Nickel complexes cyclopentadienyls

TC-Cyclopentadienyl Nickel Complexes. Nickel bromide dimethoxyethane [29823-39-9] forms bis(cydopentadienyl)nickel [1271 -28-9] upon reaction with sodium cyclopentadienide (63). This complex, known as nickelocene, 7T-(C3H3)2Ni, is an emerald-green crystalline sandwich compound, mp 173°C, density 1.47 g/cm. It is paramagnetic and slowly oxidi2es in air. A number of derivatives of nickelocene are known, eg, methylnickelocene [1292-95-4], which is green and has mp 37°C, and bis( 7t-indenyl)nickel [52409-46-8], which is red, mp 150°C (87,88). 

Substituted derivatives of nickelocene, where one ring has been replaced, include the complex cyclopentadienyl nitrosyl nickel [12071 -73-7], (7T-C3H3)NiNO, a red Hquid, mp -41°C. A review of nitrosyl complexes with nickel is available (89). The dimer complex... 

Cyclopentadienyl (Cp) ligands, 16 79 Cyclopentadienylmetal complexes, 16 79 re-Cyclopentadienyl nickel complexes,... 

Pictrography 3000 system, 19 318 Pictrography 4000 system, 19 318 Pietro Proof digital color proofer, 19 320 Pictrostat 300 (PS300) system, 19 318 Pictrostat Digital 400 system, 19 318, 319 7i-cyclopentadienyl nickel complexes,... 

CjHjS, Thiophene, tetrahydro-gold complexes, 26 85-87 C4H,NO, 2-Propenamide, 2-methyl-nickel complex, 26 205 C4H1()02, Ethane, 1,2-dimethoxy-solvates of chromium, molybdenum, and tungsten carbonyl cyclopentadienyl complexes, 6 343 tungsten complex, 26 50 ytterbium complex, 26 22 C4H i02.NaC5H5, Ethane, 1,2-dimethoxy-compd. with cyclopentadienylsodium, 26 341... 

Cycloalkenes, into if-allyl palladium complexes, 8, 363 Cycloalkenyl rings, metal complex conformational interconversions, 1, 414 Cycloalkynes, in nickel complexes, 8, 147 (Cyclobutadiene)cyclopentadienyl complexes, with cobalt, polymercuration, 2, 435 Cyclobutadienes... 

Whether the nickel complexes formed from diorgano ditellurium derivatives and cyclopentadienyl(cyclopentadiene)nickel tetrafluoroborate in diethyl ether at 20° contain an intact diorgano ditellurium ligand or two tellurolato ligands is not known4. 

A second group of complexes that have received detailed attention are the (i73-allyl)nickel(i75-cyclopentadienyl) complexes, which may be prepared by reacting nickelocene with an allyl-Grignard reagent (69). Data for typical examples are shown in Table IX. In this particular case, a sufficiently large number of complexes have been studied that a series of chemical shift increments can be extracted from the data (shown in Table X) and have been used with considerable success in assigning structures to ij3-allyl nickel complexes of unknown structure. 

Figure 7-47 shows the molecular structure of the diphenylfosphinoferrocene-nickel complex [Fe(fy -C5H4PPh2)2]NiCl2 [150]. The nickel atom assumes an essentially tetrahedral coordination. The cyclopentadienyl rings of the ferrocene group are parallel and nearly eclipsed. 

The nickel complex, Ni ( 5115)2, has been made by the action of the Grignard reagent on nickel (II) acetylacetonate (217) or from potassium cyclopentadienyl and the ammine [Ni(NHs)el (S N)2 in liquid ammonia (58). It forms dark emerald-green crystals which sublime at 80-90° and which, when heated in nitrogen, melt, with decomposition and the formation of a nickel mirror, at 173-174°. It is only slowly oxidized in air, and cold water neither attacks nor dissolves it it is, however, readily soluble in organic liquids. Oxidation of the compound yields an orange-yellow solution containing the ion [Ni( 5H5)2]+, which is stable for a short period in weakly acidic media, and which may be precipitated as the reineckate or tetraphenylborate. 

For the metal—alkyne fragmait, nonlinearity also increases upon increasing valence electron count [14 valence electron (triphenylphosphine) gold alkynyl compounds <18 valence electron (cyclopentadienyl) (triphenylphosphine)nickel, and (cyclopentadienyl) bis(triphenylphosphine) ruthenium alkynyl compounds] and increasing ease of oxidation (less easily oxidizable (cyclopentadienyl)(tri-phenylphosphine)nickel alkynyl complexes < more easily oxidizable (cyclopen-tadienyl)bis(triphenylphosphine)ruthenium alkynyl complexes). 

PO2WC2SH21, Tungsten, dicarbonyl(T) -cyclopentadienyl)hydrido(triphenyl-phosphine)-, 26 98, 28 7 PO3C3H, Trimethyl phosphite, cobalt and rhodium complexes, 28 283, 284 iron complexes, 26 61, 28 171, 29 158 nickel complex, 28 101 P03C,H,5, Triethyl phosphite, iron complexes, 26 61, 28 171, 29 159 nickel complexes, 28 101,104-106 P03C,H2, Isopropyl phosphite, nickel complex, 28 101... 

The cyclobutadienepalladium complexes (XXXVI) react with alcohols, usually in the presence of weak bases, to give cyclobutenylpalladium complexes (LXXXIV) isomeric with (XXXV) (see Section VI, F) these reactions are reversed on treatment of (LXXXIV) with hydrogen halides and constitute another preparation of the cyclobutadienepalladium complexes. A related reaction on (w-cyclopentadienyl)(7r-alkoxytetraphenyl-cyclobutenyl)palladium and -nickel complexes (XLIV) (64, 65) is also discussed in Section VI, F. The mechanism of this reaction is not established, but the initial step is probably protonation of the ether. 

Hexaazatricyclo[l 1.7.7.1 ]octacosa-l, 5,7,9(28X 12,14,19,21,26-nonaene,3,11-dibenzyl-14,20-dimethyl-2,12-diphenyl-, nickel complex, 27 277 CsoHgjF.gNgPa, 3,11,15,19,22,26-Hexaaza-tricydo[l 1.7.7.1 ]octacosa-l,5,7,9(28),12,14,19ai,26-nonaene, 3,11-dibenzyl-14,20-dimethyl-2,12-diphenyl-, tri [hexafluorophosphate(l —)], 27 278 CdCl2, Cadmium dichloride, 28 322 CeCl2Li02Si4C3oHjg, Cerium, bis[ -l,3-bis(trimethylsilyl)cyclopentadienyl]di-/i-chloro-bis(tetrahydrofuran thium-, 27 170... 

OjPCgHii, Phosphonous acid, phenyl-, dimethyl ester, nickel complex, 28 101 O2PWC25H21, Tungsten, dicarbonyl( f -cyclopentadienyl)hydrido(triphenylphos-phine)-, 26 98... 

The Group VIII cyclopentadienyl complexes of formula CpM(NO) (M = Ni, Pd, Pt) have all been synthesized. The nickel complex is best prepared from nickelocene and nitric oxide, and a method for the preparation of the nickelocene m situ without its isolation has been described (56). The palladium complex can be prepared from [Pd(NO)Cl] and sodium cyclopentadienide (23) and the platinum complex from Pt2(CO)2Cl4 and sodium cyclopentadienide and nitric oxide (22). The microwave (13) and infrared spectra (18) of CpNi(NO) have received detailed study, and the electronic structure of the complex is discussed in an early paper (77). 

A cyclopentadienyl nickel complex featuring a rare Si-Ni linkage has been prepared by reacting SiGp 2 with Ni(Gl)Gp(PPh3) the solution spectra and solid-state studies have identified the product as [GpNi /i r7 (Ni),77 (Si)-(Gp -Si(Gl)(77 -Gp )], 113. The solid-state structure of 113 shows an Ni-Si bond length of 220 pm and a fairly symmetrical interaction between Ni and the rf-Cp (ca. 204 pm). 

Nickel(n) cyclopentadienyl complexes [(ri -C5Ph5)Ni(S2CNMe2)] (1464) and [(T] -C5Me5)Ni(S2CNEt2)] (1547) have been prepared, the latter from an unusual reaction between [(T] -C5Me5)Ni(CO)] and Te(S2CNEt2)2 (Eq. 146) (1547). 

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