Triprotonated 1,3,5-triaza-7-phosphaadamantane (PTA); fantasy or real intermediate on way from PTA to tetradentate tris(aminomethyl)phosphine?

Abstract

In aqueous HBr solution (58% w/w), 1,3,5-triaza-7-phosphaadamantane (PTA) yielded the hitherto unknown triprotonated PTA, as single crystals. In addition, the same reaction mixture deposited crystals of [O = P(CH₂NH₃)₃]Br₃ (2), formed presumably by ring opening of [PTA-H₃]Br₃ (3) and oxidation of the resulting [P(CH₂NH₃)₃]Br₃ (1). The solid state structure of 2 and 3 were determined by X-ray diffraction. In water/methanol mixtures, reaction of 1 and [{(η⁶-C₁₀H₁₄)RuBr₂}₂] yielded the half-sandwich [(η⁶-C₁₀H₁₄)RuBr₂{P(CH₂NH₃)₃}]Br₃ (4) which –in aqueous solution– spontaneously afforded the dinuclear [(η⁶-C₁₀H₁₄)RuBr₂{μ⁴-P(CH₂NH₂)₃}Ru(η⁶-C₁₀H₁₄)]Br₂ (5).

Graphical Abstract

Keywords:

• 1,3,5-triaza-7-phosphaadamantane
• ruthenium
• protonation
• ring opening

Conflict of interest

The authors confirm that this article content has no conflict of interest.

Additional information

Funding

The financial support of the Hungarian National Research, Development and Innovation Office (FK-128333) is greatly acknowledged. Project no. TKP2020-NKA-04 has been implemented with the support provided from the National Research, Development and Innovation Fund of Hungary, financed under the 2020-4.1.1-TKP2020 funding scheme. The research was supported by the EU and co-financed by the European Regional Development Fund under the projects GINOP-2.3.3-15-2016-00004 and GINOP 2.3.2-15-2016-00008.