Zink‐Komplexe von Tris(2‐pyridyl)phosphan und Tris(2‐pyridyl)arsan

Zinc Complexes of Tris(2‐pyridyl)phosphane and Tris(2‐pyridyl)arsane Reactions of zinc salts with the two title ligands are described which reveal several dissimilarities in their coordination behavior. From tris(2‐pyridyl)phosphane (1) and the zinc halides compounds with an L2Zn3 stoichiometry are isolated which, according to their Raman spectra, have the constitution [LZnHal]2[ZnHal4]. With tris(2‐pyridyl)arsane (2) the zinc halides form the 1:1 complexes LZnHal2. With Zn(SCN)2 and 1 only the L2Zn2+ species can be observed, while 2 produces the molecular complex LZn(SCN)2. Both 1 and 2 form a neutral 1:1 compound with Zn(NO3)2 which was shown for 1 · Zn(NO3)2 by an X‐ray structure analysis to consist in the solid state of octahedral complexes containing tridentate 1 and both monodentate and bidentate NO3‐. According to NMR spectroscopy this constitution seems to be maintained in solution. While the complexes 1 · ZnHal2 are insoluble, the complexes 2 · ZnHal2 and 2 · Zn(NO3)2 can be shown by NMR to undergo an equilibration in solution involving the LZn2+ and L2Zn2+ species of which only the LZn2+ species crystallizes as LZnX2. The zinc salts Zn(ClO4)2 and Zn(BF4)2 with noncoordinating anions react with 1 and 2 to form exclusively the L2Zn2+ complexes whose highly symmetrical octahedral geometry was ascertained for (1)2Zn(ClO4)2 by an X‐ray structure analysis.