(Benzene‐1,3,5‐triyl)tris[phosphine] (C6H3(PH2)3) and (Benzene‐1,3,5‐triyl)tris[phosphonic Acid] (C6H3[P(O)(OH)2]3). Absence of Hydrogen Bonding in Solid Primary Phosphines

The prolonged photo‐Arbuzov reaction (3 weeks, Hg lamp) of 1,3,5‐trichloro‐benzene with a large excess of trimethyl phosphite (as a solvent) at 50° gives moderate yields of dimethyl (3,5‐dichlorophenyl)phosphonate ( 1 ; 14.5%), tetramethyl (5‐chloro‐1,3‐phenylene)bisphosphonate] ( 2 ; 35.4%), and hexamethyl (benzene‐1,3,5‐triyl)trisphosphonate] ( 3 ; 30.1%). The products can be separated by fractional distillation. Acid hydrolysis of the esters gives almost quantitative yields of the corresponding phosphonic acids 4 – 6 . Reduction of the esters 1 – 3 by LiAlH₄ in tetrahydrofuran affords the primary phosphines (3,5‐dichlorophenyl)phosphine ( 7 ; 46.5%), (5‐chloro‐1,3‐phenylene)bisphosphine] ( 8 ; 34.5%) and (benzene‐1,3,5‐triyl)trisphosphine] ( 9 ; 25.2% yield). In the crude reduction products from 2 (preparation of 8 ) and from 3 (preparation of 9 ), (3‐chlorophenyl)phosphine and (1,3‐phenylene)bisphosphine], respectively, are observed as by‐products. All compounds are characterized by standard analytical, spectroscopic, and (for 1, 7 , and 8 ) structural techniques. The arrangement of the molecules in the crystal structures of 7 and 8 suggest that H‐bonding between the primary arylphosphines is virtually insignificant for the packing of the components. This is in marked contrast to the importance of H‐bonding for the supramolecular chemistry of arylamines. The new primary polyphosphines and polyphosphonic acids are to be employed in the construction of extended arrays.