Lars Wesemann

Stannaborate Transition Metal Chemistry: Ligand Properties, Reactivity, and Density Functional Theory Calculations of Platinum and Palladium Complexes

Three stannaborate complexes of platinum(II) and a novel stannoborate palladium(II) derivative have been prepared in excellent yield. The tin transition metal bond is formed through nucleophilic substitution and the resulting complexes [Bu3MeN] [trans-[(Et3P)2Pt(SnB11H11)H]] (6), [trans-[(Et3P)2Pt(SnB11H11)(CNtBu)]] (7), [Bu3MeN]2[trans-[(Et3P)2Pt(SnB11H11)2-(CNtBu)]] (8), and [Bu3MeN][(dppe)-Pd(SnB11H11)Me] (12) (dppe = 1,2-bis-(diphenylphosphanyl)ethane) were characterized by NMR spectroscopy and elemental analysis. In the cases of the zwitterion 7, the pentacoordinated complex 9, the palladium salt 12 and [(triphos)Pt(SnB11H11)] (10) (triphos = 1,1,1-tris(diphenylphosphanylmethyl)ethane), their solid-state structures are determined by X-ray crystal structure analyses. The trans influence of the [SnB11H11] ligand is evaluated from the results of the IR spectroscopy and X-ray crystallographic structures of complexes 6, 7, and 12. The dipole moment of the zwitterion 7 is calculated by density functional theory (DFT) methods. The alignment of the dipole moments of the polar molecules 7 and 12 in the solid state is discussed.

Coordination of acloso-Cluster at Rhodium and Iridium

Stanna-closo-dodecaborate [Bu3MeN]2[SnB11H11] reacts as a nucleophile with the rhodium and iridium electrophiles of type [Cp*M(bipy′)Cl][BF4] under formation of a transition metal tin bond. The zwitterionic molecules [Cp*M(bipy′)(SnB11H11)] (with Mu200a=u200aRh, Ir) were characterized by NMR spectroscopy, elemental analyses and X-ray crystal structure analyses. A high dipole moment of 25.67u200aD was calculated by DFT methods in the case of the rhodium derivative. n n n nKoordination eines closo-Clusters an Rhodium und Iridium n n n nDer Stanna-closo-dodecaboratcluster [Bu3MeN]2[SnB11H11] reagiert mit den Ubergangsmetallelektrophilen [Cp*M(bipy′)Cl][BF4] von Rhodium und Iridium unter Bildung einer Zinn–Metall Bindung. Die zwitterionischen Reaktionsprodukte [Cp*M(bipy′)(SnB11H11)] (mit Mu200a=u200aRh, Ir) wurden durch NMR-Spektroskopie, Elementaranalysen sowie Kristallstrukturbestimmungen charakterisiert. Im Fall der Rhodiumverbindung wurde ein Dipolmoment von 25.67u200aD durch DFT Methoden berechnet.

Synthesis and structure of [Zr{η5:η1-C9H6B(NiPr2)NPh}2]: a new complex with a boron-bridged amido-indenyl ligand

A boron-bridged amido-cyclopentadienyl ligand was recently shown to form constrained-geometry titanium-complexes that are capable of olefin polymerisation. Here, the synthesis of the corresponding amido-indenyl ligand η 1 -C 9 H 7 B(N i Pr 2 )N(H)Ph (C 9 H 7 =indenyl) ( 2a / 2v ) and its allyl–vinyl isomerisation are discussed. Deprotonated 2a reacts with ZrCl 4 to give the strongly distorted zirconocene-type complex [Zr{η 5 :η 1 -C 9 H 6 B(N i Pr 2 )NPh} 2 ] ( 3 ) in a 2:1 reaction. All compounds have been characterised by multinuclear NMR methods and structures of both the ligand 2a and the complex 3 have been confirmed by X-ray diffraction.

Platinum complexes of stanna-closo-dodecaborate

Abstract The platinum(II)chlorides cis -L 2 PtCl 2 (Lue605PPh 3 , PEt 3 ), (dppe)PtCl 2 , trans ue5f8(Ph 3 P) 2 Pt(Cl)Ph, (dppe)Pt(Cl)Me and (dppe)Pt(Cl)Ph were treated with [Bu 3 MeN] 2 [SnB 11 H 11 ] ( 1 ) to give the air and moisture inert stannaborate substituted complexes [Bu 3 MeN] 2 [ trans -L 2 Pt(SnB 11 H 11 ) 2 ] ( 2 : Lue605PPh 3 , 3 : Lue605PEt 3 ), [Bu 3 MeN] 2 [(dppe)Pt(SnB 11 H 11 ) 2 ] ( 4 ), [Bu 3 MeN][ trans -(Ph 3 P) 2 Pt(SnB 11 H 11 )Ph] ( 8 ), [Bu 3 MeN][(dppe)Pt(SnB 11 H 11 )Me] ( 9 ) and [Bu 3 MeN][(dppe)Pt(SnB 11 H 11 )Ph] ( 10 ). The nearly square planar coordination at the transition metal centre in the anion of 8 was confirmed by X-ray crystal structure analysis. (dppe)PtCl 2 reacts with one equivalent of 1 to give a 1:1 mixture of 4 and (dppe)PtCl 2 . Reaction of 9 and 10 with one equivalent of HCl resulted not in the isolation of the monochloride [(dppe)Pt(SnB 11 H 11 )Cl] − ( A ), instead the 1:1 mixture between was 4 and (dppe)PtCl 2 isolated. From the reaction of [(triphos)PtCl][BF 4 ] and 1 a zwitterionic platinum complex (triphos)Pt(SnB 11 H 11 ) ( 11 ) was isolated.

Alkylderivatives of Stanna-closo-dodecaborate

Abstract The reactions of [SnB11H11]2− with organic halides like 1-chloro-3-iodopropane, allylbromide, propargylbromide and 2,6-bis-(bromomethyl)pyridine lead in a nucleophilic substitution at room temperature to the products [Bu3MeN][Cl(CH2)3SnB11H11] (4), [Bu3MeN][H2Cue605CHue5f8CH2ue5f8SnB11H11] (6), [Bu4N][HCCue5f8CH2SnB11H11] (7), and [Bu4N]2[2,6-(H11B11Snue5f8CH2)2(C5H3N)] (8). In water Na2[SnB11H11] reacts with 2-bromoethylamine hydrobromide at 50xa0°C and 3-bromopropylamine hydrobromide at 70xa0°C to the zwitterionic products [H11B11Snue5f8(CH2)nNH3] (n=2, 3), which were characterized by X-ray crystal structure analysis. [H11B11Snue5f8(CH2)2NH3] crystallizes with one equivalent of water under the formation of Nue5f8Hue5f8O hydrogen bonding. In the case of chloroiodomethane and diiodomethane the substitution reaction proceeds differently and the monosubstituted components were not detected. The disubstituted compound [Bu3MeN]2[H2C(SnB11H11)2] (5), whose structure could be confirmed by X-ray crystal structure analysis, is the only observed reaction product.

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.