Abstract:The title ruthenium complex was found to catalyze the hydrosilylation and/or dimerization of phenylacetylene in the presence of a variety of hydrosilanes. Chlorohydrosilanes (HSiMeC12, HSiMe2C1 and HSiC13) favored the formation of the corresponding Ysilylstyrenes while HSiEt3 favored the formation of 1,4-diphenylbuteneyne; Z-isomers were the major product regardless of the substituents on silicon.
“…GC analysis of the mother liquor for the formation of 2 showed the presence of octane, indicating that 1-octene was acting as a hydrogen scavenger in this reaction. Also, no hydrosilylation products of 1-octene were observed, consistent with the reported observation that the RuCl(PPh 3 ) 3 /HSiMeCl 2 system did not hydrosilylate styrene . The reaction of HSiEt 3 with RuCl 2 (PPh 3 ) 3 in benzene did not produce (η 6 -C 6 H 6 )Ru(PPh 3 )(SiEt 3 ) 2 but instead formed RuHCl(PPh 3 ) 3 ; the formation of RuHCl(PPh 3 ) 3 from the reaction of HSiEt 3 with RuCl 2 (PPh 3 ) 3 has been reported. − …”
The reaction of RuCl2(PPh3)3 with HSiX3 in benzene produced (η6-benzene)Ru(PPh3)(SiX3)2
(SiX3 = SiCl3 (1), SiMeCl2 (2)) as white to light yellow solids in high yields (>80%). A mixture
of (η6-benzene)Ru(PPh3)(SiMe2Cl)2 (3), (η6-benzene)Ru(PPh3)(SiMe2Cl)(SiMeCl2) (4), and 2,
due to silicon substituent redistribution, was obtained from the reaction of RuCl2(PPh3)3
with HSiMe2Cl in benzene. (η6-benzene)Ru(PPh3)(SiMe3)2 (5) was prepared by the methylation of 1, 2, or the 3/4 mixture with AlMe3. The related complexes (η6-arene)Ru(PPh3)(SiMeCl2)2 (arene = toluene (6), o-xylene (7), m-xylene (8), p-xylene (9), mesitylene (10),
anisole (11)) were obtained from the reaction of RuCl2(PPh3)3 with HSiMeCl2 in the
corresponding arene solvent at elevated temperature. Complexes 1, 2, and 5 were structurally
characterized by single-crystal X-ray diffraction and exhibit a characteristic three-legged
“piano-stool” geometry. The Ru−Si distances, in these complexes, ranged from 2.322 to 2.438
Å; the Ru−Si distance increased as the number of methyl groups on silicon increased.
“…GC analysis of the mother liquor for the formation of 2 showed the presence of octane, indicating that 1-octene was acting as a hydrogen scavenger in this reaction. Also, no hydrosilylation products of 1-octene were observed, consistent with the reported observation that the RuCl(PPh 3 ) 3 /HSiMeCl 2 system did not hydrosilylate styrene . The reaction of HSiEt 3 with RuCl 2 (PPh 3 ) 3 in benzene did not produce (η 6 -C 6 H 6 )Ru(PPh 3 )(SiEt 3 ) 2 but instead formed RuHCl(PPh 3 ) 3 ; the formation of RuHCl(PPh 3 ) 3 from the reaction of HSiEt 3 with RuCl 2 (PPh 3 ) 3 has been reported. − …”
The reaction of RuCl2(PPh3)3 with HSiX3 in benzene produced (η6-benzene)Ru(PPh3)(SiX3)2
(SiX3 = SiCl3 (1), SiMeCl2 (2)) as white to light yellow solids in high yields (>80%). A mixture
of (η6-benzene)Ru(PPh3)(SiMe2Cl)2 (3), (η6-benzene)Ru(PPh3)(SiMe2Cl)(SiMeCl2) (4), and 2,
due to silicon substituent redistribution, was obtained from the reaction of RuCl2(PPh3)3
with HSiMe2Cl in benzene. (η6-benzene)Ru(PPh3)(SiMe3)2 (5) was prepared by the methylation of 1, 2, or the 3/4 mixture with AlMe3. The related complexes (η6-arene)Ru(PPh3)(SiMeCl2)2 (arene = toluene (6), o-xylene (7), m-xylene (8), p-xylene (9), mesitylene (10),
anisole (11)) were obtained from the reaction of RuCl2(PPh3)3 with HSiMeCl2 in the
corresponding arene solvent at elevated temperature. Complexes 1, 2, and 5 were structurally
characterized by single-crystal X-ray diffraction and exhibit a characteristic three-legged
“piano-stool” geometry. The Ru−Si distances, in these complexes, ranged from 2.322 to 2.438
Å; the Ru−Si distance increased as the number of methyl groups on silicon increased.
“…The bonding of silicon to a transition metal center is an area of considerable interest and attention. − Metal silicon complexes play key roles in important catalytic processes such as hydrosilylation − and dehydrogenative silylation. − Ancillary groups on silicon exhibit a substantial influence on the product distribution in these processes. RuCl 2 (PPh 3 ) 3 efficiently catalyzed the hydrosilylation of phenylacetylene with HSiMeCl 2 , but no hydrosilylation products were observed when the hydrosilane was changed to HSiEt 3 …”
The preparation and characterization of Cp(PR3)2RuSiX3 [PR3 = PPhMe2, SiX3 = SiCl3
(1), SiHCl2 (2), SiH2Cl (3), SiHMeCl (4), SiH3 (7), SiMeH2 (8), SiMe3 (9); PR3 = PPh2Me,
SiX3 = SiCl3 (10), SiHCl2 (5), SiH2Cl (6), SiMeCl2 (11)] are described. Ruthenium silyl
complexes 1−6 are prepared by the reaction of the ruthenium hydrides, Cp(PR3)2RuH, with
the corresponding chlorosilane, ClSiX3; the ruthenium dihydrides [Cp(PR3)2RuH2]Cl were
obtained as coproducts. Increasing the steric demand of the phosphine decreased the
reactivity of the corresponding ruthenium hydride toward chlorosilanes. Silyl complexes 1−4
undergo chloride/hydride exchange with LiAlH4 to give the corresponding ruthenium
hydrosilyl complexes Cp(PPhMe2)2RuSiHX2 [SiHX2 = SiH3 (7), SiMeH2 (8)]. Methylation of
1 with AlMe3 produces Cp(PPhMe2)2RuSiMe3 (9). Complexes 10 and 11 were prepared by
the reaction of Cp(PPh2Me)2RuMe with neat hydrosilanes HSiX3 (SiX3 = SiCl3, SiMeCl2) at
100 °C. The effects of the silicon substituents on the spectroscopic properties of 1−11 and
the related Cp(PMe3)2RuSiX3 complexes were examined as a function of Tolman's electronic
parameter (χ
i
) for the substituents on silicon. The NMR resonance PR3 δ(31P) and the NMR
coupling constants, 1
J
SiH and 2
J
SiP, exhibit a linear relationship with ∑χ
i
(SiX3). On the other
hand, the silyl groups differentiated into three classes, dichlorosilyl, monochlorosilyl, and
“non-chlorosilyl”, when the NMR resonances SiX3 δ(29Si), SiH δ(1H), and SiMe δ(13C) were
examined as a function of ∑χ
i
(SiX3). This “chloro effect” was attributed to Ru−Si silylene
character from d(Ru)−σ*(Si−Cl) π-back-bonding interactions. Surprisingly, changing the
phosphine attached to ruthenium had no effect on the spectroscopic properties of the silyl
group.
“…For a number of years, we have been studying the reaction of ruthenium complexes with hydrosilanes. Ruthenium alkyl complexes Cp(PR 3 ) 2 RuR‘ (R = Me, R‘ = CH 2 SiMe 3 ; R = Ph, R‘ = Me) react with hydrosilanes to form ruthenium silyl and ruthenium hydridobis(silyl) complexes. , Recently, we reported that RuCl 2 (PPh 3 ) 3 is a catalytic precursor for the hydrosilylation of phenylacetylene . We have investigated the reaction of RuCl 2 (PPh 3 ) 3 with various hydrosilanes to elucidate the possible ruthenium−silicon species involved in the hydrosilylation chemistry.…”
The reaction of RuCl 2 (PPh 3 ) 3 with HSiMeCl 2 in hexanes at 65 °C produced the trihydridosilylruthenium complex RuH 3 (SiMeCl 2 )(PPh 3 ) 3 (1). In the 1 H{ 31 P} NMR spectrum of 1, the ruthenium hydrides were observed at -9.76 ppm as a singlet with 29 Si satellites (J SiH ) 39.7 Hz), indicating the presence of nonclassical Ru‚‚‚H‚‚‚Si interactions. These nonclassical interactions were confirmed by a single-crystal X-ray diffraction study of 1. The silyl and phosphine groups occupy a tetrahedral arrangement around ruthenium, with the hydrides capping the faces defined by the silyl and two phosphines groups. Complex 1 exhibited a short Ru-Si bond (2.2760(4) Å) with three normal Ru-H distances (ca. 1.6 Å) and three long Si‚‚‚H interactions (ca. 1.9 Å). The Ru-H and Si‚‚‚H distances are consistent with interligand hypervalent interaction (IHI) theory in which Ru-H electron density is donated to Si-halogen σ* orbitals, giving rise to Ru-H‚‚‚Si interactions. Differences between the three Si‚‚‚H separations in the solid state reflect the asymmetry in the substituent pattern at silicon and are further reinforced by the extent to which the hydride ligands (and one chloride substituent) engage in weak hydrogen bonds with the ortho hydrogens of the phenyl groups.
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