Preparation, properties and reactions of metal-containing heterocycles: Part C: tetraazatetraphosphadimolybdacyclophanes: synthesis, isolation, characterization, and X-ray crystal structures

The ditopic aminodiphosphines CH2(4,4′-Ph2PNHC6H4)2 (2) and CH2(4,4′-Ph2PCH2NHC6H4)2 (5) are obtained by reaction of 4,4′-diaminodiphenylmethane with ClPPh2 and (i) (CH2O)n/NaOMe/(ii) HPPh2, respectively. Treatment of (η4-nbd)Mo(CO)4 with 2 and 5 under high-dilution conditions in CH2Cl2 affords the tetraazatetraphosphadimolybdaclophanes [CH2(4,4′-(OC)4Mo(Ph2PNHC6H4)2)]2 (3) and [CH2(4,4′-(OC)4Mo(Ph2PCH2NHC6H4)2)]2 (6) in relatively high yields. The structures of 3 and 6 were investigated by X-ray crystal-structure analyses. Whereas the cavity of the molecular structure of 3 can be described by a parallelogram, that of 6 has the shape of a boat in which the diphenylmethane building blocks form the hull and the cis-(Ph2P)2Mo(CO)4 fragments represent the bow and stem, respectively. Because of the formation of only very weak hydrogen bonds in 3 and 6, no binding to molecules like p-benzoquinone, 1,4-cyclohexanedione, 2,5-piperazinedione and trans-1,4-diaminocyclohexane could be detected.