Divalent Platinum Complexes of the Carbanion 2-C₆F₄AsPh₂: Monodentate or Bidentate Coordination?

Abstract

The reaction of [PtI 2 (1,5-COD)] with 2-LiC 6 F 4 AsPh 2 affords the planar platinum(II) fluoroaryl complex [PtI(κC-2-C 6 F 4 AsPh 2 )(1,5-COD)] (7), in which the arsenic atom is not coordinated to the metal atom. Attempts to prepare the bis(chelate) complex [Pt(κ 2 As,C-2-C 6 F 4 AsPh 2 ) 2 ] analogous to the known phosphorus compound failed. Removal of iodide ion from 7 with TlPF 6 gave [Pt(κ 2 As,C-2-C 6 F 4 AsPh 2 )(1,5-COD)]PF 6 (8), in which 2-C 6 F 4 AsPh 2 is now coordinated as a bidentate ligand, giving a four-membered chelate ring. Alternatively, protonolysis (with triflic acid) of the methyl complex [PtMe(κC-2-C 6 F 4 AsPh 2 )(1,5-COD)] (15), which is obtained from 7 and dimethylzinc, gives the triflate salt 16 of the same chelate cation. The chelate As,C ring in 8 is readily reopened when the complex is treated with pyridine or with halide ions, forming respectively [Pt(py)(κC-2-C 6 F 4 AsPh 2 )(1,5-COD)]PF 6 (9) and [PtX(κC-2-C 6 F 4 AsPh 2 ](1,5-COD)] (X = Cl (10), Br (11), I (7)). The appearance of two pairs of olefinic COD resonances in the proton NMR spectra of 7, 10, 11, and 15 may indicate that there is restricted rotation about the Pt−κC-2-C 6 F 4 AsPh 2 bond; the additional signals are not evident in the spectra of 8 or 16. Complexes 7 and 10 form the 1:1 adducts [PtX(μ-2-C 6 F 4 AsPh 2 )(1,5-COD)AuY] (X = Cl, Y = I (12); X = Y = I (13); X = Y = Cl (14)) by attachment of gold(I) halides to their dangling arsenic atoms. In 12 the halides are scrambled between platinum and gold. The X-ray structures of 7, 8, 9, 12, 15, and 16 are reported, and possible reasons for the poorer chelating ability of 2-C 6 F 4 AsPh 2 in comparison with that of 2-C 6 H 4 PPh 2 are discussed.

Different solvates of the dinuclear cyclometallated gold(i) complex [Au2(μ-2-C6H4AsMe2)2]: a computational study insight into solvent-effected optical properties

“…The dinuclear complex [Au 2 (μ-2-C 6 H 4 AsMe 2 ) 2 ] 1 can be obtained as a pale yellow air-and moisture-stable solid by reaction of 2-LiC 6 H 4 AsMe 2 with [AuBr(PEt 3 )] 19 or [AuCl(PPh 3 )]. 20 Recrystallization of 1 from a mixture of dichloromethanehexane or dichloromethane-methanol afforded two different solvates of the dinuclear cyclometallated gold(I) complex [Au 2 (μ-2-C 6 H 4 AsMe 2 ) 2 ] appearing as colorless (type A, dichloromethane solvate, shown in Fig. 1) or yellow crystals (type B, dichloromethane-methanol solvate, shown in Fig.…”