The “masked” terminal Zn sulfide, [K(2.2.2‐cryptand)][MeLZn(S)] (
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Divalent Titanium via Reductive N‐C Coupling of a TiIV Nitrido with π‐Acids.
The nitrido‐ate complex [(PN)2Ti(N){μ2‐K(OEt2)}]2 (1) reductively couples CO and isocyanides in the presence of DME or cryptand, to form rare, five‐coordinate TiII complexes having a linear cumulene motif, [K(L)][(PN)2Ti(NCE)] (E = O, L = Kryptofix222, (2); E = NAd, L = 3 DME, (3); E = NtBu, L = 3 DME, (4); E = NAd, L = Kryptofix222, (5)). Oxidation of 2‐5 with [Fc][OTf] afforded an isostructural TiIII center containing a neutral cumulene [(PN)2Ti(NCE)] (E = O, (6); E = NAd (7), NtBu (8)). Moreover, 1e‐ reduction of 6 and 7 in the presence of cryptand cleanly reformed corresponding discrete TiII complexes 2 and 5, which were further characterized by solution magnetization measurements and high‐ frequency and ‐field EPR (HFEPR) spectroscopy. Furthermore, oxidation of 7 with [Fc*][B(C6F5)4] resulted in a ligand disproportionated TiIV complex having transoid carbodiimides, [(PN)2Ti(NCNAd)2] (9). Comparison of spectroscopic, structural, and computational data for the divalent, trivalent, and tetravalent systems, including their 15N enriched isotopomers demonstrate these cumulenes to decrease in order of backbonding as TiII→TiIII→TiIV and increasing order of p‐donation as TiII→TiIII→TiIV, thus displaying more covalency in TiIII species. Lastly, we show a synthetic cycle whereby complex 1 can deliver an N‐atom to π‐acids.
more » « less- Award ID(s):
- 2154620
- NSF-PAR ID:
- 10509745
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Angewandte Chemie
- ISSN:
- 0044-8249
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract 2 ) (MeL={(2,6‐iPr2C6H3)NC(Me)}2CH), was isolated via reaction of [MeLZnSCPh3] (1 ) with 2.3 equivalents of KC8in THF, in the presence of 2.2.2‐cryptand, at −78 °C. Complex2 reacts readily with PhCCH and N2O to form [K(2.2.2‐cryptand)][MeLZn(SH)(CCPh)] (4 ) and [K(2.2.2‐cryptand)][MeLZn(SNNO)] (5 ), respectively, displaying both Brønsted and Lewis basicity. In addition, the electronic structure of2 was examined computationally and compared with the previously reported Ni congener, [K(2.2.2‐cryptand)][tBuLNi(S)] (tBuL={(2,6‐iPr2C6H3)NC(tBu)}2CH). -
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Abstract The “masked” terminal Zn sulfide, [K(2.2.2‐cryptand)][MeLZn(S)] (
2 ) (MeL={(2,6‐iPr2C6H3)NC(Me)}2CH), was isolated via reaction of [MeLZnSCPh3] (1 ) with 2.3 equivalents of KC8in THF, in the presence of 2.2.2‐cryptand, at −78 °C. Complex2 reacts readily with PhCCH and N2O to form [K(2.2.2‐cryptand)][MeLZn(SH)(CCPh)] (4 ) and [K(2.2.2‐cryptand)][MeLZn(SNNO)] (5 ), respectively, displaying both Brønsted and Lewis basicity. In addition, the electronic structure of2 was examined computationally and compared with the previously reported Ni congener, [K(2.2.2‐cryptand)][tBuLNi(S)] (tBuL={(2,6‐iPr2C6H3)NC(tBu)}2CH). -
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