Compounds featuring a bond between a Group 13 (M) and a Group 15 element (N or P) and with the formulae HmMNHn and HmMPHn: structural aspects and bonding
Hj. Himmel et al., Compounds featuring a bond between a Group 13 (M) and a Group 15 element (N or P) and with the formulae HmMNHn and HmMPHn: structural aspects and bonding, J CHEM S DA, (5), 2001, pp. 535-545
Citations number
89
Categorie Soggetti
Inorganic & Nuclear Chemistry
Journal title
JOURNAL OF THE CHEMICAL SOCIETY-DALTON TRANSACTIONS
Following studies of the thermal and photoactivated reactions of the Group
13 metal atoms Al, Ga or In (M) with NH3 or PH3 in solid argon matrices, th
e properties of the observed or potential reaction products are discussed.
These are molecules with the general formula HmMEHn, where M=Al, Ga or In,
E=N or P, and m, n=0-3. All the molecules have been characterised structura
lly, energetically and vibrationally by Density Functional Theory (DFT) cal
culations. The following products have been identified experimentally by th
eir IR spectra: the adducts M . EH3, the metal(II) insertion products HMEH2
, the metal(III) derivatives H2MNH2 and H2MPH, and the metal(I) amides MNH2
. The observation of most of the IR-active fundamentals for different isoto
pic forms of the molecules MNH2 and H2MNH2 allowed normal coordinate analys
is calculations to be performed, thereby endorsing the vibrational assignme
nts and affording reliable force constants. Observed and hypothetical HmMEH
n molecules have been compared with particular reference to structural and
energetic differences according to whether E=N or P. Questions of bonding h
ave been addressed through calculations of barriers to rotation of planar m
olecules and of barriers to inversion for molecules containing pyramidal MP
H2 moieties. pi -Type interactions play only a minor part in the bonding of
planar molecules like H2MNH2. The much larger barrier to inversion of PH3
compared with NH3 results in pyramidal MPH2 but planar MNH2 fragments. With
the help of an appropriate MO scheme it is possible to rationalise how the
inversion barrier changes when one hydrogen of PH3 is replaced by an MHm g
roup.