William Kaska pursued doctoral studies with John Eisch in mechanistic organometallic chemistry, first with organolithium reactions at St. Louis University and then at the University of Michigan with organoaluminum reactions. Thereby he revealed the change in mechanism from nucleophilic lithiation and carbolithiation to that of electrophilic alumination, carboalumination and hydroalumination of organic substrates, which reactions were previously observed by Karl Ziegler in his empirical studies of organoaluminum reactions. Our findings were the first mechanistic studies attempting to set such Ziegler chemistry on a modern theoretical basis.

The starting 6,11-diphenyldibenzo[b,f][1,4]diazocine has been individually treated with R-Li reagents in THF, where R = AlH4, PhCH2, Ph2CH, Ph3C, CH3, CH3(CH2)(3), C6H5 or Ph-C C, to learn whether an expected 1,2- or 1,4-addition would cleanly occur. Contrary to such an assumption based on nucleophilic attack, this [1,4] diazocine with PhCH2Li yielded only the enantiomers of (4b, 11R)-11-benzyl-4b, 11-diphenyl-4b,11-dihydro-5H-benzo[4,5]imidazo[2,1-a]isoindole; with Ph2CHLi yielded 2-[1-( 4-benzhydrylphenyl)-phenyl-2H-isoindol-2-yl] analine; and with LiAlH4 2-(2-aminophenyl)-1,3-diphenylisoindole. Finally, individual reactions of the [1,4] diazocine with CH3Li, nBuLi or PhLi gave 4-5 inseparable products, instead of any simple 1,2 or 1,4 adduct. The anomalous carbolithiations and hydrolithiation observed are irreconcilable with a nucleophilic mechanism but in excellent accord with a SET radical-anion pathway.

The puckered tricyclic heterocycle 6,12-diphenyldibenzo[b,f][1,5]diazocine, a novel probe for revealing single-electron transfer (SET) reactions, is here employed as a model substrate for investigating the carbolithiation of imines and the stereochemistry, the regiochemistry, and the electronic nature (polar or SET) of such R-Li additions. The chemical behavior of the following organolithium reagents (mainly in THF) toward the diazocine was studied: benzyl-, methyl-, phenyl-, n-butyl-, and phenylethynyllithiums, as well as the reactive allylmagnesium chloride and the typical tert-butylmagnesium chloride. The only reagent that failed to carbometalate or to reduce the diazocine transannularly was phenylethynyllithium. The tert-butyl Grignard reagent could not carbometalate but did reduce the diazocine with photocatalysis. The other five organometallics yielded both carbometalation of the diazocine and, upon hydrolysis, transannular SET reduction to 4b, 9b-diphenyl-4b, 5,9b, 10-tetrahydroindolo[3,2-b]indole ("indoloindole") in varying pro-portions. Three types of carbometalation products were observed in such hydrolyzed reactions: (1) exo-1,2-addition to a C=N bond by C6H5CH2Li, H2C=CHCH2MgCl, and CH3Li, as established by spectral and XRD data; (2) 1,4-addition to the ortho-phenyl carbon Co=C-C=N linkage by phenyllithium with the subsequent elimination of LiH; and (3) 1,4-addition, as in type 2, by n-butyllithium but without the elimination of LiH. The foregoing modes of reactivity, the concomitant formation of the telltale SET reduction product, "indoloindole", and the failure of PhC CLi to react at all with the diazocine are marshaled to support the conclusion that the organometallics reacting with the diazocine, by carbometalation and by transannular reduction, do so by SET processes and not by straightforward nucleophilic attack. The relative stabilities of sp(3)-, sp(2)-, and sp-hybridized carbon radicals possibly involved were assessed in concluding that PhC CLi is incapable of reacting through any SET pathway.

In the original article,1 the following changes should be applied: (i) On page 3527 of the original article in the 2nd column, the 4th paragraph composed of 17 lines should be replaced by the following paragraph: Given the demonstrated versatility of the zirconium reagents discussed here, one might wonder how the titanium and hafnium derivatives compare with those of zirconium. First, with reagents of the type nBu2MCl2, the zirconium analog is readily prepared and sufficiently stable to serve as a hydrozirconating agent for diverse π-bonded substrates (cf. supra). The titanium counterpart, nBu2TiCl2, is difficult to generate, because it decomposes too readily into TiCl2, and the hafnium hydride, nBu2HfCl2, is much too stable to serve as a source of HfCl2 and thus functions as an alternative hydride to nBu2ZrH2, albeit twice as expensive. As to the accessible epimetallating agents, TiCl2 or ZrCl2 in THF, prior work with aromatic aldehyde reduction dimerizations has led us to conclude that they were comparable in their selectivity.[16] But this present study and a subsequent doctoral dissertation33 have compelled us to correct this misconception. The interaction of a 1:1 molar ratio of ZrCl2 and benzaldehyde (4) on a 2.0 millimolar scale, according to the procedure described on p. 3529, 1st column, 1st paragraph, led upon workup solely to rac-1,2-diphenyl-1,2-ethanediol (7). No trace of the meso isomer 8 of 7 nor any benzyl alcohol (6) was detected. Recently, the corresponding interaction of a 1:1 molar ratio of TiCl2 and 4 was undertaken and reported in Wei Liu's doctoral dissertation with 13C NMR and TLC analyses as follows: rac-1,2-diphenyl-1,2-ethanediol (7; 54 %), the meso isomer (8; 25 %) benzyl alcohol (6; 15 %) and benzaldehyde (4; at least 6%, because some 4 could well have been oxidized and lost during workup). From this experiment, reproduced about 10 times in this study, it is evident that ZrCl2 is far more selective in producing the rac-diol and in favoring the diol over benzyl alcohol. The reaction mechanisms leading to this differing array of products cannot yet be depicted, but these results have immediate value in the synthesis of geminal diols. (ii) Reference [33] of the original article will have its text changed to the new ref.33 These changes in the original manuscript are necessary, because the 4th paragraph in the 2nd column on page 3527 of the original article was inaccurate and ambiguous in the wording. The new paragraph and its more accurate and clear wording stem from the completed doctoral dissertation of Wei Liu (now cited in reference [33]). The Authors

In our continuing attempts to convert tub-shaped dibenzo[1,4]diazocines or dibenzo[1,5]diazocines into necessarily planar Huckel aromatic ten--electron dianions or dihydro derivatives of the central diazocine ring, we have added requisite electrons by Na or Li metal in THF. Subsequent hydrolysis yielded no evidence for the formation of such Huckel aromatic products but in each case a profound rearrangement of the tricyclic diazocine had instead occurred. In the present study we have attempted to form the unknown aromatic 6,11-diphenyldibenzo[b,f][5,12]-dihydro[1,4]diazocine at 25 degrees C by such a straightforward addition of two electrons to 6,11-diphenyldibenzo[b,f][1,4]diazocine. We were encouraged by the prior reduction of the unsubstituted [1,4]diazocine to 1,4-dihydro-[1,4]diazocine, which by X-ray and H-1 NMR evidence displays aromatic-like properties. However, this diphenyldibenzo[1,4]-diazocine upon reduction underwent instead an unusual, serendipitous rearrangement to yield quantitatively 2-(2-aminophenyl)-1,3-diphenylisoindole. Then in a purposive search for other reductants capable of reductively rearranging this [1,4]diazocine to its corresponding isoindole, we discovered three other reductants, namely o-diaminobenzene, titanium(II) salts, and concentrated aqueous hydriodic acid with visible light. Conversely, again in a serendipitous observation, it was found that O-2 in CHCl3 with visible light could readily convert the isoindole in an oxidative rearrangement back into the [1,4]diazocine. A purposive method for achieving this oxidative rearrangement was then found to be treatment with DDQ. General mechanistic pathways are proposed via SET intermediates for both redox interconversions.

In the present study, 6,12-diphenyldibenzo[b,f][1,5]diazocine, which X-ray diffraction measurements have now shown to possess a tub-shaped, eight-membered central ring, has been treated with sodium or lithium metal at 25 degrees C in THF, in an attempt to form the planar, Huckel-aromatic dianion by the addition of two electrons to the central diazocine. Hydrolysis of such an aromatic dianion should have led to the isomeric 5,12- or 5,6-dihydro derivative of the original diazocine. In actuality, the only product obtained quantitatively upon hydrolytic workup was the interesting quadricyclic transannular reduction product, 4b,9b-diphenyl-4b,5,9b,10-tetrahydroindolo[3,2-b]indole, whose 3D structure has now been confirmed by X-ray crystallography and 13C NMR spectroscopy. Preferential SET transannular reduction of the diazocine to yield the quadricyclic indolo[3,2-b]indole dianion, rather than the planar, Huckel-aromatic anion, is ascribed to the transannular electronic stabilization operative in the tub-shaped diazocine radical-anion. The quantitative generation of the indolo[3,2-b]indole dianion can be employed for the oxidative dimerization of the organic groups in benzylic lithium reagents. Thus treating one equivalent of the diazocine with two equivalents of benzyllithium, benzhydryllithium, or trityllithium yields quantitatively bibenzyl, 1,1,2,2-tetraphenylethane, or (4-benzhydrylphenyl)triphenylmethane, respectively. This oxidative dimerization is potentially of practical preparative scope, since the hydrolysis byproduct, the indolo[3,2-b]indole, is conveniently reconverted into the starting diazocine reagent by oxidation with chromium trioxide in acetic acid. The formation of the indolo[3,2-b]indole as a byproduct in the carbometalation of the diazocine by various RLi and Grignard reagents offers a clue as to the SET mechanism of carbometalation.

ADVERTISEMENT RETURN TO ISSUEReviewNEXTADDITION / CORRECTIONThis article has been corrected. View the notice.Fifty Years of Ziegler–Natta Polymerization: From Serendipity to Science. A Personal AccountJohn J. Eisch*View Author Information Department of Chemistry, The State University of New York at Binghamton, Binghamton, New York 13902-6000, United States *E-mail: [email protected]Cite this: Organometallics 2012, 31, 14, 4917–4932Publication Date (Web):July 2, 2012Publication History Received26 April 2012Published online2 July 2012Published inissue 23 July 2012https://pubs.acs.org/doi/10.1021/om300349xhttps://doi.org/10.1021/om300349xreview-articleACS PublicationsCopyright © 2012 American Chemical SocietyRequest reuse permissionsArticle Views4050Altmetric-Citations38LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose SUBJECTS:Alkyls,Aluminum,Gallium,Hydrocarbons,Indium Get e-Alerts

The detection, site of binding and quantification of bonds between carbon and a main-group metal can be readily achieved by a combination of proto-and deuteriodemetallation of such stable organometallics, combined with NMR spectral and mass spectrometric analyses of the organic products. Only with chiral sp(3)-carbon-metal bonds, with geometrically isomeric sp(2)-carbon-metal bonds or with allylic carbon-metal bonds will further structural physical data be required to identify the actual 3D-structure of the carbon binding site.The thermal and photochemical lability of carbon bonds to transition metals imposes restrictions on the detection of C-M-t bonds by deuteriodemetallation. Often the homolytic rupture of such bonds competes greatly and will lead to geometric isomers. Results of such apparent protodemetallation should be cross-checked with other structural information.The detection of C=M-t and possibly C M-t bonds may prove to be generally achievable by cycloadditions of such metal carbenes or carbynes with nitriles or alkynes.The addition of low-valent transition metal salts to alkenes or alkynes leads to complexes viewable as pi-complexes or as epimetallated adducts. By examination of available structural parameters and the chemical reactions undergone by such adducts, the adducts between ethylene and Ti(OiPr)(2) and between diphenylacetylene and alpha,alpha-bipyridyl-nickel(0) can best be considered as titana(IV)cyclopropane and nickel(II)cyclopropene structures, respectively. (C) 2010 Elsevier B.V. All rights reserved.

In previous studies of transition metal alkyls the 2:1 molar aggregate of n-butyllithium and zirconium(IV) salts has been found to react both with benzylic hydrocarbons and aromatic carbonyl derivatives in diverse and useful ways. In the present study the reactions of the aggregates, 2nBuLi center dot ZrE4 (E = Cl, OEt), with benzaldehyde have involved carbometallation, hydrometallation and reductive dimerization (paths 1-3) in THF and were selectively achievable by temperature control alone. First, at -78 degrees C benzaldehyde underwent carbolithiation to give upon hydrolysis 1-phenyl-1-pentanol. However, short-term reaction times and prompt D2O quenching revealed that with Zr(OEt)(4) both benzaldehyde and 1-phenyl-1-pentanol were deuteriated, consistent with the presence of a phenyl(lithioxy)carbene intermediate. The observed dimerization of benzaldehyde to benzyl benzoate by lithium 2,2,6,6-tetramethylpiperidide is also consistent with such a phenyl(lithioxy)carbene intermediate. Second, at 25 degrees C the 2nBuLi center dot ZrE4 aggregate reduced benzaldehyde exclusively to benzyl alcohol, which observation is consistent with the formation of the hydrozirconating agent, H2ZrE2. Third, heating the aggregate at reflux and subsequent reaction with benzaldehyde produced solely the reduced dimer, 1,2-diphenyl-1,2-ethanediol with high stereoselectivity: E = Cl, rac/meso of 93:7 and E = OEt, rac/meso of 100:0. The proposed mechanism involves the formation of ZrE2, the epizirconation of benzaldehyde and the insertion of the second benzaldehyde into the zirconaoxacyclopropane under steric control. Finally, the high selectivity in hydrozirconation and reductive dimerization shown by 2nBuLi center dot ZrE4 appears at this time to be superior to that attainable with analogous titanium or hafnium aggregates.

Studies of the reactions between group 4 metal chlorides (M = Ti, Zr, Hf) and methyllithium at -78 degrees C in toluene can lead to methylidene-metal complexes, H2C=MCl2, by a sequence of monomethylation, alpha-carbon lithiation and alpha,mu-elimination of LiCl. Here study of the preparation of alkylidene derivatives of iron was attempted by the interaction of FeCl3 with n-butyllithium in various ratios at -78 degrees C. The presence of any resulting butylidene-iron(III) derivative, nPrCH=FeE (E = Cl, nBu), was probed by adding chemical trapping agents, such as diphenylacetylene, benzonitrile, methyl benzoate and benzophenone. In each experiment the hydrolyzed products were consistent with a cycloaddition reaction of nPrCH=FeE with the trapping agent. The products from diphenylacetylene and from benzonitrile with D2O workup are uniquely in accord with such a carbene precursor. A 3:1 ratio of nBuLi/FeCl3 gave the optimal yield of nPrCH=FenBu, ca. 80%, from the nBu(2)FeCl precursor. When a 3:1 reaction mixture was simply brought to 25 degrees C and hydrolyzed, the purple alkylidene-iron complex decomposed completely to iron metal. A study of a 3:1 interaction of PhCH2MgCl and FeCl3 under similar conditions and trapping with diphenylacetylene provided evidence for the formation of PhCH=Fe-CH2Ph in ca. 40%. These results support the hope that alkylidene-iron(III) analogs of the Grubbs reagents may be accessible by this process.

Subvalent vanadium(I) salts, of empirical formulas, VCl, vanadium(I) chloride and LiVH2, lithium vanadium(I) dihydride, whose efficient preparation, structural constitution and mode of reaction toward certain organic substrates have been described in a preceding article, are here evaluated in their reactions toward a wide variety of pi- and sigma-bonded organic substrates, namely carbonyl, imine, azo, alkene, 1,3-diene, nitrile pi-bonds and C-X, C-O, C-N and N-N sigma-bonds. Compared with the high reactivity of CrCl and LiCrH2 reagents in attacking both types of bonds, the VCl and LiVH2 reagents were much milder and selective in epimetallating pi-bonds, often forming the 1:1 adduct of LiVH2 and pi-bonded substrate as the major product. Finally, the vanadium reagents showed little tendency to cleave C-O, C-S and C-N bonds and a smaller scope in cleaving C-X bonds than their chromium counterparts. Because of their selectivity these vanadium reagents offer the following preparative promise: 1) smooth McMurry carbonyl coupling to their reductive dimers; 2) deoxygenation of epoxides; 3) selective aromatic C-X reduction; 4) high yields of epimetallated carbonyls or imines as intermediates to a-hydroxy and a-amino acids; 5) 1,4-reductions of 1,3-alkadienes; 6) reductive dimerization of nitriles to ketones; 7) 1,4 or 1,n-epimetallations leading to acyloins or indoles; and 8) reductive dimerizations of azines to produce unusual imidazole derivatives. In explaining the greater kinetic stability of the 1:1 LiVH2 adduct with carbonyl or imine substrates it is pointed out that such epimetallated adducts from LiVH2 would likely be diamagnetic, whereas such adducts from LiCrH2 have an unpaired electron on the Cr center and hence would rupture, so that the electron would be on the C center. (C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008.

The attempted generation of the potentially aromatic 6,7-diphenyldibenzo[e,g][1,4]diazocine dianion from sodium in THF leads with profound rearrangement to the isomeric N-(2-amino-1,2-diphenylethenyl)carbazole dianions and, after hydrolysis, to a 55:45 mixture of Z- and E-isomers of N-(2-amino-1,2-diphenylethenyl)carbazoles. These isomers were separated and their individual structures determined by X-ray diffraction. Since treatment of the starting diazocine first with tert-butyllithium and then with water also yielded the same Z- and E-isomeric mixture, electron transfer reduction is clearly involved.

The claims that 3,4,7,8-tetraphenyl-1,2,5,6-tetraazocine can be prepared by the thermal condensation of two moles of benzil monohydrazone or of an equimolar mixture of benzil and benzil dihydrazone have been thoroughly reinvestigated. When such thermolyses were conducted in moist air, neither the claimed 3,4,7,8-tetraphenyl-1,2,5,6-tetraazocine nor the precedented isomeric tetraazapentalene derivative was detected. The following products were unambiguously formed from the heating of molten benzil monohydrazone (%): benzil (10), benzaldehyde (10), benzamide (22), benzyl phenyl ketone (19), benzil bis(ketazine) (11), 3,4,5,6-tetraphenylpyridazine (9), benzil benzaldehyde azine (10), and, after column chromatography, 2,4,5-triphenylimidazole (2). This last component had a melting point and the fluorescent properties in UV light attributed by the original investigator to the mistakenly presumed 3,4,7,8-tetraphenyl-1,2,5,6-tetraazocine. Thus, the original claims for the synthesis of such a novel tetraazocine ring or even for the synthesis of the precedented isomeric zwitterionic tetraazapentalene have now been repudiated. The formation of 2,4,5-triphenylimidazole as a side reaction in the thermolysis of benzil monohydrazone can readily be rationalized as arising from benzil, benzaldehyde, and a source of ammonia, namely, benzamide, in the long-known Radziszewski reaction. Corroborating evidence was provided by data from the thermolysis of benzil dihydrazone. In addition, the origin of other side products is explained in terms of other possible condensations. Finally, preliminary experiments on using irreversible dehydrating agents such as titanium(IV) isopropoxide with benzil monohydrazone indicate that 3,4,7,8-tetraphenyl-1,2,5,6-tetraazocine is formed at room temperature as a transitory intermediate, which eliminates dinitrogen to produce 3,4,5,6-tetraphenylpyridazine. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008).

Subvalent vanadium(I) salts, of empirical formulas, VCl, vanadium(I) chloride and LiVH2, lithium vanadium(I) dihydride, can be conveniently prepared in THF solution, starting at –78 °C, by treating either VCl3 or VCl4 with an appropriate number of equivalents of nBuLi. As judged by the stability of solutions or solid samples of LiVH2, the preparation of LiVH2 from VCl4 is the preferred method. Individual physical characterization of solid samples of VCl or of LiVH2, admixed with their LiCl by-product, was carried out after removal of all volatiles in vacuo and by the following measurements: 1) gasometric protolysis with glacial acetic acid and measurement of the H2 evolved in the oxidation of VI to VII; 2) infrared spectroscopic search for V–H bands; and 3) examination for unpaired electrons by EPR activity. Such measurements applied to VCl lend strong support for a VI oxidation state but only probable evidence for paramagnetism and for the association of VCl units. Similar measurements applied to LiVH2 give unambiguous gasometric and IR evidence favoring the LiVH2 stoichiometry and the biradical nature of the VH2 anion with a linear array of H–V–H atoms. Chemical characterization of both VCl and LiVH2 toward individual organic substrates, such as olefins, ketones, epoxides and organic halides, yielded convincing evidence that organic radical mechanisms are involved, both for the proven biradical, LiVH2, as well as for the diamagnetic VCl. Finally, the question of why LiVH2 prepared from VCl4 is more stable than the LiVH2 obtained from VCl3 is addressed in terms of the actual coordination sphere of the VH2 anion in THF solution and in the solid state. Preliminary studies comparing the reactivities of LiVH2 and LiCrH2 toward organic substrates indicate that LiVH2 is the distinctly more moderate and usefully selective reductant. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

In a previous study of geminal bond cleavages of substrates of the type R2CE2 [E-2 = X-2, O, S, Li(SO2Ph)] by nickel(0) reagents [LnNi, L-n = (Cod)(2), (Et4P)(4)], leading to R2C=CR2 as products, the tentative hypothesis had been proposed that such reactions likely proceed via nickel (0)-carbene intermediates (J. J. Eisch, Y. Qian, M. Singh, J. Organomet. Chem. 1996, 512, 207). Because such proposed nickel (0)-carbenes do not satisfactorily account for reactions encountered with such alpha-eliminations, a detailed reexamination of the reaction of these nickel(0) reagents with geminal dihalides has been undertaken. For example, two reactions of such presumed nickel(0)-carbenes remained anomalous: (1) the failure of 5,5-dibromotetraphenylcyclopentadiene to form its expected dimer, octaphenylphenylfulvalene and instead the formation of triethylphosphonium tetraphenylcyclopentadienide in its reaction with (Et3P)(4)Ni; and (2) the presumed capture of intermediate R2C=Ni-0 in presence of the trapping agent (benzaldehyde or benzophenone). As to the first anomaly, a detailed study has shown that no trace of octaphenylfulvalene was formed. As to the second anomaly, the R2C fragment could be trapped by the carbonyl reagents only in reactions involving (Et3P)(4)Ni, but not in reactions with (Cod)(2)Ni. This finding compels one to conclude that the carbonyl reagent is capturing the Wittig reagent, R2C=PEt3, and not R2C=Ni-0. Based upon all present data, the mechanism of such C=C bond dimerizations is best explicable in terms of nickel(II)carbenes. The triethylphosphonium tetraphenylcyclopentadienide formed here has by single-crystal X-ray structure determination, complemented by C-13 NMR spectroscopic data, been found to have the zwitterionic structure Ph4CP--+PEt3 as its paramount resonance contributor. (c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007.

The feasibility of hydrocarboxylating carbonyl and imino derivatives by the two-step process of epimetallation and carbonation has been demonstrated with the model substrates of 9-fluorenone and 9-fluorenone anil. With lithium vanadium dihydride as the epimetallating agent, such hydrocarboxylation has led to a 75% yield of 9-hydroxy-9-fluorenecarboxylic acid and a 65% yield of 9-(N-phenylamino)-9-fluorenecarboxylic acid, respectively. Some initial success in extending the scope of this reaction to other substrates, such as benzophenone, has been achieved by using other epimetallating agents, like the presumed LiV(CH3)(2) and Ti(OPri)(2). A brief review of the processes and organic synthetic applications of epimetallation and transfer epimetallation of C-C pi-bonds is offered as background. (C) 2007 Elsevier B.V. All rights reserved.

The interaction between 1,1,2,2-tetraphenylethane and di-n-butylzirconium diethoxide (1:2 ratio) in THF at 25 degrees C does not occur in the dark but does proceed under ambient light (> 300 nm). Supplemental illumination, especially in the presence of catalytic amounts of iron salts (e.g., Fe(acac)(3) or FeCl3), can lead quantitatively to Ph2CH-Zr(OEt)(2)-CHPh2, which with H2O (D2O) provides Ph2CH2 (Ph2CHD), and to 1,8-octanediol with some 1-butanol from cleavage of THF.