Linear Pentanuclear Complexes Containing a Chain of Metal Atoms: [Co II5(μ5‐tpda)4(NCS)2] und [Ni II5(μ5‐tpda)4Cl2]

Depending on the donor ligand the average Fe-0 distances in the double octahedron are about 1.93 A (FpP(Mes)O,), 2.011(7) A (MesPO,), and 2.123(7) 8, (p3-OH). The equatorial angles 02-Fe2-010 and 08-Fe2-08a were determined to be 98.9(3) and 81.7(2)", respectively. The atoms Fe2,08, Fe2a and 08a lie in one plane and form a rhombus with the acute angle at the iron atoms; thus, a bonding interaction between Fe2 and Fe2a i s not possible (distance Fe2-Fe2a = 3.212 Aj. The trigonal-bipyramidal coordination of Fe4 is slightly distorted. The longest Fe-0 distance in 2 was determined for Fe4-08(apical) to be 2.168(7)A, the shortest for Fe4-0, (equatorial) to be about 1.895 A. The equatorial bridges 04,05, and Ola are bent slightly out of the ideal plane. The Fe4-Cl1 distance is 2.346(3) A. The bond angles at the 0 bridges lie between 124.5(4) and 146.7(4)", those at the P atoms (103.8(4)113.1(3)") have values close to the tetrahedron angle. The sum of angles Fe-0-Fe at the trigonal-pyramidal pu,-OH bridges is 345.3'; the p,-OH hyrogen atom does not participate in any hydrogen bonding. Temperature-dependent magnetic measurements for 2 revealed antiferromagnetic behavior with a Nee1 temperature of 40 K ; the bond lengths (Fe-0) and angles (Fe-0-Fe) of the four central Fe"' ions (Fe2, Fe2a, Fe4, Fe4a) allow superexchange and spin orientation. At 300K the peff value was 5.48 BM.[61 The mild aerial oxidation of the diferriophosphonium salt l a leads to many (sometimes drastic) changes in the functionality at both the iron and phosphorus atoms: We find both retention and elimination of the CpFe(CO), groups as well as complete oxidation to give iron(in) centers, and oxidation of the phosphonium building blocks to give p,-phosphinato and p3-phosphonato ligands. This wide palette of new building blocks finally readily combines to form 2. The new molecular framework of 2 is illustrated by the polyhedral representation in Figure 2. The structure contains a central double octahedron (FeO,(OH)), , two trigonal bipyramids (Fe03(0 H)Cl), and six tetrahedrons (four Fp(Mes)PO, and two MesPO,). Compound 2 is an example for the unusual combination of classic (in the corej and organometallic complex chemistry (at the periphery). We are currently investigating similar organometalated sulfonium salts,['' which also may be converted to similar coordination polyhedrons with sulfenato, sulfinato, and sulfonato ligands by aerial oxidation. Experimental Section