Syntheses and structural aspects of rigid aryl- palladium(II) and -platinum(II) complexes. X-ray crystal structure of o,o′-bis[(dimethylamino)methyl]phenyl- platinum(II) bromide

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The tridentate monoanionic ligand o,o′-(Me 2NCH 2) 2C 6H 3 (NCN′) has been used to synthesize novel aryl-palladium(II) and -platinum(II) complexes [PtR(NCN′)] and [MX(NCN′)] (M = Pt, Pd). Three synthetic procedures are described, namely: (i) reaction of the cationic complex [M(NCN′)(H 2O)] + with KX or NaX to give [MX(NCN′)] (X = Cl, I, O 2CH, NCS, NO 2, NO 3); (ii) displacement reactions using AgX with [MBr(NCN′)] to give [MX(NCN′)] (X = CN, O 3SCF 3. O 2CMe, O 2CCF 3) and (iii) transmetallation reactions of [PtBr{C 6H 3(CH 2NMe 2) 2- o,o′}] with organolithium to give [PtR{C 6H 3(CH 2NMe 2) 2- o,o′}] (R = Ph, o-, m-, p-tolyl, CCPh, CC- p-tolyl). All complexes have been characterized by elemental analysis, and IR, 1H and 13C NMR spectroscopy. An X-ray diffraction study has shown that [PtBr{C 6H 3(CH 2NMe 2) 2- o,o′}] ( 2) has a square-planar structure, in which the tridentate ligand is bonded via C( ipso) (PtC 1.90(1) Å), and two mutually trans-N donor atoms (PtN(1) 2.07(1), PtN(2) 2.09(1) Å). The fourth site trans to C( ipso) is occupied by bromine (PtBr 2.526(2) Å). The two chelate rings (NPtC( ipso) 82.9(5) and 81.5(5)°) are distinctly puckered, with the two NMe 2 groups on opposite sides of the aryl plane. The PtC bond in 2 is shorter than analogous bonds in other arylplatinum(II) complexes, as a result of (i) the rigid structure of the tridentate ligand and (ii) the presence of two hard N donor atoms trans to one another across the platinum centre.