Tin, Lead, Amides N-Silyl-aminotin trichlorides, R !R2N-SnCL [R1 = R2 = SiMe3 (la), R 1 = SiMe3, R2 = 'Bu (lb), R = SiMe3, R2 = 9-borabicyclo[3.3.1]nonyl (lc), R 'R 2 = Me2 SiCH2CH2 SiMe2 (ld)] were prepared by the reaction of tin tetrachloride with the respective bis(amino)plumbylenes, (R 'R 'N^P b 4. The analogous reactions with bis(amino)stannylenes, (R 'R 2 N)?Sn 3, afforded only mixtures of the aminotin trichlorides 1 and bis(amino)tin dichlorides, (R 'R 2 N)2 SnCl2 2 . The products were characterised by H, 1 'B, l3C, 13N, 29Si and 1 l9Sn NMR spectroscopy, and the NMR data of 1 were compared with those of the corresponding N-silylamino(trimethyl)tin compounds 8 .

Two equivalents of N-lithio-N-trimethylsilyl-amino-9-borabicyclo[3.3.1]nonane (1) react with tin and lead dichloride by salt elimination to give the corresponding bis(amino)stannylene 2 and -plumbylene 3, respectively. The compounds 2 and 3 are monomers in solution and were characterized by 1H, 13C, 14N, 29Si, 119Sn and 207Pb NMR spectroscopy.

N‐Silylaminotitanium trichlorides, Me3S(R)N‐TiCl3 (18) [R = tBu (a), SiMe3 (b), 9‐borabicyclo[3.3.1]nonyl (9‐BBN)(c)], and (CH2SiMe2)2N‐TiCl3 (18d) were obtained in high yield and high purity from the reaction of the respective bis(silylamino)plumbylene with an excess of titanium tetrachloride. The crystal structure of 18a was determined by X‐ray analysis. The reactions of the analogous stannylenes with an excess of TiCl4 did not lead to 18. N‐Lithio‐trimethylsilyl[9‐(9‐borabicyclo[3.3.1]nonyl)]amine (8) was prepared, structurally characterized and used for the synthesis of a new bis(amino)stannylene 10 and a plumbylene 11. The compounds 18a—d served as ideal starting materials for the synthesis of bis(silylamino)titanium dichlorides, where the silylamino groups can be identical (19) or different (20). This was achieved either by the reaction of 18 again with bis(amino)plumbylenes or with lithium N‐silylamides. In contrast to the direct synthesis starting from titanium tetrachloride and two equivalents of the respective lithium amide, which in general affords 19 with identical amino groups only in low yield, the procedure starting from 18 is much more versatile and gave the pure compounds 19 or 20 in almost quantitative yield. Further treatment of the dichlorides 19 or 20 with lithium amides led to tris(amino)titanium chlorides 21. The dichlorides 19 or 20 reacted with two equivalents of alkynyllithium reagents to give the first well characterized examples of di(alkyn‐1‐yl)bis(N‐silylamino)titanium compounds 22—27. These compounds reacted with trialkylboranes (triethyl or tripropylborane) by 1, 1‐organoboration. In some cases, the extremely reactive reaction products could be identified as novel 1, 1‐bis(silylamino)titana‐2, 4‐cyclopentadienes 28—31 bearing a dialkylboryl group in 3‐position. In solution, the proposed structures of all products were deduced from a consistent set of data derived from multinuclear magnetic resonance spectroscopy (1H, 11B, 13C, 14N, 15N, 29Si, 35Cl NMR).

No abstract

No abstract

N-Lithio-N-trimethylsilyl-9-amino-9-borabicyclo[3.3.1]nonane (2) was prepared from the reaction of N-trimethylsilyl-9-amino-9-borabicyclo-[3.3.1]nonane (1) with rert-butyl lithium; 2 crystallizes as a trim er with a planar N3Li3 ring. The nitrogen atoms are tetrahedrally coordinated, but should be treated as sp2 hybridised, because the BN double bond, typical of aminoboranes, is retained.

The l5N-labelled trimethylstannylamines 1 - 3 [(Me3Sn)3N, (Me3Sn)2NPh, (Me3Sn)2NBCgHi4 (BCgHi4 = 9-borabicyclo[3.3.0]nonyn and the non-labelled 4, Me3Sn-N(BC8Hi4)2 , were prepared and studied by 1H, 1C, 15N and 119Sn NMR. The 15N ultrahigh resolution NMR spectra of 1 revealed otherwise unobserved parameters such as 2J(15N ,Sn ,13C ) and the isotope induced chemical shift 2Δ12/13C(15N). 119Sn NMR spectra of 1, recorded under similar conditions, also show new parameters such as 3J(119Sn,N,Sn,13C) which are not resolved in the non-labelled derivative. By using various types o f two-dimensional heteronuclear shift correlations, absolute coupling signs of 1J(119Sn,15N) (all < 0) in 1 - 3 were determined. By the same techniques it proved possible to confirm the negative sign o f :7(Sn,Sn) (-195.4 Hz) in 1. In contrast, the coupling constants 2J(Sn,Sn) for 2 (+71.7) and 3 (+62.0) possess a positive sign. This sign inversion, observed here for the first time for apparently similar compounds, demonstrates the enormous influence of substituents on the nature of the lone pair of electrons at the nitrogen atom. It also shows that these experiments for sign determinations of coupling constants are necessary in order to interpret these data correctly.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.