✍ Scribed by Martijn Q. Slagt; Gema Rodríguez; Michiel M. P. Grutters; Robertus J. M. Klein Gebbink; Wim Klopper; Leonardus W. Jenneskens; Martin Lutz; Anthony L. Spek; Gerard van Koten
No coin nor oath required. For personal study only.
A variety of para‐substituted NCN‐pincer palladium(II) and platinum(II) complexes [MX(NCN‐Z)] (M=Pd^II^, Pt^II^; X=Cl, Br, I; NCN‐Z=[2,6‐(CH~2~NMe~2~)~2~C~6~H~2~‐4‐Z]^−^; Z=NO~2~, COOH, SO~3~H, PO(OEt)~2~, PO(OH)(OEt), PO(OH)~2~, CH~2~OH, SMe, NH~2~) were synthesised by routes involving substitution reactions, either prior to or, notably, after metalation of the ligand. The solubility of the pincer complexes is dominated by the nature of the para substituent Z, which renders several complexes water‐soluble. The influence of the para substituent on the electronic properties of the metal centre was studied by ^195^Pt NMR spectroscopy and DFT calculations. Both the ^195^Pt chemical shift and the calculated natural population charge on platinum correlate linearly with the σ~p~ Hammett substituent constants, and thus the electronic properties of predesigned pincer complexes can be predicted. The σ~p~ value for the para‐PtI group itself was determined to be −1.18 in methanol and −0.72 in water/methanol (1/1). Complexes substituted with protic functional groups (CH~2~OH, COOH) exist as dimers in the solid state due to intermolecular hydrogen‐bonding interactions.
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