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Wong CY, McDonald R, Cavell RG: Hexacoordinate Phosphorus. 7. Inorg Chem. 1996 Jan 17;35(2):325-334.
Synthesis and Characterization of Neutral Phosphorus (V) Compounds Containing Divalent Tridentate Diphenol Imine, Azo, and Thio Ligands.. The reactions of bis (trimethylsilyl) ated forms of the Schiff base ligands N-(2-hydroxyphenyl) salicylideneamine {(HO) C (6) H (4) N (CH) C (6) H (4)(OH)}, N-(4-tert-butyl-2-hydroxyphenyl) salicylideneamine {(HO)((t) Bu) C (6) H (3) N (CH) C (6) H (4)(OH)}, N-(2-hydroxy-4-nitrophenyl) salicylideneamine {(HO)(O (2) N) C (6) H (3) N (CH) C (6) H (4)(OH)}, and the structurally related ligand 2,2'-azophenol with halogeno- and (trifluoromethyl) halogenophosphoranes yield a series of neutral hexacoordinate phosphorus (V) compounds by means of trimethylsilyl halide elimination. In all of these cases the ligands chelate in a meridional conformation in which bicyclic five- and six-membered chelate rings are formed through structures containing two phenolic P-O bonds and one N-P bond. The hexacoordinate nature of these compounds is evidenced by their high-field (31) P NMR chemical shifts and their characteristic J (PF) coupling patterns and is further substantiated by the crystal structures of {O ((t) Bu) C (6) H (3) N (CH) C (6) H (4) O}PCl (3) and {OC (6) H (4) N=NC (6) H (4) O}PF (3). Crystal data for {O ((t) Bu) C (6) H (3) N (CH) C (6) H (4) O}PCl (3): triclinic, space group P&onemacr; (No. 2), a = 11.167 (1) A, b = 15.684 (1) A, c = 17.047 (2) A, V = 2840 (1) A (3), Z = 2. Final R and R (w) values were 0.051 and 0.079, respectively. Crystal data for {OC (6) H (4) N=NC (6) H (4) O}PF (3): monoclinic, space group P2 (1)/c (No. 14), a = 6.9393 (8) A, b = 12.450 (2) A, c = 13.907 (2) A, V = 1190.7 (6) A (3), Z = 4. Final R and R (w) values were 0.045 and 0.056, respectively. The molecular structures of {O ((t) Bu) C (6) H (3) N (CH) C (6) H (4) O}PCl (3) and {OC (6) H (4) N=NC (6) H (4) O}PF (3) show that in both cases the Schiff base ligand chelates occupy the meridional plane about the six-coordinate phosphorus atom. In the case of {OC (6) H (4) N=NC (6) H (4) O}PF (3) the equivalent nitrogen atoms in the chelate rings are disordered to form half-occupancy pairs. The silylated form of the related thiobis (phenol), 2,2'-thiobis (4,6-tert-butylphenol), reacted similarly with pentavalent halides to form the six-coordinate complex [{2-O-3,5-((t) Bu)(2) C (6) H (2)}(2) S] PCl (3) which was also verified by a crystal structure. Crystal data for [{2-O-3,5-((t) Bu)(2) C (6) H (2)}(2) S] PCl (3): monoclinic P2 (1)/n, a = 13.989 (2), b = 13.594 (2), c = 16.483 (2) A, beta = 97.98 (2) degrees, V = 3104 (2) A (3), Z = 4; final R and R (w)() values were 0.039 and 0.052, respectively. In contrast to the above six coordinate complexes, this compound possesses a facial structure in which two phenoxy substituents form planar chelates centered on the bridging sulfur and intersecting at the P-S axis. The P-S bond length, 2.331 (1) A, is slightly shorter than has been previously observed in the example wherein the ligand possesses two tert-butyl groups and the phosphorus carries three OCH (2) CF (3 ) substituents indicating stronger interaction between P and S in the present case. |
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