Synthesis and Reactivity of Dimeric Ar‘TlTlAr‘ and Trimeric (Ar‘ ‘Tl)3 (Ar‘, Ar‘ ‘ = Bulky Terphenyl Group) Thallium(I) Derivatives: Tl(I)−Tl(I) Bonding in Species Ligated by Monodentate Ligands

The synthesis and characterization of three new organothallium(I) compounds are reported.
Reaction of (Ar‘Li)2 (Ar‘ = C6H3-2,6-(C6H3-2,6-Pri2)2) and Ar‘ ‘Li (Ar‘ ‘ = C6H3-2,6-(C6H3-2,6-Me2)2) with TlCl
in Et2O afforded (Ar‘Tl)2 (1) and (Ar‘ ‘Tl)3 (2). The “dithallene” 1 is the heaviest group 13 dimetallene and
features a planar, trans-bent structure with Ar‘Tl−Tl = 119.74(14)° and Tl−Tl = 3.0936(8) Å. Compound
2 is the first structurally characterized neutral, three-membered ring species of formula c-(MR)3 (M = Al−Tl; R = organo group). The Tl3 ring has Tl−Tl distances in the range ca. 3.21−3.37 Å as well as pyramidal
Tl geometries. The Tl−Tl bonds in 1 and 2 are outside the range (2.88−2.97 Å) of Tl−Tl single bonds in
R2TlTlR2 compounds. The weak Tl−Tl bonding in 1 and 2 leads to their dissociation into Ar‘Tl and Ar‘ ‘Tl
monomers in hexane. The Ar‘Tl monomer behaves as a Lewis base and readily forms a 1:1 donor−acceptor
complex with B(C6F5)3 to give Ar‘TlB(C6F5)3, 3. Adduct 3 features an almost linear thallium C(ipso)−Tl−B
angle of 174.358(7)° and a Tl−B distance of 2.311(2) Å, which indicates strong association. Treatment of
1 with a variety of reagents resulted in no reactions. The lower reactivity of 1 is in accord with the reluctance
of Tl(I) to undergo oxidation to Tl(III) due to the unreactive character of the 6s2 electrons.

本报告揭示了三种新型有机铊(I)化合物的合成与表征。通过将（Ar‘Li）2（Ar‘ = C6H3-2,6-(C6H3-2,6-Pri2)2）和Ar‘‘Li（Ar‘‘ = C6H3-2,6-(C6H3-2,6-Me2)2）与TlCl在乙二醇中的反应，得到了（Ar‘Tl）2（1）和（Ar‘‘Tl）3（2）。其中，名为“二铊烯”的1是13族最重的二金属烯，其结构为平面、反式弯曲，Ar‘Tl−Tl键角为119.74(14)°，Tl−Tl键长为3.0936(8) Å。化合物2是首次结构表征的中性、三员环物种，其化学式为c-(MR)3（M = Al−Tl；R = 有机基团）。Tl3环的Tl−Tl键长在约3.21−3.37 Å范围内，且具有金字塔形的Tl几何结构。1和2中的Tl−Tl键长超出R2TlTlR2化合物中Tl−Tl单键的长度范围（2.88−2.97 Å）。1和2中较弱的Tl−Tl键合导致其在己烷中解离成Ar‘Tl和Ar‘‘Tl单体。Ar‘Tl单体作为路易斯碱，容易与B(C6F5)3形成1:1的供体-受体复合物，生成Ar‘TlB(C6F5)3，3。加合物3具有近乎线性的铊C(ipso)−Tl−B角为174.358(7)°和Tl−B键长为2.311(2) Å，这表明了强烈的结合。对1处理多种试剂均未发生反应。1的低反应性与其Tl(I)氧化为Tl(III)的惰性有关，这是由于6s2电子的非活性特性。