Geometry and electronic structure of a heterometallic cluster Mo2Mg2 in different oxidation states of Mo: a DFT study (original) (raw)
Related papers
Dinitrogen Cleavage by Three-Coordinate Molybdenum (III) Complexes: Mechanistic and Structural Data1
Journal of the …, 1996
The synthesis and characterization of the complexes Mo[N(R)Ar] 3 (R ) C(CD 3 ) 2 CH 3 , Ar ) 3,5-C 6 H 3 Me 2 ), (µ-N 2 ){Mo[N(R)Ar] 3 } 2 , (µ-15 N 2 ){Mo[N(R)Ar] 3 } 2 , NMo[N(R)Ar] 3 , 15 NMo[N(R)Ar] 3 , Mo[N(t-Bu)Ph] 3 , (µ-N 2 ){Mo-[N(t-Bu)Ph] 3 } 2 , and NMo[N(t-Bu)Ph] 3 are described. Temperature-dependent magnetic susceptibility data indicate a quartet ground state for Mo[N(R)Ar] 3 . Single-crystal X-ray diffraction studies for Mo[N(R)Ar] 3 and NMo[N(t-Bu)Ph] 3 are described. Extended X-ray absorption fine structure (EXAFS) structural studies for Mo[N(R)Ar] 3 , (µ-N 2 ){Mo[N(R)Ar] 3 } 2 , and NMo[N(R)Ar] 3 are reported.
2010
The complexes of M 2? (M = Mn, Co, Ni, Cu, Zn), trans-[M(H 2 O) 4 (NO 3) 2 ] in their high-spin ground electronic states have been investigated theoretically for the first time using several correlated DFT levels as well as with the MP2 method in conjunction with two different basis sets, 6-311??G(d, p) and LANL2TZ?/6-311??G(d, p), to examine their equilibrium structures and stabilities. Among the correlated methods, the X3LYP level together with the 6-311??G(d, p) basis set gives the best estimate of geometries in these complexes. The metal-ligand binding energies obtained follow the trend Cu 2? [ Ni 2? [ Zn 2? [ Co 2? [ Mn 2? across the series examined, in precise agreement with the Irving-Williams series. The DFT methods largely overestimate the binding energies compared to the MP2 level and the trend follows the order PW91PW91 \ PBEPBE \ X3LYP \ B3LYP \ MP2. The use of an ECP basis on the central metal cation and a 6-311??G(d, p) basis set on the main group elements increases the binding energies of the complexes compared to that found using the full-core basis set 6-311??G(d, p) and the energy difference between them can be as large as 20 kcal mol-1. There are significant differences between the structures calculated in the gas phase and those calculated with the PCM model to simulate the effect of solvent. Solvation shortens the M-OH 2 bonds and lengthens the MONO 2 bonds such that the difference between the computed and the crystallographically observed bond lengths tends to decrease; it increases complex stability; and that it leads to the disappearance of two intramolecular H bonds between OH 2 and NO 3 ligands that are present in the gas-phase structures. While there are differences between the natural populated atomic charges and Bader's approach of the quantum theory of atoms in molecules (QTAIM), all show charge transfer from the ligands to the metal ion. However, the MP2-level-computed charges were found to be unreliable compared with the DFT-derived charges. The metal-ligand bonding and the intramolecular H bonding in the complex are explored with QTAIM and the insight gained into the electronic structure of these complexes is discussed. Keywords Late transition metal complexes Á Nitrate complexes Á Polarized continuum solvent model Á Intramolecular hydrogen bonding Á Atoms in molecules-DFT & MP2 studies Electronic supplementary material The online version of this article (
Inorganic Chemistry Communications, 2013
Six new complexes 1-6 with the common formula [M(NiL) 4 ][M(NCS) 4 ] (M=Mn, Fe, Co, Ni, Cu and Zn for 1, 2, 3, 4, 5 and 6, respectively; the same below) were synthesised and structurally characterised by X-ray single crystal analysis. NiL acts as a complex ligand. L denotes the dianion of dimethyl 5,6,7,8,15,16-hexahydro-6,7dioxodibenzo-[1,4,8,11]tetraazacyclotetradecine-13,18-dicarboxylate. Each M(II) centre of the [M(NiL) 4 ] 2+ complex cations in 1-6 adopts a distorted square-antiprism coordination geometry with a O 8 donor set. All the M\O bonds in the six complexes are abnormally long (2.444-2.528 Å). M(II) complexes having such weak coordination environments have not been reported, and eight-coordinate M(II) complexes with all the eight oxygen donor atoms coming from metalloligands have also not been documented. Each M(II) centre of the [M(NCS) 4 ] 2− anions in 1-6 has a distorted tetrahedral coordination environment with a N 4 donor set. Theoretical calculations for the bond dissociation energies (BDEs) of the M\O semi coordinate bonds were performed using density functional theory at B3LYP level. The calculated BDE values are 23.8, 25.5, 20.0, 22.3, 19.8 and 18.2 kcal/mol for 1, 2, 3, 4, 5 and 6, respectively. The BDE values suggest that the long Mn\O bonds in 1 and the long Co\O bonds in 3 are significantly weaker than their significantly shorter counterparts in the formerly reported [Mn(NiL) 2 (NCS) 2 ] and [Co(NiL) 2 (NCS) 2 ], respectively.
Inorganic Chemistry, 1988
T h i synthesis and reactivity of a series of mono-N2 complexes of molybdenum are reported. Reduction of MoCl,(triphos), where triphos = PhP(CH2CH2PPh2)2, with sodium amalgam in the presence of 2L or L2 and with a regulated amount of N 2 led to the formation of Mo(N2)(triphos)(L2) (1-5): 1, L = PMa2Ph; 2, L2 = Me2PCH2PMe2, dmpm; 3, L2 = 1,2-(Me2As)2C,H,, diars; 4, L2 = Ph2PCH2PPh2, dppm; 5, L2 = Ph2PCH2CH2PPh2, dppe. Complexes 3 and 5 were each a mixture of two isomeric mono-N2 complexes. Complexes 1-5 reacted with excess HX (X = Br, C1) to afford varying yields of ammonia, hydTazine, and N2 (and some H2). Loss of N2 occurred readily from 1 when it was evacuated in the solid state to give 7. Five-coordinate 7 reacted with H2, CO, and C2H4 in the solid state to form MoH2(triphos)(PMe2Ph), (8), M~(CO)(triphos)(PMe,Ph)~ (9), and Mo(C2H4)-(triphos)(PMe,Ph), (lo), respectively. Reaction of solids 7,8, and 10 with N2 regenerated 1. Structural assignments of the new complexes are based upon and 'H NMR spectral data. Triphos is shown to adopt bothfac and mer configurations.
Journal of Molecular Structure-theochem, 1997
Molecular orbitals are the main electronic structural units for analysis and solution of chemical problems at the electronic level. Historically, application of the MO method to transition metal and rare-earth complexes began with the improvement of crystal field theory by means of including covalency effects, and in this aspect it was called ligand field theory. However, in its present form the MO method in application to coordination compounds basically does not differ from that widely used for organic and maingroup systems, although practically the treatment of coordination system with this method is more complicated because of the presence of active d and f electrons. In this chapter the main ideas and special features of the MO approach are presented in a form applicable to transition metal coordination compounds. The general presentation of the MO method is discussed together with the methods of numerical calculations (ab initio, nonempirical, semiquantitative, and semiempirical), as well as other related approaches, including density-functional methods. The application of these methods to the solution of the main problem of coordination chemistry-the origin of chemical bonding-is given in Chapter 6, while specific calculations of electronic structure using these methods are demonstrated in Chapters 6, 9, 10, 11, and Solutions to Problems.
X-ray photoelectron spectra of molybdenum dinitrogen complexes and their derivatives
Journal of the Less Common Metals, 1977
The X-ray photoelectron spectra of 13 molybdenum compounds including ~r~~s-[Mo(N~)~(Ph~PCH~~H~PPh~)~] , trans-[MoCl(Nz)(PhzPCHzCH2-PPh&], trans-[MoBr(Nz)(Ph2PCHzCHZPPh2)21, trans-[MoI(N,Me)-(Ph2PCH&H2PPhz)z], trans-[MoI(N2CsH1,)(Ph2PCH2CH2PPh2)], MOM-{o-(M+&W&H&, ~~~~~~~~~~~~~~~~~~~~~~~~~ MW%CNWdN%. (Bu~N)~[Mo~O~S~ @32C:WW2121, Moz(SzCNEt2)203(SPh)2 and Mo2 O4 (S2 CNEt2)2 have been investigated. The Mo(3d,,,) binding energies range from 227.2 eV for MO(O) complexes to 232.5 eV for Mo(V1) complexes. The two N(ls) binding energies at 399.6 and 398.6 eV which were observed for tram-[Mo(N2)2(dppe)2] were assigned to the endo and exo nitrogen atoms, respectively. The effects of oxidation state and alkyl substituents on the N(ls) binding energies are also discussed.
Inorganic Chemistry, 2000
Reaction of [MoV(TpMe,Me)(O)Cl2] with 1,3-, 1,5-, 1,6-, 2,6-, and 2,7-dihydroxynaphthalene affords the dinuclear complexes [[Mo(TpMe,Me)(O)Cl]2(mu-C10H6O2)], abbreviated as 1,3-Mo2, 1,5-Mo2, 1,6-Mo2, 2,6-Mo2, and 2,7-Mo2, according to the substitution pattern of the bridging ligand. Electrochemical, UV-vis/NIR spectroscopic, and variable-temperature magnetic susceptibility studies have been used to probe the effects of the bridging-ligand topology on the metal-metal electronic and magnetic interactions. The complexes can be split into two classes according to the properties of the bridging ligands. Complexes 1,3-Mo2, 1,6-Mo2, and 2,7-Mo2 all have bridging ligands that are topologically equivalent to meta-substituted bridging ligands such as 1,3-dihydroxybenzene, in that (i) there is an odd number of C atoms separating the two oxygen atoms, regardless of the pathway that is taken through the ligand skeleton, and (ii) the doubly oxidized from of the bridging ligand is a diradical. These complexes are classified as being "T-meta" (= topologically equivalent to meta). Complexes 1,5-Mo2 and 2,6-Mo2 have bridging ligands that are topologically equivalent to para-substituted groups such as 1,4-dihydroxybenzene, in that (i) there is an even number of C atoms separating the two oxygen atoms, whichever pathway is taken through the ligand skeleton, and (ii) the doubly oxidized form of the bridging ligand is a diamagnetic quinone. These complexes are classified as "T-para". Electrochemical studies show that the comproportionation constants for the Mo(V)/Mo(IV) mixed-valence states of the T-meta complexes are smaller than those for the T-para complexes. Spectroelectrochemical studies show that the Mo(V)/Mo(IV) mixed-valence states of the T-para complexes show pronounced Mo(IV)-->Mo(V) IVCT transitions, whereas those of the T-meta complexes do not show these transitions. Magnetic susceptibility studies show that the T-meta complexes all display ferromagnetic exchange between the metal centers, whereas the T-para complexes all display antiferromagnetic exchange. Thus, both the electronic and the magnetic properties of these complexes show a clear demarcation into two sets according to the bridging-ligand topology.