53152-36-6

Upstream product

• 15668-64-1 tetracarbonyl(2,2'-bipyridine)molybdenum 
• 2071-20-7 bis-diphenylphosphinomethane 
• 13939-06-5 molybdenum hexacarbonyl 

Relevant academic research and scientific papers

Organometallic chemistry in a conventional microwave oven: The facile synthesis of group 6 carbonyl complexes

Syntheses proceeding by reflux may be improved, accelerated and simplified, by carrying out the reaction in a modified conventional microwave oven. To demonstrate the potential of this method, the synthesis of over 20 group 6 organometallic compounds is reported. Hexacarbonyls, most notably Mo(CO)6, react with a range of mono, and bi, and tridentate ligands in a modified conventional microwave oven. They generally proceed without an inert atmosphere, yields are high and reaction times are short. For example, cis -[Mo(CO)4(dppe)] is prepared in >95% yield in 20 min. Reaction of Mo(CO)6 with dicyclopentadiene affords a simple one-step synthesis of [CpMo(CO)3]2 in >90% yield, which reacts further with alkynes in toluene to produce dimetallatetrahedrane derivatives, [Cp2Mo2(CO)4 (μ-RC2R)]; presumably via the in situ formation of air-sensitive [CpMo(CO)2]2. Dimolybdenum tetra-acetate is also prepared in 48% yield in 45 min, however, this reaction requires an inert atmosphere. While W(CO)6 reacts rapidly with amines to give cis diamine adducts in high yields, direct reactions with phosphines are not so clean. Bis(phosphine) complexes are, however, cleanly formed when a small amount of piperidine is added to the reaction mixture, presumably via the bis(piperidine) complex cis-[W(CO)4(pip)2]. Reactions with Cr(CO)6 generally require an inert atmosphere and proceed less cleanly, although the important synthon [Cr(CO)5 Cl][NEt4] was prepared in 30 min (74% yield), while [(η6-C6H5OMe)Cr(CO)3] can be prepared in 45% after 4 h.

Calorimetric studies of the heats of protonation of the metal in cis-M(CO)2(bidentate phosphine)2 complexes of chromium, molybdenum, and tungsten

Titration calorimetry has been used to determine the heats of protonation (ΔHHM) of cis-M(CO)2(L 'down curve sign' L)2 complexes (M = Cr, Mo, W; L 'down curve sign' L = dppm, dppe, dppp, arphos, dmpe) with CF3SO3H in 1,2-dichloroethane solvent at 25.0°C. Spectroscopic studies show that protonation occurs at the metal center to form [M(H)(CO)2(L 'down curve sign' L)2]CF3SO3 complexes with trans CO groups. For the M(CO)2[Ph2P(CH2)nPh 2]2 complexes, ΔHHM becomes less exothermic as the chelate size increases from n = 1 (-29.7 kcal mol-1) to n = 3 (-19.0 kcal mol-1) for Mo and from n = 1 (-31.5 kcal mol-1) to n = 2 (-25.1 kcal mol-1) for W. The higher basicities of complexes with small chelates are ascribed to distortions imposed on the M(CO)2(L 'down curve sign' L)2 complexes by the chelate ligand and to reduced steric hindrance in the protonated product. Substituting the dppe chelates in Mo(CO)2(dppe)2 (ΔHHM = -27.4 kcal mol-1) with dmpe increases metal basicity (ΔHHM = -38.7 kcal mol-1), and with the arphos ligand metal basicity is decreased (ΔHHM = -23.8 kcal mol-1). In descending group 6, the basicities (ΔHHM) of the M(CO)2(dppm)2 complexes increase in the order Cr (-25.5 kcal mol-1) ? Mo (-29.7 kcal mol-1) -1), but for the M(CO)2(dppe)2 complexes metal basicity decreases in the order Mo (-27.4 kcal mol-1) > W (-25.1 kcal mol-1). The group 8 complex, (η5-C5Me5)2Os (ΔHHM = -26.6 kcal mol-1), is substantially more basic than (η5-C5Me5)2Ru (ΔHHM = -19.0 kcal mol-1). The heats of protonation (ΔHHN) of a series of organonitrogen bases have also been determined.