Potassium naphthalenide

Perhaps because of inadequate or non-existent back-bonding (p. 923), the only neutral, binary carbonyl so far reported is Ti(CO)g which has been produced by condensation of titanium metal vapour with CO in a matrix of inert gases at 10-15 K, and identified spectroscopically. By contrast, if MCI4 (M = Ti, Zr) in dimethoxy-ethane is reduced with potassium naphthalenide in the presence of a crown ether (to complex the K+) under an atmosphere of CO, [M(CO)g] salts are produced. These not only involve the metals in the exceptionally low formal oxidation state of —2 but are thermally stable up to 200 and 130°C respectively. However, the majority of their carbonyl compounds are stabilized by n-bonded ligands, usually cyclopentadienyl, as in [M(/j5-C5H5)2(CO)2] (Fig. 21.8). 

A solution of potassium naphthalenide is prepared from 2.0 g (50 mmol) of potassium and 6.4 g (50 mmol) of naphthalene in 40 mL ofTHF. After 1 h at r.t. this mixture is diluted with 10 mL of diethyl ether and 10 mL of petroleum ether (bp 40-60 °C) and cooled to — 120 °C. 4.5 g (25 mmol) of ( )-l-methoxy-3-phenylthio-1-propcne arc added followed by 3.36 g (25 mmol) of chlorobis(l-dimethylamino)borane. This mixture is allowed to warm to r.t. over 3 h the solvents are removed in vacuo and the residue is carefully distilled through a 5-cm column at 10 2 Torr. The distillate, containing also naphthalene, is dissolved in 30 mL of diethyl ether and treated with 2.95 g (25 mmol) of pinacol for 3 h. The crude product is chromatographed over 30 g of basic alumina (activity 1) using petroleum ether (bp 40 -60°C) giving 9.2 g of a mixture of product and naphthalene the yield of product (89% E) is determined to be 60% by H-NMR analysis. Similarly prepared is ... 

Reduction of Ni11 chloride complexes [NiCl2(L)] (L = various diphosphinomethanes, -ethanes, and -propanes) with, for example, potassium naphthalenide in THF gives the corresponding Ni1 chlorides [NiCl(L)].2368 By treatment of (963) with LiNHAr, a terminal amido complex of Ni1 (964) was prepared (Scheme 13).2369 It contains planar three-coordinate nickel and a planar amido ligand with d(Ni—N) = 1.881(2) A. The P,Ni,P and C,N,H planes are orthogonal with a 91° dihedral angle. 

Reaction of dichloro(pentamethylcyclopentadienyl)silane with lithium, sodium or potassium naphthalenide gives a mixture of elemental silicon, the corresponding alkali metal pentamethylcyclopentadienide and decamethylsilicocene (82) (equation 64)181. Compound 82 is formed as the only product in the reduction of dibromo-bis(pentamethylcyclopentadienyl)silane with potassium anthracenide (equation 65)182. 

Treatment of Sn2(CH2Bu-f)6 with potassium naphthalenide in THF at 25 °C afforded crystalline K[Sn(CH2Bu-f)3](THF)2 which in toluene gave K[Sn(CHiBu-r)3](r/6-CgHsMeA (equation 36)50. The X-ray structure of the latter revealed that potassium is in a distorted tetrahedral environment with a K—Sn bond length of 3.55 A (See Section IV). 

Of this latter point, we have utilized combined GC/MS to analyze solutions of alkali metal naphthalenide in THF (90 mM metal, 40 mM naphthalene, 25 ml THF) quenched with D2O, so that we may determine the stability of the reactant system itself on a time scale of 100 hours. The predominant product, other than naphthalene itself, for both sodium and potassium naphthalenide quenches was 1-ethyl 1-protio, 4-deutero 4-protio naphthalene (3) (and/or the 1,1 2,2 isomer (4)) rather than the expected 1-deuteFo 1-protio, 4-deutero 4-protio "naphthalene (5). 

Of course, not only the substituents but also mineral matter can react directly with potassium naphthalenide. 

Treatment of the yttrium(III) adduct 60 with potassium naphthalenide in dme-diethyl ether mixture results in deprotonation of the C4 carbon and migration to afford the abnormal carbene complex 63 (Fig. 13).72 The C2 binding carbon migrates from the yttrium(III) centre to the incorporated potassium(I) cation. The C4 carbanion forms a short bond with the yttrium(III) centre in the solid state (2.447(2) A) and exhibits a large jYc coupling constant of 62 Hz in solution. Complex 63 may be quenched with a variety of electrophiles. For example, reaction with Me3SiCl silylates the NHC backbone to afford 64. 

A green compound produced by interaction of TiCl2 and CpNa, hydrogenolysis of Cp2TiMe2, or reductions of Cp2TiCl2 has been much studied and is believed to have the structure 17-A-XV, while a more reactive form obtained by reduction of Cp2TiCl2 with potassium naphthalenide has been shown to be 17-A-XVI. 

Ellis and coworkers have extensively studied the chemistry of hexacarbonyltitanate(2-), [Ti(CO)6] . Reductive car-bonylation see Reductive Carbonylation) of Ti(CO)4 (trmpe) with (cryptand 2,2,2)potassium naphthalenide at -70 °C followed by warming to room temperature gives the thermally robust [K(cryptand 2.2.2)]2[Ti(CO)6] in quantitative yield. Treatment of Ti(CO)6 with azobenzene gives [Ti(PhN=NPh)(CO)4] (equation 3) in 40-65% yield. Hydrolysis of [Ti(PhN=NPh)(CO)4] " gives 1,2-diphenyUiydrazine and the hydroxo-carbonyl titanium complex, [Ti2(/x-OH)2(CO)8] (equation 3), which was strac-turally characterized as the [K(18-crown-6)]+ salt. ... 

Another route to bis( -arene)vanadium(0) compounds is the cocondensation of arenes with vaporized vanadium metal (see Metal Vapor Synthesis of Transition Metal Compounds) On treatment with 1,3-cyclohexadiene and butyllithium, 15-electron vanadocene (5) is converted to 16-electron ( -benzene)( -cyclopentadienyl)vanadium(l) (6) (Scheme 3). Use of potassium naphthalenide affords the corresponding naphthalene complex. 

Active copper powder. A highly reactive copper powder can be prepared by reduction of Cut with potassium naphthalenide in DME (8 hours). The slurry should be used immediately. It is particularly effective for Ullmann reactions high yields of biaryls are obtained even at 85°. It also promotes cross-coupling with allyl halides. ... 

Potassium naphthalenide, 122, 431 Potassium permanganate, 360, 388-391 Potassium ruthenate, 391 Potassium selenophenolate, 433... 

Dechlorination. Polychlorinated biphenyl (PCB) can be completely dechlorinated by sodium naphthalenide about 0.5 equiv. are required per chlorine atom since biphenyl itself forms a radical anion with sodium. Potassium naphthalenide is more effective but less economical. The resulting dechlorinated products (mol. wt. 400-600) can be burned safely for disposal. 

The Potassium complex of I8-Crown-6 or Potassium Naph-thalenide effects ring-opening to give acetates or their alkylated derivatives in good yield (eq 3). Treatment of the reaction mixture obtained from p-methyl-p-propiolactone and potassium-18-crown-6 with hydrochloric acid or alkyl halides gives the acetate (S) or its alkylated derivative (6), respectively. The a,3-unsaturated carboxylic acid (7) or its ester (8) is formed by the action of the potassium naphthalenide-18-crown-6 complex. ... 

Potassium metal, which is a powerTuI reducing agent, reacts with naphthalene lo give potassium naphthalenide, another powerful reducing agent, which has the advantage... 

The use of the 1-naphthylmethyl moiety as a P—H protecting group in the synthesis of a phosphino macrocycle has been described the protecting group is removed from the phosphine sulfide by treatment with excess potassium naphthalenide (equation 21). ... 

Reactions of r-l-chloro-l-methyl-t-2-phenylcyclopropane (114-Cl) and r-l-chloro-1-methyl-c-2-phenylcyclopropane (115-Cl) as well as of 114-Br and 115-Br with lithium, sodium and potassium naphthalenide (MN), respectively, demonstrate that neither the... 

SET reduction of dibenzonorcaradiene (147) with lithium, sodium or potassium naphthalenide followed by quenching with water led to 9-methylphenanthrene (148) (16-24%), 9-methyl-9,10-dihydrophenanthrene (149) (33-43 %) and 6,7-dihydro-5-if-dibenzo[a,c]cycloheptane (150) (23-34%). ... 

Dumbbell copolymers were also synthesized by Frechet et al.165 A difunctional PS living chain, prepared in THF using potassium naphthalenide as initiator, was end-capped with DPE and subsequently reacted with a fourth-generation dendrimer having a bromomethyl group at its converging point (Scheme 78). 

V(NPh2)4 and V(PhNCH2CH2NPh)2 have been prepared from VCl4,2THF and the appropriate potassium salts. The tetra-amide is reduced to K[V "(NPh2)4] by potassium naphthalenide (see also p. 47). 

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