STRUCTURAL AND THEORETICAL-ANALYSIS OF M-H-CENTER-DOT-CENTER-DOT-CENTER-DOT-H-M AND M-H-CENTER-DOT-CENTER-DOT-CENTER-DOT-H-C INTERMOLECULARINTERACTIONS
D. Braga et al., STRUCTURAL AND THEORETICAL-ANALYSIS OF M-H-CENTER-DOT-CENTER-DOT-CENTER-DOT-H-M AND M-H-CENTER-DOT-CENTER-DOT-CENTER-DOT-H-C INTERMOLECULARINTERACTIONS, Inorganic chemistry, 37(13), 1998, pp. 3337-3348
The relationship between molecular and crystal structures of organomet
allic complexes showing intermolecular interactions of the M-H- - -H-M
and M-H- - -H-C type has been investigated by a combined use of exten
ded Huckel and DFT calculations, and crystal packing analysis. Molecul
ar and crystal structures determined by neutron and/or X-ray diffracti
on experiments of coordination complexes and clusters showing intermol
ecular M-H- - -H-M and M-H- - -H-C interactions below 2.6 Angstrom hav
e been retrieved from the Cambridge Structural Database. Molecular orb
ital analysis has been carried out by means of extended Huckeland DFT
calculations on selected compounds. For the HMn(CO)(5) dimer, where th
e interaction is of the M-H- - -H-M type, the system is reminiscent of
a bound hydrogen molecule where the H-H bond has been greatly weakene
d. A very small binding energy of ca. 5 kJ mol(-1) has been determined
using DFT calculations. This simple interpretation does not hold in t
he cases of M-H- - -H-C short contacts, which are more appropriately d
escribed as arising from a special type of hydrogen bond associated wi
th opposite charges on the two hydrogen atoms.