Übergangsmetall‐Stannyl‐Komplexe, 31) Metall, Wasserstoff, Zinn‐Dreizentrenbindung bei Hydrido‐Stannyl‐Komplexen der 6. Nebengruppe

Transition‐Metal Stannyl Complexes, 3. – Metal, Hydrogen, Tin Three‐Center Bonding in Group VI Hydrido Stannyl Complexes The hydrido stannyl complex (π‐1,3,5‐Me 3 C 6 H 3 )(CO) 2 Cr(H)‐SnPh 3 ( 1 ) is prepared by photochemical reaction of (π‐1,3,5‐Me 3 C 6 H 3 )(CO) 3 Cr with HSnPh 3 . The 119 SnHCr coupling constant (327.6 Hz) and an X‐ray structure analysis [Sn – H 202(4), Cr – H 159(4), Cr – Sn 270.16(6) pm] show that the Sn – H bond is coordinated in an η 2 fashion. The complexes (CO) 4 (R 3 P)‐W(H)SnPh 3 (R 3 PPh 3 P, MePh 2 P) ( 2 ) and (CO) 3 (dppe)M(H)‐SnR 3 (MCr, SnR 3 =SnPh 3 ; MMo, SnR 3 =SnMe 3 , SnPh 3 ; MW, SnR 3 =SnMe 3 , SnPh 2 Me, SnPh 3 ) ( 4 – 6 ) are obtained either by thermal reaction of (CO) 4 (R 3 P)W(THF) or (CO) 3 (dppe)ML (LTHF, acetone) with HSiR 3 , or by photochemical reaction of (CO) 4 (dppe)M with HSnPh 3 . Reaction of (CO) 4 (Ph 3 P)W(THF) with HSnMe 3 yields (CO) 4 (Ph 3 P)W(Sn‐Me 3 ) 2 ( 3 ). The Sn,M,H coupling constants in the complexes 2 and (CO) 3 (dppe)M(H)SnR 3 (MCr, Mo) are in the range of 250 – 315 Hz and therefore these complexes seem to contain an η 2 ‐coordinated stannane. Contrary to this, the SnWH coupling constants in (CO) 3 (dppe)W(H)SnR 3 are considerably lower (70 – 90 Hz), suggesting complete oxidative addition of the H – Sn bond. The complexes (CO) 3 (dppe)M(H)SnPh 3 decompose in benzene solution at room temperature to give, inter alia, hexaphenyldistannane. Ph 6 Sn 2 · 2 C 6 H 6 crystallizes in the space group \documentclass{article}\pagestyle{empty}\begin{document}$ R\bar 3 $\end{document} ( Z =1); in the crystal lattice the benzene molecules are perpendicular to the three‐fold axis of symmetry of the distannane molecule.