Boryltin compounds featuring the metal in the+1 or 0 oxidation states can be synthesized from the carbene‐stabilized tin(II) bromide (boryl)Sn(NHC)Br (boryl={B(NDippCH)2}; NHC=C{(NiPrCMe)2}) by the use of strong reducing agents. The formation of the mono‐carbene stabilized distannyne and donor‐free distannide systems (boryl)SnSn(IPrMe)(boryl) (2) and K2[Sn2(boryl)2] (3), using Mg(I) and K reducing agents mirrors related germanium chemistry. In contrast to their lighter congeners, however, systems of the type [Sn(boryl)]n are unstable with respect to disproportionation. Carbene abstraction from 2 using BPh3, and two‐electron oxidation of 3 both result in the formation of a 2 : 1 mixture of the Sn(II) compound Sn(boryl)2, and the hexatin cluster, Sn6(boryl)4 (4). A viable mechanism for this rearrangement is shown by quantum chemical studies to involve a vinylidene intermediate (analogous to the isolable germanium compound, (boryl)2Ge=Ge), which undergoes facile atom transfer to generate Sn(boryl)2 and trinuclear [Sn3(boryl)2]. The latter then dimerizes to give the observed hexametallic product 4, with independent studies showing that similar trigermanium species aggregate in analogous fashion.

We report two BNB-type frustrated Lewis pairs which feature an acceptor-donor-acceptor functionalized cavity, and which differ in the nature of the B-bound fluoroaryl group (C 6 F 5 vs. C 6 H 3 (CF 3 ) 2 -3,5, Ar f ). These receptor systems are capable of capturing gaseous CO, and in the case of the -BAr f 2 system this can be shown to occur in reversible fashion at/above room temperature. For both systems, the binding event is accompanied by migration of one of the aryl substituents to the electrophilic carbon of the CO guest. Experiments utilizing an additional equivalent of P t Bu 3 allow the initially formed (non-migrated) CO adduct to be identified and trapped (via demethylation), while also establishing the reversibility of the B-to-C migration process. When partnered with the slightly less Lewis acidic -BAr f 2 substituent, this reversibility allows for release of the captured carbon monoxide in the temperature range 40-70 8C, and the possibility for CO sensing, making use of the associated colourless to orange/ red colour change.

The synthesis of a novel mono‐anionic phosphino‐amide ligand based on a xanthene backbone is reported, togetherr with the corresponding GaI complex, (PON)Ga (PON = 4‐(di(2,4,6‐trimethylphenyl)phosphino)‐5‐(2,6‐diisopropylanilido)‐2,7‐di‐tert‐butyl‐9,9‐dimethylxanthene). The solid‐state structure of (PON)Ga (obtained from X‐ray crystallography) reveals very weak O⋅⋅⋅Ga and P⋅⋅⋅Ga interactions, consistent with a R2NGa fragment which closely resembles those found in one‐coordinate amidogallium systems. Strong N‐to‐Ga π donation from the amido substituent is reflected in a very short N−Ga distance (1.961(2) Å), while the P⋅⋅⋅Ga contact (3.076(1) Å) is well outside the sum of the respective covalent radii. While the donor properties of the PON ligand towards GaI are highly unsymmetrical, oxidation to GaIII leads to much stronger coordination of the pendant phosphine as shown by P−Ga distances which are up to 20 % shorter. From a steric perspective, the PON ligand is shown to be significantly bulkier than related β‐diketiminate systems, a finding consistent with reactions of (PON)Ga towards O‐atom sources that proceed without oligomerization. Despite this, the enhanced P‐donor properties brought about by oxidation at gallium are not sufficient to quench the reactivity of the highly polar Ga−O unit. Instead, intramolecular benzylic C−H activation is observed across the Ga−O bond of a transient gallanone intermediate.

The reduction of the boryl‐substituted SnII bromide {(HCDippN)2B}Sn(IPrMe)Br with 1.5 equivalents of potassium graphite leads to the generation of the cyclic tetratin tetraboryl system K2[Sn4{B(NDippCH)2}4], a homo‐metallic heavier analogue of the cyclobutadiene dianion. This system is non‐aromatic as determined by Nucleus Independent Chemical Shift Calculations (NICS(0)=−0.28, NICS(1)=−3.17), with the primary contributing resonance structures shown by Natural Resonance Theory (NRT) to involve a Sn=Sn double bond and 1,2‐localized negative charges. Abstraction of the K+ cations or oxidation leads to contraction or cleavage of the Sn4 unit, respectively, while protonation generates the neutral dihydride 1,2‐Sn4{B(NDippCH)2}4H2 (a heavier homologue of cyclobutene) in a manner consistent with the predicted charge distribution in the [Sn4{B(NDippCH)2}4]2− dianion.

We report two BNB-type frustrated Lewis pairs which feature an acceptor-donor-acceptor functionalized cavity, and which differ in the nature of the B-bound fluoroaryl group (C 6 F 5 vs. C 6 H 3 (CF 3 ) 2 -3,5, Ar f ). These receptor systems are capable of capturing gaseous CO, and in the case of the -BAr f 2 system this can be shown to occur in reversible fashion at/above room temperature. For both systems, the binding event is accompanied by migration of one of the aryl substituents to the electrophilic carbon of the CO guest. Experiments utilizing an additional equivalent of P t Bu 3 allow the initially formed (non-migrated) CO adduct to be identified and trapped (via demethylation), while also establishing the reversibility of the B-to-C migration process. When partnered with the slightly less Lewis acidic -BAr f 2 substituent, this reversibility allows for release of the captured carbon monoxide in the temperature range 40-70 8C, and the possibility for CO sensing, making use of the associated colourless to orange/ red colour change.