Nl. Armanasco et al., CHROMIUM(0) TRICARBONYL COMPLEXES OF 1,3,5-TRIAZACYCLOHEXANES, Journal of the Chemical Society. Dalton transactions, (8), 1997, pp. 1363-1368
Three 1,3,5-trialkyl-1,3,5-triazacyclohexane chromium tricarbonyl comp
lexes fac-[Cr(CO)(3)(C3H6N3R3)] (R = Me, Et or Bu-t) have been prepare
d and their reactivities investigated. Both the kinetic and the thermo
dynamic stabilities of the complexes increase as the size of the R gro
up increases. When R = Me or Et, the ligand is susceptible to displace
ment to produce [Cr(CO)(3)L-3] [L = pyridine or P(OMe)(3)]. Room-tempe
rature single crystal X-ray studies were carried out on the R = Me and
Bu-t complexes. Both molecules adopt the expected 'piano-stool' confi
guration with putative 3m symmetry; a crystallographic mirror plane pa
sses through the methyl adduct. The Cr-N distances in the R = Me compl
ex [2.153(3), 2 x 2.181(2) Angstrom] are shorter than in the Bu-t case
[2.202(5) - 2.216(4) Angstrom]; in both the substituents are obligate
equatorial relative to the triazacyclohexane ring.