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A comparative study of the chemical reactivity of the well-known precursors [Cp*RuCl]4 (1) and [Cp*RuCl2]2 (2) is established relative to the incorporation of silyl-substituted heterodienyl compoun...

Reaction of the well-known precursors [Cp*RuCl]4 (1) and [Cp*RuCl2]2 (2) with the silyl-diene compound CH2═CHCH═CHCH2SiMe3 (3), in THF, results in the selective formation of [Cp*Ru(η4-CH2CHCHCHCH2SiMe3)Cl] (4) from the diamagnetic tetramer 1, while the reaction of dimer 2 leads to nonselective reactions with the formation of 4, [Cp*Ru(η3-CH2CHCHCHCH2)Cl2] (5), and [Cp*Ru(η3-CH2CHCHCHCHSiMe3)Cl2] (6). Reaction of 2 with 3, in ethanolic solution at room temperature, provided a preparative route to the corresponding diene 4 and the allyl ruthenium(IV) complex 5. Compound 4, in the presence of chloroform, affords 6, and recrystallization of 5 with CH2Cl2/hexane affords [Cp*Ru(η3-CH2CHCHEt)Cl2] (7), but contrastingly, the manipulation of compound 5 in plates of silica gel affords [Cp*Ru(η4-CH2CHCHCHCH2OH)Cl] (8). A CDCl3 or C6D6 solution of 8 in the presence of traces of oxygen affords Cp*Ru(η4-CH2CHCHCHCHO)Cl (9), which slowly decomposes to liberate 2,4-pentadienal in the reaction media, along with unknown Cp...

The determination of the solid state structure of Cp*Ru(2,4-dimethyl-η5-pentadienyl) (1), where Cp* = pentamethylcyclopentadienyl, fills the gap in the series of previously established structures of closely related compounds. Compound 1 does not exhibit the ideal CS symmetry and its conformation is intermediate between the CS-synperiplanar eclipsed and CS-antiperiplanar arrangements of the ligands. Density functional theory studies indicate that the CS-synperiplanar eclipsed, CS-antiperiplanar, and intermediate conformations of 1 and Cp*Rh(2,4-dimethyl-η5-pentadienyl)+ (2) do not differ by more than a few tenths of 1 kcal/mol. The geometrical features of cation 2 are similar to those of 1, and in both complexes the pentadienyl ligands are not planar. The metal–carbon distances to the Cp* ligands in 1 and 2 are comparable, while the metal–carbon distances to the pentadienyl moiety are somewhat shorter in the Ru complex. A study of the conformational flexibility of the Cp* ligand in 5610 organometallic complexes showed that it usually shields the central metal by 36.2(10)%, provided the metal–centroid(Cp*) distances are normalized to 2.28 A. The corresponding values in 1 and 2 are 37.2% and 37.4%, respectively.

A successful synthesis of Cp*Ru(η5-CH2CHCHCHO) (1) was obtained by chromatography on neutral deactivated alumina of Cp*Ru(1−4-η-CH2CHCHCHOSiMe3)Cl (2). The disproportionation reaction of 2 affords compounds 1 and Cp*Ru(1−3-η-endo-syn-CH2CHCHCHO)Cl2 (3). Reaction of compound 1 with diphenylacetylene affords compounds Cp*Ru[1−5-η-syn-CH(Ph)C(Ph)CHCHCH(CHO)] (6), Cp*Ru[1,4,5-η-C(Ph)C(Ph)CH2CHCH2]CO (7), Cp*Ru(1−3-η-CH2CHCHCHO)(η2-PhC⋮CPh) (8), and compounds with cyclic structures, such as Cp*Ru[1,6,7,10,11-η-CH(CH)4CCHC(Ph)CH(CH)2C(O)CH(C6H4)CH(Ph)] (9) and Cp*Ru[3,4,5-η-C(Ph)C(Ph)CHCHCHC(O)](η2-PhCHCHPh) (10). Reaction of compound 3 with diphenylacetylene shows the syn-aldehyde derivative 6, as well as the corresponding kinetic isomer 11, in which the terminal aldehyde group is in anti-position. Treatment of [Cp*RuCl2]2 with CH2CHCHCHOSiMe3 affords compound Cp*Ru[1−3-η-endo-syn-(Me)CHCHCH(OEt)]Cl2 (5). The Ru(IV) complex 5 reacts with diphenylacetylene to give the cyclic 1,2-diphenyl-3-methylcyclopentadieny...

A metathesis reaction of [Cp*IrCl 2 ] 2 with butadienesulfinate lithium (SO 2 CHCRCHCHR)-Li (R = H, 1Li; Me, 2Li) affords the dinuclear compounds [Cp*Ir(Cl) 2 {(5-η)-SO 2 CH=CRCH= CHR}(Li)(THF)] 2 (R = H, 3; Me, 4), respectively. The single-crystal X-ray analysis of 3 and 4 reveals the presence of metallacyclic, five- and eight-membered rings, which easily break to afford compounds Cp*IrCl[(1,2,5-η)-SO 2 CH=CRCH=CHR] [R = H, (5), Me (6)], upon displacement of THF and LiCl. The 1 H and 1 3 C NMR data are consistent with the single-crystal X-ray diffraction structures of 3 and 4. Compounds 5 and 6 showed that the butadienesulfonyl ligands are coordinated through the sulfur atoms and the terminal double bonds, according to the X-ray study of compound 5 and NMR spectroscopy. Immediate formation of compound 5 can be achieved in 83% yield from [Cp*IrCl 2 ] 2 and 1K, showing that the alkaline metal is crucial in the isolation of the lithium derivatives 3 and 4.

Reaction of Cp*RuCl(PPh 3 ) 2 ( 1 ) with atmospheric oxygen occurs at room temperature in the presence of acetone or methylene chloride leading to Cp*RuCl(O 2 )(PPh 3 ) ( 2 ). This complex is remarkably stable in the solid state and it can also release, under not unduly harsh conditions, the activated oxygen molecule, which can oxidize the phosphite L=MeOP[(OCHMe) 2 CH 2 ] to the corresponding phosphate, along with formation of the mono- and disubstituted Cp*RuCl(PPh 3 )(L) ( 5 ), Cp*RuCl(L) 2 ( 6 ) and [Cp*RuCl(PPh 3 )(L) 2 ]Cl ( 7 ), complexes. Structural information of phosphite derivatives 5 and 6 has been obtained by X-ray diffraction.