Unequivocal assignments of C(2,5) and C(3,4) on the Cp ring of scynichrodene derivatives bearing an electron-donating substituent in 13C NMR spectra and X-ray structures of (CO) 2(NO)Cr[(η 5-C 5H 4)-C(O)-(η 5-C 5H 4)]Ru(η 5-C 5H 5) and (CO) 2(NO)Cr[(η 5-C 5H 4)–CH 2–(η 5-C 5H 4)]Ru(η 5-C 5H 5)

Abstract

Friedel–Crafts acylation of ruthenocene with (η 5-chloroformylcyclopentadienyl)dicarbonylnitrosylchromium 15 has afforded cynichrodenyl ruthenocenyl ketone 6 in 39% yield. Reduction of 6 and acetylcynichrodene 11 with lithium aluminum hydride/aluminum chloride leads to cynichrodenylruthenocenylmethane 8 and ethylcynichrodene 2 in 45% and 63% yield, respectively. Structures of compound 6 and 8 have been solved by X-ray diffraction studies. Both cisoid and transoid conformations at the organic carbonyl carbon were observed in 6. The twist angle is 177.2° , 105.8°, 72.3°, and 24.4° for NO ligand of Cp(CO) 2(NO) moiety in 5, transoid 6, cisoid 6, and 8, respectively. Compared the HetCOR NMR data of 6– 8 with those of their ferrocene analogues, the opposite correlation was observed on the chemical shift assignments of C(2)–C(5) of Cp(Cr) in compound 5 and 6, while the correlation in compound 7 and 8 is the same. The electron density distribution in the cyclopentadienyl ring is discussed on the basis of 13C NMR data and those of 5, 8, and 9 are compared with the calculations via density functional B3LYP correlation-exchange method.