Monosubstituted Trinuclear and Tetranuclear VIB Metal Carbonyl Complexes: Syntheses of [{M(CO) 5 } 3 (Pf‐Pf‐Pf)] [Pf‐Pf‐Pf = PhP(CH 2 CH 2 PPh 2 ) 2 ] and [{M(CO) 5 }4(P‐Pf 3 )] [P‐Pf 3 = P(CH 2 CH 2 PPh 2 ) 3 ] (M = Cr, Mo) and Crystal Structures of the Latter Three

The triligate trimetallic complexes, [{M(CO) 5 } 3 (Pf‐Pf‐Pf)] and tetraligate tetrametallic complexes, [{M(CO) 5 } 4 (P‐Pf 3 )] (M = Cr and Mo), were prepared from [M(CO) 6 ] and the corresponding ligands in MeCN/CH 2 Cl 2 promoted by Me 3 NO at 0 °C. Crystals of trimer lb are monoclinic, space group P 2 1 /n, with a = 13.407(3), b = 15.002(5), c = 26.52(1) Å, β = 90.65(2)°, Z = 4, and R = 0.060 for 2760 observed reflections. Crystals of tetramer 2a are monoclinic, space group P 2 1 /c, with a – 14.183(8), b = 29.880(4), c = 16.103(2) Å, β = 94.98(3)°, Z = 4, and R = 0.039 for 5014 observed reflections. Crystals of 2b are monoclinic, space group C 2/c, with a = 42.120(8), b = 13.679(1), c = 23.486(2) Å, β = 92.14(1)°, Z = 8, and R = 0.032 for 6897 observed reflections. Each phosphorus atom of the ligands is coordinated to the M(CO) 5 moiety in each title compounds. The geometry of the four metals is a distorted tetrahedron for the tetramers.