含三甲基矽基之磷硫三腳四牙基的二價鐵錯合物合成及其性質與光譜探討

Abstract

本研究使用一個含磷硫多牙基的配位基Tris(3-(trimethylsilyl)2-mercaptophenyl)phosphine (P(STMS)3H3) 含磷硫多牙基的配位基，將其去質子化後與Fe(BF4)2和PPN(BF4) 在四氫呋喃與乙腈之混和溶劑下反應，可成功地合成出深綠色的二價鐵錯合物 [PPN][Fe(CH3CN)P(STMS)3] (1)。錯合物1的中心架構為二價鐵上鍵結了配位基的一個磷原子與三個硫原子，而形成雙三角錐的結構 (τ = 0.97)。將去質子化後的配位基P(STMS)33-和FeCl3與PPNCl反應後則可以得到棕色錯合物 [PPN][FeClP(STMS)3] (2)。而錯合物1中所鍵結的乙腈分子可以被外來的配位基所取代，錯合物1在室溫下與一氧化碳與PPNN3反應，可分別生成在空氣下穩定的紫色錯合物 [PPN][Fe(CO)P(STMS)3] (3)與棕色錯合物 [PPN][Fe(N3)P(STMS)3] (4)。錯合物1-4的生成可由紅外線光譜儀、紫外光-可見光光譜儀與X-ray單晶繞射儀鑑定。當錯合物1與氧氣反應時會形成深紫色的物種，在-80°C的低溫下，可由紫外光-可見光光譜儀偵測到該溶液在497 nm (ε = 2205 M-1cm-1)、561 nm (ε = 2284 M-1cm-1) 與659 nm (ε = 2807 M-1cm-1) 三個位置有電荷轉移吸收峰的生成。根據先前的文獻資料，我們推測錯合物1與氧氣在低溫反應後生成一種含氧的鐵中間體。

A tripodal tetradentate ligand, tris(3-(trimethylsilyl)-2- mercaptophenyl)phosphine (P(STMS)3H3) was prepared to synthesize several iron complexes. Addition of deprotonated P(STMS)33- to an acetonitrile solution of the mixture of equamolar iron tetrafluoroborate and PPN(BF4) gave an FeII complex, [PPN][Fe(CH3CN)P(STMS)3] (1). Complex 1 possesses a FeII center, coordinated by an apical phosphine, three equatorial thiolates and one acetonitrile, forming a trigonal bipyramidal geometry (τ = 0.97). Reaction of FeCl3, PPNCl and deprotonated P(STMS)33- provided an FeIII complex, [PPN][FeClP(STMS)3] (2). The bound acetoitrile of complex 1 is readily repleaced by an exogenous ligand. For instance, a purple complex [PPN][Fe(CO)P(STMS)3] (3) and a brown complex [PPN][Fe(N3)P(STMS)3] (4) were prepared from the reaction of complex 1 with CO and PPNN3, respectively. Complexes 1 – 4 were characterized by IR and UV/vis spectroscopies, and X-ray crystallography. As complex 1 reacted with dioxygen, a dark-purple species was formed, which was monitored by UV/vis spectroscopy at -80°C. The spectrum of the dark-purple species exhibited three charge transfer bands at 497, 561 and 659 nm (ε = 2205, 2284 and 2807 cm-1M-1), which were consistent with iron-oxygen species.