TY - JOUR
T1 - Main Group Element Phosphine Complexes. 5. Tri- and Tetracoordinated, Monomeric Tin(II) Phosphine Complexes and X-ray Structure of Sn[C(PMe2)3]2
AU - Karsch, Hans H.
AU - Appelt, Armin
AU - Müller, Gerhard
PY - 1986
Y1 - 1986
N2 - SnCl2 reacts with Li[C(PMe2)2X] to give yellow, neutral complexes Sn[C(PMe2)2X]2 (X = PMe2, 4; X = SiMe3, 7) under exclusive formation of Sn-P bonds. The X-ray structure determination of 4 (space group P21; a = 6.540 (2) Å, b = 16.338 (6) Å, c = 11.720 (4) Å; β = 98.15 (3)°; V = 1239.64 Å3; dcalcd = 1.363 g/cm3 for Z = 2; Rw= 0.043 for 189 refined parameters and 4165 reflections with Fo ≥ 4.0σ (Fo)) reveals a distorted Ψ-tbp ground-state geometry with two phosphorus donor atoms in axial (d(SnP) = 2.790 (2), 2.839 (2) Å) and two in equatorial positions (d(SnP) = 2.602 (2), 2.598 (2) Å) at the Sn(II) spiro center. Both 4 and 7 are fluxional in solution at -90 °C, due to a pseudorotation process which equilibrates axial and equatorial positions. At elevated temperatures all six phosphorus atoms in 4 are equilibrated. In contrast to 4 and 7, Sn[HC(PPh2)2]2 (9), which is obtained from SnCl2 and Li [HC(PPh2)2], exhibits a threefold Sn coordination at low temperature in solution, arising from one chelating (PP) and one monodentate (C) diphosphinomethanide ligand. The different PPh2 groups of the monodentate ligand are quilibrated at 20 °C, whereas at 70 °C, both diphosphinomethanide ligands equilibrate via a twofold coordinated Sn(II) transition state. From Li[C(PPh2)3] and SnCl2, two thermally unstable complexes are obtained, ClSn-[C(PPh2)3] (13) and Sn[C(PPh2)3]2 (14). In solution, 13 is monomeric with a threefold coordination at Sn and 14 resembles 4 and 7 in exhibiting tetracoordination. The results are explained by an inter-/intraligand repulsion model, with additional electronic effects also operating, and are based on NMR (1H, 13C, 31P, 119Sn) measurements.
AB - SnCl2 reacts with Li[C(PMe2)2X] to give yellow, neutral complexes Sn[C(PMe2)2X]2 (X = PMe2, 4; X = SiMe3, 7) under exclusive formation of Sn-P bonds. The X-ray structure determination of 4 (space group P21; a = 6.540 (2) Å, b = 16.338 (6) Å, c = 11.720 (4) Å; β = 98.15 (3)°; V = 1239.64 Å3; dcalcd = 1.363 g/cm3 for Z = 2; Rw= 0.043 for 189 refined parameters and 4165 reflections with Fo ≥ 4.0σ (Fo)) reveals a distorted Ψ-tbp ground-state geometry with two phosphorus donor atoms in axial (d(SnP) = 2.790 (2), 2.839 (2) Å) and two in equatorial positions (d(SnP) = 2.602 (2), 2.598 (2) Å) at the Sn(II) spiro center. Both 4 and 7 are fluxional in solution at -90 °C, due to a pseudorotation process which equilibrates axial and equatorial positions. At elevated temperatures all six phosphorus atoms in 4 are equilibrated. In contrast to 4 and 7, Sn[HC(PPh2)2]2 (9), which is obtained from SnCl2 and Li [HC(PPh2)2], exhibits a threefold Sn coordination at low temperature in solution, arising from one chelating (PP) and one monodentate (C) diphosphinomethanide ligand. The different PPh2 groups of the monodentate ligand are quilibrated at 20 °C, whereas at 70 °C, both diphosphinomethanide ligands equilibrate via a twofold coordinated Sn(II) transition state. From Li[C(PPh2)3] and SnCl2, two thermally unstable complexes are obtained, ClSn-[C(PPh2)3] (13) and Sn[C(PPh2)3]2 (14). In solution, 13 is monomeric with a threefold coordination at Sn and 14 resembles 4 and 7 in exhibiting tetracoordination. The results are explained by an inter-/intraligand repulsion model, with additional electronic effects also operating, and are based on NMR (1H, 13C, 31P, 119Sn) measurements.
UR - http://www.scopus.com/inward/record.url?scp=19644368968&partnerID=8YFLogxK
U2 - 10.1021/om00139a025
DO - 10.1021/om00139a025
M3 - Article
AN - SCOPUS:19644368968
SN - 0276-7333
VL - 5
SP - 1664
EP - 1670
JO - Organometallics
JF - Organometallics
IS - 8
ER -