Studies of tetrakis(trifluoroacetate) dirhodium: Part 4. Solventless synthesis of Rh2(O2CCF3)2(CO)4 combined with Rh2(O2CCF3)4, a compound with infinite chains of rhodium atoms

By reaction of Rh2(O2CCF3)4 and Mo(CO)6 in an evacuated sealed tube placed in a thermal environment where there is a thermal gradient (125–120°C), we have obtained a compound in which one Rh2(O2CCF3)4 unit is sandwiched between two Rh2(O2CCF3)2(CO)4 units, to give an essentially linear array of six rhodium atoms, with Rh–Rh distances of 2.960(1), 2.790(1) and 2.412(1) Å. These arrays of six rhodium atoms are then linked into infinite chains which lie parallel in the crystal, with Rh to Rh contacts of 3.062(1) Å. The crystals are markedly dichroic and relatively air stable.