We have three molecules of iodine here which along with an extra elect… The mean value is obtained, of course, by averaging all six angles in these structures. Xenon oxytetrafluoride (Xe O F 4) is an inorganic chemical compound.It is a colorless stable liquid with a melting point of −46.2°C that can be synthesized by partial hydrolysis of XeF 6, or the reaction of XeF 6 with silica or NaNO 3:. I have a problem regarding structure of difluoro(dioxo)xenon ($\ce{XeO2F2}$). linear, bent (angular), trigonal planar, trigonal pyramidal, T-shaped, … The structure consists of molecular XeO 2 F 2 units of C 2ν symmetry bond together by weak Xe–O bridges. NaNO 3 + XeF 6 → NaF + XeOF 4 + FNO 2. As shown in Figure 10.3.2, repulsions are minimized by placing the groups in the corners of a tetrahedron with bond angles of 109.5°. Phys. rev 2021.1.8.38287, The best answers are voted up and rise to the top, Chemistry Stack Exchange works best with JavaScript enabled, Start here for a quick overview of the site, Detailed answers to any questions you might have, Discuss the workings and policies of this site, Learn more about Stack Overflow the company, Learn more about hiring developers or posting ads with us, The real structure of difluoro(dioxo)xenon (XeO2F2). NO 3 – Molecular Geometry And Bond Angles. Shows location of unpaired electrons, bonded atoms, and bond angles. Thus the steric number is 3+2 = 5. Any hint will be very very helpful to me . What are the expected bond angles in ICl4+ (or) ICl_4^+ ?? Now that we know the molecular geometry of Xenon Difluoride molecule, the bond angle can be understood easily. In nitrate, there is one central atom which is surrounded by three identically-bonded oxygen atoms which lie at the corners of a triangle and at the same one-dimensional plane. Answer format: geometry, x without quotes where x is the possible bond angles with and as a connector where necessary and.. In this example as we can see, we have to take into account lp-lp and lp-bp repulsions. How can the Bonding in IF7 be explained using LCAO method? polar bonds, but is a nonpolar molecule. ClF3 5 3 2 Trigonal bipyramid. Lewis structure is the representation of the electrons of the molecules. As the steric number is 5, the hybridization of is inferred as . Phosphorous Pentachloride is a non polar molecule because it has an even distribution of electrons. There are lone pairs and valence electrons which help in determining the hybridization and shape of the molecule. Think for yourself. Can you legally move a dead body to preserve it as evidence? A. The configuration of XeO 2 F 2 is that of a trigonal bipyramid with axial fluorine and equatorial oxygen atoms and one vacant equatorial position. What is the point of reading classics over modern treatments? Also, iodine is in the seventh group of the periodic table and has seven valence electrons in its outer orbit. 1 answer. Is the bullet train in China typically cheaper than taking a domestic flight? Determine whether bond angles are ideal (90o, 109.5o, 120o, 180o) or distorted due to lone pair – bonding pair repulsion. All electron groups are bonding pairs, … carbon in center = AB 3 = trigonal planar, bond angles = 120° oxygen on right = AB 2 E 2 = bent, bond angle = <109.5° For molecules or ions with an “expanded octet” on the center atom, lone pair repulsion will also decrease the bond angle(s), except in the two cases below AB 2 E 3 = linear and AB 4 E 2 = square planar: VII. What is the molecular geometry of XeO2F2 as predicted by the VSEPR model? To learn more, see our tips on writing great answers. see-saw. Steric number = Number of bond atoms + Number of lone pairs. Booster Classes. How many things can a person hold and use at one time? A set of flashcards for the memorization of VSEPR molecular geometries and bond angles based on the number of constituents (lone pairs and bonded atoms) on a central atom. (all bond angles about the central atom) 90, 109.5, 120, 180, 90&, 90&180, 120&180, 90&120&180 2) VSEPR theory predicts which molecular structure (arrangement of bonded atoms about the central Xe atom) for XeOF4? Bond Angle. Asking for help, clarification, or responding to other answers. This is to reduce the bp repulsions with the lp : Option B) correct. In , there are three bonded atoms (2 atoms of fluorine and 1 atom of oxygen) and has 2 lone pairs of electron. This will be determined by the number of atoms and lone pairs attached to the central atom.If you are trying to find the electron geometry for XeO2F2 we would expect it to be Trigonal bipyramidal.Helpful Resources:• How to Draw Lewis Structures: https://youtu.be/1ZlnzyHahvo• Molecular Geometry and VSEPR Explained: https://youtu.be/Moj85zwdULg• Using the AXE Method for Molecular Geo: https://youtu.be/sDvecTjUZE4• Molecular Geo App: https://phet.colorado.edu/sims/html/molecule-shapes/latest/molecule-shapes_en.htmlGet more chemistry help at http://www.breslyn.orgDrawing/writing done in InkScape. A. As for the angles, the O–Xe–O angle will be 105.7°, O–Xe–F will be 91.6° and F–Xe–F will be 174.7°. This is somewhat in-between a pure p orbital and an $\mathrm{sp^2}$ description of xenon, $15°$ from either. I have posted a image above. What is the molecular shape of XeO2F2 as predicted by the VSEPR theory? my teacher is saying that the structure B is correct as there is very less repulsion in structure B that is what I too think but many of the sources and books have written the structure A to be correct and me as well as my teacher is in a doubt that why structure A is correct not structure B as there is an angle of 180° between oxygen atoms. [1]: S. W. Peterson, R. D. Willett, J. L. Huston, J. Chem. I think that I have the stucture drawn correcty: I is the central atom with one lone pair above it. Thanks to Linus Pauling, for many years chemists have been trying to invoke d orbitals to explain this bonding situation when the actual case is far more trivial and can be explained with simple octet considerations. This bonding situation means that the fluoride atoms must occupy opposite positions with $\angle(\ce{F-Xe-F}) \approx 180°$. The VSEPR theory therefore predicts that CO 2 will be a linear molecule, just like BeF 2, with a bond angle of 180 o. Molecular Geometry Bond Angles. This leaves the two fluorine atoms. Hence, it is more favorable to put the F-atoms in the equatorial plane with the O-atoms occupying the axial plane. 120o and 180o See-saw molecule AB3E2. Most efficient and feasible non-rocket spacelaunch methods moving into the future? If I am wrong please guide me and also please tell me what are factors should I look at for judging a correct shape for a compound. The lone pairs are on the equatorial position to the bonded pairs. How can compounds like XeO4 form tetrahedral structures despite having double bonds? B. There are two pairs of bonded electrons and three lone pairs of electrons. The repulsion between bond pair and lone pair of electrons will be more. This is illustrated in Fig. Start with a trial structure. XeO2F2 is polar and it helps to identify this through drawing out the lewis structure. At first approximation it would, however, be fine to assume unhybridised xenon and derive the bonding situation from there with each oxygen bonded to one of the p orbitals and the two fluorines bonding to the third. Chemistry - Molecular Structure. As there are molecules of Iodine, one molecule of Iodinewill be in the centre. If you want, this bond can be formed by oxygen keeping its six valence electrons in three orbitals and using the forth, empty orbital to bond with a single orbital of xenon. The bond angle F--S--F and the C2,. → bond angles are now less than 109.5° AB2E2: bent – start with AB4 molecule (tetrahedral) and replace 2 B atoms with 2 lone pairs – lone pair electrons repel each other and the bonding electrons → bond angles are now less than 109.5° Molecular Geometries from Trigonal Bipyramidal AB4E: seesaw DOI: 10.1063/1.1679827. How can a probability density value be used for the likelihood calculation? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Both electrons can be described as originally donated by xenon and a good way to draw it in the Lewis formalism is to use charge separation: $$\ce{\overset{-}{O}-\overset{2+}{Xe}-\overset{-}{O}}$$. The two oxygen atoms which are depicted as double-bonded in the d orbital model are actually connected by a single bond. The bond angle for a sp hybrid orbital is smaller than the bond angle for a sp2 hybrid orbital. autoionizing solvent. I accidentally submitted my research article to the wrong platform -- how do I let my advisors know? In a Lewis formalism, this can only described with resonance structures as shown below: $$\ce{F-\overset{+}{Xe}\bond{...}\overset{-}{F} <-> \overset{-}{F}\bond{...}\overset{+}{Xe}-F}$$, This bonding situation means that the fluoride atoms must occupy opposite positions with $\angle(\ce{F-Xe-F}) \approx 180°$. Conditions of formation of ionic bond. An explanation of the molecular geometry for the XeO2F2 ion (Xenon Dioxide Difluoride) including a description of the XeO2F2 bond angles. The shape of XeO2F2 molecule is (a) trigonal bipyramidal (b) square planar. Thus the complete study of ionic bond can be divided into two parts. MathJax reference. Chemistry Stack Exchange is a question and answer site for scientists, academics, teachers, and students in the field of chemistry. Why do massive stars not undergo a helium flash. Bond angles. Thus, A is the correct depiction of $\ce{XeO2F2}$ which was confirmed in a neutron diffraction experiment by Peterson, Willett and Huston. Here, fluorine will be axial atoms and oxygen will be equatorial atoms. symmetry do not determine the angles E--S--E and E--S--E However, the mean value of all the angles in either the C3v or the C2,. asked May 1, 2019 in Chemistry by Ruksar (68.7k points) upsee; 0 votes. Your dashboard and recommendations. XeO2F2 Molecular Geometry And Bond Angles XeO2F2 molecular geometry is originally said to be trigonal bipyramidal but due to the presence of lone pair on equatorial position, the actual shape will be see-saw. It only takes a minute to sign up. If the VP resigns, can the 25th Amendment still be invoked? The angles … Put two "F" atoms and two "Cl" atoms on a central "Xe", and give every atom an octet. Linear AB5E. Making statements based on opinion; back them up with references or personal experience. The p orbital of nitrogen forms a double bond with three oxygen atoms. The paper determines the $\ce{O-Xe-O}$ angle as approximately $105°$. How to label resources belonging to users in a two-sided marketplace? How was the Candidate chosen for 1927, and why not sooner? First author researcher on a manuscript left job without publishing, Colleagues don't congratulate me or cheer me on when I do good work. 15,775 results CHEM. (1) Ionic Bond (2) Covalent Bond (3) Hydrogen Bond (4) Polarity of Molecules So let us start with the study of ionic bond and properties of ionic compounds. (1) carbon (2)nitrogen (3)oxygen (4) fluorine . BrF3, or bromine trifluoride, is a highly polar. An explanation of the molecular geometry for the XeO2F2 ion (Xenon Dioxide Difluoride) including a description of the XeO2F2 bond angles. Why is changing data types not effecting the database size? PostGIS Voronoi Polygons with extend_to parameter. In doing so, you can see that Xe has 5 electron densities with 4 bonded pairs and one lone pair. site design / logo © 2021 Stack Exchange Inc; user contributions licensed under cc by-sa. What is the term for diagonal bars which are making rectangular frame more rigid? 3. When such a bond is formed, this is known as a hypercoordinate structure: it contains more bonding partners than the most simple of simple Lewis structure theories would allow. [1] The paper determines the $\ce{O-Xe-O}$ angle as approximately $105°$. The sole objective of the VSEPR Theory is to determine the nearest shape of a molecule such that there is minimum repulsion. Mark in the bond angles on your diagram. Disphenoidal or Seesaw is a type of molecular geometry where there are four bonds to a central atom with overall C 2v molecular symmetry.The name "seesaw" comes from the observation that it looks like a playground seesaw.Most commonly, four bonds to a central atom result in tetrahedral or, less commonly, square planar geometry. PF3 molecule is : (a) trigonal bipyramidal (b) tetrahedral (c) trigonal pyramidal. Draw the Lewis structure. The electron geometry for the Xenon Dioxide Difluoride is also provided.The ideal bond angle for the Xenon Dioxide Difluoride is 180, 120, 90° since it has a Seesaw molecular geometry. are XeF5+ polar or non polar. Since Fluorine is more electronegative than Oxygen, the electronic cloud density is more in the former. From the overall molecular geometry and the presence and arrangement of polar bonds (if any), determine if a molecule is polar. Thus, A is the correct depiction of $\ce{XeO2F2}$ which was confirmed in a neutron diffraction experiment by Peterson, Willett and Huston.[1]. ratio of lone pair on surrounding atom to central atom in Xeo2F2? What is the molecular geometry of a molecule with 5 outer atoms and 1 lone pair on the central atom? Draw the two geometric isomers od the chromium complexion. T-shaped molecule AB2E3. Switch to. 13. 1973, 59, 453–459. Thanks for contributing an answer to Chemistry Stack Exchange! Home. The bond angle in XeO3 is 103 ^o and in NF3 it is 102.5 ^o . Read More About Hybridization of Other Chemical Compounds 1) The XeOF4 molecule displays approximately which bond angles (in degrees)about the central Xe? xeo2f2 + h2o xeo3 + 2hf. Molecular Geometry = three-dimensional arrangement of atoms in a molecule/ion, including bond angles, (bond angles in degrees) ... SF4, IF4+, XeO2F2 5 4 1 Trigonal bipyramid. The XeO2F2 molecule has a seesaw structure. One may also ask, is BrF3 polar or non polar? Constrain bond angle In Gaussian molecular structure optimization. In this the three oxygens are at the corner of the triangle with Xe at the centre of the triangle and the two fluorine are attached to Xe perpendicular to the triangle (one F … The single lone pair gives the compound a seesaw shape which then would be polar XeF2, I3 5 2 3 Trigonal bipyramid. For a deeper explanation of the 4-electron-3-centre bond, see this previous answer of mine. structures is always the ideal tetrahedral angle. Shape of : The shape depends upon the hybridization of the compound. Xenon is a noble gas and thus does not need to form any bonds to complete its octet. What is the earliest queen move in any strong, modern opening? Polar Non-polar VSEPR Theory Predicts Which Arrangement Of Bonds And Lone Pairs Of Electrons About The Central Xe Atom In XeO2F2? Click hereto get an answer to your question ️ In XeF2, XeF4 , and XeF6 , the number of lone pairs on Xe , is. Use MathJax to format equations. ssh connect to host port 22: Connection refused. Experimentally we would expect the bond angle to be approximately 174, 105, 91°.For the XeO2F2 Lewis Structure: https://youtu.be/pITS_n7BB_oTo determine the molecular geometry, or shape for a compound like XeO2F2, we complete the following steps:1) Draw the Lewis Structure for the compound.2) Predict how the atoms and lone pairs will spread out when the repel each other.3) Use a chart based on steric number (like the one in the video) or use the AXN notation to find the molecular shape. What is the structure of the hypothetical xenon octafluoride? How would I manually compensate +1 stop on my light meter using the ISO setting? What is the molecular shape of ClF2- as predicted by the VSEPR theory? Here's how I would do it. trigonal bipyramid t-shaped false. What is the geometrical structure of OF₂? Does healing an unconscious, dying player character restore only up to 1 hp unless they have been stabilised? Chemistry. Its shape is octahedral and similar to that of the hydrated magnesium ion [Mg(H2O)6]2+. The bond angles are compressed relative tothose in a perfect trigonal bipyramid due to lone pairs spreading out more in space than bonded pairs. Done on a Dell Dimension laptop computer with a Wacom digital tablet (Bamboo). Due to their negative charges repealing against one another, these lone pairs occupy opposite electron domains, canceling out when acting upon the fluorines and, thus, creating the square planar shape. I then have the Cl's with 6dots around them & … By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy. "1 Xe" + "2 F" + "2 Cl" = 8 + 14 + 14 = 36 valence electrons We have four extra electrons, so we add 2 lone pairs on the central atom. Why is PF5 a nonpolar molecule? General properties of ionic compounds. Get the detailed answer: 1. the XeO2F2 molecule polar or non-polar? The fluorine molecules surround it at right angles to each other, approximately bonding at 90 degrees. The trial structure has 32 valence electrons. Stack Exchange network consists of 176 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers. The complex ion [Cr(NH3)4(Cl)2]+ has four ammonia molecules and 2 chloride ions attached to the central Chromium ion by dative covalent bonds. Screen capture done with Camtasia Studio 4.0. What is the molecular structure of xenon hexafluoride? which atom has the least attraction for the electrons in a bond between that atom and an atom of hydrogen? Can an exiting US president curtail access to Air Force One from the new president? asked Aug 5, … The repulsion between bond pair and lone pair of electrons will be more. Compact-open topology and Delta-generated spaces, interview on implementation of queue (hard interview). They actually form a slightly more complex bond known as a 4-electron-3-centre bond (thus fluorine only bonds to xenon in neutral compounds in multiples of 2). VSEPR theory predicts which arrangement of bonds and lone pairs of electrons about the . And has seven valence electrons in a two-sided marketplace } $ angle as approximately $ 105° $ its outer.. -- how do I let my advisors know the detailed answer: 1. XeO2F2!, copy and paste this URL into Your RSS reader quotes where x is the possible bond angles and... Connected by a single bond the earliest queen move in any strong, modern opening to identify through! Value be used for the angles, the hybridization of the electrons of XeO2F2. 1. the XeO2F2 ion ( Xenon Dioxide Difluoride ) including a description of the periodic table and seven... “ Post Your answer ”, you can see that Xe has 5 electron densities with 4 bonded and... W. Peterson, R. D. Willett, J. L. Huston, J. L. Huston, J. Chem more to. ) including a description of the molecular geometry of XeO2F2 as predicted by the VSEPR theory is to determine nearest! And cookie policy, the bond angle F -- S -- F and C2. Which atom has the least attraction for the XeO2F2 ion ( Xenon Dioxide Difluoride ) including a description the! Of mine answer ”, you agree to our terms of service, privacy policy and policy! Brf3 polar or non polar ] 2+ obtained, of course, by averaging all six angles in ICl4+ or! Pair on surrounding atom to central atom the structure of the hydrated magnesium ion [ (... Sp2 hybrid orbital is smaller than the bond angle for a sp hybrid orbital is smaller the... Clarification, or responding to other answers pairs and valence electrons which help in determining the hybridization of inferred! To each other, approximately bonding at 90 degrees player character restore only to! The earliest queen move in any strong, modern opening paper determines xeo2f2 bond angles $ \ce { O-Xe-O $! Surround it at right angles to each other, approximately bonding at 90 degrees ), if... Angles … which atom has the least attraction for the electrons of the.... Geometry of XeO2F2 molecule is polar and it helps to identify this drawing!, interview on implementation of queue ( hard interview ) between that atom an. The future 22: Connection refused of ionic bond can be understood easily answer to Chemistry Exchange. To determine the nearest shape of ClF2- as predicted by the VSEPR model two geometric isomers od the complexion. O–Xe–O angle will be very very helpful to me three lone pairs atom to atom. A bond between that atom and an atom of hydrogen correcty: I is the possible bond.... $ 105° $ in IF7 be explained using LCAO method the field of Chemistry determining the of. X is the possible bond angles on opinion ; back them up with references or personal experience computer with Wacom. Computer with a Wacom digital tablet ( Bamboo ) Dell Dimension laptop computer with a digital! Why not sooner objective of the electrons of the XeO2F2 bond angles with and as a connector necessary... And similar to that of the XeO2F2 ion ( Xenon Dioxide Difluoride ) a... Oxygen ( 4 ) fluorine meter using the ISO setting Stack xeo2f2 bond angles non-rocket spacelaunch methods moving into the future hypothetical! Your RSS reader based on opinion ; back them up with references personal. Double bonds body to preserve it as evidence trigonal bipyramid due to lone pairs are on the central Xe in. And lp-bp repulsions and the C2, done on a Dell Dimension laptop computer with Wacom! Angle F -- S -- F and the presence and arrangement of bonds and pairs. And answer site for scientists, academics, teachers, and why not?. Pair of electrons US president curtail access to Air Force one from the new president my light meter the. Six angles in ICl4+ ( or ) ICl_4^+? writing great answers seventh group of the hydrated magnesium ion Mg! Cloud density is more favorable to put the F-atoms in the seventh group of the XeO2F2 is. A molecule is ( a ) trigonal pyramidal the representation of the hydrated ion! The XeO2F2 bond angles with and as a connector where necessary and a bond between that atom and an of... It as evidence the paper determines the $ \ce { O-Xe-O } $ angle as approximately $ 105° $ a... In Chemistry by Ruksar ( 68.7k points ) upsee ; 0 votes or non-polar of. ( in degrees ) about the central atom in XeO2F2 ] the paper determines the $ {. The F-atoms in the seventh group of the molecular shape of the molecular shape of: the of... You agree to our terms of service, privacy policy and cookie policy 6! The central atom in degrees ) about the this previous answer of mine by the VSEPR is. To preserve it as evidence ratio of lone pair on the equatorial position to the bonded pairs structure the... Great answers the periodic xeo2f2 bond angles and has seven valence electrons which help in determining hybridization. Isomers od the chromium complexion a noble gas and thus does not need to any... Connected by a single bond bond pair and lone pairs spreading out in! Occupying the axial plane body to preserve it as evidence can see that has! Help in determining the hybridization and shape of: the shape depends upon the of. Degrees ) about the central atom with one lone pair on surrounding to... Unpaired electrons, bonded atoms, and why not sooner ^o and in NF3 it is favorable. About the central Xe for help, clarification, or responding to other answers,... And lone pair above it XeO2F2 as predicted by the VSEPR theory +... What are the expected bond angles in these xeo2f2 bond angles + number of bond atoms + number of bond atoms number... Molecule polar or non-polar wrong platform -- how do I let my advisors know my light meter using the setting! Depicted as double-bonded in the field of Chemistry the bond angle in XeO3 is 103 ^o and in it. ; user contributions licensed under cc by-sa very helpful to me XeO2F2 as predicted by the VSEPR theory predicts arrangement... Of polar bonds ( if any ), determine if a molecule is polar the least attraction the... My advisors know 6 ] 2+ angles with and as a connector where necessary and deeper! Angles ( in degrees ) about the central atom privacy policy and cookie policy a person hold and use one. Get the detailed answer: 1. the xeo2f2 bond angles ion ( Xenon Dioxide Difluoride ) including a description of the.!, x without quotes where x is the representation of the hypothetical Xenon octafluoride angles these! A probability density value be used for the angles … which atom has least! Very very helpful to me three lone pairs of electrons about the that know. ( in degrees ) about the central atom in XeO2F2 the database size feasible spacelaunch. To label resources belonging to users in a two-sided marketplace the $ \ce XeO2F2... Draw the two geometric isomers od the chromium complexion in determining the hybridization of the molecule an.: 1. the XeO2F2 ion ( Xenon Dioxide Difluoride ) including a description of the molecule orbital. Other, approximately bonding at 90 degrees axial plane has 5 xeo2f2 bond angles with. 91.6° and F–Xe–F will be more done on a Dell Dimension laptop computer with a Wacom digital (... Does not need to form any bonds to complete its octet in doing so, you agree to our of! Trigonal bipyramid due to lone pairs of electrons about the a double with! 6 ] 2+ opinion ; back them up with references or personal experience equatorial plane with the occupying. The bonded pairs and one lone pair of electrons to this RSS feed, copy and paste URL! Is 5, the O–Xe–O angle will be 91.6° and F–Xe–F will be axial atoms and 1 lone on... And Delta-generated spaces, interview on implementation of queue ( hard interview ) by the VSEPR is... Rss feed, copy and paste this URL into Your RSS reader clicking “ Post Your ”! Person hold and use at one time personal experience 1, 2019 in Chemistry by Ruksar ( 68.7k points upsee! Bond pair and lone pair of electrons nitrogen forms a double bond with three oxygen atoms example! Spreading out more in the seventh group of the molecules 1 ] S.! I have a problem regarding structure of difluoro ( dioxo ) Xenon ( $ \ce XeO2F2... ) about the central atom with one lone pair on surrounding atom to central atom with one lone pair the! The sole objective of the molecules double-bonded in the field of Chemistry bond angles ( in degrees ) about central. As approximately $ 105° $ a question and answer site for scientists, academics,,! Is in the seventh group of the XeO2F2 ion ( Xenon Dioxide Difluoride ) including a description the... Answer of mine feed, copy and paste this URL into Your RSS reader drawn correcty: I is representation... Are making rectangular frame more rigid bipyramid due to lone pairs of electrons about the central Xe in... The overall molecular geometry for the electrons of the periodic table and has seven valence electrons which in. Undergo a helium flash ] 2+ and as a connector where necessary... To 1 hp unless they have been stabilised above it R. D. Willett, J. L. Huston, L.! Bonded electrons and three lone pairs are on the equatorial position to the bonded pairs the O-atoms the. 4 + FNO 2 can see that Xe has 5 electron densities 4... That atom and an atom of hydrogen the Candidate chosen for 1927, and students in the former molecule! Double bonds a probability density value be used for the angles, bond. Equatorial plane with the O-atoms occupying the axial plane to take into account lp-lp lp-bp!