Chiral Platinum(II) Compounds Containing Ferrocenyl Schiff Bases Acting as (N), (N,O) – , [C(sp 2 ,ferrocene),N] – or [C(sp 2 ,ferrocene),N,O] 2– Ligands

A study of the reactions of the following ferrocenyl Schiff bases: ( S C )‐(+)‐[FcCH=NCH(R 1 )CH 2 OH] {Fc = (η 5 ‐C 5 H 5 )Fe(η 5 ‐C 5 H 4 ), R 1 = Me ( 1a ) or CHMe 2 ( 1b )} with cis ‐[PtCl 2 (dmso) 2 ] under different experimental conditions is reported. This study enabled the isolation and characterisation of the enantiomerically pure platinum(II) complexes trans ‐( S C )‐[Pt{FcCH=NCH(R 1 )CH 2 OH}Cl 2 (dmso)] {R 1 = Me ( 2a )or CHMe 2 ( 2b )} and cis ‐( S C )‐[Pt{FcCH=NCH(R 1 )CH 2 OH}Cl 2 (dmso)] {R 1 = Me ( 3a ) or CHMe 2 ( 3b )} as well as four isomeric forms of ( S C )‐[Pt{FcCH=N–CH(R 1 )CH 2 O}Cl(dmso)] {R 1 = Me or CHMe 2 } ( 4 – 7a , b ). These isomers differ in the conformation of the imine { anti ‐( E ) (in 4 and 6 ) or syn ‐( Z ) (in 5 and 7 )} or in the relative arrangement of the nitrogen and the dmso group { trans (in 4 and 5 ) or cis (in 6 and 7 )}. Imines 1 behave as a N‐donor ligand in 2 and 3 and as a (N,O) – group in 4 – 7 . We also prepared the diastereomers {( S p , S C ) and ( R p , S C )} of the platinacycles [Pt{[(η 5 ‐C 5 H 3 )CH=NCH(R 1 )CH 2 OH]Fe(η 5 ‐C 5 H 5 )}Cl(dmso)] { 8 and 9 ; R 1 = Me ( S p , S C ) ( 8a ) and ( R p , S C ) ( 9a ) or R 1 = CHMe 2 ( S p , S C ) ( 8b ) and ( R p , S C ) ( 9b )}, [Pt{[(η 5 ‐C 5 H 3 )CH=NCH(R 1 )CH 2 O]Fe(η 5 ‐C 5 H 5 )}(dmso)] { 10 and 11 ; R 1 = Me ( S p , S C ) ( 10a ) and ( R p , S C ) ( 11a ) or R 1 = CHMe 2 ( S p , S C ) ( 10b ) and ( R p , S C ) ( 11b )} and [Pt{[(η 5 ‐C 5 H 3 )CH=NCH(R 1 )CH 2 OH]Fe(η 5 ‐C 5 H 5 )}Cl(PPh 3 )] { 12 and 13 ; R 1 = Me ( S p , S C ) ( 12a ) and ( R p , S C ) ( 13a ) or R 1 = CHMe 2 ( S p , S C ) ( 12b ) and ( R p , S C ) ( 13b )}, containing a [C(sp 2 ,ferrocene),N] – (in 8 , 9 , 12 and 13 ) or a [C(sp 2 ,ferrocene),N,O] 2– (in 10 and 11 ) group. The X‐ray crystal structures of 1b· H 2 O, 3b , 7b· CH 2 Cl 2 · 1/2H 2 O and 9a are also reported. Our study allows the elucidation of the factors affecting the preferential formation of a given platinum(II) complex. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)