Open-ended, singly metalated dithiolene complexes with 1,2,4,5-tetrakis(diphenylphosphino)benzene (tpbz) are prepared either by a direct reaction between tpbz and [M(S2C2R2)2] (M = Ni, Pd, Pt; R = Ph, p-anisyl) in a 1:1 ratio or by ligand transfer to [Cl2M(μ-tpbz)] from (R2C2S2)SnR2 (R= CN, R=Me; R= Me, R′= nBu). The formation of homodimetallic [(R2C2S2)M(μ-tpbz)M(S2C2R2)] attends these syntheses in modest amounts, but the open-ended compounds are readily separated by silica chromatography. X-ray crystallographic affirmed characterization of numerous members of the set, the [(R2C2S2)M(μ-tpbz)] compounds show dithiolene ligands in their fully reduced ene-1,2-dithiolate form conjoined with divalent Group 10 ions. Minor amounts of octahedral [(Ph2C2S2)2PtIV(tpbz)], a presumed intermediate, are isolated from the preparation of [(Ph2C2S2)PtII(tpbz)]. Heterodimetallic [(Ph2C2S2)Pt(μ-tpbz)Ni(S2C2Me2)] is prepared from [(Ph2C2S2)PtII(tpbz)]; its cyclic voltammogram, upon anodic scanning, shows two pairs of closely spaced, but resolved, 1e− oxidations corresponding first to [R2C2S2]2− − 1e− → [R2C2S.S−] and then to [R2C2S.S−] − 1e− → [R2(C=S)2]. Heterotrimetallic [[(R2C2S2)M(μ-tpbz)]2Au]1+ compounds are prepared by reaction between Au(PPh3)Cl and [(R2C2S2)M(μ-tpbz)] (M = Ni, Pd, Pt; R = Ph, p-anisyl, CN) in a 1:2 ratio. The X-ray crystallographic structures of a set of trimetallic [[(R2C2S2)Ni(μ-tpbz)]2Au](CF3SO3) (R = Ph, p-anisyl, CN) show distorted tetrahedral geometry around Au(I). The open diphosphine groups of [(R2C2S2)M(tpbz)] can be oxidized to afford open-ended [(R2C2S2)M(tpbzE2)] (E = O, S). Synthesis of the octahedral [(dppbO2)3Ni][I3]2 [dppbO2 = 1,2- bis(diphenylphosphoryl)benzene] suggests that the steric profile of [(R2C2S2)M(tpbzE2)] is moderated enough that three could be accommodated as ligands around a metal ion.

Redox-active open-ended metallodithiolene complexes with the 1,2,4,5- tetrakis(diphenylphosphino)benzene ligand: Modular building blocks for the synthesis of heterometallic assemblies

ACS Spring 2022

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