Synthesis, structures and reactions of cyclometallated gold complexes containing (2-diphenylarsino-n-methyl)phenyl (n = 5, 6)

Abstract

Reaction of (C6H3-2-AsPh2-n-Me)Li (n = 5 or 6) with [AuBr(AsPh3)] at -78 degrees C gives the corresponding cyclometallated gold(I) complexes [Au2[(mu-C6H3-n-Me)AsPh2]2] [n = 5, (1); n = 6, (9)]. 1 undergoes oxidative addition with halogens and with dibenzoyl peroxide to give digold(II) complexes [Au2X2[(mu-C6H3-5-Me)AsPh2]2] [X = Cl (2a), Br (2b), I (2c) and O2CPh (3)] containing a metal-metal bond between the 5d9 metal centres. Reaction of 2a with AgO2CMe or of 3 with C6F5Li gives the corresponding digold(II) complexes in which X = O2CMe (4) and C6F5 (6), respectively. The Au-Au distances increase in the order 4 < 2a < 2b < 2c < 6, following the covalent binding tendency of the axial ligand. Like the analogous phosphine complexes, 2a-2c and 6 in solution rearrange to form C-C coupled digold(I) complexes [Au2X2[mu-2,2-Ph2As(5,5-Me2C6H3C6H3)AsPh2]] [X = Cl (5a), X = Br (5b), X = I (5c) and C6F5 (7)] in which the gold atoms are linearly coordinated by As and X. In contrast, the products of oxidative additions to 9 depend markedly on the halogens. Reaction of 9 with chlorine gives the gold(I)-gold(III) complex, [ClAu[mu-2-Ph2As(C6H3-6-Me)]AuCl[(6-MeC6H3)-2-AsPh2]-kappa2As,C] (10), which contains a four-membered chelate ring, Ph2As(C6H3-6-Me), in the coordination sphere of the gold(III) atom. When 10 is heated, the ring is cleaved, the product being the digold(I) complex [ClAu[mu-2-Ph2As(C6H3-6-Me)]Au[AsPh2(2-Cl-3-Me-C6H3)]] (11). Reaction of 9 with bromine at 50 degrees C gives a monobromo digold(I) complex (12), which is similar to 11 except that the 2-position of the substituted aromatic ring bears hydrogen instead halogen. Reaction of 9 with iodine gives a mixture of a free tertiary arsine, (2-I-3-MeC6H3)AsPh2 (13), a digold diiodo compound (14) analogous to 11, and a gold(I)-gold(III) zwitterionic complex [I2Au(III)[(mu-C6H3-2-AsPh2-6-Me)]2Au(I)] (15) in which the bridging units are arranged head-to-head between the metal atoms. The structures of 2a-2c and 4-15 have been determined by single-crystal X-ray diffraction analysis. The different behaviour of 1 and 9 toward halogens mirrors that of their phosphine analogues; the 6-methyl substituent blocks C-C coupling of the aryl residues in the initially formed oxidative addition product. In the case of 9, the greater lability of the Au-As bond in the initial oxidative addition product may account for the more complex behaviour of this system compared with that of its phosphine analogue.

Gold(I)‐Catalyzed Alkoxyhalogenation of β‐Hydroxy‐α,α‐Difluoroynones

“…The alkoxybromination6e and alkoxychlorination6f,g were attempted using N ‐bromosuccinimide (NBS) and N ‐chlorosuccinimide (NCS). The gold(I)‐catalyzed alkoxybromination delivered the brominated pyranones 4 b and 4 d in 82 and 70 % yield, respectively 9.…”

Gold–Gold Interactions

“…Ab initio HF/II and MP2/II calculations have been performed in order to analyze the metallophilic attraction in both complexes [314]. A head to tail arrangement is also observed in [Au 2 (ER 2 -R 0 -C 6 H 3 ) 2 ] (Figure 2.59) (E ¼ P, As, R ¼ Ph, Et, R 0 ¼ H; E ¼ As, R ¼ Ph; R 0 ¼ Me) [315][316][317].…”

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

“…The crystal structures of both the colorless (type A) and yellow (type B) crystals of 1 reveal stacks of discrete dimers forming infinite chains by unbridged aurophilic contacts [type A: 3.2418(2), type B: 3.1268(5) and 3.0384(5) Å]. Short intermolecular Au⋯Au separations are not observed in the other structurally similar tertiary arsine 19,21,22 or tertiary phosphine [23][24][25] digold(I) complexes.…”