Srereochemical and Electronic Control of M-SO2 Bonding Geometry in d6 Molybdenum and Tungsten SO2 Complexes: Novel η1 η2 SO2 Linkage Isomerization in Mo(CO)2(PPh3)2(CNR)(SO2) and Structures of Mo(CO)3(P-i-Pr3)2(SO2) and 2

Article abstract of DOI:10.1021/ja00345a035

New complexes, mer,trans-M(CO)3(PR3)2(SO2) (M = Mo, W; R = Ph, Cy, i-Pr) (I), cis,trans-Mo(CO)2(PPh3)2(SO2)(L) (L = NCMe, py, CNCy, CN-t-Bu and CN(p-tolyl)) (II), and 2, have been prepared and characterized by infrared spectroscopy, 17O and 31P NMR spectroscopy, and X-ray crystallography.Syntheses for fac-Mo(CO)3(η²-SO2)(LL) (LL = dppe, bpy, phen, 2 py) have also been developed.Depending upon L, II has been found to coordinate SO2 either in the S-bonded (η¹ planar) or O,S-bonded (η²) geometries.Remarkably, for L = CNCy or CN-t-Bu, II has been found to contain, in the solid state, an apparent equimixture of both coordination types.Isomerization of fac-M(CO)3(dppe)(η²-SO2) (M = Mo, W; dppe = 1,2-bis(diphenylphosphino)ethane) to an η¹-planar SO2 form, mer-M(CO)3(dppe)(SO2), has also been found to occur.Thus, control of the SO2 coordination geometry has been achieved by varying either the electronic properties of the ancillary ligands or their disposition with respect to the SO2.The X-ray crystal structure of mer, trans-Mo(CO)3(P-i-Pr3)3(SO2) revealed η¹-planar SO2 binding, the first example of this geometry for group 6 metals.The M-S distance, 2.239 (3) Angstroem, is the longest such distance for this geometry recorded to date.Crystal data: Pbca, Z = 8, a = 24.712 (8) Angstroem, b = 16.033 (6) Angstroem, c = 14.058 (5) Angstroem, R = 0.079 for 2934 reflections with I <*> 2?(I).The structure of 2 showed a novel SO2 bridging geometry in which all three atoms of SO2 are metal coordinated.Crystal data: P<*>, Z = 1, a = 14.833 (4) Angstroem, b = 9,264 (2) Angstroem, c = 10.808 (2) Angstroem, R = 0.039 for 3282 reflections with I<*> 2?(I).