Activation of σ(C−H) Bonds in C₆H₅CHNCH₂CH₂SEt Induced by Platinum(II). X-ray Crystal Structure of [Pt{C₆H₄CHNCH₂CH₂SEt}Cl]

Platinum(II) and Palladium(II) Compounds Containing Chiral Thioimines

“…The two-dimensional heteronuclear { 1 H-13 C} NMR spectrum suggested that the activation of the σ(C sp 2 ,phenyl ϪH) bond had taken place. The position of the signal detected in the 195 Pt NMR spectrum was similar to that reported for 2 [17] and for related platinum(II) compounds with a ''Pt(C,N,S,Cl)'' core. [21] Recent studies have shown that for optically pure organic imines or amines, such as: R 1 ϪCHϭNϪCH(Me)ϪR 2 {R 1 ϭ phenyl or ferrocenyl groups and R 2 ϭ phenyl or naphthyl groups} or C 10 H 7 ϪCH(R 1 )ϪNR 2 R 3 {R 1 , R 2 , R 3 ϭ alkyl groups} the formation of the metallacycle through the activation of the σ(C sp 2 ,aryl ϪH) bond does not modify the absolute configuration of the stereogenic centre of the ligand.…”

“…This indicated that the crude material contained at least three platinum(II) compounds. The position of signals at δ ϭ Ϫ3029 and Ϫ3059 was similar to those reported for: [Pt(C 6 H 5 ϪCHϭ NϪCH 2 ϪCH 2 ϪSEt)Cl 2 ], [17] [Pt(H 2 NϪCH 2 ϪCH 2 ϪSEt)-Cl 2 ], [20] and for related compounds containing a ''Pt(N,S)Cl 2 '' core. [21] (2), [17] [Pt{(η 5 -C 5 H 5 )Fe[(η 5 -C 5 H 3 )ϪCH(R)ϪNMe 2 ]}Cl(dmso)], [22] and related compounds.…”

“…The position of signals at δ ϭ Ϫ3029 and Ϫ3059 was similar to those reported for: [Pt(C 6 H 5 ϪCHϭ NϪCH 2 ϪCH 2 ϪSEt)Cl 2 ], [17] [Pt(H 2 NϪCH 2 ϪCH 2 ϪSEt)-Cl 2 ], [20] and for related compounds containing a ''Pt(N,S)Cl 2 '' core. [21] (2), [17] [Pt{(η 5 -C 5 H 5 )Fe[(η 5 -C 5 H 3 )ϪCH(R)ϪNMe 2 ]}Cl(dmso)], [22] and related compounds. [21,23] Unfortunately, attempts to separate the major components of the mixture by either column chromatography or fractional crystallization failed due to the formation of metallic platinum during these experiments.…”

“…The comparison of the bond lengths and angles involving the platinum(II) atom in 3a and in 2, [17] which contains a [6.5.5] tricyclic system, shows that in 3a the PtϪC(7) bond length [1.954(14) Å ] is clearly shorter than in 2 [2.012(8) Å ]. However, this variation does not significantly affect the length of the PtϪS bond in a trans position [2.349(3) Å in 3a and 2.334(10) Å in 2].…”

“…This arrangement of groups on the stereogenic centres of 3a is formally identical to that found in [Pd 2 {(C 4 H 3 S)ϪCHϭNϪC(CO 2 Me)ϪCH 2 ϪCH 2 Ϫ SMe} 2 Cl 2 ] (4). [18] The comparison of the results obtained in the reaction of cis-[PtCl 2 (dmso) 2 ] with 1 or C 6 H 5 ϪCHϭNϪCH 2 Ϫ CH 2 ϪSEt [17] shows that cycloplatination of 1 occurs easily, leading to one of the two diastereomers. These differences may be attributed to the presence of a bulky group [28] in the proximity of the imine nitrogen.…”