TY - JOUR

T1 - Structural preferences of quadruply bonded bimetallic complexes. A DFT study of the chelated (α) and bridged (β) isomers in Mo2Cl4(H2P(CH2)(n)PH2)2 (n = 1, 2)

AU - Blasco, Sophie

AU - Demachy, Isabelle

AU - Jean, Yves

AU - Lledós, Agustí

PY - 2000/4/30

Y1 - 2000/4/30

N2 - The structure of the quadruply bonded Mo2Cl4(H2P(CH2)(n)PH2)2 (n = 1, 2) bimetallic complexes, with two chelating (α isomer) or two bridging (β isomer) diphosphine ligands, is studied by means of DFT calculations with the B3LYP functional. For each complex (1-α, 1-β and 2-α, 2-β, for n = 1 and 2, respectively), full geometry optimization is performed for both the lowest singlet (δ2) and triplet (3δδ*) states. The chelated α isomers (1-α and 2-α) adopt an essentially eclipsed conformation in both the singlet and the triplet states. The 1-β complex is found to be staggered in the triplet state. Three structures are optimized for the 2-β isomer with a chair (2-β(c)), a twist (2-β(t)) or a boat (2-β(b)) conformation of the Mo-P-C-C-P-Mo six-membered rings. The 2-β(c) and 2-β(t) complexes adopt a twisted conformation in both the singlet and the triplet states while the 2-β(b) complex is eclipsed in the singlet state. A singlet ground state is found for all these complexes, the β isomer being more stable than the α isomer by 17.1 and 7.0 kcal mol-1 for n = 1 and n = 2, respectively. These geometrical and energetic results are discussed with respect to available experimental data. (C) 2000 Elsevier Science S.A.

AB - The structure of the quadruply bonded Mo2Cl4(H2P(CH2)(n)PH2)2 (n = 1, 2) bimetallic complexes, with two chelating (α isomer) or two bridging (β isomer) diphosphine ligands, is studied by means of DFT calculations with the B3LYP functional. For each complex (1-α, 1-β and 2-α, 2-β, for n = 1 and 2, respectively), full geometry optimization is performed for both the lowest singlet (δ2) and triplet (3δδ*) states. The chelated α isomers (1-α and 2-α) adopt an essentially eclipsed conformation in both the singlet and the triplet states. The 1-β complex is found to be staggered in the triplet state. Three structures are optimized for the 2-β isomer with a chair (2-β(c)), a twist (2-β(t)) or a boat (2-β(b)) conformation of the Mo-P-C-C-P-Mo six-membered rings. The 2-β(c) and 2-β(t) complexes adopt a twisted conformation in both the singlet and the triplet states while the 2-β(b) complex is eclipsed in the singlet state. A singlet ground state is found for all these complexes, the β isomer being more stable than the α isomer by 17.1 and 7.0 kcal mol-1 for n = 1 and n = 2, respectively. These geometrical and energetic results are discussed with respect to available experimental data. (C) 2000 Elsevier Science S.A.

KW - Bimetallic complexes

KW - DFT calculations

KW - Quadruple bonds

KW - Structural preferences

U2 - 10.1016/S0020-1693(00)00026-8

DO - 10.1016/S0020-1693(00)00026-8

M3 - Article

VL - 300-302

SP - 837

EP - 845

JO - Inorganica Chimica Acta

JF - Inorganica Chimica Acta

SN - 0020-1693

ER -