Reactivity of the TpRu(HN=CPh2)(PPh3)−Azido complex and Insertion of Methylene into the Tp B−H Bond

• Published in: Journal of organometallic chemistry 2022-12, Vol.982, p.122533, Article 122533
• Main Authors: Yang, Cian-Wei, Gao, Shi-Xiang, Hsu, Yu-Chieh, Chan, Wei-Chieh, Yan, Chi-Fong, Kuo, Yu-Lin, Lo, Yih-Hsing
• Format: Article
• Language: English
• Subjects: Azido Complexs; B−H Bond; Insertion; Methylene; Ruthenium
• ISSN: 0022-328X; 1872-8561
• DOI: 10.1016/j.jorganchem.2022.122533

•We report [3+2] cycloaddition reactions of alkyne with the ruthenium azido complex.•The stable triazolato and tetrazolato products obtained in all cases were N(2)-bound.•We report that during protonation of ruthenium azido complex, methylene insertion accidentally took place, to yield unusual boron-methylated product.•Their structures are elucidated by IR, NMR and X-ray crystallography. Herein, we report on the reactivity of an Ru(II) azido complex allowing the facile synthesis of further interesting complexes. Starting from the parent chlorido complex (HN=CPh2)[Ru]−Cl {1, [Ru] = Tp(PPh3)Ru; Tp = HB(pz)3, pz = pyrazolyl)} the title complex (HN=CPh2)[Ru]−N3 (2) was obtained upon reaction with NaN3. The N(2)-bound 4,5-bis-(methoxycarbonyl)-1,2,3-triazolato complex (HN=CPh2)[Ru]−{N3C2(CO2Me)2} (3) was obtained from reaction of 2 with dimethyl acetylene dicarboxylate (DMAD). Protonation of 3 with HCl afforded the N-coordinated triazolato complex {HN3C2(CO2Me)2}[Ru]−Cl (4). Reaction of CS2 with 2 produced the thiocyanato complex (HN=CPh2)[Ru]−NCS (5). The Ru tetrazolato complex (HN=CPh2)[Ru]−N4C[C(CN)=C(CN)2] (6) was prepared from 2 and tetracyanoethylene (TCNE). The reaction of 2 with HX gave the 17-electron Ru(III) complexes (Cl)[Ru]−X (7a, X = Cl; 7b, X = Br) and the Ru(II) complexes containing the methyl tris(pyrazolyl)borate ligand MeTp(PPh3)(HN=CPh2)Ru−X (8a, X = Cl; 8b, X = Br), as a result of an unusual methylene insertion into the B−H bond of the Tp ligand with the CH2Cl2 solvent as the assumed source for the methylene. The structures of 4, 5, 7a, 7b and 8b had been determined by X-ray diffraction analysis. [Display omitted]