Tetranuclear zigzag Ag4 and Ag2Pt2 complexes supported by rac-Ph2PCH2P(Ph)CH2P(Ph)CH2PPh2 (rac-dpmppm)

Reaction of AgOTf with a tetraphosphine, rac-bis[(diphenylphosphinomethyl) phenylphosphino]methane (rac-dpmppm), afforded [Ag-4(rac-dpmPPm)(2)](TfO)(4) (3) which consists of zigzag-arrayed tetranuclear silver(I) ions supported by syn-arrangement of two enantiomeric (RR/SS) dpmppm ligands. Complex 3 readily reacted with XylNC (Xyl = 2,6-dimethylphenyl) to give [Ag-4(rac-dpmppm)(2)(XylNC)(2)](TfO)(4) (4), where two terminal isocyanides attach to the outer Ag sites. Complex 3 has been shown a good precursor for Pt-Ag-Ag-Pt mixed metal array as incubation of 3 with trans-[Pt(CCPh)(2)(PPh3)(2)] yielded [Ag2Pt2(CCPb)(4)(rac-dpmppm)(2)](TfO)(2) (5). Two trans-Pt(CCPh)(2) units are incorporated into the terminal positions in a site-selective fashion and the Pt-Ag-Ag-Pt tetranuclear core also adopts a zigzag array supported by syn-arrangement of two rac-dpmppm ligands. The d(8) and d(10) closed-shell mixed metal centers of 5 exhibited an intense photoluminescence at 534 nm, mainly from an unsymmetric triplet state generated by charge transfer transitions from ligand (acetylide pi) to metal centers (Ag-2 and PtAg s/p(sigma)), 3 LMCT, and to ligands (acetylide pi* and dpmppm), 3 LLCT. The present results provide fundamental and useful information to construct multinuclear closed-shell metal alignments by utilizing polyphosphine ligands. (C) 2020 Elsevier B.V. All rights reserved.