Electron-Deficient Pt2M2Pt2 Hexanuclear Metal Strings (M = Pt, Pd) Supported by Triphosphine Ligands

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• 作者：Eri Goto ; Rowshan Ara Begum ; Chiaki Ueno ; Aya Hosokawa ; Chie Yamamoto ; Kanako Nakamae ; Bunsho Kure ; Takayuki Nakajima ; Takashi Kajiwara ; Tomoaki Tanase
• 刊名：Organometallics
• 出版年：2014
• 出版时间：April 28, 2014
• 年：2014
• 卷：33
• 期：8
• 页码：1893-1904
• 全文大小：663K
• 年卷期：v.33,no.8(April 28, 2014)
• ISSN：1520-6041

文摘

Electron-deficient Pt₂M₂Pt₂ hexanuclear clusters, [Pt₄M₂(渭-dpmp)₄(XylNC)₂](PF₆)₄ (M = Pt (7), Pd (8); dpmp = bis((diphenylphosphino)methyl)phenylphosphine), were synthesized by oxidation of hydride-bridged hexanuclear clusters [Pt₄M₂(渭-H)(渭-dpmp)₄(XylNC)₂](PF₆)₃ (M = Pt (2), Pd (3)) and were revealed to involve a linearly ordered Pt₂M₂Pt₂ array joined by delocalized bonding interactions with 84 cluster valence electrons, which are discussed on the basis of DFT calculations. The central M鈥揗 distances of 7 and 8 are significantly reduced upon the apparent loss of a hydride unit from the M鈥揌鈥揗 central part of 2 and 3, indicating that the bonding electrons in the adjacent M鈥揚t bonds migrate into the central M鈥揗 bond to result in a dynamic structural change during two-electron oxidation of the hexanuclear metal strings. A similar Pt₆ complex terminated by two iodide anions, [Pt₆I₂(渭-dpmp)₄](PF₆)₂ (9), was synthesized from [Pt₆(渭-H)I₂(渭-dpmp)₄](PF₆) (5) by treatment with [Cp₂Fe][PF₆]. Complexes 7 and 8 were readily reacted with the neutral two-electron donors XylNC, CO, and phosphines to afford the trinuclear complexes [Pt₂M(渭-dpmp)₂(XylNC)L](PF₆)₂ (M = Pt, L = XylNC (1a), CO (10), PPh₃ (11); M = Pd, L = XylNC (1b)) through cleavage of the electron-deficient central M鈥揗 bond. When complex 7 was reacted with the diphosphines (PP) trans-Ph₂PCH鈺怌HPPh₂ (dppen) and Ph₂P(CH₂)₂PPh₂ (dppe), the diphosphine was inserted into the central M鈥揗 bond to afford [(XylNC)Pt₃(渭-dpmp)₂(PP)Pt₃(渭-dpmp)₂(XylNC)](PF₆)₄ (12), which was transformed by treatment with another 1 equiv of diphosphine into the asymmetric trinuclear complexes [Pt₃(渭-dpmp)₂(XylNC)(PP)](PF₆)₂ (13). A further ligand exchange reaction of 13a (PP = trans-dppen) provided the diphosphine-terminated symmetrical Pt₃ complex [Pt₃(渭-dpmp)₂(L)₂](PF₆)₂ (L = trans-dppen (14a)). Complexes 7 and 8 were also reacted with [AuCl(PPh₃)] to yield the Pt₂MAu heterotetranuclear complexes [Pt₂MAuCl(渭-dpmp)₂(PPh₃)(XylNC)](PF₆)₂ (M = Pt (15), Pd (16)), in which the Pt₂M trinuclear fragment is inserted into the Au鈥揅l bond in a 1,1-fashion on the central M atoms of the Pt₂M₂Pt₂ string.