Novel germylenes and stannylenes based on pyridine-containing dialcohol ligands

Stabilized germylenes based on dialkanolamines: Synthesis, structure, chemical properties

“…For the germanium atom in 10 the "octet rule" is followed so the GeeN bond is a classical donoreacceptor interaction. The geometrical characteristics of 10 are close to those found earlier in the related monomeric structure of [2,6-C 5 H 3 N(CH 2 CPh 2 O) 2 ]Ge (d(GeeO) 1.827(1), 1.881(1), d(GeeN) 2.110(1) Å) which contains not penta-but hexamembered chelate cycles [9]. It should be noted that the d(GeeO) in 10 are close to the distances found by X-ray analysis in single monomeric dialkoxygermane (Ge[OC(t-Bu) 3 ] 2 (1.833(3), 1.855(3) vs. 1.83(1) Å)) where the coordination number of Ge atom is equal to 2 [14].…”

“…The thermodynamic stabilization may be achieved by donation of electron density from substituents to a vacant orbital of the central atom (n-and p-donation as in Ge[N(SiMe 3 ) 2 ] 2 or Nheterocyclic germylenes (NHGe) [4a,b,c]), or by intra-or intermolecular interaction with electron donors (for example, this type of stabilization may be caused by using N-heterocyclic carbenes (NHC) [4d,e] or b-diketiminate [5], amidinate [6], aminotroponimine [7] ligands). However application of tridentate ligands for the synthesis of stabilized germylenes is very rare [8,9]. It is evident that stabilization of Ge(II) centers with dialkanolamine dianions (RN(CH 2 CH 2 O À ) 2 ) as ligands is achieved by all these ways.…”

Germylenes derived from pyridine-containing diols: reactions with diphenylphosphoryl azide and 9,10-phenanthrenequinone*

“…The bond in the N→Ge-O(4) fragment should be considered as a three-centered four-electron interaction, which is supported by the lengthening of the Ge-O(4) bond in comparison with the Ge-O(3) bond. The Ge←N bond in the spirocycle 4 is shorter than the analogous bond in germylene 1 (2.110(1) Å), studied in our previous work [9]. Thus, the strength of the hypervalent interaction may exceed the strength of a classical Ge←N donor-acceptor bond found in germylenes due to donation of the nitrogen atom lone electron pair to the vacant p-orbital of the germanium atom.…”

“…The elemental analysis data were obtained on a Vario Micro Cube CHN analyzer. Germylenes 1 and 2 were prepared according to procedures described in literature [9].…”

“…We have recently showed that pyridine-containing diols are efficient ligands for the synthesis of stable germylenes and stannylenes [9] also found to undergo facile oxidation by bromine to give the corresponding germanium(4+) dibromides [9]. In a continuation of this investigation, we carried out the reaction of germylene 1 with diphenylphosphoryl azide and germylene 2 with 9,10-phenanthrenequinone.…”