The relationship between the structure and the properties of a drug or material is a key concept of chemistry. Knowledge of the three-dimensional structure is considered to be of such...

The sulfur-bridged dimers [{Cp'(2)Ln(μ-SSiPh(3))}(2)] (Ln=Gd (1), Dy (2); Cp'=η(5)-C(5)H(4)Me) were synthesized by the transmetalation reactions between [Cp'(3)Ln] and Ph(3)SiSLi. Compound 2 is a single-molecule magnet with slow relaxation of magnetization up to 40 K and an anisotropy barrier of U(eff) =133 cm(-1). Insight into the SMM properties of 2 and closely related SMMs has been obtained using ab initio calculations.

Exclusively hydrogen-substituted arsanylboranes: The synthesis of the unprecedented Lewis base stabilized monomeric parent compound of the arsanylborane H2AsBH2⋅NMe3 was achieved in a one-pot reaction in high yield and purity. The analogous phosphanylborane was synthesized in a similar manner. A series of different reactions was performed on H2AsBH2⋅NMe3 to show its broad reactivity pattern.

Dedicated to Professor Wolfgang A. Herrmann on the occasion of his 65th birthday Since its discovery and structural characterization in 1951, ferrocene (Fc) has been a fundamental compound in organometallic chemistry and is still of important synthetic and analytic interest. Apart from its use as a reference redox system (Fc + /Fc), [1] chiral ferrocene-based ligands are one of the most important classes of auxiliaries in asymmetric homogeneous catalysis, [2] and ferrocene-based polymeric materials have attracted intense interest with their unique physical and chemical features. [3] The isolobal relationship between Cp À and cyclo-P 5 À ligands [4] led to an enlarged understanding of the relations of such compounds, and the discovery of pentaphosphaferrocene can be regarded as a milestone in chemistry. [5] Like ferrocene, the compound [Cp*Fe(h 5 -P 5 )] (1) was subject of extensive reactivity studies towards organometallic reagents. Similarities are observed in the formation of triple-decker complexes [6,7] or in Cp/cyclo-P 5 -transfer reactions. [8] Fragmentations and distortions of the cyclo-P 5 ring of 1 were found to be significant differences between both compounds. [9,10] Furthermore, the existence of lone pairs at the P atoms opened up an extensive coordination chemistry of the cyclo-P 5 unit that led to 1D and 2D polymers [11] and spherical fullerene-like supramolecules. [12] A view of the HOMO/LUMO orbitals of ferrocene reveals the iron-centered reactivity of ferrocene during oxidation and reduction. In contrast, the HOMOs of the pentaphosphaferrocene show pronounced contributions of the P atoms, whereas for the LUMOs metal contributions are also observed along with P atom portions. [13] Thus, for ferrocene a metal-based redox behavior is found (reversible for oxidation and irreversible for the one-and two-electron reductions accompanied by Cp À elimination and formation of CpFe À species [14] ), while for pentaphosphaferrocene (1) redox reactions will lead to structural changes under participation of P atoms. This was confirmed by Winter et al. by a spectroelectrochemistry study of 1. [15] They found one irreversible reduction and oxidation to give 19e À and 17e À species that rapidly equilibrate to dimeric products for which structures were proposed. Unfortunately, these products were neither isolated nor spectroscopically completely characterized. Therefore, it was of fundamental interest to approach the open questions of the redox properties and possible structural changes of 1 in a preparative scale. Herein, the high-yield syntheses of the one-electron redox products of 1 are presented, which confirm and clarify the earlier proposed structures. Furthermore, an additional two-electron reduction product was obtained that was not detectable by CV studies. Moreover, first reactivity studies of the resulting reactive species are presented that reveal their high potential for subsequent synthetic purposes.The chemical reduction of 1 with KH in THF affords the diamagnetic dianion 2 as a dipotassium salt...

While tetrahedranes as a family are scarce, neutral heteroatomic species are all but unknown, with the only reported example being AsP3. Herein, we describe the isolation of a neutral heteroatomic X2Y2 molecular tetrahedron (X, Y=p‐block elements), which also is the long‐sought‐after free phosphaalkyne dimer. Di‐tert‐butyldiphosphatetrahedrane, (tBuCP)2, is formed from the monomer tBuCP in a nickel‐catalyzed dimerization reaction using [(NHC)Ni(CO)3] (NHC=1,3‐bis(2,4,6‐trimethylphenyl)imidazolin‐2‐ylidene (IMes) and 1,3‐bis(2,6‐diisopropylphenyl)imidazolin‐2‐ylidene (IPr)). Single‐crystal X‐ray structure determination of a silver(I) complex confirms the structure of (tBuCP)2. The influence of the N‐heterocyclic carbene ligand on the catalytic reaction was investigated, and a mechanism was elucidated using a combination of synthetic and kinetic studies and quantum chemical calculations.