Abstract
YbI2(thf)2 reacts with two equiv of KPPh2 in tetrahydrofuran to give Yb[PPh2]2 (thf)4, 1.1 can also be obtained from the reaction of YbI3(thf)3 with KPPh2 in tetrahydrofuran in a 1:3 ratio with half an equiv of Ph2P-PPh2 as a byproduct as well as from Yb[N(SiMe3)2]2 (thf)2 and two equiv of Ph2PH in tetrahydrofuran. 1 can be converted to Yb [PPh2]2(N-MeIm)4, 2, in tetrahydrofuran using four equiv of the strong donor ligand N-methylimidazole (N-MeIm). 2 crystallizes in space group P21/n. Crystal data for 2 at 217 K: a = 9.881 (l) Å, b = 17.717 (2) Å, c = 11.153 (2) Å, β = 95.61 (1)°; V = 1943.1 (5) Å3; Z = 2; Dcalcd = 1.490 g cm−3; RF = 2.01%. The structure of 2 shows the hexacoordinate ytterbium atom, which lies on an inversion center, in a slightly distorted octahedral environment with two phosphido ligands in trans positions. A significant feature of the molecular structure of 2 is the only slightly pyramidal configuration of the metal-coordinated phosphorus atoms (sum of angles: 343.9°).
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