Oxime-substituted NCN-pincer palladium and platinum halide polymers through non-covalent hydrogen bonding (NCN = [C6H2(CH2NMe2)2-2,6]−)

The oxime-substituted NCN-pincer molecules HONCH-1-C6H3(CH2NMe2)2-3,5 (2a) and HONCH-4-C6H2(CH2NMe2)2-2,6-Br-1 (2b) were accessible by treatment of the benzaldehydes H(O)C-4-C6H3(CH2NMe2)2-3,5 (1a) and H(O)C-4-C6H2(CH2NMe2)2-2,6-Br-1 (1b) with an excess of hydroxylamine. In the solid state both compounds are forming polymers with intermolecular O–H⋯N connectivities between the Me2NCH2 substituents and the oxime entity of further molecules of 2a and 2b, respectively. Characteristic for 2a and 2b is a helically arrangement involving a crystallographic 21 screw axis of the HONCH-1-C6H3(CH2NMe2)2-3,5 and HONCH-4-C6H2(CH2NMe2)2-2,6-Br-1 building blocks.The reaction of 2b with equimolar amounts of [Pd2(dba)3 · CHCl3] (3) (dba = dibenzylidene acetone) or [Pt(tol)2(SEt2)]2 (4) (tol = 4-tolyl) gave by an oxidative addition of the C–Br unit to M coordination polymers with a [(HONCH-4-C6H2(CH2NMe2)2-2,6)MBr] repeating unit (5: M = Pd, 6: M = Pt). Complexes 5 and 6 are in the solid state linear hydrogen-bridged polymers with O–H⋯Br contacts between the oxime entities and the metal-bonded bromide.

Graphical abstractThe synthesis of the oxime-substituted NCN-pincer molecules HONCH–1-C6H3(CH2NMe2)2-3,5, HONCH–4-C6H2(CH2NMe2)2-2,6-Br-1 and [(HONCH-4-C6H2(CH2NMe2)2-2,6)MBr] (M = Pd, Pt) is described. The solid state structures of these compounds are reported. By molecular recognition O–H⋯N and O–H⋯Br bonds are formed and hence, coordination polymers are set-up.Figure optionsDownload full-size imageDownload as PowerPoint slide