CHLOROMETHYLCHLOROPHOSPHANES R(CL)P-CH2-C L SYNTHONES FOR THE STRUCTURE OF PHOSPHAALKENES IN THE METAL TEMPLATE

On reaction of the chloromethylchlorophosphines R(Cl)P-CH2-Cl (R = Cl, Pr-i, (t)Bu, NEt(2), N(Pr-i)(2), NPh(2), O-2,6-(Pr2C6H3)-Pr-i; 1-7) wi th diiron enneacarbonyl the iron carbonyl complexes 8-14 are formed in good yields. Dehalogenation of the phosphine complexes 9-14 with Fe-2 (CO)(9) affords the phosphaalkene clusters [mu(3),eta(2)-RP=CH2]Fe-3(C O)(10) (15-19). If Fe-3(CO)(12) is used instead of Fe-2(CO)(9), for th e dehalogenation of 10-13 phosphinidene phosphaalkene clusters [mu(3) eta(2)-RP=CH2][mu(3)-PR]Fe-3(CO)(9) (25-28) and binuclear complexes wi th bridging RP=CH2 ligands (21-24) or a-metallated phosphido-phosphine bridges (20) (mu(2)-P(R)-CH2-P(R)-CH2 (R =(t)Bu)) are obtained. The c rystal structure of 18 (R = Ph(2)N; space group P2(1)/n) shows the pho sphaalkene ligand to be twisted about the P=C bond (dihedral angle N(1 )-P(1)-C(31)-Fe(3) 177.5(1)degrees) the CH2 group being pyramidalized (H(31)-C(31)-H(32) 104.0 degrees). In the binuclear complex 20 (space group P2(1)/c) the phosphinoalkyl unit of the mu(2),eta(3)-P(R)-CH2-P( R)-CH2 ligand spans the Fe-Fe bond forming a distorted four-membered F e-P-C-Fe ring with a short P-C bond (P(2)-C(12) 176.5(4) pm). The P-C- P donor set is coordinated to Fe(1) within a strained four-membered P2 CFe chelate ring. The eta(1),eta(2)-RP=CH2 ligand (R = N(Pr-i)(2)) in 23 with a short P-C bond (P(1)-C(1) 173.4(4) pm) bridges two iron atom s, a distorted, almost planar Fe2P2 ring being formed.