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Transition Metal Complexes with more than one Dihydrogen Ligand: Structure and Bonding of M(CO) 6–x (H 2 ) x (M = Cr, Mo, W; x = 1, 2, 3) [1]
Author(s) -
Dapprich Stefan,
Frenking Gernot
Publication year - 1998
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/(sici)1521-3749(199804)624:4<583::aid-zaac583>3.0.co;2-p
Subject(s) - chemistry , crystallography , bond dissociation energy , dihydrogen complex , dissociation (chemistry) , ligand (biochemistry) , ab initio , transition metal , ab initio quantum chemistry methods , metal , hydrogen bond , molecule , hydride , catalysis , biochemistry , receptor , organic chemistry
Quantum mechanical ab initio calculations at the MP2 and CCSD(T) level of theory have been used to investigate the geometries and bond energies of the complexes M(CO) 6–x (H 2 ) x (M = Cr, Mo, W; x = 1, 2, 3). The theoretically predicted M(CO) 5 –(H 2 ) bond dissociation energies are in excellent agreement with experimental values. The M–(H 2 ) dissociation energies of the bis‐ and tris‐dihydrogen complexes are very similar to the values for the mono‐dihydrogen complexes. In M(CO) 5 (H 2 ) the dihydrogen ligand prefers an eclipsed conformation relative to the equatorial carbonyl groups. For M(CO) 4 (H 2 ) 2 the cis and trans isomers are nearly equal in energy for M = W, while a cis configuration is favoured for M = Cr. For M(CO) 3 (H 2 ) 3 the facial configurations are more stable than the meridial structures for all three metals M. The charge decomposition analysis (CDA) classifies dihydrogen as a donor ligand with moderate acceptor properties. In trans ‐M(CO) 4 (H 2 ) 2 back donation is increased and the M–(H 2 ) bonds are stronger than in M(CO) 5 –(H 2 ). Back donation in M(CO) 3 (H 2 ) 3 is slightly weaker than in the mono‐dihydrogen complexes M(CO) 5 (H 2 ).