Hydroxo hydride complexes of iron and cobalt (Sn-Fe-Sn, Sn-Co-Sn): Probingagostic Sn center dot center dot center dot H-M interactions in solution and in the solid state

Bis(toluene)iron 9 reacts with Lappert's stannylene [Sn{CH(SiMe3)(2)}(2)] ( 4) to form the paramagnetic bis-stannylene complex [{(eta(6)-toluene)Fe-Sn- [CH(SiMe3)(2)](2)}(2)] (10). Compound 10 reacts with H2O to form the hydrox o hydride complex [(eta(6)-C7H8)(mu-OH)(H)-Fe-{Sn[CH(SiMe3)(2)](2)}(2)] (12 ) in high yield; its solid-state structure has been elucidated by X-ray and neutron diffraction analysis. In agreement with the H-1 NMR results, 12 co ntains a hydridic ligand whose exact coordination geometry could be determi ned by neutron diffraction. The H-1 and Sn-119 NMR analysis of 12 suggested a multicenter Sn/Sn/H/Fe bonding interaction in solution, based on signifi cantly large values of J(Sn,H,Fe) = 640 +/- 30 Hz and j(Sn-119, Sn-119) = 4 340 +/- 100 Hz. In solution, complex 12 exists as two diastereomers in a ra tio of about 2:1. Neutron diffraction analysis has characterized 12 as a cl assical metal hydride complex with very little Sn H interaction and a typic al Fe-H single bond (1.575(8) Angstrom). This conclusion is based on the fa ct that the values of the Sn H contact distances (2.482(9) and 2.499(9) Ang strom) are not consistent with strong Fe-H Sn interactions. This finding is discussed in relation to other compounds containing M-H;Sn units with and without strong three-center interactions. The neutron diffraction analysis of 12 represents the first determination of a Sn-H atomic distance employin g this analytical technique. The cobalt analogues [(eta(5)-Cp)(mu-OH)(H)Co- {Sn[CH(SiMe3)(2)](2)}(2)] (15) and [(eta(5)-Cp)(OD)(D)Co-{Sn[CH(SiMe3)(2)]( 2)}(2)] [D-2]15, which are isolobal with 12, were prepared by the reaction of [(eta(5)-Cp)Co-Sn{CH(SiMe3)(2)}(2)] (14) with H2O and D2O, respectively. The magnitude of J(Sn,H) (539 Hz) in 15 is in the same range as that found for 12, The molecular structure of 15 has been determined by X-ray diffrac tion which reveals it to be isostructural with 12. The coordination geometr ies of the Co(Fe)-Sn1-O-Sn2 arrangements in 12 and 15 are fully planar with in experimental error. Compounds 10 and 15 are rare examples of fully chara cterized complexes obtained as primary products from water activation react ions.