The synthesis, spectroscopic and structural characterization of an extensive series of acyclic, monomeric tetrylene dichalcogenolates of formula M(ChAr)2 (M = Si, Ge, Sn, Pb; Ch = O, S, or Se; Ar = bulky m-terphenyl ligand) are described. They were found to possess several unusual features-the most notable of which is their strong tendency to display acute interligand, Ch-M-Ch, bond angles that are often well below 90°.Furthermore, and contrary to normal steric expectations, the interligand angles were 2 found to become narrower as the size of the ligand was increased. Experimental and structural data in conjunction with high-level DFT calculations, including corrections for dispersion effects, led to the conclusion that dispersion forces play a key role in stabilizing their acute interligand angles.

Treatment of toluene solutions of the silylenes Si(SAr Me 6 ) 2 (Ar Me 6 = C 6 H 3 -2,6(C 6 H 2 -2,4,6-Me 3 ) 2 , 1) or Si(SAr Pr i 4

One decade after the first characterization of Zintl ions by Kummer and Diehl [1a] and Corbett, [1b, c]

Two K([2.2.2]crypt) salts of lanthanide-doped semimetal clusters were prepared, both of which contain at the same time two types of ternary intermetalloid anions, [Ln@Sn(7)Bi(7)](4-) and [Ln@Sn(4)Bi(9)](4-), in 0.70:0.30 (Ln = La) or 0.39:0.61 (Ln = Ce) ratios. The cluster shells represent nondeltahedral, fullerane-type arrangements of 14 or 13 main group metal atoms that embed the Ln(3+) cations. The assignment of formal +III oxidation states for the Ln sites was confirmed by means of magnetic measurements that reveal a diamagnetic La(III) compound and a paramagnetic Ce(III) analogue. Whereas the cluster anions with a 14-atomic main-group metal cage represent the second examples in addition to a related Eu(II) cluster published just recently, the 13-atomic cages exhibit a yet unprecedented enneahedral topology. In contrast to the larger cages, which accord to the Zintl-Klemm-Busmann electron number-structure correlation, the smaller clusters require a more profound interpretation of the bonding situation. Quantum chemical investigations served to shed light on these unusual complexes and showed significant narrowing of the HOMO-LUMO gap upon incorporation of Ce(3+) within the semimetal cages.

The reduction of the tribromoamidosilane {N(SiMe )Dipp}SiBr (Dipp=2,6-iPr C H ) with potassium graphite or magnesium resulted in the formation of [Si {N(SiMe )Dipp} ] (1), a bicyclo[1.1.0]tetrasilatetraamide. The Si motif in 1 does not adopt a tetrahedral substructure and exhibits two three-coordinate and two four-coordinate silicon atoms. The electronic situation on the three-coordinate silicon atoms is rationalized with positive and negative polarization based on EPR analysis, magnetization measurements, and DFT calculations as well as Si CP MAS NMR and multinuclear NMR spectroscopy in solution. Reactivity studies with 1 and radical scavengers confirmed the partial charge separation. Compound 1 reacts with sulfur to give a novel type of silicon sulfur cage compound substituted with an amido ligand, [Si S {N(SiMe )Dipp} ] (2).

Experimental and theoretical studies on intermetalloid cluster anions, [1] that is, main-group-element cages with interstitial transition metal atom(s), have attracted the interest of chemists and physicists for about a decade. This is due to a large variety of novel structural types, unprecedented bonding situations, and unexpected chemical and physical properties of the resulting phases; furthermore, the compounds are discussed as being models for doped materials and/or precursors to novel intermetallic phases.[2] The structures of the known intermetalloid anions are controlled by both the synthetic reaction route and the embedded transition metal atom. , [4] that would not exist without interstitial atom. These anions feature exclusively nondeltahedra faces and thus direct toward fullerene-like molecular structures.[2a]To date, it has not been possible to isolate main-groupmetal cages stabilized by Ln ions, although these elements are well-known as both components of intermetallic phases, for example, in EuSn 3 Sb 4 , [5] and as guests in doped main-groupelement host lattices, for example in nanocrystalline LED phosphors such as M 2 Si 5 N 8 :Eu 2+ (M = Sr, Ba) [6] or laser materials such as Nd:YAG.[7] Moreover, photoelectron spectroscopy [8] and quantum chemical investigations [9] indicated the existence of [LnSi n ] À species (3 n 13; Ln = Ho, Gd, Pr, Sm, Eu, Yb), [EuSi n ] À (3 n 17), and Yb@Pb 12 in the gas phase. In the condensed phase, Ln ions have only been trapped by carbon cages such as M@C 82 and M 2 @C x (M = LaNd, Sm-Lu; x = 72, 78, 80).[10] These clusters have been discussed as "designer" materials because a small variation in their composition can significantly manipulate their chemical, electronic, and magnetic properties. For instance, the magnetic moment is tunable by the type and oxidation state of the incorporated lanthanide ion. [8] We (Figure 1) form a polyhedron that consists of nine nondeltahedral faces, namely six pentagons and three square faces. This enneahedron has been unknown to date in an isolated, ligand-free form. However, topologically identical polyhedra were previously observed and discussed as part of complicated networks within two solid-state phases: elongated in the intermetallic phase Ag 7 Te 4[13] or undistorted in

Since first reports by Joannis and Kraus [1] through the honorable work of Zintl in the 1930s [2] and first structural reports in the 1970s, [3] interest in compounds containing Zintl ions has not stopped even today, owing to their outstanding structural and electronic properties.[4] However, the size of the homoatomic molecular cages seems to be limited to nine in [E 9 ] 4À (E = tetrel), [5] owing to the instability of larger deltahedral cavities.The 21st century gave the research field a new dimension by the synthesis of intermetalloid Zintl anions with endohedral d 10 transition-metal atoms stabilizing a larger maingroup-atom deltahedron (which sometimes contains additional transition-metal atoms).[ 3À [14] were also shown to be suitable interstitial atoms for nondeltahedral cages. Being interesting objects for the exploration of the bonding situation, [15] these anions also serve as models for doped metals and might be useful precursors for nanostructured intermetallic phases, as was realized with [Ge 9 ] 4À in the formation of nanostructured Ge. [16] Such compounds are usually prepared by treating solutions of homoatomic Zintl ions with transition-metal complexes, leading to fragmentation and rearrangement of the main-group cage incorporating the transition-metal atom or atoms, which is not yet well understood. Hence, this type of synthesis has to date been restricted to [E 9 [17,18] have not yet been explored.To contribute both to a bottom-up strategy for the formation of heterometallic and intermetalloid clusters from smaller precursors and to an expansion of the field to the unknown ternary M/14/15 systems, we are currently investigating reactions of tetrahedral Group 14/15 Zintl anions, based on our comprehensive experience in the reactivity of binary 14/16 anions.[ (2). Compound 2 contains a novel binary nine-atom cage. Both compounds were structurally characterized by single-crystal X-ray diffraction. [22,23] Compound 1 contains an unprecedented ternary intermetalloid cluster anion, [Zn@Zn 5 Sn 3 Bi 3 @Bi 5 ] 4À (Figure 1), which may be described as a derivative of an 11-atom nido cluster: a pentagonal antiprism of a Bi-capped Zn 5 ring and an uncapped Sn 3 Bi 2 ring (with statistical occupation of the atomic positions by 0.6 Sn and 0.4 Bi atoms each) enclose an endohedral Zn atom. Five additional Bi atoms cap the five Zn 2 E triangles (E = Sn 0.6 Bi 0.4 ) between the two five-membered rings but are displaced from the centers of the triangles towards the ZnÀZn bonds.Statistic disorder of main-group metal atoms is an intrinsic peculiarity of Sn/Bi Zintl anions and was also observed in the binary [Sn 2 Bi 2 ] 2À anion in the starting material.[21] Therefore, it is not surprising that both 1 and 2 exhibit Sn/Bi disorder. The compositions of 1 and 2 that represent the best crystallographic models have been confirmed by energy-dispersive Xray spectroscopy (EDX) analyses (see the Supporting Information) and agree with the observation of diamagnetic compounds.Quantum chemical investigations of the an...

Reaction of the bicyclo[1.1.0]tetrasilatetraamide Si4{N(SiMe3)Dipp}4 1 (Dipp=2,6‐diisopropylphenyl) with 5 equiv of the N‐heterocyclic carbene NHCMe4 (1,3,4,5‐tetramethylimidazol‐2‐ylidene) affords a bifunctional carbene‐coordinated four‐membered‐ring compound with a Si=N group and a two‐coordinate silicon atom Si4{N(SiMe3)Dipp}2(NHCMe4)2(NDipp) 2. When 2 reacts with 0.25 equiv sulfur (S8), two sulfur atoms add to the divalent silicon atom in plane and perpendicular to the plane of the Si4 ring, which confirms the silylone character of the two‐coordinate silicon atom in 2.