Synthesis, Structure, and Reactivity of [Zr6Cl18H5]2-, the First Paramagnetic Species of Its Class

Abstract

Reaction of [Zr(6)Cl(18)H(5)](3)(-) (1) with 1 equiv of TiCl(4) yields a new cluster anion, [Zr(6)Cl(18)H(5)](2)(-) (2), which can be converted back into [Zr(6)Cl(18)H(5)](3)(-) (1) upon addition of 1 equiv of Na/Hg. Cluster 2 is paramagnetic and unstable in the presence of donor molecules. It undergoes a disproportionation reaction to form 1, some Zr(IV) compounds, and H(2). It also reacts with TiCl(4) to form [Zr(2)Cl(9)](-) (4) and a tetranuclear mixed-metal species, [Zr(2)Ti(2)Cl(16)](2)(-) (3). The oxidation reaction of 1 with TiCl(4) is unique. Oxidation of 1 with H(+) in CH(2)Cl(2) solution results in the formation of [ZrCl(6)](2)(-) (5) and H(2), while in py solution the oxidation product is [ZrCl(5)(py)](-) (6). There is no reaction between 1 and TiI(4), ZrCl(4), [TiCl(6)](2)(-), [ZrCl(6)](2)(-), or CrCl(3). Compounds [Ph(4)P](2)[Zr(6)Cl(18)H(5)] (2a), [Ph(4)P](2)[Zr(2)Ti(2)Cl(16)] (3a), [Ph(4)P](2)[Zr(2)Cl(9)] (4a), [Ph(4)P](2)[ZrCl(6)].4MeCN (5a.4MeCN), and [Ph(4)P][ZrCl(5)(py)] (6a) were characterized by X-ray crystallography. Compound 2a crystallized in the trigonal space group R&thremacr; with cell dimensions (20 degrees C) of a = 28.546(3) Å, b = 28.546(3) Å, c = 27.679(2) Å, V = 19533(3) Å(3), and Z = 12. Compound 3a crystallized in the triclinic space group P&onemacr; with cell dimensions (-60 degrees C) of a = 11.375(3) Å, b = 13.357(3) Å, c = 11.336(3) Å, alpha = 106.07(1) degrees, beta = 114.77(1) degrees, gamma = 88.50(1) degrees, V = 1494.8(7) Å(3), and Z = 1. Compound 4a crystallized in the triclinic space group P&onemacr; with cell dimensions (-60 degrees C) of a = 12.380(5) Å, b = 12.883(5) Å, c = 11.000(4) Å, alpha = 110.39(7) degrees, beta = 98.29(7) degrees, gamma = 73.12(4) degrees, V = 1572(1) Å(3), and Z = 2. Compound 5a.4MeCN crystallized in the monoclinic space group P2(1)/c with cell dimensions (-60 degrees C) of a = 9.595(1) Å, b = 19.566(3) Å, c = 15.049(1) Å, beta = 98.50(1) degrees, V = 2794.2(6) Å(3), and Z = 2. Compound 6a crystallized in the monoclinic space group P2(1)/c with cell dimensions (20 degrees C) of a = 10.3390(7) Å, b = 16.491(2) Å, c = 17.654(2) Å, beta = 91.542(6) degrees, V = 3026.4(5) Å(3), and Z = 4.