The synthesis of new weakly coordinating diborate anions: anion stability as a function of linker structure and steric bulk

Mark H. Hannant; Joseph A. Wright; Simon J. Lancaster; David L. Hughes; Peter N. Horton; Manfred Bochmann

doi:10.1039/b515548g

The synthesis of new weakly coordinating diborate anions: anion stability as a function of linker structure and steric bulk

Mark H. Hannant, Joseph A. Wright, Simon J. Lancaster, David L. Hughes, Peter N. Horton, Manfred Bochmann

Research output: Contribution to journal › Article › peer-review

29 Citations (Scopus)

Abstract

The successive addition of KCN and Ph₃CCl to B(C₆F₄-C₆F₅-2)₃ (PBB) affords triphenylmethyl salts of the [NC-PBB]^- anion. By contrast, the analogous reaction with sodium dicyanamide followed by treatment with Ph₃CCl leads to the zwitterionic aminoborane H₂NB(C₁₂F₉)₂C₁₂F₈, via nucleophilic attack on an o-F atom, together with CPh₃[F-PBB]. Whereas treatment of [NC-PBB]^- with either PBB or B(C₆F₅)₃ fails to give isolable cyano-bridged diborates, the reaction of Me₃SiNC-B(C₆F₅)₃ with PBB in the presence of Ph₃CCl affords [Ph₃C][PBB-NC-B(C₆F₅)₃]. Due to steric hindrance this anion is prone to borane dissociation. The longer linking group N(CN)₂^- gives the very voluminous anions [N{CNB(C₆F₅)₃}₂]^- and [N(CN-PBB)₂]^-. A comparison of propylene polymerisations with rac-Me₂Si(Ind)₂ZrMe₂ activated with the various boranes or trityl borates gives an anion-dependent activity sequence, in the order [NC-PBB]^- < [MeB(C₆F₅)₃]^- < [MePBB]^- ˜ [PBB-NCB(C₆F₅)₃]^- ˜ [N{CNB(C₆F₅)₃}₂]^- < [F-PBB]^- « [B(C₆F₅)₄]^- < [N(CN-PBB)₂]^-. The anion [N(CN-PBB)₂]^- gives a catalyst productivity about 2500 times higher than that of [NC-PBB]^- and exceeds that of [B(C₆F₅)₄]^- based catalysts. The van der Waals volumes and surface areas of the anions have been calculated and provide a rationale for the observed reactivity trends in polymerisation reactions.

Original language	English
Pages (from-to)	2415-2426
Number of pages	12
Journal	Dalton Transactions
Issue number	20
DOIs	https://doi.org/10.1039/b515548g
Publication status	Published - 2006

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@article{e64fda04b11e4b65b2d747e6e0b15e19,

title = "The synthesis of new weakly coordinating diborate anions: anion stability as a function of linker structure and steric bulk",

abstract = "The successive addition of KCN and Ph3CCl to B(C6F4-C6F5-2)3 (PBB) affords triphenylmethyl salts of the [NC-PBB]- anion. By contrast, the analogous reaction with sodium dicyanamide followed by treatment with Ph3CCl leads to the zwitterionic aminoborane H2NB(C12F9)2C12F8, via nucleophilic attack on an o-F atom, together with CPh3[F-PBB]. Whereas treatment of [NC-PBB]- with either PBB or B(C6F5)3 fails to give isolable cyano-bridged diborates, the reaction of Me3SiNC-B(C6F5)3 with PBB in the presence of Ph3CCl affords [Ph3C][PBB-NC-B(C6F5)3]. Due to steric hindrance this anion is prone to borane dissociation. The longer linking group N(CN)2- gives the very voluminous anions [N{CNB(C6F5)3}2]- and [N(CN-PBB)2]-. A comparison of propylene polymerisations with rac-Me2Si(Ind)2ZrMe2 activated with the various boranes or trityl borates gives an anion-dependent activity sequence, in the order [NC-PBB]- < [MeB(C6F5)3]- < [MePBB]- ˜ [PBB-NCB(C6F5)3]- ˜ [N{CNB(C6F5)3}2]- < [F-PBB]- « [B(C6F5)4]- < [N(CN-PBB)2]-. The anion [N(CN-PBB)2]- gives a catalyst productivity about 2500 times higher than that of [NC-PBB]- and exceeds that of [B(C6F5)4]- based catalysts. The van der Waals volumes and surface areas of the anions have been calculated and provide a rationale for the observed reactivity trends in polymerisation reactions.",

author = "Hannant, {Mark H.} and Wright, {Joseph A.} and Lancaster, {Simon J.} and Hughes, {David L.} and Horton, {Peter N.} and Manfred Bochmann",

year = "2006",

doi = "10.1039/b515548g",

language = "English",

pages = "2415--2426",

journal = "Dalton Transactions",

issn = "1477-9226",

publisher = "Royal Society of Chemistry",

number = "20",

}

TY - JOUR

T1 - The synthesis of new weakly coordinating diborate anions: anion stability as a function of linker structure and steric bulk

AU - Hannant, Mark H.

AU - Wright, Joseph A.

AU - Lancaster, Simon J.

AU - Hughes, David L.

AU - Horton, Peter N.

AU - Bochmann, Manfred

PY - 2006

Y1 - 2006

N2 - The successive addition of KCN and Ph3CCl to B(C6F4-C6F5-2)3 (PBB) affords triphenylmethyl salts of the [NC-PBB]- anion. By contrast, the analogous reaction with sodium dicyanamide followed by treatment with Ph3CCl leads to the zwitterionic aminoborane H2NB(C12F9)2C12F8, via nucleophilic attack on an o-F atom, together with CPh3[F-PBB]. Whereas treatment of [NC-PBB]- with either PBB or B(C6F5)3 fails to give isolable cyano-bridged diborates, the reaction of Me3SiNC-B(C6F5)3 with PBB in the presence of Ph3CCl affords [Ph3C][PBB-NC-B(C6F5)3]. Due to steric hindrance this anion is prone to borane dissociation. The longer linking group N(CN)2- gives the very voluminous anions [N{CNB(C6F5)3}2]- and [N(CN-PBB)2]-. A comparison of propylene polymerisations with rac-Me2Si(Ind)2ZrMe2 activated with the various boranes or trityl borates gives an anion-dependent activity sequence, in the order [NC-PBB]- < [MeB(C6F5)3]- < [MePBB]- ˜ [PBB-NCB(C6F5)3]- ˜ [N{CNB(C6F5)3}2]- < [F-PBB]- « [B(C6F5)4]- < [N(CN-PBB)2]-. The anion [N(CN-PBB)2]- gives a catalyst productivity about 2500 times higher than that of [NC-PBB]- and exceeds that of [B(C6F5)4]- based catalysts. The van der Waals volumes and surface areas of the anions have been calculated and provide a rationale for the observed reactivity trends in polymerisation reactions.

AB - The successive addition of KCN and Ph3CCl to B(C6F4-C6F5-2)3 (PBB) affords triphenylmethyl salts of the [NC-PBB]- anion. By contrast, the analogous reaction with sodium dicyanamide followed by treatment with Ph3CCl leads to the zwitterionic aminoborane H2NB(C12F9)2C12F8, via nucleophilic attack on an o-F atom, together with CPh3[F-PBB]. Whereas treatment of [NC-PBB]- with either PBB or B(C6F5)3 fails to give isolable cyano-bridged diborates, the reaction of Me3SiNC-B(C6F5)3 with PBB in the presence of Ph3CCl affords [Ph3C][PBB-NC-B(C6F5)3]. Due to steric hindrance this anion is prone to borane dissociation. The longer linking group N(CN)2- gives the very voluminous anions [N{CNB(C6F5)3}2]- and [N(CN-PBB)2]-. A comparison of propylene polymerisations with rac-Me2Si(Ind)2ZrMe2 activated with the various boranes or trityl borates gives an anion-dependent activity sequence, in the order [NC-PBB]- < [MeB(C6F5)3]- < [MePBB]- ˜ [PBB-NCB(C6F5)3]- ˜ [N{CNB(C6F5)3}2]- < [F-PBB]- « [B(C6F5)4]- < [N(CN-PBB)2]-. The anion [N(CN-PBB)2]- gives a catalyst productivity about 2500 times higher than that of [NC-PBB]- and exceeds that of [B(C6F5)4]- based catalysts. The van der Waals volumes and surface areas of the anions have been calculated and provide a rationale for the observed reactivity trends in polymerisation reactions.

U2 - 10.1039/b515548g

DO - 10.1039/b515548g

M3 - Article

SP - 2415

EP - 2426

JO - Dalton Transactions

JF - Dalton Transactions

SN - 1477-9226

IS - 20

ER -