Abstract
Reaction of simple amides with TiCl4 affords mixed amido-chloride species Ti(NR2)4-nCln The trisamide-chloride species Ti(NR2)3Cl can be prepared directly employing three equivalents of amide or by reaction Ti(NR2)4 with TiCl4. The compound Ti(NMe2)3Cl, 1, crystallizes in the trigonal space group Ric, with a = 11.525(5), c = 14.939(3) A, Z = 6, and V = 1718(1) Å;3. The compound Ti(NEt2)3Cl, 2, crystallizes in the monoclinic space group P21/c, with a = 8.385(2) Å, b = 15.958(2) Å, c = 14.230(4) Å, β= 107.79(1)°, Z = 4, and V = 1813(1) Å;3. The geometry of the Ti coordination sphere in these complexes is best described as pseudo-tetrahedral. The structural data are consistent with Ti-N multiple bonding. Preliminary results of EHMO calculations are consistent with dπ-pπ Ti-N bonding. Attempts to replace thehalides with phosphides (LiPR2, R = Me, Et, Ph) led not to the Ti(IV) phosphido species, but rather to redox chemistry yielding Ti(III) amides and P2R4. The barrier to rotation about the Ti-N bonds has been considered. Variable temperature 'H NMR studies reveal that the barrier is small. Extended Hiickel total energy minimization calculations have been performed. In addition, MMX calculations of the barrier to Ti-N rotation are reported. The results of these calculations imply that the rotational barrier is dominated by steric effects.
| Original language | English |
|---|---|
| Pages (from-to) | 357-362 |
| Number of pages | 6 |
| Journal | Canadian Journal of Chemistry |
| Volume | 69 |
| Issue number | 2 |
| DOIs | |
| Publication status | Published - Jan 1 1991 |
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Keywords
- Structures
- Ti-N bonding
- Titanium amides
ASJC Scopus subject areas
- Catalysis
- Chemistry(all)
- Organic Chemistry
Cite this
Lewis acidic titanium species : The synthesis, structure, bonding and molecular modelling considerations of the complexes Ti(NR2)3CI (R = Me, Et). / Dick, David G.; Rousseau, Roger; Stephan, Douglas W.
In: Canadian Journal of Chemistry, Vol. 69, No. 2, 01.01.1991, p. 357-362.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Lewis acidic titanium species
T2 - The synthesis, structure, bonding and molecular modelling considerations of the complexes Ti(NR2)3CI (R = Me, Et)
AU - Dick, David G.
AU - Rousseau, Roger
AU - Stephan, Douglas W.
PY - 1991/1/1
Y1 - 1991/1/1
N2 - Reaction of simple amides with TiCl4 affords mixed amido-chloride species Ti(NR2)4-nCln The trisamide-chloride species Ti(NR2)3Cl can be prepared directly employing three equivalents of amide or by reaction Ti(NR2)4 with TiCl4. The compound Ti(NMe2)3Cl, 1, crystallizes in the trigonal space group Ric, with a = 11.525(5), c = 14.939(3) A, Z = 6, and V = 1718(1) Å;3. The compound Ti(NEt2)3Cl, 2, crystallizes in the monoclinic space group P21/c, with a = 8.385(2) Å, b = 15.958(2) Å, c = 14.230(4) Å, β= 107.79(1)°, Z = 4, and V = 1813(1) Å;3. The geometry of the Ti coordination sphere in these complexes is best described as pseudo-tetrahedral. The structural data are consistent with Ti-N multiple bonding. Preliminary results of EHMO calculations are consistent with dπ-pπ Ti-N bonding. Attempts to replace thehalides with phosphides (LiPR2, R = Me, Et, Ph) led not to the Ti(IV) phosphido species, but rather to redox chemistry yielding Ti(III) amides and P2R4. The barrier to rotation about the Ti-N bonds has been considered. Variable temperature 'H NMR studies reveal that the barrier is small. Extended Hiickel total energy minimization calculations have been performed. In addition, MMX calculations of the barrier to Ti-N rotation are reported. The results of these calculations imply that the rotational barrier is dominated by steric effects.
AB - Reaction of simple amides with TiCl4 affords mixed amido-chloride species Ti(NR2)4-nCln The trisamide-chloride species Ti(NR2)3Cl can be prepared directly employing three equivalents of amide or by reaction Ti(NR2)4 with TiCl4. The compound Ti(NMe2)3Cl, 1, crystallizes in the trigonal space group Ric, with a = 11.525(5), c = 14.939(3) A, Z = 6, and V = 1718(1) Å;3. The compound Ti(NEt2)3Cl, 2, crystallizes in the monoclinic space group P21/c, with a = 8.385(2) Å, b = 15.958(2) Å, c = 14.230(4) Å, β= 107.79(1)°, Z = 4, and V = 1813(1) Å;3. The geometry of the Ti coordination sphere in these complexes is best described as pseudo-tetrahedral. The structural data are consistent with Ti-N multiple bonding. Preliminary results of EHMO calculations are consistent with dπ-pπ Ti-N bonding. Attempts to replace thehalides with phosphides (LiPR2, R = Me, Et, Ph) led not to the Ti(IV) phosphido species, but rather to redox chemistry yielding Ti(III) amides and P2R4. The barrier to rotation about the Ti-N bonds has been considered. Variable temperature 'H NMR studies reveal that the barrier is small. Extended Hiickel total energy minimization calculations have been performed. In addition, MMX calculations of the barrier to Ti-N rotation are reported. The results of these calculations imply that the rotational barrier is dominated by steric effects.
KW - Structures
KW - Ti-N bonding
KW - Titanium amides
UR - http://www.scopus.com/inward/record.url?scp=0001436008&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0001436008&partnerID=8YFLogxK
U2 - 10.1139/v91-054
DO - 10.1139/v91-054
M3 - Article
VL - 69
SP - 357
EP - 362
JO - Canadian Journal of Chemistry
JF - Canadian Journal of Chemistry
SN - 0008-4042
IS - 2
ER -