Reactions of tetraphosphine complex [Mo{meso-o-C6H4(PPhCH2CH2PPh2)2}(Ph2PCH2CH2PPh2)] with nitrile, CO, and isocyanide

When treated with three equivalents of PhCN in benzene at room temperature, [Mo(eta(4)-P-4)(dppe)] (1) containing a linear tetraphosphine meso-o-C6H4(PPhCH2CH2PPh2)(2) (P-4) as well as a diphosphine Ph2PCH2CH2PPh2 (dppe) afforded a nitrile complex [Mo(PhCN)(fac-eta(3)-P-4)(dppe)] (2), whereas treatment of 1 with CO (1 atm) in benzene at room temperature resulted in the formation of a 1:1 mixture of the CO analogue of 2 [MO(CO)(fac-eta(3)-P-4)(dppe)] and a bis(carbonyl) complex cis-[Mo(CO)(2)(eta(4)-P-4)] In contrast, reactions of 1 with XyNC (Xy = 2,6-Me2C6H3) gave more diversified products varying from mono(isocyanide) to tris(isocyanide) complexes. Thus, reaction of 1 with an equimolar amount of XyNC gave a mixture of two isomers of mono(isocyanide) complex [Mo(XyNC)(fac-eta(3)-P-4)(dppe)] (5 and 6) along with a bis(isocyanide) complex cis-[Mo(XyNC)(2) (eta(4)-P-4)] (7). It has also been found that mono (isocyanide) complexes 5 and 6 are treated further with one equivalent of XyNC at elevated temperatures to form the expected bis(isocyanide) complex 7 as well as the other bis(isocyanide) complex trans-[Mo(XyNC)(2)(eta(2)-P-4)(dppe)] (8). By heating in solution, the latter was converted into the former. From the reaction of 7 with excess XyNC, a tris(isocyanide) complex [Mo(XyNC)(3)(fac-eta(3)-P-4)] was obtained The X-ray analyses have disclosed the detailed structures for 2, 5, 7, and 8. (C) 2002 Elsevier Science B.V. All rights reserved.