Charge density analysis for crystal engineering

Chemistry Central Journal

Anna Krawczuk²  Piero Macchi¹ 

[1] Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, Bern 3012, Switzerland

[2] Faculty of Chemistry, Jagiellonian University, Ingardena 3, Krakow 30-060, Poland

关键词: X-ray diffraction;    Supramolecular chemistry;    Crystal engineering;    Charge density analysis;   

Others  :  1213788
DOI  :  10.1186/s13065-014-0068-x

 received in 2014-07-10, accepted in 2014-10-30,  发布年份 2014

【 摘 要 】

This review reports on the application of charge density analysis in the field of crystal engineering, which is one of the most growing and productive areas of the entire field of crystallography.

While methods to calculate or measure electron density are not discussed in detail, the derived quantities and tools, useful for crystal engineering analyses, are presented and their applications in the recent literature are illustrated. Potential developments and future perspectives are also highlighted and critically discussed.

【 授权许可】

   
2014 Krawczuk and Macchi; licensee Chemistry Central Ltd.

【 图 表 】

Figure 1.

Figure 2.

Figure 3.

Figure 4.

Figure 5.

【 参考文献 】

• [1]Pepinsky R: Crystal Engineering: New Concepts in Crystallography. Phys Rev 1955, 100:971.
• [2]Schmidt GMJ: Photodimerization in the solid state. Pure Appl Chem 1971, 27:647-678.
• [3]Desiraju GR: Crystal engineering: A brief overview. J Chem Sci 2010, 122:667-675.
• [4]Figgis BN, Hitchman MA: Ligand Field Theory and Its Applications. Wiley-VCH, New York; 2000.
• [5]Jeffrey GA: An Introduction to Hydrogen Bonding. Oxford University Press, Oxford; 1997.
• [6]Peresypkina EV, Blatov VA: Topology of molecular packings in organic crystals. Acta Cryst 2000, B56:1035-1045.
• [7]Debye P: Zerstreuung von Röntgenstrahlen. Ann Phys 1915, 46:809-823.
• [8]Coppens P: Comparative X-Ray and Neutron Diffraction Study of Bonding Effects in s-Triazine. Science 1967, 158:1577-1579.
• [9]Coppens P: X-Ray charge densities and chemical bonding. Oxford University Press, Oxford; 1997.
• [10]Bader RFW: Atoms in Molecules: a quantum theory. Oxford University Press, Oxford; 1990.
• [11]Macchi P, Sironi A: Chemical bonding in transition metal carbonyl clusters: complementary analysis of theoretical and experimental electron densities. Coord Chem Rev 2003, 238:383-412.
• [12]Stalke D: Meaningful Structural Descriptors from Charge Density. Chem. Eur J 2011, 17:9264-9278.
• [13]Flaig R, Koritsanszky T, Dittrich B, Wagner A, Luger P: Intra- and intermolecular topological properties of amino acids:A comparative study of experimental and theoretical results. J Am Chem Soc 2002, 124:3407-3417.
• [14]Kubicki M, Borowiak T, Dutkiewicz G, Souhassou M, Jelsch C, Lecomte C: Experimental electron density of 1-phenyl-4-nitroimidazole and topological analysis of C––H–-O and C––H–-N hydrogen bonds. J Phys Chem B 2002, 106:3706-3714.
• [15]May E, Destro R, Gatti C: The unexpected and large enhancement of the dipole moment in the 3,4-bis(dimethylamino)-3-cyclobutene-1,2-dione (DMACB) molecule upon crystallization: A new role of the intermolecular CH–-O interactions. J Am Chem Soc 2001, 123:12248-12254.
• [16]Gatti C, May E, Destro R, Cargnoni F: Fundamental properties and nature of C-H–-O interactions in crystals on the basis of experimental and theoretical charge densities. The case of 3,4-bis(dimethylamino)-3-cyclobutene-1,2-dione (DMACB) crystal. J Phys Chem A 2002, 106:2707-2720.
• [17]Tsirelson VG, Ozerov RP: Electron Densities and Bonding in crystals. Institute of Physics, Bristol/Philadelphia; 1996.
• [18]Koritsanszky TS, Coppens P: Chemical applications of X-ray charge-density analysis. Chem Rev 2001, 101:1583-1627.
• [19]Macchi P: Modern charge density studies: The entanglement of experiment and theory Cryst. Cryst. Rev 2013, 19:58-101.
• [20]Stewart RF: Electron Population Analysis with Rigid Pseudoatoms. Acta Cryst 1976, A32:565-574.
• [21]Hansen NK, Coppens P: Electron population analysis of accurate diffraction data. 6 Testing aspherical atom refinements on small-molecule data sets. Acta Cryst 1978, A34:909-921.
• [22]Hirshfeld FL: Bonded-atom fragments for describing molecular charge-densities. Theor Chim Acta 1977, 44:129-138.
• [23]Spackman MA, Byrom PG: A novel definition of a molecule in a crystal. Chem Phys Lett 1997, 267:215-220.
• [24]McKinnon JJ, Spackmam MA, Mitchell AS: Novel tools for visualizing and exploring intermolecular interactions on molecular crystals. Acta CrystB 2004, 60:627-668.
• [25]McKinnon JJ: Jayatilaka D. Towards quantitative analysis of intermolecular interactions with Hirshfeld surfaces Chem Commun, Spackman MA; 2007.
• [26]Spackman MA, Jayatilaka D: Hirshfeld Surface Analysis. CrystEngComm 2009, 11:19-32.
• [27]Gillet JM, Koritsanszky T: Past, Present and Future of Charge Density and Density Matrix Refinements. In Modern Charge Density Analysis. Edited by Gatti C, Macchi P. Springer, New York; 2012.
• [28]Bader RFW: Why are there atoms in chemistry? Can J Chem 1998, 76:973-988.
• [29]Bader RFW, MacDougall PJ, Lau CDH: Bonded and nonbonded charge concentrations and their relation to molecular geometry and reactivity. J Am Chem Soc 1984, 106:1594-1605.
• [30]Macchi P, Proserpio DM, Sironi A: Experimental Electron Density in a Transition Metal Dimer: Metal-Metal and Metal-Ligand Bonds. J Am Chem Soc 1998, 120:13429-13435.
• [31]Cremer D, Kraka E: Chemical Bonds without Bonding Electron Density – Does the Difference Electron-Density Analysis Suffice for a Description of the Chemical Bond? Angew Chem 1984, 23:627-628.
• [32]Bader RFW, Stephens ME: Spatial localization of the electronic pair and number distributions in molecules. J Am Chem Soc 1975, 97:7391-7399.
• [33]Koch U, Popelier P: Characterization of C-H-O Hydrogen-Bonds on the Basis of the Charge-Density. J Physical Chem 1995, 99:9747-9754.
• [34]Popelier PLA: Atoms in Molecules. An Introduction. Pearson Education, Harlow, Great Britain; 2000.
• [35]Espinosa E, Molins E, Lecomte C: Hydrogen bond strengths revealed by topological analyses of experimentally observed electron densities. Chem Phys Lett 1998, 285:170-173.
• [36]Abramov YA: On the Possibility of Kinetic Energy Density Evaluation from the Experimental Electron-Density Distribution. Acta Cryst A 1997, 53:264-272.
• [37]Spackman MA: Hydrogen bond energetics from topological analysis of experimental electron densities: Recognising the importance of the promolecule. Chem Phys Lett 1999, 301:425-429.
• [38]Munshi P, Guru Row TN: Intra- and intermolecular interactions in small bioactive molecules: cooperative features from experimental and theoretical charge-density analysis. Acta Cryst. B 2006, 62:612-626.
• [39]Munshi P, Guru Row TN: Topological Analysis of Charge Density Distribution in Concominant Polymorphs of 3-Acetylcoumarin, A Case of Packing Polymorphism. Cryst Growth Des 2006, 6:708-718.
• [40]Srinivasa Gopalan R, Kumaradhas P, Kulkarni GU, Rao CNR: An experimental charge density study of aliphatic dicarboxylic acids. J Mol Structure 2000, 521:97-106.
• [41]Howard JAK, Mahon MF, Raithby PR, Sparkes HA: Trans-cinnamic acid and coumarin-3-carboxylic acid: experimental charge-density studies to shed light on [2 + 2] cycloaddition reactions. Acta Cryst B 2009, 65:230-237.
• [42]Bushmarinov IS, Nabiev OG, Kostyanovsky RG, Antipin MY, Lyssenko KA: The azide anion as a building block in crystal engineering from a charge density point of view. Cryst Eng Comm 2011, 13:2930-2934.
• [43]Becke AD, Edgecombe KE: A simple measure of electron localization in atomic and molecular systems. J Chem Phys 1990, 92:5397-5403.
• [44]Tsirelson V, Stash A: Determination of the electron localization function from electron densityChem. Phys Lett 2002, 351:142-148.
• [45]Gopalan RS, Kulkarni GU, Rao CNR: An Experimental Charge Density Study of the Effect of the Noncentric Crystal Field on the Molecular Properties of Organic NLO Materials. ChemPhysChem 2000, 1:127-135.
• [46]Hassel O, Romming C: Direct structural evidence for weak charge-transfer bonds in solids containing chemically saturated molecules. Q Rev Chem Soc 1962, 16:1-18.
• [47]Hassel O: Structural aspects of interatomic charge-transfer bonding. Science 1970, 170:497-502.
• [48]Legon AC: Prereactive Complexes of Dihalogens XY with Lewis Bases B in the Gas Phase: A Systematic Case for the Halogen Analogue B–-XY of the Hydrogen Bond B–-HX. Angew Chem Int Ed Eng 1999, 38:2686-2714.
• [49]Bianchi R, Forni A, Pilati T: The Experimental Electron Density Distribution in the Complex of (E)-1,2-Bis(4-pyridyl)ethylene with 1,4-Diiodotetrafluorobenzene at 90K. Chem Eur J 2003, 9:1631-1638.
• [50]Bui TTT, Dahoui S, Lecomte C, Desiraju GR, Espinosa E: The Nature of Halogen · · · Halogen Interactions: A Model Derived from Experimental Charge-Density Analysis. Angew Chem Int Ed Eng 2009, 48:3838-3841.
• [51]Brinck T, Murray JS, Politzer P: Surface electrostatic potentials of halogenated methanes as indicators of directional intermolecular interactions. Int J Quantum Chem 1992, 44:57-64.
• [52]Brinck T, Murray JS, Politzer P: Molecular-surface electrostatic potentials and local ionization energies of group-v-vii hydrides and their anions - relationships for aqueous and gas-phase acidities. Int J Quantum Chem 1993, 48:73-88.
• [53]Nelyubina YV, Antipin MY, Dunin DS, Kotov VY, Lyssenko KA: Unexpected “amphoteric” character of the halogen bond: The charge density study of the co-crystal of N-methylpyrazine iodide with I2. Chem Comm 2010, 46:5325-5327.
• [54]Brezgunova ME, Aubert E, Dahaoui S, Fertey P, Lebègue S, Jelsch C, Ángyán JG, Espinosa E: Charge density analysis and topological properties of Hal 3-synthons and their comparison with competing hydrogen bonds. Cryst Growth Des 2012, 12:5373-5386.
• [55]Pavan MS, Durga Prasad K, Guru Row TN: Halogen bonding in fluorine: Experimental charge density study on intermolecular F–-F and F–-S donor-acceptor contacts. Chem Comm 2013, 49:7558-7560.
• [56]Stone AJ: Are Halogen Bonded Structures Electrostatically Driven? J Am Chem Soc 2013, 135:7005-7009.
• [57]Spackman MA: Rationalizing Molecular Crystal Structures using Hirshfeld Surfaces. XXIII Congress and General Assembly of the International Union of Crystallography, Montreal; 2014.
• [58]Spackman MA, McKinnon JJ: Fingerprinting Intermolecular Interactions in Molecular Crystals. CrystEngComm 2002, 4:378-392.
• [59]Wolff SK, Grimwood DJ, McKinnon JJ, Turner MJ, Jayatilaka D, Spackman MA: CrystalExplorer (Version 3.1). University of Western Australia, Perth; 2012.
• [60]Johnson ER, Keinan S, Mori-Sánchez P, Contreras-García J, Cohen AJ, Yan W: Revealing Noncovalent Interactions. J Am Chem Soc 2010, 132:6498-6506.
• [61]Contreras-García J, Johnson ER, Keinan S, Chaudret R, Piquemal J-P, Beratan DN, Yang W: NCIPLOT: A Program for Plotting Noncovalent Interaction Regions. J Chem Theory Comput 2011, 7:625-632.
• [62]Saleh G, Gatti C, Lo Presti L, Contreras-García J: Revealing non-covalent Interactions in Molecular Crystals through Their Experimental Electron densities. Chem Eur J 2012, 18:15523-15536.
• [63]Hey J, Leusser D, Kratzert D, Fliegl H, Dieterich JM, Mata RA, Stalke D: Heteroaromaticity approached by charge density investigations and electronic structure calculations. Phys Chem Chem Phys 2013, 15:20600-20610.
• [64]Krawczuk A, Pérez D, Macchi P: PolaBer: a program to calculate and visualize distributed atomic polarizabilities based on electron density partitioning. J Appl Cryst 2014, 47:1452-1458.
• [65]Matta CF, Bader RFW: An Atoms-In-Molecules study of the genetically-encoded amino acids: I. Effects of conformation and of tautomerization on geometric, atomic, and bond properties. Proteins 2000, 40:310-329.
• [66]Krawczuk-Pantula A, Pérez D, Macchi P: Distributed atomic polarizabilities from electron density. 1. Motivations and Theory. Trans Amer Cryst Ass 2012, 42:1-25.
• [67]Keith TA: Atomic Response Properties. In The Quantum Theory of Atoms in Molecules: from Solid State to DNA and Drug Design. Edited by Matta CF, Boyd RJ. Viley-VCH, Weinheim; 2007.
• [68]Lipinski CA: Pharmaceutical Profiling in Drug Discovery for Lead Selection. AAPS Press Arlington, USA; 2004.
• [69]Trask AV, Motherwell WDS, Jones W: Pharmaceutical Cocrystalization: Engineering a Remedy for caffeine Hydration. Crystal Growth Design 2005, 5:1013-1021.
• [70]Aakeröy CB, Forbes S, Desper J: Using Cocrystals To Systematically Modulate Aqueous Solubility and Melting Behavior of an Anticancer Drug. J Am Chem Soc 2009, 131:17048-17049.
• [71]Steed JW: The role of co-crystals in pharmaceutical design. Trends Pharmacol Sci 2013, 34:185-193.
• [72]Hathwar VR, Pal R, Guru Row TN: Charge Density Analysis of Crystals of Nicotinamide with Salicylic Acid and Oxalic Acid: An Insight into the Salt to Cocrystal Continuum. Cryst Growth Des 2010, 10:3306-3310.
• [73]Hathwar VR, Thakur TS, Guru Row TN, Desiraju GR: Transferability of multipole charge density parameters for supramolecular synthons: A new tool for quantitative crystal engineering. Cryst Growth Des 2011, 11:616-623.
• [74]Volkov A, Messerschmidt M, Coppens P: Improving the scattering-factor formalism in protein refinement: application of the University at Buffalo Aspherical-Atom Databank to polypeptide structures. Acta Cryst D 2007, 63:160-170.
• [75]Volkov A, Li X, Koritsanszky T, Coppens P: Ab Initio   Quality Electrostatic Atomic and Molecular Properties Including Intermolecular Energies from a Transferable Theoretical Pseudoatom DatabankJ. Phys Chem A 2004, 108:4283-4300.
• [76]Dominiak PM, Volkov A, Li X, Messerschmidt M, Coppens P: A Theoretical Databank of Transferable Aspherical Atoms and Its Application to Electrostatic Interaction Energy Calculations of MacromoleculesJ. Chem Theory Comput 2007, 3:232-247.
• [77]Dittrich B, Hubschle CB, Luger P, Spackman MA: Introduction and validation of an invariom database for amino-acid, peptide and protein molecules. Acta Cryst D 2006, 62:1325-1335.
• [78]Hubschle CB, Luger P, Dittrich BJ: Automation of invariom and of experimental charge density modelling of organic molecules with the preprocessor program InvariomToolJ. Appl Cryst 2007, 40:623-627.
• [79]Dittrich B, Strumpel M, Spackman MA, Koritsanszky T: Invarioms for improved absolute structure determination of light-atom crystal structures. Acta Cryst A 2006, 62:217-223.
• [80]Zarychta B, Pichon-Pesme V, Guillot B, Lecomte C, Jelsch C: On the application of an experimental multipolar pseudo-atom library for accurate refinement of small-molecule and protein crystal structures. Acta CrystA 2007, 63:108-125.
• [81]Jelsch C, Pichon-Pesme V, Lecomte C, Aubry A: Transferability of Multipole Charge-Density Parameters: Application to Very High Resolution Oligopeptide and Protein StructuresActa Cryst. Acta Cryst D 1998, 54:1306-1318.
• [82]Guillot B, Jelsch C, Podjarny A, Lecomte C: Charge-density analysis of a protein structure at subatomic resolution: the human aldose reductase case. Acta Cryst D 2008, 64:567-588.
• [83]Hathwar VR, Thakur TS, Dubey R, Pavan MS, Guru Row TN, Desiraju GR: Extending the supramolecular synthon based fragment approach (SBFA) for transferability of multipole charge density parameters to monofluorobenzoic acids and their co-crystals with isonicotinamide: importance of C–H · · · O, C–H · · · F and F · · · F intermolecular regions. J Phys Chem A 2011, 115:12852-12863.
• [84]Gryl M, Krawczuk-Pantula A, Stadnicka K: Charge-density analysis in polymorphs of urea-barbituric acid co-crystalsActa Cryst. Acta Cryst. B 2011, 67:144-154.
• [85]Gryl M, Krawczuk A, Stadnicka K: Polymorphism of urea–barbituric acid co-crystals. Acta Cryst B 2008, 64:623-632.
• [86]Schmidtmann M, Farrugia LJ, Middlemiss DS, Gutmann MJ, McIntyre GJ, Wilson CC: Experimental and Theoretical Charge Density Study of Polymorphic isonicotinamide-Oxalic Acid Molecular Complexes with Strong O…H…N Hydrogen Bonds. J Phys Chem A 2009, 113:13985-13997.
• [87]Dubey R, Pavan MS, Guru Row TN, Desiraju GR: Crystal landscape in the orcinol: 4,4′-bipyridine system: synthon modularity, polymorphism and transferability of multipole charge density parameters. IUCrJ 2014, 1:8-18.
• [88]Mossotti OF: Memorie di Matematica e di Fisica della Società Italiana delle Scienze Residente in Modena. 1850, 24:49–74.
• [89]Clausius R: Die mechanische Behandlung der Electricität. Vieweg, Braunschweig; 1858.
• [90]Dunmur DA: The local electric field in anisotropic molecular crystals. Mol Physics 1972, 22:109-115.
• [91]Fkyerat A, Guelzim A, Baert F, Zyss J, Perigaud A: Assessment of the polarizabilities of a nonlinear optical compound [N-(4-nitrophenyl)-(L)-prolinol] from an experimental electronic density study. Phys Rev 1996, 53:16236-16246.
• [92]Hamzaoui F, Zanoun A, Vergoten G: The molecular linear polarizability from X-ray diffraction study. The case of 3-methyl 4-nitropyridine N-oxide (POM). J Mol Struct 2004, 697:17-22.
• [93]Chouaih A, Hamzaoui F, Vergoten G: Capability of X-ray diffraction to the determination of the macroscopic linear susceptibility in a crystalline environment: the case of 3-Methyl 4-Nitropyridine N-oxide (POM)J. Mol Struct 2005, 738:33-38.
• [94]Robinson FNH: Nonlinear optical coefficients. Bell Syst Tech J 1967, 46:913-956.
• [95]Whitten AE, Jayatilaka D, Spackman MA: Effective molecular polarizabilities and crystal refractive indices estimated from x-ray diffraction data. J Chem Phys 2006, 125:174505-174514.
• [96]Grimwood DJ, Jayatilaka D: Wavefunctions derived from experiment. II. A wavefunction for oxalic acid dihydrate. Acta Cryst A 2001, 57:87-100.
• [97]Jayatilaka D, Grimewood DJ, Lee A, Lemay A, Russell AJ, Taylor C, Wolff SK, Cassam-Chenai P, Whitten A: TONTO, a system for computational chemistry. 2005.
• [98]Hickstein DD, Cole JM, Turner MJ, Jayatilaka D: Modeling electron density distributions from X-ray diffraction to derive optical properies: Constrained wavefunction versus multipole refinement. J Chem Phys 2013, 139:064108-064114.
• [99]Genoni A: Molecular orbitals Strictly Localized on Small Molecular Fragments from X-ray Diffraction Data. J Phys Chem Lett 2013, 4:1093-1099.
• [100]Chimpri AS, Gryl M, Dos Santos LHR, Krawczuk A: Correlation between accurate Electron density and Linear Optical Properties in Amino acid derivatives: L-Histidinium Hydrogen Oxalate. Crystal Growth Design 2013, 13:2995-3010.
• [101]Yaghi OM, Li G, Li H: Selective binding and removal of gusts in a microporous metal-organic framework. Nature 1995, 378:703-706.
• [102]Spackman MA, Jayatilaka D: Hirshfeld surface analysis. CrystEngComm 2009, 11:19-32.
• [103]Filsø MO, Turner MJ, Gibbs GV, Adams S, Spackman MA, Iversen BB: Visualizing Lithium-Ion Migration Pathways in Battery Materials.Chemistry. Eur J 2013, 19:15535-15544.
• [104]Wheatley RJ: An overlap model for exchange-induction: application to alkali halides. Chem Phys Lett 1998, 294:487-492.
• [105]Spackman MA: Atom-Atom potentials via electron gas theory. J Chem Phys 1986, 85:6579-6586.
• [106]Spackman MA: A simple quantitative model of hydrogen bonding. J Chem Phys 1986, 85:6587-6601.
• [107]Spackman MA: A simple quantitative model of hydrogen bonding. Applications to more complex systems. J Phys Chem 1987, 91:3179-3186.
• [108]Spackman MA: The use of the promolecular charge density to approximate the penetration contribution to intermolecular electrostatic energies. Chem Phys Lett 2006, 418:158-162.
• [109]Buckingham AD: Intermolecular Interactions: From Diatomics to Biopolymers. Wiley, Winchester; 1978.
• [110]McWeeny R: Methods of molecular quantum mechanics. Academic Press, London; 1989.
• [111]Coppens P, Abramov Y, Carducci M, Korjov B, Novozhilova I, Alhambra C, Pressprich MR: Experimental Charge Densities and Intermolecular Interactions: Electrostatic and Topological Analysis of DL-Histidine. J Am Chem Soc 1999, 121:2585-2593.
• [112]Lennard-Jones JE: On the determination of molecular fields. II From the equation of state of a gas. Proc R Soc Lond A 1924, 106:463-477.
• [113]Gavezzotti A: Calculation of Intermolecular Interaction Energies by Direct Numerical Integration over Electron Densities. I. Electrostatic and Polarization Energies in Molecular Crystals. J Phys Chem B 2002, 106:4145-4154.
• [114]Volkov A, Koritsanszky T, Coppens P: Combination of the exact potential and multipole methods (EP/MM) for evaluation of intermolecular electrostatic interaction energies with pseudoatom representation of molecular electron densities. Chem Phys Lett 2004, 391:170-175.
• [115]Volkov A, King H, Coppens P: Dependence of the Intermolecular Electrostatic Interaction Energy on the Level of Theory and the Basis Set. J Chem Theor Comput 2006, 2:81-89.
• [116]Gavezzotti A: Calculation of Intermolecular Interaction Energies by Direct Numerical Integration over Electron Densities. 2. An Improved Polarization Model and the Evaluation of Dispersion and Repulsion Energies. J Phys Chem B 2003, 107:2344-2353.
• [117]Komorowski L, Lipinski J, Szarek P: Polarization justified Fukui functions. J Chem Phys 2009, 131:124120.
• [118]London F: On the Theory and Systematic of Molecular Forces. Z Physik 1930, 63:245-279.
• [119]Adams S, Rao RP: Transport pathways for mobile ions in disordered solids from the analysis of energy-scaled bond-valence mismatch landscapes. Phys Chem Chem Phys 2009, 11:3210-3216.
• [120]Chimpri AS, Macchi P: Electron density building block approach for metal organic frameworks. Phys Scr 2013, 87:048105-048109.
• [121]Li H, Eddaoudi M, O’Keeffe M, Yaghi O: Design and synthesis of an exceptionally stable and highly porous metal-organic framework. Nature 1999, 402:276-279.
• [122]Civalleri B, Napoli F, Nöel Y, Roetti C, Dovesi R: Ab-initio prediction of materials properties with CRYSTAL: MOF-5 as a case study. CrystEngComm 2006, 8:364-371.
• [123]Poulsen RD, Bentien A, Graber T, Iversen BB: Synchrotron charge-density studies in materials chemistry: 16 K X-ray charge density of a new magnetic metal-organic framework material [Mn2(C8H4O4)2(C3H7NO)2]. Acta Cryst 2004, A60:382-389.
• [124]Poulsen RD, Bentien A, Chevalier M, Iversen BB: Synthesis, physical properties, multitemperature crystal structure, and 20 K synchrotron X-ray charge density of a magnetic metal organic framework structure [Mn2(C8H4O4)2(C3H7NO)2]. J Am Chem Soc 2005, 127:9156-9166.
• [125]Poulsen RD, Jørgensen MRV, Overgaard J, Larsen FK, Morgenroth W, Graber T, Chen YS, Iversen BB: Synchrotron X-Ray Charge-Density Study of Coordination Polymer [Mn(HCOOH)2(H2O)2]∞Chemistry. Eur J 2007, 13:9775-9979.
• [126]Holladay A, Leung P, Coppens P: Generalized relations between d-orbital occupancies of transition metal atoms and electron density multipole population parameters from X-ray diffraction data. Acta Cryst 1983, A39:377-387.
• [127]Jauch W, Reehuis M: Electron density distribution in paramagnetic and antiferromagnetic CoO: A γ-ray diffraction study. Phys Rev B 2002, 65:125111-125118.
• [128]Jauch W, Reehuis M: Electron density distribution in paramagnetic and antiferromagnetic MnO: A γ-ray diffraction study. Phys Rev B 2003, 67:184420-184428.
• [129]Schweizer J: Polarized neutrons and polarization analysis. In Neutron scattering from magnetic crystals. Edited by Chatterji T. Elsevier, Amsterdam; 2006:153-213.
• [130]Pillet S, Souhassou M, Pontillon Y, Caneschi A, Gatteschi D, Lecomte C: Investigation of magnetic interaction pathways by experimental electron density measurements: application to an organic free radical, p(methylthio)phenyl nitronyl nitroxide. New J Chem 2001, 25:131-143.
• [131]Pillet S, Souhassou M, Mathonière C, Lecomte C: Electron density distribution of an oxamato bridged Mn(II)-Cu(II) bimetallic chain and correlation to magnetic properties. J Am Chem Soc 2004, 126:1219-1228.
• [132]Claiser N, Souhassou M, Lecomte C, Gillon B, Carbonera C, Caneschi A, Dei A, Gatteschi D, Bencini A, Pontillon Y, Lelièvre-Berna E: Combined charge and spin density experimental study of the yttrium(III) semiquinonato complex Y(HBPz3)2(DTBSQ) and DFT calculations. J Phys Chem B 2005, 109:2723-2732.
• [133]Deutsch M, Gillon B, Claiser N, Gillet JM, Lecomte C, Souhassou M: First spin-resolved electron distributions in crystals from combined polarized neutron and X-ray diffraction experiments. IUCr J 2014, 1:194-199.