η³‐Coordination and Functionalization of the 2‐Phosphaethynthiolate Anion at Lanthanum(III)**

Abstract

We present the η3‐coordination of the 2‐phosphaethynthiolate anion in the complex (PN)2La(SCP) (2) [PN=N‐(2‐(diisopropylphosphanyl)‐4‐methylphenyl)‐2,4,6‐trimethylanilide)]. Structural comparison with dinuclear thiocyanate‐bridged (PN)2La(μ‐1,3‐SCN)2La(PN)2 (3) and azide‐bridged (PN)2La(μ‐1,3‐N3)2La(PN)2 (4) complexes indicates that the [SCP]− coordination mode is mainly governed by electronic, rather than steric factors. Quantum mechanical investigations reveal large contributions of the antibonding π*‐orbital of the [SCP]− ligand to the LUMO of complex 2, rendering it the ideal precursor for the first functionalization of the [SCP]− anion. Complex 2 was therefore reacted with CAACs which induced a selective rearrangement of the [SCP]− ligand to form the first CAAC stabilized group 15–group 16 fulminate‐type complexes (PN)2La{SPC(RCAAC)} (5 a,b, R=Ad, Me). A detailed reaction mechanism for the SCP‐to‐SPC isomerization is proposed based on DFT calculations.

Deciphering the Differences in Ambident Reactivity between the Cyanate, Thiocyanate Ions, and their P‐ and As‐Containing Analogues

“…The coordination of the [PCS] − anion toward tungsten pentacarbonyl resulted in the formation of both possible isomers, the P‐ and the S‐coordinated species, in a nearly equimolar ratio. Interestingly, the [PCS] − anion can even coordinate in an η 3 fashion involving all three centres, as recently demonstrated for a lanthanum(III)‐complex [66] . The [AsCO] − anion paved the way to several metal‐complexes ([M]−As=C=O) via salt metathesis reactions, [67,68] and this anion also reacts at its As centre both with a stannylene and a germylene [65,69] .…”