Osmium alkylations

Alkylations, osmium(ll), 37 348 Alkyl azides, UV spectra, 26 178 Alkylbarium halides, solvated, 11 390 Alkylbery Ilium alkoxides, 11 395 alkylperoxides, 11 395 amides, 11 401 03 anions, 11 369-370 crystal structure of, 11 369 halides, solvated, 11 389 hydrides, 11 371-373 B-Alkylborolane, 16 241... 

Reduction of alkyl osmium complex 160 with NaBH4 or NaBD4 gives the methyl hydrido and methyl deutero osmium complexes 169. Treatment of 169 with trityl cation gives the metallaheterocycle 170. This reaction probably occurs via cationic intermediates 171 and 172. The coordinatively unsaturated 172 then undergoes an intramolecular oxidative addition with... 

Osmacycle (48) arises from an alkyl osmium compound by a complex thermal rearrangement which has been studied in detail (Equation (19)) <86JAI346, 90JA704). A phosphonium-platinacyclopropane arises by intramolecular addition to an alkene (Equation (20)) <90OMl2ll>. Metallacycles are also available by addition of a sulfoxonium ylide to a metal-phosphorus double bond (Equation (21)) <90CB739>. 

Organometallic chemistry of pyrrole is characterized by a delicate balance of the ti N)- and -coordination modes. Azacymantrene is an illustration of the considerable nucleophilicity of the heteroatom. However, azaferrocene can be alkylated at C2 and C3 sites. Ruthenium and osmium, rhodium, and iridium chemistry revealed the bridging function of pyrroles, including zwitterionic and pyrrolyne complex formation. The ti (CC) coordination of osmium(2- -) allows versatile derivatizations of the heteroring. 

The osmium(VI) complexes 0s02X2(PR3)2 are not generally obtainable with the smaller alkyl and alkyl(aryl)phosphines, which tend to be good... 

Ruthenium and osmium form some remarkably stable alkyls and aryls compounds, often in unusually high oxidation states. 

B. Ruthenium and Osmium o-Bonded Alkyl and Aryl Complexes. 266... 

Diazoalkanes are u.seful is precursors to ruthenium and osmium alkylidene porphyrin complexes, and have also been investigated in iron porphyrin chemistry. In an attempt to prepare iron porphyrin carbene complexes containing an oxygen atom on the /(-carbon atom of the carbene, the reaction of the diazoketone PhC(0)C(Ni)CH3 with Fe(TpCIPP) was undertaken. A low spin, diamagnetic carbene complex formulated as Fe(TpCIPP)(=C(CH3)C(0)Ph) was identified by U V-visible and fI NMR spectroscopy and elemental analysis. Addition of CF3CO2H to this rapidly produced the protonated N-alkyl porphyrin, and Bit oxidation in the presence of sodium dithionitc gave the iron(II) N-alkyl porphyrin, both reactions evidence for Fe-to-N migration processes. ... 

The first ruthenium porphyrin alkyls to be reported were prepared from the zerovalent dianion, [Ru(Por)] with iodomethane or iodocthane, giving the ruthe-nium(lV) dialkyl complexes Ru(Por)Me2 or Ru(Por)Et2 (Por = OEP, TTP). Alternatively, the Ru(lV) precursors Ru(Por)X2 react with MeLi or ArLi to produce Ru(Por)Mc2 or Ru(Por)Ar2 (Ar = / -C(,H4X where X = H, Me, OMe, F or Cl) 147-149 The osmium analogues can be prepared by both methods, and Os(Por)R2 where R = Me, Ph and CH2SiMe2 have been reported.Some representative structures are shown in Fig. 5, and the preparation and interconversion of ruthenium porphyrin alkyl and aryl complexes are shown in Scheme 10. 

Non-ionic thiourea derivatives have been used as ligands for metal complexes [63,64] as well as anionic thioureas and, in both cases, coordination in metal clusters has also been described [65,66]. Examples of mononuclear complexes of simple alkyl- or aryl-substituted thiourea monoanions, containing N,S-chelating ligands (Scheme 11), have been reported for rhodium(III) [67,68], iridium and many other transition metals, such as chromium(III), technetium(III), rhenium(V), aluminium, ruthenium, osmium, platinum [69] and palladium [70]. Many complexes with N,S-chelating monothioureas were prepared with two triphenylphosphines as substituents. 

Osmium tetroxide used in combination with sodium periodate can also effect alkene cleavage.191 Successful oxidative cleavage of double bonds using ruthenium tetroxide and sodium periodate has also been reported.192 In these procedures the osmium or ruthenium can be used in substoichiometric amounts because the periodate reoxidizes the metal to the tetroxide state. Entries 1 to 4 in Scheme 12.18 are examples of these procedures. Entries 5 and 6 show reactions carried out in the course of multistep syntheses. The reaction in Entry 5 followed a 5-exo radical cyclization and served to excise an extraneous carbon. The reaction in Entry 6 followed introduction of the allyl group by enolate alkylation. The aldehyde group in the product was used to introduce an amino group by reductive alkylation (see Section 5.3.1.2). 

The osmium hydroxycarbene complex 18 is formed in an acid-assisted migratory-insertion reaction of OsClEt(CO)2(PPh3)2. This alkyl compound results from reaction of the ethylene adduct 19 with one equivalent of acid 46). 

Homogeneous Processes with Tris-phenanthroline Metal(III) Oxidants. The rates of electron transfer for the oxidation of these organometal and alkyl radical donors (hereafter designated generically as RM and R, respectively, for convenience) by a series of tris-phenanthroline complexes ML33+ of iron(III), ruthe-nium(III), and osmium(III) will be considered initially, since they have been previously established by Sutin and others as outer-sphere oxidants (5). 

There is a rich chemistry of alkyl nitrido complexes of ruthenium(VI) and osmium(VI), which has been well documented. " ... 

Osmium tetroxide reacts with amines, undergoing partial substitution of NR2 (where R=alkyl group) with O to form compounds such as OsOs (NR) and OsO(NR)3. 

Alkylcadmium alkoxides, 11 399-400 alkylperoxides, 11 399-400 anions, 11 370-371 halides, 11 377 solvated, 11 392-394 Alkylcalcium halides, solvated, 11 390 Alkyl complexes, osmium, 37 239-242 Alkyl copper compounds, 17 140, 142, 143 Alkyl derivatives, phosphoniuilic halides and, 1 363... 

Bromoanions, irivalent uranium, 34 98-99 Bromo complexes, osmium, 37 297-299 Bromocuprates(I), 37 39 Bromocyclophosphazene alkyl and aryl derivatives, 21 43 synthesis, 21 43, 44... 

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