Caspar H. Stam

Synthesis and reactivity towards diiodine of palladium(II) and platinum(II) complexes with non-cyclic and cyclic ligands (C6H3{CH2NR1R2}2-2,6)−. End-on diiodine-platinum(II) bonding in macrocyclic [PtI(C6H3{CH2NMe(CH2)7MeNCH2}-2,6)(η1-I2)]

Several new organo-platinum(II) and -palladium(II) complexes [MX(C{6}H{3}{CH{2}NR}1{R}2{}{2}-2, 6)] (X = halide, M = Pt, Pd; R}1{ = R}2{ = Et; R}2{ = Me, R}1{ = }t{Bu, M = Pt: R}2{ = Me, R}1{ = Ph) have been synthesized from [PtCl{2}(SEt{2}){2}] or [PdCl{2}(COD)] (COD = 1, 5-cyclooctadiene) by reaction with [Li(C{6}H{3}{CH{2}NR}1{R}2{}{2}-2,6]{n}. Two of the intermediate Li complexes, i.e. [Li((tBu)MeNCN)]{2} and [Li((Ph)MeNCN)]{2} were isolated. In the platinum and palladium complexes the NCN ligands are terdentate bonded through C{i}{p}{s}{o} and two trans-positioned amine donor atoms. The complexes [PtI(C{6}H{3}{CH{2}NMe(CH{2}){7}MeNCH{2}}-2,6)] (4), in which the N(Me) atoms of the terdentate ligand are connected by a short (CH{2}){7} chain, and [PtCl(C{6}H{3}{CH{2}NPh{2}}{2}-2,6)(SEt{2}){2}], in which the Ph{2}NCN ligand is chain, and [PtCl(C{6}H{3}{CH{2}NPh{2}}{2}-2,6)(SEt{2}){2}], in which the Ph{2}NCN ligand is only monodentate bonded via C{i}{p}{s}{o}, were also made. The coordination ability of the NR}1{R}2{ donor atoms in these compounds was found to decrease in the order Me{2}N ~ (}t{Bu)MeN > Et{2}N > (Ph)MeN > Ph{2}N.

Monodentate-N coordination of 1-aza-4-oxo-1,3-butadienes [R'N=C(R2)C(R3)=O] to platinum(II), X-ray structure of trans-[PtCl2(PEt3){s-N-t-BuN=CHC(Me)=O)}]

Reaction of dimeric trans-[PtCl,(PR3)] 2 with 1-aza-4-oxo-1,3-butadienes [R’N=C(R’)C(R’)=O, R3 = Me, Ph, OMe, NEtz] in a 1:2 molar ratio results in almost quantitative formation of mononuclear complexes WLWZS- [PtC12(PR3){u-N-(R’N=C(R’)C(R3)=O)}]. The ligands are bonded in the monodentate u-N bonding mode to the platinum(I1) centre. This has been established by an X-ray structure determination of trans-[PtCl,(PEt,)(o-N-(tBuN=CHC(Me)=O)}]. Crystals of the latter compound are orthorhombic with space group Pc2,n; cell constants are II = 14.712(3), b = 15.053(2), c = 9.025(5) A, Z= 4 and R, = 0.056 for 3281 reflections. The 1-aza-4-oxo-l,3-butadiene (Gminoketone for R3 is alkyl or aryl) has the E-configuration about the imine bond (C=N 1.34(4) A), with a C(5)-C(6) distance of 1.44(5) 8, and a N=C(5)/ C(6)=0 torsion angle of 89(4)‘. As a result of this ligand conformation, the acetyl hydrogen atoms are positioned (on average) into the neighbourhood of the Pt-atom above the Pt-coordination plane. Infrared and NMR (‘H, 13C, 31P) data show that these structural features are also predominant in solution. organometallic reagent used, i.e. organo-zinc or -aluminum, a variety of products could be made in a chemoselective way. Examples of selective transfer of alkyl groups from alkyl-aluminum or -zinc reagents to each of the four atoms of the 1,3-butadiene system have now been established [3,4]. In order to understand the mechanistic details of these transfer reactions, more information on the coordination properties of the a-iminoketones is required than is available in the literature.