Novel N,N,O scorpionate ligands and transition metal complexes thereof suitable for polymerisation

Esterification of 2,2-bis(3,5-dimethylpyrazol-1-yl)-3-hydroxy-propionic acid (2) with methacryloyl chloride led to the new kappa(3)-N,N,O ligand 2,2-bis(3,5-dimethylpyrazol-1-yl)-3-meth-acrylato-propionic acid (Hbdmpzmp) (3). The kappa(3)-N,N,O coordination as known from his (3,5-dimethylpyrazol-1-yl)acetic acid (Hbdmpza, 1) was proven by syntheses of the complexes [Mn(bdmpzmp)(CO)(3)] (4) and [Re(bdmpzmp)(CO)3] (5) and the single-crystal X-ray structure of 4. The methacrylic ester functionality makes 3, 4 and 5 suitable for polymerisation. Thus, copolymerisation of 3 with methyl methacrylate (MMA), a combination of MMA and ethylene glycol dimethacrylate (EGDMA) or pure EGDMA led to various solid phases (P1a-P1c, P2, P3a, P3b) with incorporated ligand. Polymer-bound manganese and rhenium tricarbonyl complexes could be obtained by copolymerisation of 4 and 5 with MMA as well as by a polymer analogous reaction of P1a with appropriate metal salts. In both cases, the facial tripodal binding behaviour was evidenced by IR spectra of the polymer supported transition metal complexes and the uptake of manganese was proven by AAS measurements. Reaction of the soluble deprotonated solid phase P1a with copper(II) chloride led to a deep-blue solid phase (P-Cu-I). The UV/Vis absorption maximum at 715 nm indicates the copper centres to act as crosslinking agent by a similar binding behaviour as in [Cu(bdmpza)2], In contrast, the heterogeneous reaction of P1b with copper(II) chloride formed a lime-green solid phase (P-Cu-II). The bathochromic shift of the absorption maximum by 78 nm suggests one-sided bound copper centres. EPR spectra do not show exchange narrowing between the copper centres indicating the metal centres to be far enough apart from each other to prevent magnetic interactions. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008).