Reaction of benzyltriphenylphosphonium bicyclo[2.2.1]hepta-2,5-diene-carbonyltrichlororuthenate(<scp>II</scp>) with Lewis bases

A detailed investigation of the reactions of the salt [Ph3(PhCH2)P][RuCl3(CO)(C7H8)](I; C7H8= bicyclo[2.2.1]-hepta-2,5-diene) with ligands (L) containing Group VB or VIB donor atoms is presented. Several different types of behaviour are found, depending on both the nature and amount of added L. For L = Me2S, Me2SO, and CH2CH–CN, the salts[Ph3(PhCH2)P][RuCl3(CO)L2], (II), have been isolated in high yield, whereas for L = AsPh3. SbPh3, and C5H5N, a mixture of (II) and [RuCl2(CO)L(C7H8)], (III), have been obtained [(I) : L = 1 :2 molar ratio]. Reaction of complex (I) with excess of SbPh3 gives (II), (III), and [RuCl2(CO)(SbPh3)3], (IV). In contrast, reaction of complex (I) with PPh3(1 :2 molar ratio) gives [{RuCl2(CO)(PPh3)2}2], (V), whereas with PMe2Ph, only [RuCl2(PMe2Ph)2(C7H8)], (VI), is isolated. A similar complex of type (VI) is formed with PMePh2, together with some [RuCl2(CO)(PMePh2]3(IV), whilst with 2,2′-bipyridyl or 1,10-phenanthroline (L′), the complexes [{RuCl2(CO)(L′)}n], (VII), and [Ph3(PhCH2)P][RuC3CO(L′)], (II), are obtained. Reaction mechanisms consistent with this observed variation in product composition are tentatively proposed.