Synthesis and X-ray structure of (η 5-C 5H 5) 2W 2Ir 2(CO) 7(CHCO 2Et) 2, a tetrahedral heterometal cluster with two different environments for ethylcarboxylatocarbene ligands

Abstract

The tetrahedral heteronuclear cluster complex (η 5-C 5H 5) 2W 2Ir 2(CO) 10 reacts with N 2CHCO 2R (R = Et, Me) at room temperature to form the dicarbene species (η 5-C 5H 5) 2W 2Ir 2(CO) 7(CHCO 2R) 2. An X-ray diffraction study (R = Et) shows an intact tetrahedral metal framework with two distinct sites for the CHCO 2Et ligands. The first uses its carbon atom to bridge the IrIr bond; the second uses its carbon atom to bridge an IrW bond and, additionally, forms a donor bond from a carbonyl oxygen atom to the second tungsten atom.