LIST OF LIGANDS AND CHARGES PDF



List Of Ligands And Charges Pdf

Donor–Acceptor Ligand-to-Ligand Charge-Transfer. 1/10/2006 · Integrin-ligand partners. Historically, most integrin-ligand pairs have been identified either by affinity chromatography or through the ability of subunit-specific monoclonal antibodies to block cell adhesion to specific ligands., Coordination compounds are metal ions surrounded by ligands. Ligands are either anions or molecules Ligands are either anions or molecules that can donate electrons into the d-orbitals of the metal ion and form a bond..

introducing complex ions ligands and bonding

Lecture 3 Department of Chemistry Texas A&M University. Ligand. Ligand is a company that has achieved the status of having launched products, and as of 2005, its portfolio included the following US Food and Drug Administration-approved drugs: morphine sulfate extended-release capsules, alitretinoin (7), bexarotene, and denileukin diftitox., Start studying Chemistry Common Ligands. Learn vocabulary, terms, and more with flashcards, games, and other study tools..

A ligand is an ion or molecule which exists independently of any complex that it might form. In the complex [Co(NH 3) 6] 3+, the ammonia molecules, which can exist outside of the complex, are acting as ligands. can u give a list of possible ligands with their types and charges - Chemistry - Coordination Compounds

Prefixes bis-, tris-, tetrakis-, pentakis-, hexakis- for ligands whose names contain a prefix of the first type, neutral ligands without special names, ionic ligands with particularly long names. Start studying Chemistry Common Ligands. Learn vocabulary, terms, and more with flashcards, games, and other study tools.

ligands are also called chelating agents because of their ability to hold the metal atom like a claw (from the Greek Chele, meaning “claw”) one example is ethylenediaminetetraacetate ion (EDTA), a polydentate (hexadentate) ligand. A family of charge-transfer chromophores comprising square-planar nickel(II) complexes with one catecholate donor ligand and one α-diimine acceptor ligand is reported. The nine new chromophores were prepared using three different catecholate ligands and three different α-diimine ligands. Single-crystal X-ray diffraction studies on all members

The ligand charges may play key roles in tuning the frameworks of compounds 1–3. The solid state The solid state luminescence of compounds 1 – 3 and all ligands have been investigated here. arene is strongerelectron donor than three CO ligands electron-releasingsubstituents on aromatic ring invariably stabilize 6 -arene ligand steric interactions counteract this electronic effect

Coordination compounds are metal ions surrounded by ligands. Ligands are either anions or molecules Ligands are either anions or molecules that can donate electrons into the d-orbitals of the metal ion and form a bond. Start studying Chemistry Common Ligands. Learn vocabulary, terms, and more with flashcards, games, and other study tools.

ENV/JM/MONO(2018)11 │3 ASSESSMENT OF BIODURABILITY OF NANOMATERIALS AND THEIR SURFACE LIGANDS Unclassified OECD Environment, Health and Safety Publications Structure and bonding of coordination compounds. Werner originally postulated that coordination compounds can be formed because the central atoms carry the capacity to form secondary, or coordinate, bonds, in addition to the normal, or valence, bonds.

Prefixes bis-, tris-, tetrakis-, pentakis-, hexakis- for ligands whose names contain a prefix of the first type, neutral ligands without special names, ionic ligands with particularly long names. Structure-Based Identification of Binding Sites, Native Ligands and Potential Inhibitors for G-Protein Coupled Receptors Claudio N. Cavasotto,#† Andrew J.W. Orry,# and Ruben A. Abagyan*

The term ligand (ligare [Latin], to bind) was first used by Alfred Stock in 1916 in relation to silicon chemistry. It became more commonly associated with coordination chemistry following the publication of an article by H. Irving and R.J.P. Williams in Nature, 1948, 162, 746. Coordination Chemistry and Ligand Exchange reactions in the Synthesis of New Functional Inorganic Compounds S. Natarajan Framework Solids Laboratory, Solid State and Structural Chemistry Unit, IISc, Bangalore 560012 E-mail: snatarajan@sscu.iisc.ernet.in . Novosibirsk, 2009 What is a Coordination Complex/Compound? One of a number of complex compounds in which an atom or …

In contrast with the behaviour of pyridines, the positive charge on the phosphorous atom of free PPh(3) increases upon coordination to Pt(II), moreover the PPh(3) ligands acquire a substantial positive charge, thus efficiently delocalising the charge of the cationic complex. Naming Coordination Compounds A complex is a substance in which a metal atom or ion is associated with a group of neutral molecules or anions called ligands . Coordination compounds are neutral substances (i.e. uncharged) in which at least one ion is present as a complex.

introducing complex ions ligands and bonding

list of ligands and charges pdf

Complexes of π–bonded and aromatic ligands uniroma2.it. A spectrochemical series is a list of ligands ordered on ligand strength and a list of metal ions based on oxidation number, group and its identity. In crystal field theory, ligands modify the difference in energy between the d orbitals Δ, Structure-Based Identification of Binding Sites, Native Ligands and Potential Inhibitors for G-Protein Coupled Receptors Claudio N. Cavasotto,#† Andrew J.W. Orry,# and Ruben A. Abagyan*.

Classifications of Ligands – Everyscience.com. A spectrochemical series is a list of ligands ordered on ligand strength and a list of metal ions based on oxidation number, group and its identity. In crystal field theory, ligands modify the difference in energy between the d orbitals Δ, Structure and bonding of coordination compounds. Werner originally postulated that coordination compounds can be formed because the central atoms carry the capacity to form secondary, or coordinate, bonds, in addition to the normal, or valence, bonds..

Common Ligand Types Web.UVic.ca

list of ligands and charges pdf

Spectrochemical series Wikipedia. 1.0 Ligands A ligand can be an ion or an atom that can form a co-ordination complex with a central atom, usually a metal. A ligand is a molecule that selectively binds to another molecule. The ligand charges may play key roles in tuning the frameworks of compounds 1–3. The solid state The solid state luminescence of compounds 1 – 3 and all ligands have been investigated here..

list of ligands and charges pdf

  • The Organometallic HyperTextBook Electron Counting
  • Display of common ligands wwwchem.uwimona.edu.jm
  • Effect of Charge on the Structures of Zn(II) Coordination

  • The most critical point we should remember is that like oxidation state assignments, electron counting is a formalism and does not necessarily reflect the distribution of electrons in the molecule. However, these formalisms are very useful to us, and both will give us the same final answer. 1.0 Ligands A ligand can be an ion or an atom that can form a co-ordination complex with a central atom, usually a metal. A ligand is a molecule that selectively binds to another molecule.

    Coordination compounds are metal ions surrounded by ligands. Ligands are either anions or molecules Ligands are either anions or molecules that can donate electrons into the d-orbitals of the metal ion and form a bond. 1) Neutral ligand (no ligand carries a charge—therefore X ligands are one electron donors, L ligands are 2 electron donors.) 2) Both L and X are 2-electron donor ligand (ionic method)

    The most critical point we should remember is that like oxidation state assignments, electron counting is a formalism and does not necessarily reflect the distribution of electrons in the molecule. However, these formalisms are very useful to us, and both will give us the same final answer. Identify the ligands and their charges in Co(en)2(CN)2^+. Expert Answer. 100 % (1 rating) This problem has been solved! See the answer. Previous question Next question . Get more help from Chegg. Get 1:1 help now from expert Chemistry tutors

    Page 3 of 6 2. The total charge of a compound is zero, the charge of the cation9s) should be balanced by the charge of anion(s) 3. 3. In the complex ion, neutral ligands are written before anionic ligands… 1) Neutral ligand (no ligand carries a charge—therefore X ligands are one electron donors, L ligands are 2 electron donors.) 2) Both L and X are 2-electron donor ligand (ionic method)

    Structure-Based Identification of Binding Sites, Native Ligands and Potential Inhibitors for G-Protein Coupled Receptors Claudio N. Cavasotto,#† Andrew J.W. Orry,# and Ruben A. Abagyan* Common Ligand Types X type ligands: halides F-, Cl-, Br-, I-formally anionic: terminal reduced basicity relative to ‘free’ halide 3 bridging (μ)

    Both ligands are neutral, so they are ordered alphabetically with H 2 O before NH 3. Their order in the formula is the opposite of that in the complex's name since one uses their chemical symbols and the other uses the names of the ligands. In chemistry, a coordination complex consists of a central atom or ion, which is usually metallic and is called the coordination centre, and a surrounding array of bound molecules or ions, that are in turn known as ligands or complexing agents.

    The term ligand (ligare [Latin], to bind) was first used by Alfred Stock in 1916 in relation to silicon chemistry. It became more commonly associated with coordination chemistry following the publication of an article by H. Irving and R.J.P. Williams in Nature, 1948, 162, 746. The nature of ligands coordinated to the center metal is an important feature of a complex compound along with other properties such as metal identify and its oxidation state. More specifically, it is the identity and consequently the ability of the ligand to donate or accept electrons to the center

    list of ligands and charges pdf

    Weak and strong field ligands. the spectrochemical series. If the ligand is a weak field splitter then the complex will be high spin. If th li d i t fi ld litt th th l ill b l If the ligand is a strong field splitter then the complex will be low spin. 10 6.Revisiting Crystal Fiel d Theory and Magnetism ligands are also called chelating agents because of their ability to hold the metal atom like a claw (from the Greek Chele, meaning “claw”) one example is ethylenediaminetetraacetate ion (EDTA), a polydentate (hexadentate) ligand.

    introducing complex ions ligands and bonding

    list of ligands and charges pdf

    introducing complex ions ligands and bonding. Page 3 of 6 2. The total charge of a compound is zero, the charge of the cation9s) should be balanced by the charge of anion(s) 3. 3. In the complex ion, neutral ligands are written before anionic ligands…, Weak and strong field ligands. the spectrochemical series. If the ligand is a weak field splitter then the complex will be high spin. If th li d i t fi ld litt th th l ill b l If the ligand is a strong field splitter then the complex will be low spin. 10 6.Revisiting Crystal Fiel d Theory and Magnetism.

    Definition of ligand Chemistry Dictionary

    Coordination Chemistry and Ligand Exchange reactions in. AutoDock is an automated procedure for predicting the interaction of ligands with biomacromolecular targets. The motivation for this work arises from problems in the design of, arene is strongerelectron donor than three CO ligands electron-releasingsubstituents on aromatic ring invariably stabilize 6 -arene ligand steric interactions counteract this electronic effect.

    Structures With Monodentate Ligands. Monodentate ligands are Lewis bases that donate a single pair ("mono") of electrons to a metal atom. Monodentate ligands can be either ions (usually anions) or neutral molecules. Structures With Monodentate Ligands. Monodentate ligands are Lewis bases that donate a single pair ("mono") of electrons to a metal atom. Monodentate ligands can be either ions (usually anions) or neutral molecules.

    1/10/2006 · Integrin-ligand partners. Historically, most integrin-ligand pairs have been identified either by affinity chromatography or through the ability of subunit-specific monoclonal antibodies to block cell adhesion to specific ligands. For ligands with more than one double bond, each double bond contributes a pair of electrons for the 18-electron rule. Thus, butadiene, benzene, COD and COT can contribute 4, 6, 4, and 8

    can u give a list of possible ligands with their types and charges - Chemistry - Coordination Compounds ENV/JM/MONO(2018)11 │3 ASSESSMENT OF BIODURABILITY OF NANOMATERIALS AND THEIR SURFACE LIGANDS Unclassified OECD Environment, Health and Safety Publications

    We demonstrated that NBO charges of the coordinating atoms of the ligands, like pK a 1 values of the conjugated acids of the ligands, can reflect the relative coordination abilities of the ligands to metal ions and the strength of the resulting M–L bonds. In dye-sensitized solar cells (DSCs), the redox mediator is responsible for the regeneration of the oxidized dye and for the hole transport towards the cathode. Here, we introduce new copper complexes with tetradentate 6,6′-bis(4-(S)-isopropyl-2-oxazolinyl)-2,2′-bipyridine ligands, Cu(oxabpy), as redox mediators. Copper coordination

    In contrast with the behaviour of pyridines, the positive charge on the phosphorous atom of free PPh(3) increases upon coordination to Pt(II), moreover the PPh(3) ligands acquire a substantial positive charge, thus efficiently delocalising the charge of the cationic complex. 1.0 Ligands A ligand can be an ion or an atom that can form a co-ordination complex with a central atom, usually a metal. A ligand is a molecule that selectively binds to another molecule.

    AutoDock is an automated procedure for predicting the interaction of ligands with biomacromolecular targets. The motivation for this work arises from problems in the design of Coordination Chemistry and Ligand Exchange reactions in the Synthesis of New Functional Inorganic Compounds S. Natarajan Framework Solids Laboratory, Solid State and Structural Chemistry Unit, IISc, Bangalore 560012 E-mail: snatarajan@sscu.iisc.ernet.in . Novosibirsk, 2009 What is a Coordination Complex/Compound? One of a number of complex compounds in which an atom or …

    This page explains the terms complex ion and ligand, and looks at the bonding between the ligands and the central metal ion. It discusses various sorts of ligand (including some quite complicated ones), and describes what is meant by co-ordination number. We report on the synthesis of tridentate-nitrogen pyrazole–pyridine–tetrazole (L 1 H) and pyrazole–pyridine–triazole (L 2 H) ligands and their complexation with lanthanides (Ln = Gd(III), Eu(III) and Tb(III)) resulting in stable, charge-neutral complexes Ln(L 1) 3 and Ln(L 2) 3, respectively.

    Identify the ligands and their charges in Co(en)2(CN)2^+. Expert Answer. 100 % (1 rating) This problem has been solved! See the answer. Previous question Next question . Get more help from Chegg. Get 1:1 help now from expert Chemistry tutors Coordination compounds contain an ion and an array of ligands. Naming coordination compounds involves a set of rules which includes the oxidation number of the central ion and the chemical composition of the ligand, focusing on the anionic and cationic properties of the molecule.

    Common Ligand Types X type ligands: halides F-, Cl-, Br-, I-formally anionic: terminal reduced basicity relative to ‘free’ halide 3 bridging (μ) This page explains the terms complex ion and ligand, and looks at the bonding between the ligands and the central metal ion. It discusses various sorts of ligand (including some quite complicated ones), and describes what is meant by co-ordination number.

    Start studying Chemistry Common Ligands. Learn vocabulary, terms, and more with flashcards, games, and other study tools. For ligands with more than one double bond, each double bond contributes a pair of electrons for the 18-electron rule. Thus, butadiene, benzene, COD and COT can contribute 4, 6, 4, and 8

    Coordination compounds are metal ions surrounded by ligands. Ligands are either anions or molecules Ligands are either anions or molecules that can donate electrons into the d-orbitals of the metal ion and form a bond. Coordination compounds are metal ions surrounded by ligands. Ligands are either anions or molecules Ligands are either anions or molecules that can donate electrons into the d-orbitals of the metal ion and form a bond.

    The basis of the model is the interaction of d-orbitals of a central atom with ligands, which are considered as point charges. According to CFT, the attraction between the central metal and ligands in a complex is purely electrostatic. Consisting of a metal and ligands, their formulas follow the pattern [Metal Anions Neutrals] ±Charge, while names are written Prefix Ligands Metal(Oxidation State). Introduction According to the Lewis base theory , ligands are Lewis bases since they can donate electrons to the central metal atom.

    The nature of ligands coordinated to the center metal is an important feature of a complex compound along with other properties such as metal identify and its oxidation state. More specifically, it is the identity and consequently the ability of the ligand to donate or accept electrons to the center Type Charge Ligand Formula Name in Complexes monodentate neutral ammonia NH3 ammine water H2O aqua carbon monoxide CO carbonyl pyridine pyr pyridine

    Weak and strong field ligands. the spectrochemical series. If the ligand is a weak field splitter then the complex will be high spin. If th li d i t fi ld litt th th l ill b l If the ligand is a strong field splitter then the complex will be low spin. 10 6.Revisiting Crystal Fiel d Theory and Magnetism 1/10/2006 · Integrin-ligand partners. Historically, most integrin-ligand pairs have been identified either by affinity chromatography or through the ability of subunit-specific monoclonal antibodies to block cell adhesion to specific ligands.

    A spectrochemical series is a list of ligands ordered on ligand strength and a list of metal ions based on oxidation number, group and its identity. In crystal field theory, ligands modify the difference in energy between the d orbitals Δ can u give a list of possible ligands with their types and charges - Chemistry - Coordination Compounds

    The nature of ligands coordinated to the center metal is an important feature of a complex compound along with other properties such as metal identify and its oxidation state. More specifically, it is the identity and consequently the ability of the ligand to donate or accept electrons to the center Coordination compounds contain an ion and an array of ligands. Naming coordination compounds involves a set of rules which includes the oxidation number of the central ion and the chemical composition of the ligand, focusing on the anionic and cationic properties of the molecule.

    The role of the atomic charges on the ligands and platinum

    list of ligands and charges pdf

    Complexes of π–bonded and aromatic ligands uniroma2.it. Consisting of a metal and ligands, their formulas follow the pattern [Metal Anions Neutrals] ±Charge, while names are written Prefix Ligands Metal(Oxidation State). Introduction According to the Lewis base theory , ligands are Lewis bases since they can donate electrons to the central metal atom., Prefixes bis-, tris-, tetrakis-, pentakis-, hexakis- for ligands whose names contain a prefix of the first type, neutral ligands without special names, ionic ligands with particularly long names..

    Structure-Based Identification of Binding Sites Native

    list of ligands and charges pdf

    Toward the Syntheses of Universal Ligands for Metal Oxide. chloride has a –1 charge, the charge on the complex ion must be +3. • From the charge on the complex ion and the charge on the ligands, we can calculate the oxidation number of the metal. The basis of the model is the interaction of d-orbitals of a central atom with ligands, which are considered as point charges. According to CFT, the attraction between the central metal and ligands in a complex is purely electrostatic..

    list of ligands and charges pdf


    We report on the synthesis of tridentate-nitrogen pyrazole–pyridine–tetrazole (L 1 H) and pyrazole–pyridine–triazole (L 2 H) ligands and their complexation with lanthanides (Ln = Gd(III), Eu(III) and Tb(III)) resulting in stable, charge-neutral complexes Ln(L 1) 3 and Ln(L 2) 3, respectively. In dye-sensitized solar cells (DSCs), the redox mediator is responsible for the regeneration of the oxidized dye and for the hole transport towards the cathode. Here, we introduce new copper complexes with tetradentate 6,6′-bis(4-(S)-isopropyl-2-oxazolinyl)-2,2′-bipyridine ligands, Cu(oxabpy), as redox mediators. Copper coordination

    For ligands with more than one double bond, each double bond contributes a pair of electrons for the 18-electron rule. Thus, butadiene, benzene, COD and COT can contribute 4, 6, 4, and 8 Subsequent evaluation of the atomic charges, by resorting to two independent methods, i.e., the Natural Bond Order analysis of the wavefunction and the Bader's Quantum Theory of Atoms in Molecules, allowed for rationalization of the origin of the cis and trans influences.

    metric analysis (TGA) data that the surface coverage of the particles was ˘1 ligand/nm2 for 1, and independent of particle size. For 2 we estimated the surface coverage to be ˘11 ligands/nm2. The role of the atomic charges on the ligands and platinum(ii) in affecting the cis and trans influences in [PtXL(PPh3)2]+ complexes (X = NO3, Cl, Br, I; L = 4-substituted pyridines, amines, PPh3).

    Structure-Based Identification of Binding Sites, Native Ligands and Potential Inhibitors for G-Protein Coupled Receptors Claudio N. Cavasotto,#† Andrew J.W. Orry,# and Ruben A. Abagyan* Effects of Ligands on Charge Generation and Recombination in Hybrid Polymer/Quantum Dot Solar Cells Adam E. Colbert , Wenbi Wu , Eric M. Janke , Fei Ma , and David S. Ginger * Department of Chemistry, University of Washington , Box 351700, Seattle, Washington 98195-1700, United States

    The term ligand (ligare [Latin], to bind) was first used by Alfred Stock in 1916 in relation to silicon chemistry. It became more commonly associated with coordination chemistry following the publication of an article by H. Irving and R.J.P. Williams in Nature, 1948, 162, 746. Identify the ligands and their charges in Co(en)2(CN)2^+. Expert Answer. 100 % (1 rating) This problem has been solved! See the answer. Previous question Next question . Get more help from Chegg. Get 1:1 help now from expert Chemistry tutors

    Complex ion: a charged species consisting of a metal ion surrounded by ligands (see e). c. Counter ions: anions or cations that balance the charge on a complex ion in a coordina- tion compound. The design of new PHOX ligands is still subject to current research and the synthesis of a lot of different PHOX ligands have been reported during the last years . Kunz reported the preparation of a carbohydrate based PHOX ligand 2 [19] .

    The term ligand (ligare [Latin], to bind) was first used by Alfred Stock in 1916 in relation to silicon chemistry. It became more commonly associated with coordination chemistry following the publication of an article by H. Irving and R.J.P. Williams in Nature, 1948, 162, 746. can u give a list of possible ligands with their types and charges - Chemistry - Coordination Compounds

    Structure and bonding of coordination compounds. Werner originally postulated that coordination compounds can be formed because the central atoms carry the capacity to form secondary, or coordinate, bonds, in addition to the normal, or valence, bonds. The most critical point we should remember is that like oxidation state assignments, electron counting is a formalism and does not necessarily reflect the distribution of electrons in the molecule. However, these formalisms are very useful to us, and both will give us the same final answer.

    This is a worksheet that asks students to identify the coordination, number, the shape and the ligand surrounding example meta ions. Coordination compounds are metal ions surrounded by ligands. Ligands are either anions or molecules Ligands are either anions or molecules that can donate electrons into the d-orbitals of the metal ion and form a bond.

    For ligands with more than one double bond, each double bond contributes a pair of electrons for the 18-electron rule. Thus, butadiene, benzene, COD and COT can contribute 4, 6, 4, and 8 The basis of the model is the interaction of d-orbitals of a central atom with ligands, which are considered as point charges. According to CFT, the attraction between the central metal and ligands in a complex is purely electrostatic.

    6 Chemistry of Transition Metals ***** Simple substances of transition metals have properties Most ligands are neutral or anionic s ubstances but cationic ones, such as the there are relatively few Mo(III) or W(III) compounds compared with many Cr(III) ones. Aqua ions (ions with water ligands) are very common among compounds of first series metals but few are known amongst the second and We report on the synthesis of tridentate-nitrogen pyrazole–pyridine–tetrazole (L 1 H) and pyrazole–pyridine–triazole (L 2 H) ligands and their complexation with lanthanides (Ln = Gd(III), Eu(III) and Tb(III)) resulting in stable, charge-neutral complexes Ln(L 1) 3 and Ln(L 2) 3, respectively.

    6 Chemistry of Transition Metals ***** Simple substances of transition metals have properties Most ligands are neutral or anionic s ubstances but cationic ones, such as the there are relatively few Mo(III) or W(III) compounds compared with many Cr(III) ones. Aqua ions (ions with water ligands) are very common among compounds of first series metals but few are known amongst the second and The basis of the model is the interaction of d-orbitals of a central atom with ligands, which are considered as point charges. According to CFT, the attraction between the central metal and ligands in a complex is purely electrostatic.

    1.0 Ligands A ligand can be an ion or an atom that can form a co-ordination complex with a central atom, usually a metal. A ligand is a molecule that selectively binds to another molecule. Lecture 3 Ligands and Bonding and Electron ligands are derived from charge-neutral precursors: NH 3, amines, N-heterocycles such as pyridine, PR 3, CO, alkenes etc. X ligands are derived from anionic precursors: halides, hydroxide, alkoxide alkyls—species that are one-electron neutral ligands, but two electron . donors as anionic ligands. EDTA 4-is classified as an L 2 X 4 ligand

    Coordination Chemistry and Ligand Exchange reactions in the Synthesis of New Functional Inorganic Compounds S. Natarajan Framework Solids Laboratory, Solid State and Structural Chemistry Unit, IISc, Bangalore 560012 E-mail: snatarajan@sscu.iisc.ernet.in . Novosibirsk, 2009 What is a Coordination Complex/Compound? One of a number of complex compounds in which an atom or … Start studying Chemistry Common Ligands. Learn vocabulary, terms, and more with flashcards, games, and other study tools.

    Structures With Monodentate Ligands. Monodentate ligands are Lewis bases that donate a single pair ("mono") of electrons to a metal atom. Monodentate ligands can be either ions (usually anions) or neutral molecules. In ligand field theory, the various d orbitals are affected differently when surrounded by a field of neighboring ligands and are raised or lowered in energy based on the strength of their interaction with the ligands.

    Coordination Chemistry Coordination compounds • neutral coordination compounds include the metal and its bound ligands • the number of bonds in a coordination complex does not correlate 31/08/1999 · Furthermore, many large, tight-binding ligands have no formal charges. Thus, although electrostatic interactions have a critical role to play in specific complexes, they do not, by themselves, offer a general explanation of the binding data.