Influence of the Cis Ligand on the H−H Separation and the Rotation Barrier of the Dihydrogen in Osmium-Elongated Dihydrogen Complexes Containing an Ortho-Metalated Ketone

Abstract

Treatment of the complex (1) with HBF4·OEt2 in diethyl ether−acetone (2:1) affords the elongated dihydrogen derivative (2), which reacts with NaCl and CsF to give (X = Cl (3), F (4)). The X-ray diffraction studies on 2 and 4 and DFT calculations on the model complexes (1t), (2t), and (X = Cl (3t), F (4t)) suggest that one of the hydrogen atoms bonded to the osmium atom undergoes a cis electrostatic attraction with the L ligand (L = H (1, 1t), (CH3)2CO or H2O (2, 2t), Cl (3, 3t), F (4, 4t)), which increases in the sequence (CH3)2CO or H2O < Cl ≤ F < H. This interaction provokes a lengthening of the hydrogen−hydrogen bond and an increase in the rotation barrier of the elongated dihydrogen ligand. Thus, it is observed that the separation between the hydrogen atoms of the dihydrogen decreases in the sequence 1t (1.695 Å) > 4t (1.544 Å) > 3t (1.489 Å) > 2t (1.455 Å), whereas the rotation barrier of the dihydrogen increases in the sequence 2 (<9 kcal·mol-1) < 3 (≅9 kcal·mol-1) < 4 (10.1 ± 0.8 kcal·mol-1) < 1 (13.9 ± 0.3 kcal·mol-1).

(NHC)Palladium Complexes from Hydroxy‐Functionalized Imidazolium Salts as Catalyst for the Microwave‐Accelerated Fluorine‐Free Hiyama Reaction

“…The hydroxy hydrogen atoms point out towards the chlorido ligands of adjacent molecules. The separations between these atoms of 2.34 [H(1A) ··· Cl(2A)] and 2.40 [H(2A) ··· Cl(1A)] Å are smaller than the sum of the van der Waals radii of hydrogen and chlorine [ r vdW (H) = 1.20 Å, r vdW (Cl) = 1.75 Å], which is in agreement with the presence of intermolecular hydrogen bonds 24…”

Amide-Directed Formation of Five-Coordinate Osmium Alkylidenes from Alkynes

“…An extended view of the structure (Figure ) reveals that the molecules of this complex form infinite chains by means of intermolecular N–H···O hydrogen bonds between the NH of the amide of a molecule and the amidic oxygen atom of the adjacent one. Thus, the intermolecular H(1)–O(1) separation of 2.05(7) Å is shorter than the sum of the van der Waals radii of hydrogen and oxygen ( r vdW (H) = 1.20 Å; r vdW (O) = 1.52 Å), whereas the N(1)–H(1)–O(1) angle is almost linear (167(7)°).…”

“…An extended view of the structure (Figure ) reveals that, like those of 2 , the molecules of this complex form infinite chains, in this case by means of intermolecular N–H···Cl(2) hydrogen bonds (chlorine trans to hydride). Thus, the intermolecular H(1)···Cl(2) separation of 2.32(5) Å is shorter than the sum of the van der Waals radii of hydrogen and chlorine ( r vdW (Cl) = 1.75 Å) and the N(1)–H(1)–Cl(2) angle is almost linear (169(4)°).…”

Carbonyl group‐containing organometallic intramolecular‐coordination five‐membered ring compounds

“…The carbonyl group‐containing organometallic intramolecular coordination five‐membered ring compounds prepared by orthometalation are shown in equation (4). Sixteen kinds of elements and 79 types of compounds are included in the Cambridge Structural Database 18–52. For example, the orthometalations of alkyl phenyl ketone [equation (5)29], aryl phenyl ketone [equation (6)36], benzaldehyde [equation (7)35], phenyl amide [equation (8)46], etc.…”