A series of neutral ruthenium(II) carbonyl, carbene, vinylidene, and allenylidene complexes
[Ru(bdmpza)(Cl)(L)(PPh3)] (L = C(OR‘)R, CCHR, CCCR2, CO) containing the bis(3,5-dimethylpyrazol-1-yl)acetato (bdmpza) ligand, an N,N,O heteroscorpionate ligand, have been prepared. Treatment
of [Ru(bdmpza)(Cl)(PPh3)2] (1a) with a variety of alkynes HC⋮CR (R = Ph, Tol, Pr, Bu) afforded the
vinylidene complexes [Ru(bdmpza)(Cl)(CCHR)(PPh3)] (2a−d). The carbonyl complex [Ru(bdmpza)(Cl)(CO)(PPh3)] (3) is formed via oxidative or acid-induced degradation pathways from the vinylidene
complexes. Reaction of 1a with the hydroxy-functionalized alkynes HC⋮C(CH2)
n
OH (n = 2, 3) yielded
the cyclic Fischer type carbene complexes
(4a) and
(4b). The ruthenium(II) allenylidene complexes [Ru(bdmpza)(Cl)(CC
CR2)(PPh3)] (5a, R = Ph; 5b, R = Tol) were prepared by the reaction of 1a with propargyl alcohols
HC⋮CC(R)2OH via the vinylidene intermediates [Ru(bdmpza)(Cl)(CCHCR2OH)(PPh3)]. X-ray crystal
structures of one structural isomer of the vinylidene complex [Ru(bdmpza)(Cl)(CCHTol)(PPh3)]
(2b), the carbonyl complex [Ru(bdmpza)(Cl)(CO)(PPh3)] (3), the carbene complex
(4b
-
I), and two structural isomers of [Ru(bdmpza)(Cl)(CCCPh2)(PPh3)] (5a
-
I
and 5a-II) are reported.
New ruthenium(II) and ruthenium(III) complexes with the ligands bis(pyrazol-1-yl)acetate (bpza) and bis(3,5-dimethylpyrazol-1-yl)acetate (bdmpza) are reported. The reaction of ruthenium trichloride hydrate, H[bpza], and excess PPh 3 yielded [Ru(bpza)Cl(PPh 3 ) 2 ] as a racemic mixture of an unsymmetrical isomer with traces of a symmetrical isomer. Sim-
Neutral Fischer-type ruthenium(II) aminocarbene complexes bearing the bis(3,5-dimethylpyrazol-1yl)acetato (bdmpza) ligand have been synthesized by addition of ammonia or methylamine to the R-carbon atom of vinylidene and allenylidene complexes. Reaction with dimethylamine was not successful. These differences in the chemical behavior can be explained by the intermediate formation of intramolecular hydrogen bridges that have been indicated by DFT calculations. Furthermore, octahedral ruthenium(II) benzylidene complexes with the bis(pyrazol-1-yl)acetato (bpza) and the bdmpza ligand were obtained by reacting [RuCl 2 (dCHPh)(PR 3 ) 2 ] (R ) Cy, Ph) with K[bpza] or K[bdmpza], respectively. The latter complexes have successfully been tested for RCM reactions.
N-Trimethylsilyl-benzophenoneimine Ph2C=NSiMe3 is able to “store" the silaethene Me2Si = C(SiMe3)2 (1). produced from Me2SiF-CLi(SiMe3)2, under formation of a [2+4]- and [2+2]-cycloadduct (2, 3), respectively. Above 60 °C (above 120 °C) 2 or 3 by the way of 1 transform into a 1:5 mixture of 2 and 3 (into a 1:1 mixture of the dimer of 1 and the insertion product of 1 into the SiN-bond of Ph2C=NSiMe3). In the presence of 2,3-dimethyl-1.3-butadiene (dmb), 2 or 3 form by way of the reaction of the intermediate 1 with dmb a [2 + 4]-cycloadduct (75%) and an ene reaction product (25%). The rate constants of the first order decomposition of 2 or 3 in the presence of dmb (80 °C. solvents like Et2O, Q6H6 are in the order of 2x10-4s-1 (τ1/2ca. 1 h) and 3x10-5s-1 (τ1/2 ca. 6 h). respectively.
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