Isocyanide insertion reaction in alkylcomplexes of iron: A dihaptoiminoacyl derivative of iron (II) (original) (raw)
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Organometallics, 1985
The He I and X-ray photoelectron spectra of the iron tetracarbonyl complexes of methyl, tert-butyl, trimethylsilyl, and phenyl isocyanide have been obtained. The bonding properties of these isocyanides are compared with those of carbon monoxide by using the core-binding energy data to interpret the valence ionization energies. The data show that all the isocyanides have comparable a-donor ability and that, in the Fe(C0I4CNR complexes, they are significantly weaker u donors than carbon monoxide. The stronger u-donor character of the coordinated CO ligands is presumably due to the u-a synergism of the Fe-CO bonding. The net interaction of an isocyanide ligand with the iron d orbitals leaves the energy of the d orbitals destabilized relative to Fe(C0)5. The data indicate that the relative energies of interaction of the d orbitals with the filled ligand a orbitals and the empty ligand a* orbitals are different in Fe-CO and Fe-CNR bonds, with the interactions of the filled ligand a orbitals being relatively more important in Fe-CNR bonds than in Fe-CO bonds. The net electron withdrawal by a coordinated isocyanide ligand, although significant, is much lower than that by a coordinated carbonyl ligand. It is clear that the interactions of transition metals with isocyanides (and probably also with other ligands with similar electronic structures) cannot be adequately described without considering the combined a-donor, a-acceptor, and a-donor characters of the ligands. '-tris(trimethylene)ferrocene, 111, with n-butyllithium (n-BuLi) and N,N,N',N'-tetramethylethylenediamine (TMEDA) or potassium tert-butoxide (KO-t-Bu) gave metal derivatives which were converted to the corresponding mono-and dicarboxylic acids and their methyl esters and in the case of I11 to the 3,3'-dibromo derivative. With a few modifications due to the peculiarities of the individual compounds, the explanation for the selectivity of the metalation reactions is essentially that given2 for the metalation of 1,l'-trimethyleneferrocene, IV. The crystal structure of the dibromide was determined.
Organometallics, 1993
The series of complexes Fe(CNR)&-Pr-a-diimine) (4: R = 2,6-xylyl (a), t-Bu (b), c-Hex (c)) has been prepared by starting from Fe(a-diimine)p and isocyanides. NMR measurements indicate a dynamic process which scrambles the three isocyanide ligands and interchanges the a-diimine halves. IR revealed that the complex Fe(t-BuNC)&Pr-a-diimine) (4b) exists in two distinct isomeric forms, visible not only at 147 K but also at 293 K. The relative amounts of the two isomers depend on the temperature. Reaction of Fe(CNR)3(i-Pr-a-diimine) with dimethyl acetylenedicarboxylate gives two types of products, depending on the type of isocyanide used. For the aromatic isocyanide, a ferra 12.2.21 bicyclic complex (7a) is formed via 1,3-dipolar cycloaddition to the Fe-N=C unit, followed by isocyanide insertion. 1,4,3a,6a-Tetrahydropyrrolo[3,2-b]pyrrole complexes (lOb,c) are formed with aliphatic isocyanides, as the result of two successive cycloadditions of alkyne to both Fe-N-C units. The single-crystal X-ray structure of Fe(t-BuNC)3(tetrahydropyrrol0[3,2-b] pyrrole) (lob; FeC35H55N508, triclinic, space group Pi, a = 10.292 (2) A, b = 10.915 (2) A, c = 18.833 (3) A, = 79.81 ( 1 ) O , ,b = 77.75 (U0, y = 80.23 (2)", 2 = 2, R = 0.081,RW = 0.089) shows that the Fe(t-BuNC)B moiety is q3-coordinated to one of the pyrrole rings. In the presence of water, the r2.2.21 bicyclic complex 7a was found to undergo a cyclometalation reaction with one of the ester groups to form the tricyclic complex 8a. The molecular structure of Fe(2,6-xylylNC)3(tric) (8a) consists of three five-membered rings, with the metal incorporated in two of them. (5) (a) Friihauf, H.-W.; Seils, F.; Goddard, R. J.; RomHo, M.
Organometallics, 1993
In the reaction of Fe(CNR)&-Pr-a-diimine) (6; R = 2,6-xylyl (a), t-Bu (b), c-Hex (c)) with dimethyl maleate, two totally different pathways are followed, depending on the type of isocyanide used. With the aromatic isocyanide, a l,&dipolar cycloaddition of the alkene to the Fe-N=C unit occurs followed by an isocyanide insertion, forming a ferra [2.2.21 bicyclic compound (7a). When this mixture is warmed above room temperature, the reaction is reversed, disassembling 7a into its starting components. During this facile retro-cycloaddition, C-C, C-N, and Fe-C bonds are broken. Also, the first unambiguous example of an isocyanide deinsertion is encountered. The starting complexes 6b,c, with aliphatic isocyanides, react with dimethyl maleate to give two products. The first, a purely organic product (8), is a dimer of two coupled alkenes. The second product is the organometallic tricyclic complex Fe(CNR)&ric) (9b,c), in which two alkenes are coupled and bonded to the metal and the a-diimine ligand. In the cyclization reaction, a y-lactam ring is formed and a methoxy group of one of the four ester groups is removed, with formation of methanol. The molecular structure of the 12.2.21 bicyclic complex 7a (FeCmHmNeOr, triclinic, space group Pi, a = 10.367 (1) A, b = 14.615 (3) A, c = 15.787 (2) A, a = 95.78 (2)", / 3 = 96.62 ( 1 ) O , y = 92.21 ( 1 ) O , 2 = 2, R = 0.053, R, = 0.055) consists of three six-membered rings with the metal in a bridgehead position. The single-crystal X-ray structure of the organic dimer 8 (ClzHl6O6, monoclinic, space group A2/a, a = 8.291 (2) A, b = 8.291 (2) A, c = 20.551 (2) A, B = 96.09 ( 1 ) O , 2 = 4, R = 0.068, R, = 0.089) reveals a symmetric alkene. The molecular structure of the Fe(t-BuNC)3(tric) species 9b (FeCMH55N50,*0.5CHz-C12-0.5C4Hlo0, monoclinic, space group Pc, a = 11.201 (1) A, b = 12.251 (2) A, c = 32.019 (3) A, B = 96.43 ( 1 ) O , 2 = 4, R = 0.0581, R, = 0.0629) consists of a four-, a five-, and a six-membered ring. The metal is incorporated in the six-and the four-membered rings. * To whom correspondence should be addressed. (1) (a) Part of this work has been published in preliminary form: de Boer, R. P.; de Lange, P. P. M.; FrQhauf, H.-W.; Vrieze, K. J . Chem. SOC., Chem.Commun. 1992,580. (b)PartlO deLnnge,P.P.M.;van Wijnkoop, M.; FrOhauf, H.-W.; Vrieze, K. Organometallics, preceding paper in this issue. 0276-7333/93/2312-0440$04.00/0
A Stereochemical study of the reaction between tricarbonyl(vinylketene)iron(O)complexes and alkynes
Tetrahedron-asymmetry, 1997
The formation of 1:1 adducts between tricarbonyl(vinylketene)iron(O) complexes and alkynes, and their subsequent conversion into tricarbonyl(cyclohexadienone)iron(O) complexes occur with complete retention of planar chirality.GraphicTricarbonyl(5-phenyl-3-iso-propyloxapenta-1,2,4-triene)iron(0) - methyl propiolate adductC20H18FeO6E.e. = 97±1%[α]d24 = +544±20 (c 0.5, CH2Cl2)Source of chirality: (S)-α-methylbenzylamineAbsolute configuration: 5pSTricarbonyl(5-phenyl-3-iso-propyloxapenta-1,2,4-triene)iron(0) - dimethyl acetylenedicarboxylate adductC22H20FeO8E.e. = 99±1%[α]d24 = +586±20 (c 1.07, CH2Cl2)Source of chirality: (S)-α-methylbenzylamineAbsolute configuration: 5pSTricarbonyl(5-phenyl-3-iso-propyloxapenta-1,2,4-triene)iron(0) - ethyl ethynyl ether adductC20H20FeO5E.e. = 95±2%[α]d28 = +509±15 (c 1.65, CH2Cl2)Source of chirality: (S)-α-methylbenzylamineAbsolute configuration: 5pSTricarbonyl(3-tert-butyl-5-phenyl-1-oxapenta-1,2,4-triene)iron(0) - ethyl ethynyl ether adductC21H22FeO5E.e. = 95±2%[α]d24 = +405±20 (c 1.18, CH2Cl2)Source of chirality: (S)-α-methylbenzylamineAbsolute configuration: 5pSTricarbonyl(5-ethoxy-4-phenyl-2-iso-propylcyclohexa-2,4-dienone)iron(0)C20H20FeO5E.e. = 95±1%[α]d25 = −164±10 (c 1.3, CH2Cl2)Source of chirality: (S)-α-methylbenzylamineAbsolute configuration: 4pSTricarbonyl(2-tert-butyl-5-ethoxy-4-phenylcyclohexa-2,4-dienone)iron(0)C21H22FeO5E.e. = 94±1%[α]d25 = +94±10 (c 0.8, CH2Cl2)Source of chirality: (S)-α-methylbenzylamineAbsolute configuration: 4pS
Organometallics, 1992
were carried out under a nitrogen atmosphere. Reaction conditions and results are summarized in . Hydroboration of 2-methyl-l-buten-3-yne (la) with catecholborane in the preaence and PPh2(Cpd is illustrative of the general methods for all catalytic reactions dewxibed in this study. A mixture of 8.3 mg (0.008 "01) of Pd2(dba)&HCls and 11 mg (0.03 "01) of PPh&&FJ in 1 mL of chloroform was stirred at room tempexature until the solution changed from red-purple due to P&(dba)&HC& to yellow. To the catalyst solution was added successively at 25 O C 53 mg (0.80 "01) of 2-methyl-l-buten-3-yne (la) and 126 mg (1.0 "01) of catecholborane, and the mixture was stirred at the same temperature for 30 min. Solvent was evaporated and the residue was distilled (bulb-to-bulb, bath temperature 100 OC/0.1 mmHg) to give 109 mg (73% yield) of the hydroboration product, which consisted of (3-methyl-1,2-butadienyl)-1,3,2benzodioxaborole (20) and ( )d-methyl-1 ,&butadienylJ-1,3,2benzodioxaborole (3a) in a ratio of 8317. The ratio was determined by the 'H NMR spectrum. 'H NMR (CDCla/TMS) data for the hydroboration products are as follows. (3-Methyl-1,2butadienyl)-1,3,2-benzodioxaborole (2a): 6 1.79 (d, J = 3.4 Hz, 6 H), 5.18 (heptet, J = 3.4 Hz, 1 H), 7.01-7.13 (m, 2 HI, 7.167.26 (m, 2 H). 1 (Z)-3-Methyl-1,3-butadienyl)-l,3,2-benzodioxaborole Supplementary Material Available: Figures of 'H NMR spectra of hydroboration products 2a4, 3a-c, and 4a-c (5 page& Ordering information is given on any current masthead page. Summa~~: Nonakis(phenyl isocyank!e)diiron was prepared by sodium amalgam reduction of either c&-or irans-[FeI&NPh),], The new complex was characterired s p e~o s c o p~~~ a d by singlecrystal xqaY anabsis. Crystal data: monoclinic, space group P2,ln, B = 92.90 (2)O, 1/ = 5402 (3) A3, Z = 4,
Organometallics, 1994
The 1,3-dipolar cycloaddition reaction of Fe((2,6-~ylyl)NC)&PrDAB) (7) with para-substituted phenyl isothiocyanates (R"C&NCS; R" = H (a), Me (b), OMe (c), NO2 (d)) is followed by one or two isonitrile insertions. Depending on the solvent and type of isothiocyanate used, [2.2.2] and i3.2.21 bicyclic products (10 and 11) are isolated. C tals of loa, C S I H S~N~S F~, are monoclinic, space group 12/a, with cell constants a = 24.041(2) f f b = 12.095(2) A, c = 36.161(6) A, V = 10502(3) A3,Z = 8, and R = 0.109 for 2918 observed reflections with I > 2.5aQ. Compounds 11 undergo a unique reversible isocyanide deinsertion reaction when warmed in toluene. The equilibria lla-d * l0a-d + 2,6-xylyl-NC have been studied by lH NMR. The equilibrium constants at various temperatures (303 K I T I 368 K) have been determined from which for the first time AGO (a, 16.2 f 2.7; b, 22.7 f 1.6; c, 23.2 f 1.9; d, 24.7 f 1.1 kJ/mol), AHo (a, 61.6 f 6.3; b, 74.5 f 3.3; c, 65.5 f 2.0; d, 86.9 f 2.5 kJ/mol), and ASo (a, 152 f 29; b, 174 i 14; c, 142 f 12; d, 208 f 11 J/(mol*K)) values could be calculated for isocyanide deinsertion. These values provide an explanation for the observed product selectivities in different solvents. The reactions 7 G 10 are also reversible; however equilibrium constants could not be determined because at the required temperatures compound 7 is itself too labile. To whom correspondence should be addressed. Abstract publiehed in Advance ACS Abstracts, May 15, 1994. (1) Part 1 3 van Wijnkoop,M.;Siebenliat,R.; Emsting, J. M.;deLange, P.P.M.;Fdmuf,H.-W.;Vrieze, K.;Horn,E.;Spek,A.L. J. Organomet. Chem., in preee. (2) The 1,4-dii-1,3-dienee of formula R'N--CH-CH=NR' are abbreviated an R'DAB. (3) (a) Part 1: Fmhauf, H.-W.; Sei, F.; Goddard, R. J.; RomAo, M. Part 5: Fdmuf, H.-W.; Seile, F.; Stam, C. H. Organometallics 1989,8,2338. (0 Part 6 de Lange, P. P. M.; Fdmuf, H.-W.; van Wijnkoop, M.; Vrieze, K.; Wang, Y.; Heijdenrijk, D.; Stam, C. H. Organometallics 1990,9,1691. (g) Part 7: vanWijnkoop,M.;deLange,P.P.M.;Frtihauf,H.-W.;Vrieze,K.; Wang, Y.; Goubitz, K.; Stam, C. H. Organometallics 1992,11,3607. (h) Part 8: de Lange, P. P. M.; Fmhauf, H.-W.; K " a n , M. J. A.; van Wijnkoop, M.; Kranenbug, M.; Groot, A. H. J. P.; Vrieze, K.; Fraanje, J.; Wang, Y.; Numan, M. Organometallics 1998,12,417. (i) Part9 van Wijnkoop, M.; Siebenliat,R.;deLange,P.P. M.;Fdmuf,H.-W.;Smeets, W. J. J.; Spek, A. L. Organometallics 1998,12,4172. cj) Part 1 0 de Lange, P. P. M.; Frtihauf, H.-W.; Vrieze, K.; Goubitz, K. Organometallics 1993,12,428. (4) (a) de Boer, R. P.; de Lange, P. P. M.; W u f , H.-W.; Vrieze, K. J. Chem. Soc., Chem. Commun. 1992,580. (b) Part 11: de Lange, P. P. M.; de Boer, R. P.; van Wijnkoop, M.; Emeting, J. M.; Fdihauf, H.-W.; Vrieze, K.; Smeeta, W. J. J.; Spek, A. L.; Goubitz, K. Organometallics 1993,12,440. (b) Part 2 Fmhauf, H.-W.; Sei, F.; RomAo, M. J.; Goddard, R. J. 0276-7333/94/2313-2825$04.50/0
Inorganica Chimica Acta, 1978
The photoreaction of 5,6dimethylene-7'-oxabicycle [2.2.l]hept-2-ene(1) with Fe(CO)5 yields initially the tiapto-tetracarbonyl iron complex (3), which reacts further to give a dihapto-tetracarbonyl-tetrahapto-tricarbonyl complex (CsHaO)Fez(CO), (4). The molecular structure of 4 has been detemzined by X-ray crystallography. Both the Fe(CO)4 and Fe-(CO), groups are in exo position with respect to the roof-shaped triene. The ligand is bound through its lone double bond to an equatorial position of a substituted tngonal-bipyramidal Fe(CO)& moiety and through its diene group to two basal positions of a tetragonal pyramidal Fe(CO)3L2 moiety. Hydrogen atom positions have been determined in the last cycles (final residual R = 0.023). H(Z) atoms deviate by 39" from the diene plane away from the metal and H(E) atoms deviate by 11" towards the metal. H atoms of the lone CC double bond deviate by 34" from the C(1)<(2)<(3)<(4) plane away from the metal. The structures of complexes 3,4 and (C$r,O)-Mo(COj3 (7) in solution were deduced from their 'H NMR data and the unknown geometries of ligands 1 and 5,6dimethylenebicyclo [2.2. I] hept-2-ene (2) were simulated by MINDO/3. Deoxygenation of the ligand is observed in the presence of Fe2(CO), in benzene at 60 "C, giving oquinodimethane complexes 5 and 6, 5 being also obtained by direct thermolysis of complex 4.
Journal of the American Chemical Society, 1982
The preparation and characterization of two six-coordinate (porphinato)iron(III) derivatives having the mixed-axial ligation of pyridine and isothiocyanate is described. One derivative, (isothiocyanato)(meso-tetraphenylporphinato)(pyridine)iron(III), Fe(TPP)(py)(NCS), is essentially a low-spin (S = I/*) complex while the second derivative, (isothiocyanato)(octaethylporphinato)(pyridine)iron(III), Fe(OEP)(py)(NCS), is a high-spin (S = 5/2) complex. The crystal and molecular structure of the two complexes has been determined. The structure determination of Fe(OEP)(py)(NCS) is the first high-spin six-coordinate iron(II1) porphyrinate having nonequivalent axial ligands to be characterized. The structure of Fe(TPP)(py)(NCS) is that expected for a low-spin (porphinato)iron(III) species with an average Fe-N, distance of 1.988 (9) A, Fe-N(py) = 2.082 (3) A, and Fe-N(NCS) = 1.942 (4) A. The Fe-N-C-S group is partly bent with an Fe-N-C angle of 155.6 (3)O. The bending is attributed to packing interactions in the solid state. The structure of Fe(OEP)(py)(NCS) shows an average increase in bond distance of 0.1 15 A which is quite anisotropic in distribution: average Fe-N, = 2.048 (4) A, Fe-N(py) = 2.442 (2) A, Fe-N(NCS) = 2.031 (2) A. The iron(II1) atom is displaced by 0.24 A from the mean plane of the core toward the isothiocyanate ligand. The Fe-N-C-S group is linear. Crystal data for Fe(TPP)(py)(NCS): a = 13.238 (3) A, b = 23.917 (5) A, c = 14.269 (3) A, and @ = 104.74 (l)', Z = 4, space group P2,/n, 5878 unique observations used in the structure determination. Crystal data for Fe(OEP)(py)(NCS): a = 12.348 (3) A, b = 15.625 (4) A, c = 10.535 (2) A, and a = 92.30 (2)', @ = 105.10 (2)', y = 101.10 (2)', Z = 2, space group Pi, 7549 unique reflections. Thiocyante, NCS-, is a linear ambidentate ligand4 which can bind to metals either via its nitrogen or its sulfur atom. When N bound, the M-NCS group is generally linear, and when S bound, the M-S-C angle is bent (-1 10'). The mode of coordination depends on the metal ion, the other ligands of the metal: and stereochemical factors.$ Recently Korszun and Moffat6 have determined the structure of thiocyanate-ligated hemoglobin. Some of their results are unexpected in terms of the normal coordination behavior of thiocyanate. In (NCS)MetHb,' the thiocyanate ligand is bound
Journal of the American Chemical Society, 1993
Fe(I1) and Fe(1) u-alkynyl complexes of the general formula [(PP3)Fe(C=CR)]"+ (n = 1, 0) have been synthesized as BPh4-salts or neutral molecules and characterized by chemical, spectroscopic, X-ray, and electrochemical techniques [R = Ph, SiMe3, n-CjH7, n-C5HII, CMe3; PP3 = P(CH2CH*PPh2)3]. All of the compounds undergo electron-transfer reactions that encompass Fe(O), Fe(I), Fe(II), and Fe(II1) oxidation states of the metal. X-ray crystal structures of the 16-and 17-electron complexes [(PP3)Fe(C=-CPh)]BPhgC4H8O and [(PP3)Fe(C=CPh)] have been determined. The Fe(I1) compound crystallizes in the space group P2,/c, and the cation assumes an almost regular trigonal-bipyramidal structure with the alkynyl ligand trans to the bridgehead phosphorus atom of PP3 (P4-Fe-C7 bond angle = 177.2(6)'). The Fe(1) compound crystallizes in the space group P2,/n and assumes a strongly distorted trigonal-bipyramidal structure with the Pd-Fe-C, bond angle of 170.3(3)' and equatorial bond angles of 143.9(1)O, 102.4(1)O, and 1 1 1. 1 (1)O. A decrease in the Fe-P bond distances on going from Fe(I1) to Fe(1) is interpreted in terms of significant metalphosphorus r-back-bonding. In contrast, from a perusal of IR, structural, and electrochemical data, no significant d r (metal)r* (alkynyl) interaction occurs. All compounds are paramagnetic and have been characterized by X-band ESR spectroscopy (powder, frozen solution, fluid solution). The powder and frozen solution spectra of the Fe(1) alkynyls are interpreted in terms of S = ' / 2 and a rhombic g tensor. The fluid solution spectra show that the compounds exist in tetrahydrofuran solution as two isomeric formsexhibiting distorted trigonal-bipyramidal structures in a ratio that depends on the temperature. The ESR spectra of the Fe(1I) derivatives (powder and frozen solution) display unresolved line shape consistent with a S = 1 Hamiltonian with noticeable zero-field splitting effects at room temperature. q6-C6R6,5 q3-C8H136). To the best of our knowledge, no stable iron-(I) compound with a u-hydrocarbyl has ever been reported. In this paper, we describe the synthesis, the X-band ESR characterization, and the electrochemical behavior of a family of d7 low-spin u-alkynyl Fe(1) complexes of the general formula [(PP3)Fe(CWR)] (PP3 = P(CH2CH2PPh2)j; R = Ph, SiMe3, n-C3H7, n-CsHI I , CMe3).