Dinuclear RhII-phthalocyaninates with a Rh-Rh single bond: x-ray crystal structure of di(pyridinephthalocyaninato(2−)rhodium(II))
✍ Scribed by Heiner Hückstädt; Clemens Bruhn; Heiner Homborg
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 244 KB
- Volume
- 01
- Category
- Article
- ISSN
- 1088-4246
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✦ Synopsis
Red, diamagnetic di(phthalocyaninato(2-)rhodium(II)), [( Rhpc ^2−^)~2~] is prepared by thermal decomposition of acidophthalocyaninatorhodium(III) or di(acido)phthalocyaninatorhodates(III) in inert, high boiling solvents or under reduced pressure at T < 350° C . It is insoluble in most common solvents except pyridine ( py ), yielding red, diamagnetic di(pyridinephthalocyaninato(2-)rhodium(II)), [{ Rh ( py ) pc ^2−^}~2~]. This crystallizes as benzene solvate in the cubic space group Ia-3 (no. 206) (a = 35.960(7) Å) with Z = 24. The Rh - Rh distance (d( Rh - Rh ) = 2.741(2) Å) indicates a strong unsupported Rh - Rh single bond. Due to the axial coordination of py the Rh atoms are virtually bonded in the centre ( ct ) of the pc ^2−^ core (d( Rh - ct ) = 0.08(1) Å). The pc ^2−^ ligands are staggered with the skew angle φ( N ~iso~ - Rh - Rh '- N ~iso~ ') = 42(1)°. Asymmetrical doming of the pc ~2−~ ligands is caused by a short interplanar distance (d( ct - ct ) = 2.89(1) Å) and axial coordination of pyridine. Due to the labilizing trans influence of the Rh - Rh bond the d( Rh - N ~py~ ) = 2.309(8) Å is rather long. Two quasi-reversible anodic and four cathodic electron transfer processes are observed in the differential pulse voltammogram of [{ Rh ( py ) pc ^2−^}~2~] at 0.81, 0.55, −0.33, −0.50, −0.75 and −1.33 V. The UV/vis NIR spectrum of [{ Rh ( py ) pc ^2−^}~2~] shows the typical π-π* transitions of the pc ^2−^ ligand. The B region is split into two bands at 15 440 ( B ^−^) and 16 890 cm^−1^( B ^+^) of equal intensity due to strong excitonic coupling. The totally symmetric Rh - Rh stretching vibration is selectively enhanced in the Fourier Transform–Raman spectrum at 176 cm^−1^.