Yves Ramjoie

A Surprising Adduct of a closo Cluster

The geometry of the Si2 B10 framework remains nearly unchanged when the Si-Si edge is bridged by an electron-donating amido group. This finding is clearly evident from the single-crystal X-ray structure analysis and ab initio calculations of the uprecedented adduct that is formed by the addition of Et2 N- to o-silaborane (structure depicted bottom right).

Synthesis and Structure of 1,2-Diphenyl-1,2-disila-closo-dodecaborane(12), Reaction with [Zr(NMe2)4] and [Ta(NMe2)5]

Diphenyl-o-silaborane (1) can be obtained by sublimation as colourless crystalline material in a yield of 23%. The disilaborane 1 was characterized by NMR spectroscopy, mass spectrometry and X-ray structure analysis. The neutral closo cluster 1 reacts with [Zr(NMe2)4] or [Ta(NMe2)5] to give the dimethylamide adduct [(Me2N)(PhSi)2B10H10]– of the disilaborane. Synthese und Struktur von 1,2-Diphenyl-1,2-disila-closo-dodecaboran(12), Reaktion mit [Zr(NMe2)4] und [Ta(NMe2)5] Fur den closo-Cluster 1,2-Diphenyl-1,2-disila-closo-dodecaboran(12) (1) wird eine Synthese vorgestellt, nach der das Silaboran als farblose Kristalle durch Sublimation in Ausbeuten von 23% erhalten werden kann. 1 wurde durch NMR-Spektroskopie, hochauflosende Massenspektrometrie und eine Kristallstrukturbestimmung charakterisiert. Die Ubergangsmetallamide [Zr(NMe2)4] oder [Ta(NMe2)5] reagieren mit dem Disilaboran 1 zum Dimethylamid-Addukt [(Me2N)(PhSi)2B10H10]–.

Carbonyl Transition Metal Complexes of a Silaborate Ligand

Reaction between three equivalents of the silaborate [NEt4][MeSiB10H12] (2) and one equivalent of [Ru3(CO)12] resulted in almost quantitative formation of the mononuclear transition metal complex [NEt4][Ru(CO)3(η5-MeSiB10H10)] (5), which was characterized by X-ray structure analysis. The trinuclear ruthenium complex [NEt4][Ru3(CO)8(η5-MeSiB10H10)] (7) was synthesized in high yield from the reaction of one equivalent of 2 and [Ru3(CO)12]. The cluster 7 reacts with two equivalents of PMe2Ph with substitution of two carbonyl groups to give the substitution product [NEt4][Ru3(CO)6(PMe2Ph)2(η5-MeSiB10H10)] (8).

Adducts of o-Silaborane With Water and Methanol

The synthesis of alkoxide adducts of o-silaborane [(TMPDAH)2][(Me2Si2B10H10)2O] (3) and [TMPDAH][(Me2Si2B10H10)OMe] (4) are presented (TMPDA = tetramethylpropylenediamine). For both silaborate clusters 3 and 4 the results of the NMR spectroscopic investigations together with the X-ray single crystal structure determinations are discussed. The geometries of ab initio calculations (HF and B3LYP methods) on the hydroxide adduct [Si2B10H12(OH)]– are compared with the structures of 3 and 4. The dynamic behaviour of the adducts 3 and 4 in solution is discussed with respect to the calculated energy profile for the rotation of the HSi(OH) group.

Ein überraschendes Addukt eines closo‐Clusters

Kaum verandert wird die Geometrie des Si2B10-Gerustes durch die Uberbruckung der Si-Si-Kante mit einer elektronenschiebenden Amidgruppe. Dies ergaben die Einkristall-Rontgenstrukturanalyse und Ab-initio-Rechnungen des ungewohnlichen Addukts, das durch die Addition von Et2N− an o-Silaboran entsteht (siehe Strukturen unten).