Slinger BL, Zhu J, Widenhoefer RA. Cationic Bis(Gold) Indenyl Complexes.
Chempluschem 2024;
89:e202300691. [PMID:
38259056 DOI:
10.1002/cplu.202300691]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2023] [Revised: 01/23/2024] [Accepted: 01/23/2024] [Indexed: 01/24/2024]
Abstract
Reaction of (P)AuOTf [P=P(t-Bu)2o-biphenyl] with indenyl- or 3-methylindenyl lithium led to isolation of gold η1-indenyl complexes (P)Au(η1-inden-1-yl) (1 a) and (P)Au(η1-3-methylinden-1-yl) (1 b), respectively, in >65 % yield. Whereas complex 1 b is static, complex 1 a undergoes facile, degenerate 1,3-migration of gold about the indenyl ligand (ΔG≠ 153K=9.1±1.1 kcal/mol). Treatment of complexes 1 a and 1 b with (P)AuNTf2 led to formation of the corresponding cationic bis(gold) indenyl complexes trans-[(P)Au]2(η1,η1-inden-1,3-yl) (2 a) and trans-[(P)Au]2(η1,η2-3-methylinden-1-yl) (2 b), respectively, which were characterized spectroscopically and modeled computationally. Despite the absence of aurophilic stabilization in complexes 2 a and 2 b, the binding affinity of mono(gold) complex 1 a toward exogenous (P)Au+ exceed that of free indene by ~350-fold and similarly the binding affinity of 1 b toward exogenous (P)Au+ exceed that of 3-methylindene by ~50-fold. The energy barrier for protodeauration of bis(gold) indenyl complex 2 a with HOAc was ≥8 kcal/mol higher than for protodeauration of mono(gold) complex 1 a.
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