Interactions intramoleculaires: XXII—Constantes de couplage, équilibres conformationnels et interactions gauches avec un groupement t-butyle (molécules cyclohexéniques deutériées)

The NMR parameters are determined for a series of disubstituted (R = CH₃, (CH₃)₃C; X = COOCH₃, CN) and specifically deuterated cyclohexenes. The ³ J(HH), ³J(HD), ⁴J(HH) and ⁵ J(HH) coupling constants are used to evaluate the conformational equilibria. Three of the five compounds with an allylic t-butyl substituent, are conformationally heterogeneous; these equilibria, and those between stereoisomers are used for an analysis of this phenomenon, carried out within the framework of the hypothesis of additivity of conformational free energies and gauche interactions.     

Préparation de phosphonates de sucres ramifiés par addition nucléophile conjuguée. Communication préliminaire

Preparation of unsaturated sugars phosphonates using nucleophilic conjugate addition Different types of phosphorus nucleophiles underwent conjugate addition reaction with one of the branched-chain sugars 4, 5 or 11 the addition taking place either on the endo or the exo face of the furanose ring (or on both faces in the case of 11 ). The configuration at C(3) of these new phosphorus-bearing types of sugars as well as the configuration at the phosphorus atom of the cyclic phosphinates 9 and 10 was established by NMR. (³J_P,H–C(2), ³J_P,C(1)). Small amounts (7%) of the spiro enol phosphonate 16 were formed when 11 reacted with trimethyl phosphite.     

Interactions intramoleculaires. XXI—Constantes de couplage et interactions gauches avec un groupement t-butyle (molécules cyclohexaniques deutériées)

Different isotopic modifications of deuterated products of 1-t-butlyl-4-methoxycarbonyl cyclohexene (d₄-3,3,6,6), cis- and trans-3-methyl-4-cyanocyclohexene (d₃-3,6,6), cis- and trans-3-methyl-4-cyanocyclohexene (d₃,6,6), cis- and trans-3-t-butyl-4-methoxycarbonylcyclohexene (d₃,-3,6,6) are shown by nuclear magnetic resonance spectral analysis. By comparison of ³J and ⁴J coupling constants of model molecules and molecules with large gauche interactions, we obtain proof that the latter are in a chair conformation with moderate cycle deformations.     

The conformation of (1R,2S,4R,5S)-2,4-dimethoxybicyclo[3.3.1]nonan-9-one and some related compounds

A mixture of stereoisomers of 2,4-dimethoxybicyclo[3.3.1]nonan-9-one was prepared, separated by column chromatography and characterized by 60 MHz ¹H NMR spectroscopy using Eu(fod)₃. A double chair conformation with axial methoxyl groups is established for (1R,2S,4R,5S)-2,4-dimethoxybicyclo[3.3.1]-nonan-9-one on the basis of the J(12), J(2,H-3 exo) and J(2,3 endo) values and the chemical shifts for H-2(4). The conformation of some related compounds is subsequently inferred.     

One‐Dimensional Ferromagnetically Coupled Bimetallic Chains Constructed with trans‐[Ru(acac)2(CN)2]−: Syntheses,Structures, Magnetic Properties,and Density Functional Theoretical Study

Four cyano‐bridged 1D bimetallic polymers have been prepared by using the paramagnetic building block trans‐[Ru(acac)₂(CN)₂]^? (Hacac=acetylacetone): {[{Ni(tren)}{Ru(acac)₂(CN)₂}][ClO₄]?CH₃OH}_n ( 1 ) (tren=tris(2‐aminoethyl)amine), {[{Ni(cyclen)}{Ru(acac)₂(CN)₂}][ClO₄]? CH₃OH}_n ( 2 ) (cyclen=1,4,7,10‐tetraazacyclododecane), {[{Fe(salen)}{Ru(acac)₂(CN)₂}]}_n ( 3 ) (salen^2?=N,N′‐bis(salicylidene)‐o‐ethyldiamine dianion) and [{Mn(5,5′‐Me₂salen)}₂{Ru(acac)₂(CN)₂}][Ru(acac)₂(CN)₂]? 2 CH₃OH ( 4 ) (5,5′‐Me₂salen=N,N′‐bis(5,5′‐dimethylsalicylidene)‐o‐ethylenediimine). Compounds 1 and 2 are 1D, zigzagged NiRu chains that exhibit ferromagnetic coupling between Ni^II and Ru^III ions through cyano bridges with J=+1.92 cm^?1, z J′=?1.37 cm^?1, g=2.20 for 1 and J=+0.85 cm^?1, z J′=?0.16 cm^?1, g=2.24 for 2 . Compound 3 has a 1D linear chain structure that exhibits intrachain ferromagnetic coupling (J=+0.62 cm^?1, z J′=?0.09 cm^?1, g=2.08), but antiferromagnetic coupling occurs between FeRu chains, leading to metamagnetic behavior with T_N=2.6 K. In compound 4 , two Mn^III ions are coordinated to trans‐[Ru(acac)₂(CN)₂]^? to form trinuclear Mn₂Ru units, which are linked together by π–π stacking and weak Mn???O* interactions to form a 1D chain. Compound 4 shows slow magnetic relaxation below 3.0 K with ?=0.25, characteristic of superparamagnetic behavior. The Mn^III???Ru^III coupling constant (through cyano bridges) and the Mn^III???Mn^III coupling constant (between the trimers) are +0.87 and +0.24 cm^?1, respectively. Compound 4 is a novel single‐chain magnet built from Mn₂Ru trimers through noncovalent interactions. Density functional theory (DFT) combined with the broken symmetry state method was used to calculate the molecular magnetic orbitals and the magnetic exchange interactions between Ru^III and M (M=Ni^II, Fe^III, and Mn^III) ions. To explain the somewhat unexpected ferromagnetic coupling between low‐spin Ru^III and high‐spin Fe^III and Mn^III ions in compounds 3 and 4 , respectively, it is proposed that apart from the relative symmetries, the relative energies of the magnetic orbitals may also be important in determining the overall magnetic coupling in these bimetallic assemblies.     

Alcoxyflurophosphoranes. II—Monoalcoxyfluorophosphoranes possédant un centre d'asymétrie; diastéréotopie des fluors apicaux

Twenty-six monoalkoxyfluorophosphoranes bearing an asymmetric substituent of types R¹PF₃(OR²*)( 1 ), R¹*PF₃(OR²) ( 2 ), R¹R³PF₂(OR²* 3 ) and R₂¹PF₂(OR²*)( 4 ), have been prepared. The non-equivalence of the axial fluorine atoms is observed in the ¹⁹F NMR spectra for the compounds of types 1 δ_F′a – δ_F′a ～ 0·5 to 3·8 ppm, J(F_aF′_a) ～ 10 Hz, 2 δ_Fa – δ_F′a ～ 1·1 to 1·5 ppm, J(F_aF′_a) ～ 14 Hz and 3 δ_Fa – δ_Fa ～ 0·2 ppm, J(F_aF′_a) ～ 10 Hz but not for those of type 4 R₁²PF₂(OR²*). Its origin is assigned to the diastereotopic character of these fluorines. The possibility of a hindered rotation of the substituents as the origin of the phenomenon is excluded. The preparation of sec-BuPF₄ and EtPhPF₃ is also reported.     

Magnetic Properties of a Single‐Molecule Lanthanide–Transition‐Metal Compound Containing 52 Gadolinium and 56 Nickel Atoms

Monodisperse metal clusters provide a unique platform for investigating magnetic exchange within molecular magnets. Herein, the core–shell structure of the monodisperse molecule magnet of [Gd₅₂Ni₅₆(IDA)₄₈(OH)₁₅₄(H₂O)₃₈]@SiO₂ ( 1 a @SiO₂) was prepared by encapsulating one high‐nuclearity lanthanide–transition‐metal compound of [Gd₅₂Ni₅₆(IDA)₄₈(OH)₁₅₄(H₂O)₃₈]?(NO₃)₁₈?164 H₂O ( 1 ) (IDA=iminodiacetate) into one silica nanosphere through a facile one‐pot microemulsion method. 1 a @SiO₂ was characterized using transmission electron microscopy, N₂ adsorption–desorption isotherms, and inductively coupled plasma‐atomic emission spectrometry. Magnetic investigation of 1 and 1 a revealed J₁=0.25 cm^?1, J₂=?0.060 cm^?1, J₃=?0.22 cm^?1, J₄=?8.63 cm^?1, g=1.95, and z J=?2.0×10^?3 cm^?1 for 1 , and J₁=0.26 cm^?1, J₂=?0.065 cm^?1, J₃=?0.23 cm^?1, J₄=?8.40 cm^?1 g=1.99, and z J=0.000 cm^?1 for 1 a @SiO₂. The z J=0 in 1 a @SiO₂ suggests that weak antiferromagnetic coupling between the compounds is shielded by silica nanospheres.     

Interactions Intramolécularies—XVII Calcul des constantes de couplage en RMN du cyclohexane et de cyclohexanes substitués. Comparaison des méthodes de Pople et Santry et des perturbations finies

Proton–proton ³J, ⁴J and ⁵J NMR coupling constants have been calculated for cyclohexane and monosubstituted cyclohexane conformers (substitiuents: Li, CH₃, OH, F) by the two methods mentioned. Comparing the two methods on the basis of group theory, we show the necessity to use the second. The results from this method are compared with those of the literature.     

Bestimmung der Struktur von Phenyläthinyllithium in Lösung mittels Tieftemperatur-NMR-Spektroskopie

The dimeric and tetrametic structures of complexes of phenylethinyllithium, as recently discovered by X-ray analysis in the solid state, were also found to be present in solution. Tetrahydrofuran solutions of 1-(⁶Li)-[1-¹³C]-2-phenylethyne in the presence or absence of N,N,N′,N′-tetramethylpolymethylenediamines show a pentuplett ¹³C-NMR signal [δ=140 ppm, J(C,Li)=8.2 Hz] from the labelled C-atom at low temperatures (?95 to ?110°). This proves the dimeric structure. When (⁶Li)BuLi is added, a mixed dimer [(C₆H₅C?CLi)(C₄H₉Li)] is formed [δ=142 ppm, J(C,Li) = 7.8 Hz]. This is converted to a mixed tetramer [(C₆H₅C?CLi)(C₄H₉Li)₃] upon addition of larger amounts of (⁶Li)BuLi, as concluded from a signal at δ = 133.5 ppm, J(C,Li) = 5.6 Hz. The multiplicity of this signal suggests that a static tetramer is present, in which the C-atoms couple only with three next Li-neighbors.     

Détermination par RMN 1H et 13C des Couplages J(CH) et J(CC) dans des Monomères Precurseurs de Lignine: Vanilline,Férulate d'Ethyle et Alcool Coniférylique Sélectivement Enrichis en 2H et 13C

Some monomer model compounds of lignin have been selectively ²H and ¹³C labelled: vanillin, ethyl ferulate, coniferyl alcohol and ethyl hydrogen malonate. Deuterium isotope effects on the ¹³C chemical shifts in [formyl-²H]vanillin, [5-²H]vanillin and [α,α,5-²H₃]coniferyl alcohol made the unambiguous assignment of the aromatic ¹³C signals possible. Absolute ^1,2,3J(CC) values have been determined on ¹³C spectra of [formyl-¹³C]vanillin, and of ethyl ferulate and coniferyl alcohol in which the vinylic C-γ and C-β carbons were ¹³C enriched. It has been possible to measure ⁴J(C?O, C-4) in vanillin and ⁴J(C-γ, C-4) in ethyl ferulate. The determination of ^1,2,3,4J (CH) absolute values was done by means of gated decoupled ¹³C spectra of the non-labelled compounds. When second order effects made the use of this technique impossible we determined certain J(CH) values and their signs either by analysing the ¹H NMR spectra of ¹³C labelled coniferyl alcohol [²J(C-β, H-γ), ²J(C-β, H-α), ²J(C-γ, H-β), ³J(C-γ, H-α)] or by a double irradiation experiment on the 250 MHz ¹H NMR spectrum of ethyl [β-¹³C] ferulate [for ²J(C-β, H-γ)].     

Synthesis,Crystal Structure and Magnetic Properties of a 1‐D Polymer, [Cu(NITpPy)2(H2TCB)(H20)]·2H2O

A novel complex [Cu(NnpPy)₂(H_lTCB)(H₁O)]·2H₂O (NITpPy = 2‐(pyrid‐4′‐yl)‐4,4,5,5‐tetramethyl‐1, 3‐dioxoimidazoline; H₂TCB = 1, 5‐dicarboxybenzene carboxylic‐2, 4‐diacid) has been synthesized and characterized by X‐ray crystallography analysis. The crystal structure consists of infinite chains of Cu‐(NITpPy)₂(H₂O) units linked by H₂TCB ligands. The complex crystallizes in triclinic system with space group PI. Crystal data: a = 1.0594(2) nm, b = 1.3830(3) nm, c = 1.5551(3) nm, a = 67.75(3)°, β = 89.83(3)°, γ = 70.54(3)°. The variable magnetic susceptibility studies lead to magnetic coupling constant values of J₁= ?11.18 cm‐¹ (Cu—Rad) and J₂ = ?4.06 cm^?1 (Cu—Cu).     

The synthesis,NMR (1H, 13C, 119Sn) and IR spectral studies of some di‐ and tri‐organotin(IV) sulfonates: X‐ray crystal structure of [(n‐C4H9)2Sn(OSO2C6H4CH3‐4)2·2H2O]

A number of alkyltin(IV) paratoluenesulfonates, R_nSn(OSO₂C₆H₄CH₃‐4)_4?n (n = 2, 3; R = C₂H₅, n‐C₃H₇, n‐C₄H₉), have been prepared and IR spectra and solution NMR (¹H, ¹³C, ¹¹⁹Sn) are reported for these compounds, including (n‐C₄H₉)₂Sn(OSO₂X)₂ (X = CH₃ and CF₃), the NMR spectra of which have not been reported previously. From the chemical shift δ(¹¹⁹Sn) and the coupling constants ¹J(¹³C, ¹¹⁹Sn) and ²J(¹H, ¹¹⁹Sn), the coordination of the tin atom and the geometry of its coordination sphere in solutions of these compounds is suggested. IR spectra of the compounds are very similar to that observed for the paratoluenesulfonate anion in its sodium salt. The studies indicate that diorganotin(IV) paratoluenesulfonates, and the previously reported compounds (n‐C₄H₉)₂Sn(OSO₂X)₂ (X = CH₃ and CF₃), contain bridging SO₃X groups that yield polymeric structures with hexacoordination around tin and contain non‐linear C? Sn? C bonds. In triorganotin(IV) sulfonates, pentacoordination for tin with a planar SnC₃ skeleton and bidentate bridging paratoluenesulfonate anionic groups are suggested by IR and NMR spectral studies. The X‐ray structure shows [(n‐C₄H₉)₂Sn(OSO₂C₆H₄CH₃‐4)₂·2H₂O] to be monomeric containing six‐coordinate tin and crystallizes from methanol–chloroform in monoclinic space group C2/c. The Sn? O (paratoluenesulfonate) bond distance (2.26(2) Å) is indicative of a relatively high degree of ionic character in the metal–anion bonds. Copyright © 2003 John Wiley & Sons, Ltd.     

Etude par Résonance Magnétique Nucléaire de dérivés phosphores. Etude de dithiaphospholanes-1,3,2

The proton NMR spectral analysis of eight different 1,3,2-dithiaphospholanes with various groups attached to the phosphorus atom has been performed. The AA′BB′X (X phosphorus atom) system shows that the two ³J(P? S? C? H) coupling constants have a small magnitude and opposite signs. Using the ³J(HH) values, the torsion about the C₄—C₅ bond has been evaluated. The conformational requirements in the two isomers of the 2 phenyl-4-methyl-1,3,2-dithiaphospholane are also discussed.     

Etude RMN de β-hydroxy-phosphonates-esters. Détermination du signe du couplage stéréospécifique 4J(P?C?C?O?H) dans le diastéréoisomère RS,RS

INDOR experiments indicate ⁴J(P? C? C? O? H) to be positive for the β-hydroxyphosphonate ester RS,RS dissolved in (CD₃)₂CO or (CD₃)₂SO. The higher value observed in (CD₃)₂SO than in (CD₃)₂CO shows that a W geometry makes this coupling constant more positive.     

Dérivés Alléniques du Phosphore. Influence de l'État de Coordination du Phosphore et de la Nature des Radicaux Liés au Phosphore sur les Signes de J(P?H)

The signs of the phosphorus-proton coupling constants in various allenic organophosphorus compounds have been determined by either analysis of the AB₂X spectra or double resonance. Probable absolute signs have been obtained by taking ³J(P? H) as positive. In allenic phosphine oxides, the following signs are obtained: ²J(P? H) +ve, ³J(P? H) +ve, ⁴J(P? H) ?ve, ⁵J(P? H) +ve and the ⁴J(P? H) coupling constant varies mostly with the inductive effect of the substituents bound to the phosphorus atom. In allenic phosphines, these sings are: ²J(P? H) +ve, ³J(P? H) +ve, ⁴J(P? H) ?ve and +ve and the ⁴J(P? H) coupling constant varies with both the inductive and resonance effects to the substituents. This coupling constant is negative except when the phosphorus atom is bound to groups which are electron-donating by resonance effects. These results are discussed in relation to the pπ? dπ bonding in phosphine.     

HMBC‐1,n‐ADEQUATE spectra calculated from HMBC and 1,n‐ADEQUATE spectra

Unsymmetrical and generalized indirect covariance processing methods provide a means of mathematically combining pairs of 2D NMR spectra that share a common frequency domain to facilitate the extraction of correlation information. Previous reports have focused on the combination of HSQC spectra with 1,1‐, 1,n‐, and inverted ¹J_CC 1,n‐ADEQUATE spectra to afford carbon–carbon correlation spectra that allow the extraction of direct (¹J_CC), long‐range (ⁿJ_CC, where n ≥ 2), and ¹J_CC‐edited long‐range correlation data, respectively. Covariance processing of HMBC and 1,1‐ADEQUATE spectra has also recently been reported, allowing convenient, high‐sensitivity access to ⁿJ_CC correlation data equivalent to the much lower sensitivity n,1‐ADEQUATE experiment. Furthermore, HMBC‐1,1‐ADEQUATE correlations are observed in the F₁ frequency domain at the intrinsic chemical shift of the ¹³C resonance in question rather than at the double‐quantum frequency of the pair of correlated carbons, as visualized by the n,1, and m,n‐ADEQUATE experiments, greatly simplifying data interpretation. In an extension of previous work, the covariance processing of HMBC and 1,n‐ADEQUATE spectra is now reported. The resulting HMBC‐1,n‐ADEQUATE spectrum affords long‐range carbon–carbon correlation data equivalent to the very low sensitivity m,n‐ADEQUATE experiment. In addition to the significantly higher sensitivity of the covariance calculated spectrum, correlations in the HMBC‐1,n‐ADEQUATE spectrum are again detected at the intrinsic ¹³C chemical shifts of the correlated carbons rather than at the double‐quantum frequency of the pair of correlated carbons. HMBC‐1,n‐ADEQUATE spectra can provide correlations ranging from diagonal (⁰J_CC or diagonal correlations) to ⁴J_CC under normal circumstances to as much as ⁶J_CC in rare instances. The experiment affords the potential means of establishing the structures of severely proton‐deficient molecules. Copyright © 2013 John Wiley & Sons, Ltd.     

Caesiumchromhalogenide Cs3CrCl6, Cs3Cr2Cl9 und Cs3CrBr6 – Darstellung,Eigenschaften, Kristallstruktur

Cesium Chromium Halides Cs₃CrCl₆, Cs₃Cr₂Cl₉, and Cs₃CrBr₆ – Preparation, Properties, Crystal Structure The crystal structures of Cs₃CrCl₆ and Cs₃Cr₂Cl₉ were determined and redetermined by X‐ray single‐crystal studies (space group Pnnm, Z = 6, a = 1115.6(2) pm, b = 2291.3(5) pm, c = 743.8(1) pm, R_f = 7.73%, 1025 unique reflections with I > 2σ(I) (Cs₃CrCl₆); P6₃/mmc, Z = 2, a = 721.7(2) pm und c = 1791.0(1) pm; R_f = 2.06%, 395 unique reflections with I > 2.5σ(I) (Cs₃Cr₂Cl₉). The structure of Cs₃CrCl₆ consists of two different isolated CrCl₆ octahedra and five crystallographic different Cs⁺ ions. The CrCl₆ octahedra form ropes in the direction [001]. Because of orientational disordering of the Cr(1)Cl₆ octahedra and the an only half‐occupation of some cesium and chlorine sites Cs₃CrCl₆ is strongly disordered in direction of the (020) plane. The ionic conductivity of Cs₃CrCl₆, which was expected owing to the great disorder, however, is with 7.3 × 10^–5 Ω^–1 cm^–1 at 740 K relatively small. The compound Cs₃CrBr₆, which was firstly prepared by quenching stoichiometric amounts of CsBr and CrBr₃ from 833 K, is metastable at ambient temperature. It is probably isostructural to Cs₃CrCl₆ as shown by X‐ray powder photographs.     

Magnetic Properties of Mixed Ligand NiII2 and NiII4 Complexes Composed of Macrocyclic Hexaamine‐Dithiophenolato and Bridging Tetrazolato Ligands

The magnetic properties of the dinuclear and tetranuclear nickel(II) tetrazolato complexes [Ni₂L(RCN₄)][BPh₄] (R = H ( 4 ), Me ( 5 ), Ph ( 6 )) and [(Ni₂L)₂(1,4‐(CN₄)₂‐C₆H₄)][BPh₄]₂ ( 7 ), where (L)^2– represents a 24‐membered macrocyclic N₆S₂ supporting ligand, are reported. Analysis of temperature‐dependent magnetic susceptibility measurements over the temperature range from 2 to 300 K revealed the presence of weak ferromagnetic exchange interactions between the Ni^II ions in the binuclear [Ni₂L(μ‐L′)]⁺ subunits with magnetic exchange coupling constant values of J₁ = 13.5 cm^–1 for 4 , J₁ = 20.0 cm^–1 for 5 , J₁ = 19.2 cm^–1 for 6 , and J₁ = 15.2 cm^–1 for 7 ( H = –2JS₁S₂). The exchange coupling J₂ across the bistetrazolato bridge in 7 is less than 0.1 cm^–1, which suggests that no significant interdimer coupling occurs in this compound. The synthesis and crystal structure of the new complex 7 ·2MeCN is also reported.     

First example of the correlated calculation of the one‐bond tellurium–carbon spin–spin coupling constants: Relativistic effects,vibrational corrections,and solvent effects

This work reports on the comprehensive calculation of the NMR one‐bond spin–spin coupling constants (SSCCs) involving carbon and tellurium, ¹J(¹²⁵Te,¹³C), in four representative compounds: Te(CH₃)₂, Te(CF₃)₂, Te(C?CH)₂, and tellurophene. A high‐level computational treatment of ¹J(¹²⁵Te,¹³C) included calculations at the SOPPA level taking into account relativistic effects evaluated at the 4‐component RPA and DFT levels of theory, vibrational corrections, and solvent effects. The consistency of different computational approaches including the level of theory of the geometry optimization of tellurium‐containing compounds, basis sets, and methods used for obtainig spin–spin coupling values have also been discussed in view of reproducing the experimental values of the tellurium–carbon SSCCs. Relativistic corrections were found to play a major role in the calculation of ¹J(¹²⁵Te,¹³C) reaching as much as almost 50% of the total value of ¹J(¹²⁵Te,¹³C) while relativistic geometrical effects are of minor importance. The vibrational and solvent corrections account for accordingly about 3–6% and 0–4% of the total value. It is shown that taking into account relativistic corrections, vibrational corrections and solvent effects at the DFT level essentially improves the agreement of the non‐relativistic theoretical SOPPA results with experiment. © 2016 Wiley Periodicals, Inc.     

Observation of Slow Relaxation and Single‐Molecule Toroidal Behavior in a Family of Butterfly‐Shaped Ln4 Complexes

A family of five isostructural butterfly complexes with a tetranuclear [Ln₄] core of the general formula [Ln₄(LH)₂(μ₂‐η¹η¹Piv)(η²‐Piv)(μ₃‐OH)₂]?x H₂O?y MeOH?z CHCl₃ ( 1 : Ln=Dy^III, x=2, y=2, z=0; 2 : Ln=Tb^III, x=0, y=0, z=6; 3 : Ln=Er^III, x=2, y=2, z=0; 4 : Ln=Ho^III, x=2, y=2, z=0; 5 : Ln=Yb^III, x=2, y=2, z=0; LH₄=6‐{[bis(2‐hydroxyethyl)amino]methyl}‐N′‐(2‐hydroxy‐3‐methoxybenzylidene)picolinohydrazide; PivH=pivalic acid) was isolated and characterized both structurally and magnetically. Complexes 1 – 5 were probed by direct and alternating current (dc and ac) magnetic susceptibility measurements and, except for 1 , they did not display single‐molecule magnetism (SMM) behavior. The ac magnetic susceptibility measurements show frequency‐dependent out‐of‐phase signals with one relaxation process for complex 1 and the estimated effective energy barrier for the relaxation process was found to be 49 K. We have carried out extensive ab initio (CASSCF+RASSI‐SO+SINGLE_ANISO+POLY_ANISO) calculations on all the five complexes to gain deeper insights into the nature of magnetic anisotropy and the presence and absence of slow relaxation in these complexes. Our calculations yield three different exchange coupling for these Ln₄ complexes and all the extracted J values are found to be weakly ferro/antiferromagentic in nature (J₁=+2.35, J₂=?0.58, and J₃=?0.29 cm^?1 for 1 ; J₁=+0.45, J₂=?0.68, and J₃=?0.29 cm^?1 for 2 ; J₁=+0.03, J₂=?0.98, and J₃=?0.19 cm^?1 for 3 ; J₁=+4.15, J₂=?0.23, and J₃=?0.54 cm^?1 for 4 and J₁=+0.15, J₂=?0.28, and J₃=?1.18 cm^?1 for 5 ). Our calculations reveal the presence of very large mixed toroidal moment in complex 1 and this is essentially due to the specific exchange topology present in this cluster. Our calculations also suggest presence of single‐molecule toroics (SMTs) in complex 2 . For complexes 3 – 5 on the other hand, the transverse anisotropy was computed to be large, leading to the absence of slow relaxation of magnetization. As the magnetic field produced by SMTs decays faster than the normal spin moments, the concept of SMTs can be exploited to build qubits in which less interference and dense packing are possible. Our systematic study on these series of Ln₄ complexes suggest how the ligand design can help to bring forth such SMT characteristics in lanthanide complexes.