13272-66-7Relevant articles and documents
Planar-chiral ferrocenylphosphine-borane complexes featuring agostic-type B-H?E (E = Hg, Sn) interactions
Tagne Kuate, Alain C.,Lalancette, Roger A.,J?kle
, p. 6253 - 6264 (2017)
The synthesis of ferrocenylphosphine-borane adducts 1,2-fc(E)(PPh2·BH3) (E = SnR2R′, HgX; 1,2-fc = 1,2-ferrocenediyl) that are substituted with organotin or organomercury Lewis acid moieties in ortho-position is presented. Several compounds that feature two ferrocenylphosphine-borane moieties bridged by Sn or Hg are also introduced. The products are fully characterized by multinuclear NMR spectroscopy, high-resolution MALDI-TOF mass spectrometry and elemental analysis. The attachment of the Lewis acid substituent to the same Cp ring of the ferrocene results in planar-chirality and the close proximity between the boron hydride group and the Lewis acid is expected to allow for agostic-type B-H?E (E = Sn, Hg) interactions. Structural investigations by X-ray diffraction reveal a short B-H?Sn contact of 2.755(4) ? for 1,2-fc(SnMe2Cl)(PPh2·BH3), which is only the second reported example of such a short agostic-type contact involving a coordinatively saturated tin(iv) center. In contrast, for the tetraorganotin derivatives 1,2-fc(SnMe3)(PPh2·BH3) and [1,2-fc(PPh2)](μ-SnMe2)[1,2-fc(PPh2·BH3)], in which the Lewis acidity of the tin atom is weaker than in 1,2-fc(SnMe2Cl)(PPh2·BH3), the B-H?Sn distances are much longer but still within the sum of the van der Waals radii of Sn and H (∑vdW = 3.27 ?). The chloromercury-substituted ferrocenylphosphine-borane 1,2-fc(HgCl)(PPh2·BH3) shows a similarly short B-H?Hg contact of 2.615(5) ? (∑vdW = 3.15 ?). Inspection of the extended structure of 1,2-fc(HgCl)(PPh2·BH3) reveals that the Lewis acidic mercury atom is also involved in intermolecular Hg?Cl interactions with a neighboring molecule. An analysis of 31P and 11B NMR data reveals a correlation between the chemical shifts and the Lewis acidity of the adjacent organotin/mercury substituent. Structure optimization of 1,2-fc(SnMe3)(PPh2·BH3) and 1,2-fc(SnMe2Cl)(PPh2·BH3) by density functional theory (DFT) indicates B-H?Sn contacts respectively of 3.129 and 2.631 ? that are close to the experimental values. Natural bond orbitals (NBO) and atom in molecules (AIM) analyses reveals a B-H→Sn donor-acceptor interaction energy of 5.46 kcal mol-1 and a B-H?Sn bond path for the chlorodimethyltin-substituted derivative with a modest electron density ρ(r) of 0.0082 a.u. and a positive Laplacian at the bond critical point.
Tetraaza-λ3-diphospha-stanna-bicycloheptanes: Reactive Precursors of New Heterobicycles
Linti, Gerhard,Noeth, Heinrich,Schneider, Ellen,Storch, Wolfgang
, p. 619 - 630 (2007/10/02)
2,4,6,7-Tetraaza-1λ3,5λ3-diphospha-3-stannabicycloheptane (4) is obtained by stannazane cleavage of the diazadistannetidine (Me2SnNtBu)2 (2) with the diazadiphosphetidine (ClPNtBu)2 (1).A chloro derivative of 4, compound 8, is formed by substitution of one methyl group attached to the tin atom in 4 against chlorine in a 1:1 reaction with PhBCl2, while additional PhBCl2 leads to an exchange of the MeClSn against the PhB group to give 9.Oxidation of both phosphorus atoms of compound 4 with sulfur leads to 7.An unexpected introduction of a diphenyldiphosphane unit with formation of 11 proceeds by stannazane cleavage of 4 with PhPCl2.The structures of the bicyclic products 4, 7, 8, and 11 are ascertained by detailed NMR studies, particularly by means of 15N-NMR spectra, and by X-ray structure determinations.All heterobicycles contain a planar diazadiphosphetidine unit.The ring system 8 features an additional Sn-N bond due to transannular interaction of the tin atom with one of the nitrogen atoms of the four-membered P2N2 ring fragment.The PP bond distance in 11 with 2.175 Angstroem is one of the shortest found in heterocycles containing P2 units. Key Words: Tetraaza-diphospha-stanna-bicycloheptanes/ Tetraaza-tetraphospha-bicyclooctanes/1,3,2,4-Diazadiphosphetidines/1,3,2,4-Diazadistannetidines/SnN bond cleavage
