Crystal and Electronic Structure of Stable Nitrenium Ions. A Comparison with Structurally Related Carbenes

Abstract

The isolation of bis-amino-substituted carbenes of the Arduengo (3a) and Wanzlick type 4a has prompted us to look for stable nitrenium ions of the related structural type 3d + and 4d + . Thus 5 + I -(6 + I -) and 18 + ClO 4 -were isolated and structurally characterized by X-ray crystallography. Theoretical studies give insight into the different (electronic) structures and stabilities of 3a,d + , 4a,d + , and of related compounds.

2‐Halogeno‐1,3,2‐diazaarsolenes and 2‐halogeno‐1,3,2‐diazastibolenes: Examples for spontaneous EX bond heterolysis or not?

“…A great deal of the interest in these species was-and still is-initiated by their capability to act as ligands in transition metal complexes with similar molecular and electronic structures as Fischercarbene complexes [4], and in particular to stabilize electrophilic complexes with late metal atoms [5,6]. Although the major part of work has been dedicated to phosphenium ions [1], cations with other group-15 elements were also studied, and today stable cations centered at dicoordinate nitrogen (I, E = N [7]), arsenic (I, E = As [8][9][10]), antimony (I, E = Sb [11]), and bismuth atoms (I, E = Bi [11]) are known as well (Scheme 1).…”

“…Boche et al described the synthesis and structural characterization of a nitrenium ion (II, E = N) [7]. Efforts to access analogous cations with heavier group-15 element are to the best of our knowledge confined to a single report by Cowley et al [16] who isolated crystals representing a mixture of a pentachlorogermanate salt with a cation II (E = As), and a 2-chloro-1,3,2-diazaarsolene (IV, E = As, X = Cl), from the reaction of a germylene precursor with AsCl 3 .…”

Stability and Electrophilicity of Phosphorus Analogues of Arduengo Carbenes—An Experimental and Computational Study

“…Whereas anions with elements of the boron group are still hardly explored, [9] stable phosphenium (E P ) and arsenium (E As ) cations of type B and C are long known, [10,11] and their carbene analogue behavior has been verified by extensive chemical investigations. [10] Recently, the groups of Pudovik [12] and Denk [13] prepared 1,3,2-diazaphospholenium ions (A, E P ), which are isoelectronic and isolobal to Arduengo carbenes, and likewise nitrogen derivatives of A [14] have been reported. Theoretical and experimental studies [12±15] suggested that cyclic p delocalization is more pronounced in cationic than in neutral carbene analogues, and phosphenium ions of type A are both more stable and less electrophilic than their analogues with structures B and C.…”

Silicenium Ions: Quantum Chemical Computations

“…the 9-borabicyclo[3.3.1]nonyl group, ž stabilization via conjugation with aryl groups, which might provide resonance stabilization and steric shielding simultaneously, ž incorporation of the silicenium ion function into an aromatic ring, a strategy which has worked well in many other cases, e.g. in preparing silanol anions 65 , isolable carbenes 66 and stable nitrenium ions 67 .…”