Pyridine‐2‐thiolato Complexes of V^II, V^III, and V^IV with Unusual Structural Features

Abstract

Se-CI bonds and the Se-Cl bridging bond. Figure4 (left) shows the Laplacian distribution of the electron density of 1. Whereas the electron density distribution of the bridging C1 atom is spherically symmetrical, the terminal Cl atoms show a significant distortion of the electron density distribution and an overlap with the electron density of the Se atoms. This indicates a covalent character for the terminal Se-Cl bonds, whereas the bridging C1 atom is rather ionically bound. The calculation of the charge distribution according to M~l l i k e n~"~ supports this interpretation ( Table 1). The bridging C1 atom with a partial charge of -0.61 is clearly more negatively charged than the terminal C1 atoms (-0.21). The Se atoms in 1 have a positive partial charge (+ 0.69), which in the cation of 2 is almost identical (+ 0.70). The Laplacian distribution of the U-shaped cation (Fig. 4 right) shows that the only significant difference to the corresponding structural unit in 1 is the orientation of the Se-N-Se unit. Obviously the repulsion between the in-plane orbitals of the lone pairs at C1 and at N in the W-shaped structure of the cation of 2 is greater than that between Se and N in the U-shaped structure. Fig, 4. Laplacian distribution of the electron density in 1 (left) and in the cation of 2 (right).The calculated frequency spectra for 1 and for the cation of 2 show that the optimized structures are minima on the potential energy hypersurface (no negative eigenvalues of the Hessian matrix). In agreement with the experiment a frequency shift to higher wavenumbers is calculated for the highest positioned band (v,,(Se-N-Se), b2) from 862 cm-' (1) to 909 cm-(cation of 2) during the formation of 2 from 1. Experimental Procedure1: A solution of tris(trimethylsily1)amine (2.2 g, 9.4 mmol) in CH,CI, (20 mL) was added dropwise to a suspension of SeCI, (4.1 g, 18.7 mmol) in CH,CI, (30 mL) and stirred. This was refluxed for 12 h, filtered to remove small amounts of unreacted SeCI,, and after concentration to 10 mL cooled to 5 "C. The red crystals were separated by filtration, washed with a little cold CH,CI,, and dried in vacuum (yield 1.5 g, 57 %, based on SeCI,, m.p. 69°C). The chlorine formed by this reaction reacted with a part of the tris(trimethysilyl)amine. An improvement in the yield strived for by the addition of larger quantities of amine is not advisable since explosive by-products are formed.

Tetranuclear and Pentanuclear Vanadium(IV/V) Carboxylate Complexes: [V4O8(NO3)(O2CR)4]2- and [V5O9X(O2CR)4]2- (X = Cl-, Br-) Salts

“…Heavy crude oils with large amounts of organic sulfur compounds (thiophenes, thiols, and disulfides) also have significant amounts of metallic impurities, chiefly V, Ni, and Fe . The oil-soluble vanadyl species are reduced and sulfided and deposited on the catalyst as insoluble vanadium sulfides, which decrease the activity of the catalyst pores. 1a, The molecular mechanism for vanadium deposition on the catalyst as vanadium sulfides (chiefly V 2 S 3 and V 3 S 4 ) is not completely understood, although it has been extensively studied. 1a,− As part of our own efforts, we have prepared a variety of discrete V/S compounds with thiolate/sulfide/persulfide ligands to model the V/S intermediates to V 2 S 3 /V 3 S 4 that form under the reducing and S-rich conditions of hydrodesulfurization. , …”

Pyridine-2-selenolate complexes of palladium(II) and platinum(II): crystal structure of [(Prn3P)Cl2Pd(NC5H4Se)PdCl(PPrn3)]

“…Alternatively, small bite bidentate anionic hybrid ligands containing both soft chalcogen and hard O/N atoms have also been employed in building bi-and poly-nuclear complexes. [10][11][12] One of the families of this class of ligands is the pyridine-2-chalcogenolate ion I. The ligand chemistry of NC 5 H 4 S Ϫ is well developed.…”

“…space group P1, a = 11.592 (2), b = 11.9292 (14), c = 13.6590 (11) Å, α = 88.531 (8), β = 84.457 (11), γ = 61.357(12) 0 , U = 1649.4(4) Å 3 , T = 293(2) K, Z = 2, µ(Mo-Kα) = 2.546 mm Ϫ1 , 6107 reflections measured, 5790 unique (R int = 0.026) which were used in all calculations. The final wR2 = 0.0851, R1 = 0.0381.…”

Trinuclear Early/Late‐Transition‐Metal Thiolate Complexes

“…The molecular structure of the cluster anion [Co 2 V(SPh) 8 ] 2-in 1 is shown in Figure 1. There is an inversion centre at the vanadium atom, and 1 can be viewed as consisting of a distorted-octahedral vanadium atom sharing parallel trigonal faces with two cobalt-centred [Co (1) [26] and [V(Spy) 3 ] -{V-S: 254.5 pm (avg.)} [27] and in [V(SC 6 H 3 -2,6-Cl 2 ) 2 -(tmeda)] {V-S: 246.4(2) and 246.8(2) pm} [28] but are slightly longer than in [V(μ-SArЈ)I] 2 {ArЈ = C 6 H 3 -2,6-(C 6 H 3 -2,6-iPr 2 ) 2 ; V-S: 239.6 and 241.3(1) pm}, which comprises a η 6 -coordination of the vanadium by an aryl ring.…”