Linkage Isomerism Leading to Contrasting Carboboration Chemistry: Access to Three Constitutional Isomers of a Borylated Phosphaalkene

Abstract

We describe the reactivity of two linkage isomers of ab oryl-phosphaethynolate,[ B]OCP and[ B]PCO (where [B] = N,N'-bis(2,6-diisopropylphenyl)-2,3-dihydro-1H-1,3,2-diazaboryl), towards tris-(pentafluorophenyl)borane (BCF). These reactions afforded three constitutional isomersa ll of which contain ap hosphaalkene core. [B]OCP reacts with BCF througha1 ,2 carboboration reactiont oa fford an ovel phos-phaalkene, E-[B]O{(C 6 F 5) 2 B}C=P(C 6 F 5), which subsequently undergoes ar earrangement process involving migration of both the boryloxy and pentafluorophenyl substituents to afford Z-{(C 6 F 5) 2 B}(C 6 F 5)C=PO[B].B yc ontrast,[ B]PCO undergoes a1 ,3-carboborationp rocess accompanied by migration of the N,N'-bis(2,6-diisopropylphenyl)-2,3-dihydro-1H-1,3,2-diazaboryl to the carbonc entre.

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

“…Moreover, the character of the excitation for structure II is of a very different form compared to that of the other structures, see Figure S51. Similar carbene‐induced rearrangements of the [OCP] − anion to “fulminate‐like” structural motifs have been described by Grützmacher [33, 34] and Goicoechea [6] and co‐workers for systems based on phosphorus, [33] silicon, [34] and boron [6] . With the synthesis of complexes 5 a and 5 b we could extend this type of isomerization chemistry to a f‐block metal‐based system, yielding the first heavier group 15–group 16 analogue of a substituted “fulminate‐like” anion.…”

“…The (coordination) chemistry of the 2‐phosphaethynolate ([OCP] − ) anion continues to be a vibrant, highly topical research field in the chemical sciences [1] and has already led to the isolation of a plethora of novel or rare phosphorus‐containing heterocycles, [2] the first stable singlet phosphinidene, [3] as well as many (functional) coordination compounds covering the whole periodic table [1,4] —from main group elements [5, 6] and transition metals [7] to the lanthanides [8] and actinides [9] . In contrast, the chemistry of the heavier analogues, for example, the 2‐phosphaethynthiolate ([SCP] − ) anion, has been much less developed so far, although both the [OCP] −[10] and the [SCP] − anion [11] were first reported in the 1990s by Becker and co‐workers as their lithium salts.…”

Recent advances in the chemistry of the phosphaethynolate and arsaethynolate anions

“…In 2020, Goicoechea et al reported a gateway to achieve three structural isomers of borylated phosphaalkene via carboboration of boryl–phosphaethynolates ([B]OCP and [B]PCO; [B] = N , N ′-bis(2,6-diisopropylphenyl)-2,3-dihydro-1 H -1,3,2-diazaboryl) using tris(pentafluorophenyl)borane (B(C 6 F 5 ) 3 ). 43 E -[B]O{(C 6 F 5 ) 2 B}CP(C 6 F 5 ) ( 34a ) was isolated on reaction with equimolar B(C 6 F 5 ) 3 and [B]OCP. The 31 P NMR of 34a showed resonance at δ = 173.9 ppm.…”

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

“…The(coordination) chemistry of the 2-phosphaethynolate ([OCP] À )a nion continues to be av ibrant, highly topical research field in the chemical sciences [1] and has already led to the isolation of ap lethora of novel or rare phosphoruscontaining heterocycles, [2] thef irst stable singlet phosphinidene, [3] as well as many (functional) coordination compounds covering the whole periodic table [1,4] -from main group elements [5,6] and transition metals [7] to the lanthanides [8] and actinides. [9] In contrast, the chemistry of the heavier ana-logues,f or example,t he 2-phosphaethynthiolate ([SCP] À ) anion, has been much less developed so far, although both the [OCP] À [10] and the [SCP] À anion [11] were first reported in the 1990s by Becker and co-workers as their lithium salts.This can partly be attributed to the notorious instability of Li(DME) 3 SCP (similar to Li(DME) 2 OCP).…”