Tethered silyl complexes from nucleophilic substitution reactions at the Si–Cl bond of the chloro(diphenyl)silyl ligand in Ru(SiClPh2)(κ2-S2CNMe2)(CO)(PPh3)2

Crystal structure determination of RuH(κ2-S2CNMe2)(CO)(PPh3)2 (1) confirms that the triphenylphosphine ligands are arranged mutually trans. 1 reacts readily with HSiClPh2 to eliminate H2 and produce the six-coordinate silyl complex, Ru(SiClPh2)(κ2-S2CNMe2)(CO)(PPh3)2 (2). Crystal structure determination of 2 reveals the same geometrical arrangement of ligands as in 1 with the silyl ligand replacing the hydride ligand. The chloride bound to silicon in 2 is replaced through reactions with 2-hydroxypyridine, 2-aminopyridine, and thallium acetate, producing, respectively, the mono-PPh3 complexes, Ru(κ2(Si,N)-SiPh2OC5H4N)(κ2-S2CNMe2)(CO)(PPh3) (3), Ru(κ2(Si,N)-SiPh2NHC5H4N)(κ2-S2CNMe2)(CO)(PPh3) (4), and Ru(κ2(Si,O)-SiPh2OCMeO)(κ2-S2CNMe2)(CO)(PPh3) (5). Crystal structure determinations of 3, 4, and 5 confirm that in each case there is formation of a five-membered chelate ring tethering the silyl ligand to ruthenium. In the formation of 3, 4, and 5 the Si-ligand and the two S atoms of the dimethyldithiocarbamate ligand remain meridional but the remaining triphenylphosphine ligand and the carbonyl ligand are interchanged in position leaving the donor atom of the tether trans to the CO ligand. An alternative way of considering the tethered silyl ligands in 3, 4, and 5 is as tethered, base-stabilised, silylene ligands and the structural data give some support for a contribution from this bonding model.