6533b82ffe1ef96bd1294ed6

RESEARCH PRODUCT

Mono- and di-nuclear complexes of ortho-palladated and -platinated 4,4′-dimethylazobenzene with bis(diphenylphosphino)methane. More data on transphobia

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Abstract Complexes [Pd(κ2-R)(μ-Cl)]2 [κ2-R=κ2-C,N′-C6H3(NNC6H4Me-4′)-2-Me-5 (1)] and [Pd(κ1-R)Cl(κ1-dppm)(κ2-dppm)]TfO [dppm=bis(diphenylphosphino)methane (2)] have been used to prepare new palladium derivatives containing dppm. Thus, complex 1 reacts with one equivalent of dppm to afford [{Pd(κ2-R)Cl}2(μ-dppm)] (3) and with AgClO4 and dppm (1:2:2 molar ratios) to give [Pd(κ2-R)(κ2-dppm)]ClO4 (4·ClO4). The triflate salt of this complex (4·TfO) reacts with PPh3 to yield [Pd(κ1-R)(PPh3)(κ2-dppm)]TfO (5). Dinuclear complexes were obtained by reacting 2, (i) with [AuCl(PPh3)] or [AuCl(tht)] (tht=tetrahydrothiophene) (1:1, −60 °C) and (ii) with 1 (2:1) to give, respectively, [Pd(κ1-R)Cl(μ-dppm)2Au]TfO (6) and the A-frame complex [{Pd(κ1-R)(μ-dppm)}2(μ-Cl)]TfO (7). The latter decomposes in solution to give, among other products, [Pd(κ2-R)(κ2-P,O-dppmO)]TfO (8), containing the monoxide of dppm (dppmO). Complex 8 can be obtained by refluxing a toluene solution of 4·TfO under aerial conditions. The platinum complex trans-[Pt(κ1-R)Cl(PPh3)2] reacts with an excess of dppm to give [Pt(κ1-R)(κ1-dppm)(κ2-dppm)]Cl (10·Cl) which reacts with TlOTf to give 10·TfO. The crystal structures of complexes 3, 8 and 10·TfO have been determined by X-ray diffraction studies. The structure of complex 3 consists of a dimer formed by a dppm ligand bridging two Pd(κ2-R)Cl units. The structure of the cation of complex 8 shows both the aryl and dppmO acting as chelating ligands with the O atom trans to the C atom. The structure of complex 10·TfO shows the κ1-R ligand, one chelating and one monocoordinate dppm ligand.