A Novel Ferrocene‐Backboned Unsymmetrical Pincer‐Type Proligand and Its Organotin Derivatives

• Published in: European journal of inorganic chemistry Vol. 2019; no. 13; pp. 1799 - 1809
• Main Authors: Gawron, Matthias, Nayyar, Bastian, Krabbe, Christina, Lutter, Michael, Jurkschat, Klaus
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 09-04-2019
• Subjects: Derivatives; Ferrocene; Hydrogen peroxide; Inorganic chemistry; Iodine; Ionization; Ions; Mass spectrometry; Nitrogen; NMR spectroscopy; Phosphorus; Pincer ligands; Tin; X-ray diffraction
• ISSN: 1434-1948; 1099-0682
• DOI: 10.1002/ejic.201801567

In this contribution we report the synthesis of the novel unsymmetrical ferrocene‐based pincer‐type proligand η5‐CpFeη5‐C5H2‐1‐Br‐2‐PPh2‐5‐CH2NMe2 (1). Its reactivity is demonstrated by isolation of related organotin derivatives η5‐CpFeη5‐C5H2‐1‐SnR3‐2‐PPh2‐5‐CH2NMe2 (3, R = Ph; 4, R = Me). The reactions of compounds 3 and 4 with H2O2 and elemental sulfur gave the corresponding ferrocenylphosphane oxide (5) and the sulfides (6, 7), respectively. Most remarkably, an unprecedented reaction of the organotin derivative 3 with elemental iodine was observed, providing the ammonium salt [η5‐CpFeη5‐C5H2‐1‐SnPh2I‐2‐P(O)Ph2‐5‐CH2NHMe2]I (8). The compounds are characterized by elemental analyses, 1H, 13C, 31P, 119Sn NMR spectroscopy, electrospray ionization mass spectrometry, and single‐crystal X‐ray diffraction analyses (3–8). Also reported are the solid‐state structures of the hydrolysis products [η5‐CpFeη5‐C5H2‐1‐SnPh2(OH)‐2‐P(O)Ph2‐5‐CH2NHMe2]·0.5H2O (9a) and [η5‐CpFeη5‐C5H2‐1‐SnPh(OH)‐2‐P(O)Ph2‐5‐CH2NMe2]2[I3]2 (9b) that were isolated by serendipity.
No pincer‐type behaviour is observed for the ferrocene derivative 5 and related compounds as only one out of the two donor sites coordinates the tin atom. The high basicity of the aminomethyl nitrogen atom promotes easy hydrolysis of the organotin halide derivatives giving ammonium salts such as 8 and 9a. N···H···O hydrogen bridge outperforms intramolecular N→Sn interaction.