New ruthenium–tin clusters with bulky ligands. Crystal and molecular structures of [Ru2(CO)6(µ-SnR2)(µ-Ph2PCH2PPh2)], [Ru3(CO)9(µ-SnR′2)3], [Ru3(CO)9(µ-SnR2)(µ-SnR′2)2] and [Ru3(CO)9(µ-SnR2)2(µ-SnR′2)][R = CH(SiMe3)2, R′= C6H2Pri3-2,4,6]
Abstract
The first heterometallic clusters containing the SnR′2(R′= 2,4,6-triisopropylphenyl) moiety have been prepared. Triruthenium dodecacarbonyl reacted at low temperatures with SnR′2 or, at higher temperatures, with its trimer (SnR′2)3 to give both [Ru3(CO)10(µ-SnR′2)2]1 and [Ru3(CO)9(µ-SnR′2)3]2. Reaction of the pentametallic species [Ru3(CO)10(µ-SnL2)2][L = R = CH(SiMe3)23 or R′] with SnR′2 or SnR2 respectively afforded the hexametallic clusters [Ru3(CO)9(µ-SnR2)(µ-SnR′2)2]4 and [Ru3(CO)9(µ-SnR2)2(µ-SnR′2)]5. In the reaction of [Ru3(CO)12] with SnR2 the hexametallic cluster [Ru3(CO)9(µ-SnR2)3]6 has now been isolated in addition to the previously reported Ru3Sn2 cluster. The trimer (SnR′2)3 also reacted with [Ru3(CO)10(dppm)](dppm = Ph2PCH2PPh2) to give [Ru3(CO)8(µ-SnR′2)2(dppm)]7, whereas with SnR2 the product was [Ru2(CO)6(µ-SnR2)(µ-dppm)]8. Compound 7 can also be obtained by the reaction of 2 with dppm, using sodium–benzophenone to activate the cluster. Reaction of the dodecacarbonyl with Sn[CH(PPh2)2]2 or its lead analogue surprisingly did not yield a mixed cluster, but afforded a rapid and quantitative route to [Ru3(CO)10(dppm)]. Compound 2 behaves similarly, yielding 7 again in high yield. The crystal and molecular structures of 2, 4, 5 and 8 have been determined. In compounds 2, 4 and 5, the ruthenium triangle and the three tin atoms form a planar array. A detailed comparison of ligand steric effects is made. In 8 the metal atoms and the two P atoms are coplanar, with a long Ru–Ru vector bridged by the R2Sn group and the diphosphine [2.954(2)Å]. The structure of 4 is unusual, the characteristic aryltin twist on only two of the three tin atoms generating chirality, resulting in a spiral packing in space group P65. This structure was determined both diffractometrically and using two different image-plate systems, and the results are remarkably consistent in all three cases.