Carbonylmetallate ligand

Nowadays we look with other eyes at organometallic compounds the family of which has expanded enormously. Some members of this family are soluble in water due to their ionic nature the legions of anionic carbonylmetallates (e.g. [Ni(CN)(CO)3] ) and cationic bisphosphine Rh-chelate complexes (e.g. [Rh(BDPP)(COD)] ) just come to mind. Others obtain their solubility in water from the well soluble ligands they contain these can be ionic (sulfonate, carboxylate, phosphonate, ammonium, phosphonium etc. derivatives) or neutral, such as the ligands with polyoxyethylene chains or with a modified urotropin structure. 

The trinuclear complex trans-Pt[Mo(CO)3( /5-C5H5)]2(PhCN)2 is prepared by the reaction of two equivalents of sodium carbonylmetallate with the square planar platinum(II) complex PtCl2(PhCN)2.3 Both cis and trans isomers afford the trans trinuclear chain complex. The lability of the benzonitrile ligand in the latter can be used advantageously for cluster synthesis this will be described in the next section. 

At first glance, all of the photochemical processes in Eqs. (8)-(10) are unique, with none showing any apparent stoichiometric relationship to the others. For example, the carbonylcobalt dimerization [Eq. (8)] and disproportionation [Eq. (9)] represent 1-electron oxidation processes of Co(CO)4 , whereas the formation of Co(CO)3L in Eq. (10) relates to a nonredox ligand substitution. The incorporation of the additive L into the carbonylmetal product, whether it be Co2(CO)6L2, Co(CO)3L2+, or Co(CO)3L in Eqs. (8), (9), and (10), respectively, is the sole feature that these photochemical processes have in common. Because the carbonylmetallates Co(CO)4 , V(CO)6-, and Mn(CO)5 are all thermally substitution-stable anions (52), the introduction of L into the carbonylmetallate moiety must occur in some reactive intermediate. 

Trimetallic complexes with two identical cr,7r-bridging ring ligands having different ring sizes and numbers of tt attachments have been studied. The complexes with two bridging cyclohexadienyl (19a), cyclohepta-dienyl (19b), and cycloheptatrienyl (19c-f) ligands were synthesized by the nucleophilic addition reactions of dianionic carbonylmetallates, [M(C0)4]- (M = Os, Ru), and two equivalents of the appropriate cationic-metal allyl substrates (82). 

By the reaction with carbonylmetalate complex anions, the di- or trisubstituted cyclopropenylium ions 1 afforded the t/ -oxocyclobutenyl complexes 2 by way of ring opening and carbonyl insertion.The structure of the cobalt complex 2 (M = Co, = Ph, n = 4) was determined by X-ray crystallography." Cobalt complexes 2 (M = Co) were also prepared in good yields from 2,3-disubstituted cycloprop-2-enecarbonyl chlorides and various sodium tricarbonyl(ligand)cobaltates." ... 

Nucleophilic attack on coordinated unsaturated hydrocarbons is one of the fundamental and particularly well studied reactions in Organometallic Chemistry. The addition of carbonylme-tallates instead of common nucleophiles provides a directed synthesis of hydrocarbon bridged complexes. Carbonylmetallates (particularly Re(CO)5", Os(CO)4 ") add to 7C-bonded olefin, acetylene, allyl, diene, trimethylenemethane, dienyl, benzene, triene and cycloheptatrienyl ligands in cationic complexes and give hydrocarbon bridged bi- and trimetallic, homo- or he-teronuclear complexes [1]. 

On the basis of these data as well as the data of wide spectroscopy investigations Beletskaya and coworkers suggested that the synthesis of carbonylmetalates of REM by the metathesis, transmetallation or redox reactions includes at the first stage the formation of a compound with a direct Ln-M bond. When the compounds are in solution the graduate insertion of one of the CO ligands into the Ln-M bond takes place [73] 0-C... 

---