMR Chemical Shifts

Gauge including atomic orbitals (GIAO) (1)H NMR chemical shift calculations have been performed for 66 organic compounds at 72 different levels of theory using the multi-standard approach (MSTD) previously developed for (13)C NMR. This straightforward computational technique involves the combination of methanol and benzene as standards. The studied methodology has been shown to predict (1)H NMR chemical shifts efficiently at different levels of theory.

Aromaticity, Optical Properties and Zero Field Splitting of Homo- and Hetero-bimetallic (C8H8)M(μ2–,η8═C8H8)M(C8H8) where M = Ti, Zr, Th Complexes

This work presents a relativistic calculation of electron delocalization, optical properties, and zero field splitting in a group of molecules with the structure (C(8)H(8))M(μ(2)-,η(8)═C(8)H(8))M(C(8)H(8)), where M = Ti, Zr and Th. Additionally we also studied the heterobimetallic combinations (Ti-Th and Zr-Th). The molecular properties are discussed based on their electronic structure and the influence of the electron mobility in metal-metal communication. Nucleus independent chemical shift (NICS) was determined via the gauge-including-atomic-orbital (GIAO) method with the OPBE functional. The time-dependent density functional theory (TDDFT) was employed to calculate excitation energies, and the electronic transitions over 500 nm are presented with the objective to analyze the transition metal role as an antenna effect in the absorption band in the near-IR region. Finally the ZFS was calculated using Pederson-Khana and coupled perturbed DFT approaches implemented in the ORCA code. The contributions to spin-spin coupling (SS) and spin-orbit coupling (SOC) were analyzed, and the spin-density over the metal centers is discussed employing our scheme of metal-metal communication. Our aim is to determine the influence of the electronic structure over the optical and magnetic properties in a group of model compounds to understand the transition metals effect over these properties.

Synthesis, characterization and antimicrobial activity of m-toluenesulfonamide, N,N′-1,2-ethanediylbis (mtsen) and [Cu(II)(phenanthroline)2]mtsen complex

M-toluenesulfonamide, N,N′-1,2-ethanediylbis (a disulfonamide compound, mtsen) and [Cu(II)(phenanthroline)2]mtsen compounds were newly synthesized. The molecular structure of mtsen was investigated by using elemental analyses, liquid chromatography–mass spectrometry (LC–MS), X-ray diffraction, Fourier transform infrared spectroscopy (FT-IR), dispersive Raman spectroscopy, 1H, 13C, heteronuclear chemical-shift correlation (HETCOR) and correlation spectroscopy (COSY) NMR spectroscopies. The FT-IR, dispersive Raman and far-infrared spectra of mtsen were recorded at room-temperature and discussed assisted with B3LYP/6-311G(d,p) level of theory along with scaled quantum mechanics force field (SQM-FF) method. Furthermore, 1H and 13C NMR analyses were performed at B3LYP/6-311++G(d,p) theory level using gauge including atomic orbital (GIAO) method and compared with the experimental findings. Further analyses were also made for [Cu(II)(phenanthroline)2]mtsen complex by using elemental analysis, LC–MS, magnetic susceptibility; conductivity measurement and FT-IR. The antibacterial activities of synthesized compounds were studied against some Gram-positive and Gram-negative bacteria by using the microdilution and disk diffusion method. The biological activity screening showed that complex have more activity than ligand against the tested bacteria.

Synthesis of diosgenin p-nitrobenzoate by Steglich method, its crystal structure and quantum chemical studies

In the present study, a novel one pot synthetic route for the synthesis of diosgenin p-nitrobenzoate (2) is described from cheap, commercially available naturally occurring sapogenin–diosgenin. The molecular geometry, IR frequencies, Gauge-including atomic orbital (GIAO), 1H and 13C NMR chemical shifts of compound 2 has been calculated in the ground state by using the Hartree–Fock (HF) and density functional method (DFT/B3LYP) using 6-31G(d,p) basis set. The structure of diosgenin p-nitrobenzoate (2) has been confirmed by single crystal X-ray diffraction. The compound crystallizes in monoclinic form having space group P21 with cell parameters a=7.719(2)Å, b=8.425(2)Å and c=22.578(6)Å, α=90.00, β=98.46 and γ=90.00. The oxygen atoms O5 and O4 of the nitro and carbonyl ester, respectively display weak intermolecular N1O5⋯H7′ and C1′O4⋯H4′ interactions having dimensions of 2.61 and 2.59Å, respectively to form intricate 1D network. The study of the electronic properties such as HOMO and LUMO energy were performed using time dependent DFT (TD-DFT) calculations. The calculated HOMO and LUMO energy values indicate that charge transfer takes place within the molecule. The compound was screened for cytotoxicity and anti-adipogenic activity.

Ab initio and semi-empirical computational studies on 5-hydroxy-5,6-di-pyridin-2-yl-4,5-dihidro-2H-[1,2,4]triazine-3-thione

The title compound, 5-hydroxy-5,6-di-pyridin-2-yl-4,5-dihidro-2H-[1,2,4]triazine-3-thione (C13H11N5OS), was prepared and characterized by electronic spectroscopy and single-crystal X-ray diffraction (XRD). The compound crystallizes in the triclinic space group P-1 with a=8.5808(8)Å, b=8.7032(7)Å, c=10.0505(9)Å, α=84.194(7)°, β=75.181(7)° and γ=63.562(6)°. In addition to the molecular geometry, vibrational frequencies and gauge including atomic orbital (GIAO) 1H and 13C NMR chemical shift values of the title compound in the ground state have been calculated using the Hartree–Fock (HF) and density functional theory (DFT) methods with 6-31G(d) basis sets. To determine conformational flexibility, the molecular energy profile of the title compound was obtained by semi-empirical (AM1) calculations with respect to the selected torsion angle, which was varied from −180° to +180° in steps of 10°. The energetic behavior of the title compound in solvent media was examined using the B3LYP method with the 6-31G(d) basis set by applying the Onsager and the Polarizable Continuum Model (PCM). By using TD-DFT method, electronic absorption spectra of the title compound have been predicted and a good agreement with the TD-DFT method and the experimental one is determined. The predicted nonlinear optical properties of the title compound are much greater than ones of urea. In addition, the molecular electrostatic potential (MEP), frontier molecular orbitals (FMO) analysis and thermodynamic properties of the title compound were investigated using theoretical calculations.

13C GIAO DFT calculation as a tool for configuration prediction of N–O group in saturated heterocyclic N‐oxides

Tropane, tropinone, pseudopelletierine and cocaine were oxidized in situ in a nuclear magnetic resonance (NMR) tube providing mixtures of exo/endo N-oxides. Observed (13)C chemical shifts were correlated with values calculated by gauge-including atomic orbitals density functional theory (DFT) OPBE/6-31G* method using DFT B3LYP/6-31G* optimized geometries. The same method of (13)C chemical shift calculation was applied on series of methyl-substituted 1-methylpiperidines and their epimeric N-oxides described in literature. The results show that using this undemanding calculation method enables assignment of configuration of N-O group in N-epimeric saturated heterocyclic N-oxides. The approach enables assigning of the configuration with high degree of certainty even if NMR data of only one isomer are available. An improved method of in situ oxidation of starting amines in an NMR tube is also described.

Synthesis, crystal structure, computational study of 1-(6-chloro-pyridin-2-yl)-5-hydroxy-1H-pyrazole-3-carboxylic acid methyl ester and its 5-acetoxy analogs

Two new pyrazole derivatives of 1-(6-chloro-pyridin-2-yl)-5-hydroxy-1H-pyrazole-3-carboxylic acid methyl ester 1a and 5-acetoxy-1-(6-chloro-pyridin-2-yl)-1H-pyrazole-3-carboxylic acid methyl ester 2 were synthesized and characterized by 1H, 13C NMR, IR spectroscopies and HRMS analyses. The molecular structure of 1a and 2 were studied by X-ray diffraction and compared to density-functional-theory (DFT) calculations. The gauge-including atomic orbital (GIAO) method for calculating 1H and 13C NMR nuclear magnetic shielding tensors at the DFT method with 6-31+G* basis set were applied to the compounds 1a and 2. Additionally, thermodynamic properties of the cyclization of the compound 3 to these compounds (1a,1b,1c,4) were investigated by theoretical calculations. These theoretical calculations was shown that the compound 1a was readily formed and was the most stable one. Tautomeric forms of the compound 1a were optimized at the same methods and basis set. The calculated relative Gibbs free energies of the tautomeric forms of 1a were used to estimate the equilibrium constants. It was shown that the 1a was the most stable than tautomer of 1b and 1c in the gas phase.

On the use of effective core potentials in the calculation of magnetic properties, such as magnetizabilites and magnetic shieldings

State-of-the art effective core potentials (ECPs) that replace electrons of inner atomic cores involve non-local potentials. If such an effective core potential is added to the Hamiltonian of a system in a magnetic field, the resulting Hamiltonian is not gauge invariant. This means, magnetic properties such as magnetisabilities and magnetic shieldings (or magnetic susceptibilities and nuclear magnetic resonance chemical shifts) calculated with different gauge origins are different even for exact solutions of the Schrödinger equation. It is possible to restore gauge invariance of the Hamiltonian by adding magnetic field dependent terms arising from the effective core potential. Numerical calculations on atomic and diatomic model systems (potassium mono-cation and potassium dimer) clearly demonstrate that the standard effective core potential Hamiltonian violates gauge invariance, and this affects the calculation of magnetisabilities more strongly than the calculation of magnetic shieldings. The modified magnetic field dependent effective core potential Hamiltonian is gauge invariant, and therefore it is the correct starting point for distributed gauge origin methods. The formalism for gauge including atomic orbitals (GIAO) and individual gauge for localized orbitals methods is worked out. ECP GIAO results for the potassium dimer are presented. The new method performs much better than a previous ECP GIAO implementation that did not account for the non-locality of the potential. For magnetic shieldings, deviations are clearly seen, but they amount to few ppm only. For magnetisabilities, our new ECP GIAO implementation is a major improvement, as demonstrated by the comparison of all-electron and ECP results.