Chelating Phosphorus–An O, C, O‐Coordinating Pincer‐Type Ligand Coordinating P(III) and P(V) Centres

The sequence of reactions of the phosphorus‐containing aryllithium compound 5‐t‐Bu‐1,3‐[(P(O)(O‐i‐Pr)(2)](2)C(6)H(2)Li (ArLi) with Ph(2)PCl, KMnO(4), elemental sulfur and elemental selenium, respectively, gave the aryldiphenylphosphane chalcogenides 5‐t‐Bu‐1,3‐[(P(O)(O‐i‐Pr)(2)](2)C(6)H(2)P(E)Ph(2) (1, E=O; 2, E=S; 3, E=Se). Compound 1 partially hydrolysed giving [5‐t‐Bu‐1‐{(P(O)(O‐i‐Pr)(2)}‐3‐{(P(O)(OH)(2)}C(6)H(2)]P(O)Ph(2) (4). The reaction of ArLi with PhPCl(2) provided the benzoxaphosphaphosphole [1(P), 3(P)‐P(O)(O‐i‐Pr)OPPh‐6‐t‐Bu‐4‐P(O)(O‐i‐Pr)(2)]C(6)H(2)P (5i) as a mixture of the two diastereomers. The oxidation of 5i with elemental sulfur gave the benzoxaphosphaphosphole sulfide [1(P), 3(P)‐P(O)(O‐i‐Pr)OP(S)Ph‐6‐t‐Bu‐4‐P(O)(O‐i‐Pr)(2)]C(6)H(2) (5) as pair of enantiomers P1(R), P3(S)/P1(S), P3(R) of the diastereomer (RS/SR)‐5 (5b). The aryldiphenylphosphane 5‐t‐Bu‐1,3‐[(P(O)(O‐i‐Pr)(2)](2)C(6)H(2)PPh(2) (6) was obtained from the reaction of the corresponding aryldiphenylphosphane sulfide 2 with either sodium hydride, NaH, or disodium iron tetracarbonyl, Na(2)Fe(CO)(4). The oxidation of the aryldiphenylphosphane 6 with elemental iodine and subsequent hydrolysis yielded the aryldiphenyldioxaphosphorane 9‐t‐Bu‐2,6‐(OH)‐4,4‐Ph(2)‐3,5‐O(2)‐2,6‐P(2)‐4λ(5)‐P‐[5.3.1.0]‐undeca‐1(10),7(11),8‐triene (7). Both of its diastereomers, (RR/SS)‐7 (7a) and (RS/SR)‐7 (7b), were separated as their chloroform and i‐propanol solvates, 7a⋅2CHCl(3) and 7b⋅i‐PrOH, respectively. DFT calculations accompanied the experimental work.