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Durham e-Theses
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Azomethine derivatives of some metals and metalloids

Farmer, John Barry (1973) Azomethine derivatives of some metals and metalloids. Doctoral thesis, Durham University.



This thesis describes the preparation of some methyleneamino derivatives of beryllium, zinc, gallium and silicon. The structural, implications of their infra-red spectra and nuclear magnetic resonance spectra are discussed. As a background to the work, the characteristics of such compounds are discussed in the Introduction, and in greater detail in each chapter. Di-t-butylmethyleneaminolithium reacts with beryllium chloride giving dimeric di-t-butylmethyleneaminoberyllium chloride, (Bu(^t)(_2)C:NBeCl)(_2), and the lithium beryllates Li(_n)Be(N:CBu(^t)(_2))(_2+n) (n = 1,2). Bis(di-t-butylmethyl-eneamino)beryllium, [(Bu(^t)(_2)C:N)(_2)Be](_2) was inaccessible by this route but was prepared by reacting di-t-butylmethyleneamine with di-isobutylberyllium (2:1). The crystal structure of this compound shows that the terminal CNBe unit is nearly linear and that the Be-N bond is relatively short, appropriate for N →Be (p → p) π-bonding. The structure determination supports the postulate that a high azomethine stretching frequency, v(C=N) is indicative of a linear CNBe unit and Be-N multiple bonding. Attempts to prepare adducts with trimethylamine and tetramethylethylene-diamine were unsuccessful. Reaction between methyleneamines and dialkylberylliums afford the derivatives (R(^2)C:NBeR’)(_2) (R = Bu(^2), Ph; R' = Bu(^i) and R = Ph; R' = Bu(^t)). A new monomeric compound, di-t-butylmethyleneamino-bis(trimethylsilyl)-aminoberyllium, Bu(^t)(_2)C:NBeN(SiMe(_3))(_2) was prepared and characterised. Reactions of zinc chloride with one or two moles of di-t-butylmethyl-eneaminolithium give dimeric iminozinc compounds, (Bu(^t)(_2)C:NZnCl)(_2) and [(Bu(^t)(_2)C:N)(_2)Zn](_2). A high azomethine stretching frequency in the latter compound is attributed to significant pπpπ interaction between zinc and nitrogen. Dimethylzinc reacts with one or two moles of di-t-butylmethyl-eneamine giving [(Bu(^t)(_2)CN)(_n)ZnMe(_2-n)])_2) (n = 1,2). Reaction between di-t-butylmethyleneaminolithium and gallium trichloride affords the compounds Li(_n)Ga(N: CBu(^t)(_2))(_3+n) (n = 0,1,2). Bis(di-t-butylmethyleneamino)gallium chloride could not be isolated, presumably through disproportionation to the mono- and tris-derivatives. A high azomethine stretching frequency, v(C=N), for (Bu(^t)(_2)C:N)(_3)Ga, is taken as evidence for a linear C=N-Ga skeleton with appreciable N=Ga π-bonding. The phenyl analogue (Ph(_2)C:N)(_3)Ga was prepared by a similar method. Equimolar proportions of diphenylmethyleneaminolithium and chlorosilanes Me(_n)SiCl(_4-n), (n = 0,1,2) afford the diphenylmethy1eneamino-silanes (Ph(_2)C:N)(_2)-SiM(_n)Cl(_3-n), apparently through disproportionation of the mono-substituted compounds Ph(_2)C:NSiMe(_n)Cl(_3-n), which could only be isolated when n = 2. The spectra of these compounds show that these may have bent C:NSi skeletons. Preliminary investigations into transition metal systems (R(_2)C:N)(_3)M (M = Fe; R = Bu(^t),Ph and M = Cr; R = Bu(^t)) are discussed in an appendix.

Item Type:Thesis (Doctoral)
Award:Doctor of Philosophy
Thesis Date:1973
Copyright:Copyright of this thesis is held by the author
Deposited On:13 Nov 2013 15:41

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