The conversion of tin chloride reagents into the corresponding hydroxides typically results in the formation of oligomeric tin oxides. [1][2][3] We report herein the preparation and reactivity of a trinuclear nickel cluster that is capped by a m 3 -Sn(OH) 3 group. This is a rare example of a complex that contains an intact trihydroxy tin group, thus allowing the study of the chemistry of tin hydroxides without interference from competing reactions that form oligomeric tin oxides.
The trichlorostannyl-capped cluster [Ni 3 (m-dppm) 3 (m 3 -Cl) (m 3 -Sn(Cl) 3 ] (1; dppm = bis(diphenylphosphino)methane) is a dark-green diamagnetic species, the 31 P{ 1 H} NMR spectrum of which displays a singlet at d = À2.3 ppm that is flanked by satellites arising from coupling to the trichlorostannyl group ( 2 J ( 31 P-119 Sn, 117 Sn) = 138 Hz (unresolved)). The properties of cluster 1 are similar to the closely related m-iodo-capped cluster that was reported recently. [4] The molecular structure of the trichlorostannyl-capped cluster 1 is presented in Figure 1. The three chlorine atoms of the m 3 -SnCl 3 are staggered with respect to the three nickel atoms, resulting in an approximately octahedral coordination environment at the tin atom and approximate C 3v symmetry for the cluster. Cluster 1 may be converted into the trihydroxystannylcapped cluster [Ni 3 (m-dppm) 3 (m 3 -Cl)(m 3 -Sn(OH) 3 ] (2) in high yield by treatment with in situ hydrolyzed NaH in a CH 2 Cl 2 / THF solvent mixture [Eq. (1)]. Use of NaH provides higher yields than direct use of NaOH, most likely because the NaH powder gives more highly dispersed NaOH than the poorly soluble NaOH pellets.