Coordination chemistry of P-rich phosphanes and silylphosphanes.: XVII -: [Co(η5-Me5C5)(η3-tBu2PPCH-CH3)] from [Co(η5-Me5C5)(η2-C2H4)2] and tBu2P-P=P(Me)tBu2

[Co(eta(5)-Me5C5)(eta(3)-(Bu2PPCH)-Bu-t-CH3)] 1 is formed in the reaction of [Co(eta(5)-Me5C5)(eta(2)-C2H4)(2)] 2 With (Bu2P)-Bu-t-P 4 (generated from (Bu2P)-Bu-t-P=P(Me)Bu-t(2) 3) by elimination of one C2H4 ligand and coupling of the phosphinophosphinidene with the second one. The structure of 1 is proven by P-31, C-13, H-1 NMR spectra and the X-ray structure analysis. Within the ligand (Bu2PPCH)-Bu-t-P-1-C-2-H-1-CH3 in 1, the angle P1-P2-C1 amounts to 90 degrees. The Co, P1, P2, CI atoms in 1 look like a "butterfly". The reaction of 2 with a mixture of (Bu2P)-Bu-t-P=P(Me)Bu-t(2) 3 and Bu-t-C=P 5 yields [Co(eta(5)-Me5C5){eta(4)-((BuCP)-Bu-t)(2)}] 6 and 1. While 6 is spontaneously formed, 1 appears only after complete consumption of 5.