Research Article Active-site mutants of class B b-lactamases
... Conservation of the coordination around both zinc ions depended on the mutated residue. In turn, the position of the water molecules and/or of the other zinc ligands sometimes changed, occasionally modifying profoundly the relative disposition of catalytically important functional groups. Superimpos ...
... Conservation of the coordination around both zinc ions depended on the mutated residue. In turn, the position of the water molecules and/or of the other zinc ligands sometimes changed, occasionally modifying profoundly the relative disposition of catalytically important functional groups. Superimpos ...
Advances in f-element cyanide chemistry
... of unique examples of discrete mono- and polycyanide complexes which revealed unprecedented and unexpected coordination geometries. Until recently, the linear metallocenes of the f-elements were limited to three compounds of the divalent lanthanides (Sm, Eu, and Yb) for which the linear geometry was ...
... of unique examples of discrete mono- and polycyanide complexes which revealed unprecedented and unexpected coordination geometries. Until recently, the linear metallocenes of the f-elements were limited to three compounds of the divalent lanthanides (Sm, Eu, and Yb) for which the linear geometry was ...
Conformation Switching in Gas-Phase Complexes of Histidine with
... set with a relativistic effective core potential was used for Sr and Ba atoms. For the Ca and Ba complexes, the 6-311++G(d,p) basis set was used. Corrections for zero-point vibrational energy and basis-set superposition error were included for some complexes. For the survey calculations of all alkal ...
... set with a relativistic effective core potential was used for Sr and Ba atoms. For the Ca and Ba complexes, the 6-311++G(d,p) basis set was used. Corrections for zero-point vibrational energy and basis-set superposition error were included for some complexes. For the survey calculations of all alkal ...
ChemComm FEATURE ARTICLE - Faculty for Chemistry and
... central X atom, and so the interaction is more conveniently represented by using the X–X , Z ‘‘half-arrow’’ notation in which the ‘‘half-arrow’’ is drawn from the central X atom to the outer Z atom (Fig. 4),9 as illustrated for the bridging hydride complex, {[(CO)5Cr]2(m-H)} (Fig. 6).10 The reason ...
... central X atom, and so the interaction is more conveniently represented by using the X–X , Z ‘‘half-arrow’’ notation in which the ‘‘half-arrow’’ is drawn from the central X atom to the outer Z atom (Fig. 4),9 as illustrated for the bridging hydride complex, {[(CO)5Cr]2(m-H)} (Fig. 6).10 The reason ...
Palladium Complexes Containing Potentially
... The CH2 group in the sulfur-containing complex 3b appears as two sets of broad AB signals at room temperature, which coalesce at elevated temperatures [Tcoal = 323 K, ΔG‡ ≈ 63(⫾2) kJ mol–1]. The AB patterns are well distinguishable in CD2Cl2 solution at –20 °C and reveal two isomers due to the pres ...
... The CH2 group in the sulfur-containing complex 3b appears as two sets of broad AB signals at room temperature, which coalesce at elevated temperatures [Tcoal = 323 K, ΔG‡ ≈ 63(⫾2) kJ mol–1]. The AB patterns are well distinguishable in CD2Cl2 solution at –20 °C and reveal two isomers due to the pres ...
WOR3135 GB 38 No2
... The +2 oxidation state is very rare in mononuclear complexes but quite common in binuclear compounds containing a formal gold-gold bond [28,29]. To date, the only known water-soluble gold(II) species are those derived from halide methathesis of the bis(ylide) dimer [Au2Cl2{µ-(CH2)2PPh2}2] with the s ...
... The +2 oxidation state is very rare in mononuclear complexes but quite common in binuclear compounds containing a formal gold-gold bond [28,29]. To date, the only known water-soluble gold(II) species are those derived from halide methathesis of the bis(ylide) dimer [Au2Cl2{µ-(CH2)2PPh2}2] with the s ...
Nickel macrocycles with complex hydrides—new avenues for
... the abundant possibilities for designing transition metal borohydride complexes. Regarding the desired catalytic role, it doesn’t seem unreasonable (though recognising this as speculation in the absence of a definite mechanism) that when either discharging or recharging the hydridic hydrogen store t ...
... the abundant possibilities for designing transition metal borohydride complexes. Regarding the desired catalytic role, it doesn’t seem unreasonable (though recognising this as speculation in the absence of a definite mechanism) that when either discharging or recharging the hydridic hydrogen store t ...
coord_chem_2
... • The oxidation state of the metal centre is given by a Roman numeral. • If the complex is an anion the ending –ate is attached to the name of the metal. ...
... • The oxidation state of the metal centre is given by a Roman numeral. • If the complex is an anion the ending –ate is attached to the name of the metal. ...
Ruthenium(II/III) - Publications of the IAS Fellows
... higher energy bands in the UV region are of intra-ligand p–p* type or charge-transfer transitions involving energy levels which are higher in energy than the ligand lowest unoccupied molecular orbital (LUMO). It may be noted that for the Ru(bpy) 21 complex the ...
... higher energy bands in the UV region are of intra-ligand p–p* type or charge-transfer transitions involving energy levels which are higher in energy than the ligand lowest unoccupied molecular orbital (LUMO). It may be noted that for the Ru(bpy) 21 complex the ...
Side-on binding of p-sulphonatocalix[4]arene to the
... or are charged but stabilised by cations, these groups form the rim of the bowl opening. The hydroxyl groups however, are packed closely together at the base of the molecule, leaving only a very small opening. Given this structure it was expected that the binding of s-CX[4] to di-Pt would occur over ...
... or are charged but stabilised by cations, these groups form the rim of the bowl opening. The hydroxyl groups however, are packed closely together at the base of the molecule, leaving only a very small opening. Given this structure it was expected that the binding of s-CX[4] to di-Pt would occur over ...
structures of simple solids
... The Ionic Model by Goldschmidt states that are ions are essentially charged, incompressible, nonpolarisable spheres. More sophisticated models assume ions are composed of two parts: A central, hard, unperturbable core, where most electron density is concentrated. A soft, polarisable outer sphere, wh ...
... The Ionic Model by Goldschmidt states that are ions are essentially charged, incompressible, nonpolarisable spheres. More sophisticated models assume ions are composed of two parts: A central, hard, unperturbable core, where most electron density is concentrated. A soft, polarisable outer sphere, wh ...
Scandium and Yttrium - Mercyhurst University
... resemble sunlight. As mentioned, scandium(III) triflate (Sc(CF3SO3)3) is a useful Lewis acid in organic synthesis as it is water-stable.1 Current Research Much like transition metals ions, scandium(III) and yttrium(III) will coordinate to a variety of ligands, including crown ethers, aza-crown ether ...
... resemble sunlight. As mentioned, scandium(III) triflate (Sc(CF3SO3)3) is a useful Lewis acid in organic synthesis as it is water-stable.1 Current Research Much like transition metals ions, scandium(III) and yttrium(III) will coordinate to a variety of ligands, including crown ethers, aza-crown ether ...
Elements – (Metals)
... electrons are not as strongly held. For example K forms K+ but Cl is apt to gain electron to become Cl–. Notice that both K+ and Cl– are isoelectronic (same electronic configuration as) with noble gas Ar. High Density because of close packed arrangement many metals have 12 nearest neighbors Group 1 ...
... electrons are not as strongly held. For example K forms K+ but Cl is apt to gain electron to become Cl–. Notice that both K+ and Cl– are isoelectronic (same electronic configuration as) with noble gas Ar. High Density because of close packed arrangement many metals have 12 nearest neighbors Group 1 ...
Properties of Atomic Orbitals and Intro to Molecular Orbital Theory
... – The spatial extent of the 4f orbitals leads to negligible overlap with other orbitals. orbitals. Thus the chemistry of the lanthanides is fairly constant, and the magnetism of these elements in compounds is similar to that of a free ion. ...
... – The spatial extent of the 4f orbitals leads to negligible overlap with other orbitals. orbitals. Thus the chemistry of the lanthanides is fairly constant, and the magnetism of these elements in compounds is similar to that of a free ion. ...
building bridges between inorganic and organic chemistry
... much interested in the fragments themselves as in their bonding capabilities. The moment we interact Fe(CO) 4 or CH 2 with another ligand, the initial ordering of al and b2 becomes relatively unimportant since both are typically strongly involved in the bonding. Dimerize, conceptually, the isolobal ...
... much interested in the fragments themselves as in their bonding capabilities. The moment we interact Fe(CO) 4 or CH 2 with another ligand, the initial ordering of al and b2 becomes relatively unimportant since both are typically strongly involved in the bonding. Dimerize, conceptually, the isolobal ...
Roald Hoffmann - Nobel Lecture
... much interested in the fragments themselves as in their bonding capabilities. The moment we interact Fe(CO) 4 or CH 2 with another ligand, the initial ordering of al and b2 becomes relatively unimportant since both are typically strongly involved in the bonding. Dimerize, conceptually, the isolobal ...
... much interested in the fragments themselves as in their bonding capabilities. The moment we interact Fe(CO) 4 or CH 2 with another ligand, the initial ordering of al and b2 becomes relatively unimportant since both are typically strongly involved in the bonding. Dimerize, conceptually, the isolobal ...
Co(NH 3 ) 5 X
... Pt(II) has been studied a lot. Its complexes are stable, easy to synthesize and undergo ligand exchange reactions at rates slow enough to allow easy monitoring. Other d8 systems react much faster (105-107x) and the data on these systems is limited. Current knowledge of SP substitution reactions stem ...
... Pt(II) has been studied a lot. Its complexes are stable, easy to synthesize and undergo ligand exchange reactions at rates slow enough to allow easy monitoring. Other d8 systems react much faster (105-107x) and the data on these systems is limited. Current knowledge of SP substitution reactions stem ...
Chm 118 - Clark Science Center
... 2.20 Orbitals of d Character and the Strange One We now do something sneaky. Since quantum mechanics demands that there are only five possible d orbitals and there are six possible combinations of a pair of Cartesian coordinates, we have to combine them in some fashion. We choose to add the last two ...
... 2.20 Orbitals of d Character and the Strange One We now do something sneaky. Since quantum mechanics demands that there are only five possible d orbitals and there are six possible combinations of a pair of Cartesian coordinates, we have to combine them in some fashion. We choose to add the last two ...
“HEAVY METALS”—A MEANINGLESS TERM?
... Bjerrum’s definition of “heavy metals” is based upon the density of the elemental form of the metal, and he classifies “heavy metals” as those metals with elemental densities above 7 g/cm3. Over the years, this definition has been modified by various authors, and there is no consistency. In 1964, th ...
... Bjerrum’s definition of “heavy metals” is based upon the density of the elemental form of the metal, and he classifies “heavy metals” as those metals with elemental densities above 7 g/cm3. Over the years, this definition has been modified by various authors, and there is no consistency. In 1964, th ...
Studies on nickel(II) and palladium(II) complexes with some
... is tetra-coordinated in a square-planar arrangement involving four N atoms of the macrocyclic ring. However, the proton magnetic resonance spectral pattern of the nickel complexes also indicated42 the presence of diamagnetic square-planar configuration. Probably, dissociation of the chloride anions ...
... is tetra-coordinated in a square-planar arrangement involving four N atoms of the macrocyclic ring. However, the proton magnetic resonance spectral pattern of the nickel complexes also indicated42 the presence of diamagnetic square-planar configuration. Probably, dissociation of the chloride anions ...
IOSR Journal of Applied Chemistry (IOSR-JAC)
... Fluorescence spectroscopy studies The fluorescent spectra of complexes, viz. Cu(4-MPipzcbmH)2X2, and Cu(MorphcbmH)2X2, (X = CH3COO and X2 = SO4) display maximum emission wavelengths(λemmax) corresponding to blue light emission at 430-432 nm and 433 - 439 nm respectively, the excitation wavelength be ...
... Fluorescence spectroscopy studies The fluorescent spectra of complexes, viz. Cu(4-MPipzcbmH)2X2, and Cu(MorphcbmH)2X2, (X = CH3COO and X2 = SO4) display maximum emission wavelengths(λemmax) corresponding to blue light emission at 430-432 nm and 433 - 439 nm respectively, the excitation wavelength be ...
T1u - Hunt Research Group
... o nevertheless for d-d transitions we also know the rules can be broken since TM complexes can be highly coloured, this will be covered shortly o complexes don’t need to be octahedral, the same principles apply to lower symmetry systems o if the centre of inversion is not present then the parity sel ...
... o nevertheless for d-d transitions we also know the rules can be broken since TM complexes can be highly coloured, this will be covered shortly o complexes don’t need to be octahedral, the same principles apply to lower symmetry systems o if the centre of inversion is not present then the parity sel ...
Syntheses, spectral characterization, thermal properties and DNA
... base ligands L1, L2 and L3 showed the broad bands at 3444 cm-1 were due to stretching vibrations of phenolic OH [15-17]. These bands were absent in all the complexes, indicating deprotonation on coordination of the Schiff base ligands to metal ion. In addition, the bands at 1346–1350 cm-1 attributed ...
... base ligands L1, L2 and L3 showed the broad bands at 3444 cm-1 were due to stretching vibrations of phenolic OH [15-17]. These bands were absent in all the complexes, indicating deprotonation on coordination of the Schiff base ligands to metal ion. In addition, the bands at 1346–1350 cm-1 attributed ...
SYNTHESIS AND CHARACTERISATION OF TRANSITION AND
... 4.30 and 4.27 B.M. respectively, which are much below the range expected for octahedral cobalt(II) magnetic ...
... 4.30 and 4.27 B.M. respectively, which are much below the range expected for octahedral cobalt(II) magnetic ...
Lecture 11 – Reaction Types and Mechanisms for Inorganic
... The process repeats itself until the hexaaquo ion is formed. Each of these mechanisms involves a reaction to give a reactive intermediate with a different coordination number (5 or 7). When M = Co(III) (low-spin d6), considerable crystal field stabilization is lost because the CFSE is so much greate ...
... The process repeats itself until the hexaaquo ion is formed. Each of these mechanisms involves a reaction to give a reactive intermediate with a different coordination number (5 or 7). When M = Co(III) (low-spin d6), considerable crystal field stabilization is lost because the CFSE is so much greate ...
Ligand
In coordination chemistry, a ligand (/lɪɡənd/) is an ion or molecule (functional group) that binds to a central metal atom to form a coordination complex. The bonding between metal and ligand generally involves formal donation of one or more of the ligand's electron pairs. The nature of metal-ligand bonding can range from covalent to ionic. Furthermore, the metal-ligand bond order can range from one to three. Ligands are viewed as Lewis bases, although rare cases are known to involve Lewis acidic ""ligand.""Metals and metalloids are bound to ligands in virtually all circumstances, although gaseous ""naked"" metal ions can be generated in high vacuum. Ligands in a complex dictate the reactivity of the central atom, including ligand substitution rates, the reactivity of the ligands themselves, and redox. Ligand selection is a critical consideration in many practical areas, including bioinorganic and medicinal chemistry, homogeneous catalysis, and environmental chemistry.Ligands are classified in many ways like : their charge, their size (bulk), the identity of the coordinating atom(s), and the number of electrons donated to the metal (denticity or hapticity). The size of a ligand is indicated by its cone angle.