Synthesis of the first Metallasila-closo-dodecaborates(1−). Silaborate Complexes of Cobalt, Rhodium, and Iridium

Abstract

Complexation of the silaborate ligand [MeSiB10H10]3- is described for the first time. The syntheses of the sandwich anions [(η5-C5Me5)M(MeSiB10H10)]- (M = Co, Rh, Ir) are realized by reaction of the monodeprotonated silaborate with the respective pentamethylcyclopentadienyl transition metal chloride. The reaction products are characterized by mass spectrometry, elemental analyses, and multinuclear and two-dimensional NMR spectroscopy. Because of an unresolvable disorder in the solid state structure of [NEt4][(η5-C5Me5)Rh(MeSiB10H10)], the isobutyl-substituted derivative [Ph3PMe][(η5-C5BuiMe4)Rh(MeSiB10H10)], [Ph3PMe][4], was analyzed by an X-ray structure determination. The salt [Ph3PMe][4]·THF, C37H60OPSiB10Rh, crystallizes in the triclinic space group P1̄ (No. 2) with a = 9.838(4) Å, b = 11.312(3) Å, c = 18.858(5) Å, α = 92.68(2)°, β = 90.22(3)°, γ = 96.77(3)°, and Z = 2.

A Surprising Adduct of acloso Cluster

“…[3] Two recent papers describe the use of gold(iii) catalysts (NaAuCl 4 ) for the addition of water and methanol to nonactivated alkynes, [4] but this catalyst shows the same disadvantage: It is quickly reduced to inactive metallic gold, so no more than 50 moles of product can be synthesized per mole of gold. The fact that the literature on homogeneous catalysis with gold complexes is extremely sparse, [4,5] and that until recently gold was thought to be ªcatalytically dead,º [6] made the quest for an efficient gold(i) catalyst all the more interesting.…”

“…This eleven-vertex cluster is a versatile starting material for the synthesis of transition metal complexes with interactions between the silicon and the metal. [4,5] In this paper we present first insights into the nucleophilic degradation of o-silaborane. Attack of one equivalent OH À in H 2 O, MeO À in MeOH, or pure NH 3 , results in the removal of a silicon vertex from the closo cluster 3.…”

Periodic trends and easy estimation of relative stabilities in 11-vertex nido-p-block-heteroboranes and -borates

“…Removal of one vertex from a 12-vertex closo -heteroborane cluster also leads to 11-vertex nido -heteroboranes and -borates [ 2 , 4 , 5 ]. Experimentally known 11-vertex nido -heteroborane and -borate clusters include: group 14 heteroatoms, i.e., carbon [ 6 – 9 ], silicon [ 10 – 13 ], germanium [ 14 – 17 ] and tin [ 6 – 8 , 18 – 21 ]; group 15 heteroatoms, i.e., nitrogen, phosphorus [ 1 , 2 ], arsenic [ 5 , 22 – 32 ] and antimony [ 33 ]; group 16 heteroatoms, i.e., sulfur [ 34 ], selenium [ 35 – 41 ] and tellurium [ 35 – 37 , 42 , 53 ]. Williams’ qualitative rules predict isomers with low-coordinate heteroatoms and separated heteroatoms to be preferred [ 6 , 54 , 55 ].…”

Ein überraschendes Addukt einescloso-Clusters

“…Dieser elfeckige Cluster ist damit eine gut zugängliche Ausgangsverbindung für die Synthese von Übergangsmetallkomplexen mit Silicium-Metall-Wechselwirkung. [4,5] Hier geben wir einen ersten Einblick in den nucleophilen Abbau des o-Silaborans. Unter Angriff eines ¾quivalentes OH À in H 2 O, MeO À in MeOH oder mit reinem NH 3 wurde eine Siliciumecke aus dem closo-Cluster 3 entfernt.…”

“…Offensichtlich fungiert die Disilaeinheit als Acceptor, was an Siliciumverbindungen erinnert, die als inverse Chelatliganden auftreten können. [17] Die Sarcodictyine, [1,2] Eleutherobin [3,4] und die Eleuthoside, [5] ihr Taxol-artiger Wirkmechanismus, [6] der durch Tubulin-Polymerisation und Stablisierung der Mikrotubuli zum Tod von Krebszellen führt. Wegen der geringen Verfügbarkeit und der hohen biologischen Aktivität dieser Verbindungen beschäftigen wir uns mit der Synthese dieser Naturstoffe.…”