In general, if the atoms that make up the ring contain heteroatoms, such rings become heterocycles, and organic compounds containing heterocycles are called heterocyclic compounds. An article called Spectroscopic properties and ligand field parameters of bis(hydrotris(1-pyrazolyl)borato) trivalent metal complexes: anomalous covalency in the metal-pyrazolyl nitrogen bond and energy level splittings due to anisotropic π bonding, published in 1996-08-15, which mentions a compound: 18583-60-3, Name is Potassiumtris(1-pyrazolyl)borohydride, Molecular C9H10BKN6, Category: piperazines.
From UV-visible absorption, MCD, luminescence, and multinuclear NMR spectra of bis(hydrotris(1-pyrazolyl)borato) chromium(III) and cobalt(III) complexes, the ligand field parameters are discussed in comparison with those of the corresponding hexaam(m)ine complexes. The trigonal splitting of the quartet excited 4T2g and 4T1g states and the large separation of the lower frequency doublet states (2Eg and 2T1g) were elucidated in terms of the angular overlap model.
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Reference:
Piperazine – Wikipedia,
Piperazines – an overview | ScienceDirect Topics