Angen Chem. Inr Ed. Engl. 25 (1986) No. 3 0 VCH Verlagsgesellschafi mbH. 0-6940 Wernheim, I986 0570-0833/86/0303-0259 $ 02 50/0

Until very recently the Ni and Cu corroles, already described in the sixties, were regarded as the MII complexes 1 (M = Ni, Cu). Some doubt arose about this interpretation after the existence of FeIV corroles demonstrated that corroles can stabilize metals in unusual oxidation states. Thorough physical studies have now shown that the metal atoms in the Ni and Cu corroles do in fact have the formal oxidation state +III (2).

Cyclooctapyrroles such as 1–3 tend to form during the condensation of dipyrrolic units if cyclization to cyclotetrapyrroles is hindered for conformational reasons. These macrocycles are chiral and might afford interesting complexes with metal ions. Their most intriguing feature is their unusual figure‐eight conformation.

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should be regarded as a binuclear sandwich complex having two four-electron donor p,q2-P2 ligands (i.e., 18 valence electrons (VE) per Rh atom), the bonding in the Co analogue 6 is more complicated. The X-ray structure analysis reveals two independent molecules per unit cell,1'21 each of whose Co-Co distances is ca. 3.1 A. In this case, the P,bridging ligand forms a "long" (similar to that of 2b) and a "short" (32-VE triple-decker with cyclo-P,?) rectangle, whose average P_P values correspond almost exactly to the distance of 2.38 A in the cubic (metallic) m~d i f i c a t i o n l '~~ of black phosphorus (z(P-P) = 2.45 A for 2b). The Rh-Rh' distance of 2b (3.324(1) A) is significantly longer than d ( M-M) for triple-decker complexes (2.63-2.73 A) containing a C~C I O -P~~~, middle deck and exhibiting metal-metal i n t e r a~t i o n ; [~.~] the average Rh-P value for 2b (2.416 A) is larger than that observed for 7 (2.335 A).[141 Experimental Procedure 2a.b: la (650mg, 2.2 mmol) [Isa] [lb (600 mg, 1.95 mmol) [I5b]] and P, (547 mg, 4.4 mmol) [483 mg, 3.9 mmol) were stirred in refluxing xylene (ca. 30 mL) for 8 h. The reaction solution (containing small amounts of insoluble components) was concentrated to 10 mL under oil-pump vacuum, treatedwith 3 g of AIZO3 (basic, activity II), and then dried under oil-pump vacuum to afford a freely flowing solid. Upon chromatography (column: 25 x 2.5 cm), excess P4 was eluted as a yellow forerun with pentane. Elution with pentane/toluene ( I : I ) then afforded Za,b as a yellow-orange fraction.After removal of the solvent under oil-pump vacuum, Za,b were obtained as spectroscopically pure, orange powders. Recrystallization from pentane (ca.-18°C) afforded Z a as needle-shaped and 2 b as cube-shaped, orange crystals. Yield Za: 207 mg (31Yo) [Zb: 190mg (3IYo)l.