Electrophilic Functionalization of Donor‐Stabilized Phosphanylboranes: A New Pathway toward Heavy 13/14/15 Parent Hydride‐Containing Compounds

A novel method for the functionalization of donor‐stabilized 13/15 compounds is presented. Reacting the IDipp (1,3‐bis(2,6‐diisopropylphenyl)‐imidazolin‐2‐ylidene) stabilized parent phosphanylborane IDipp·BH 2 PH 2 with (in situ generated) main group electrophiles results in mixed 13/14/15 compounds [IDipp·BH 2 PH 2 ER 3 ][WCA] (WCA = weakly coordinating anion, ER 3 = CH 3 ( 2 ), SiEt 3 ( 3 ), Ge(SiMe 3 ) 3 ( 4 ), SnMe 3 ( 5 )) containing the complete series from carbon to tin. In contrast, reactions with the group 15 electrophiles [Cy 2 Pn ][PF 6 ] ( Pn = P, As) yielded an intriguing P–P coupling reaction, affording [IDipp·BH 2 PH 2 PHBH 2 ·IDipp][PF 6 ] ( 6 ). The protonated phosphanylboranes reveal acidic protons at the phosphorus atom, and this can be exploited by reactions with LiGaH 4 and LiAlH 4 , resulting in either deprotonation to the parent phosphanylborane or chain extension to yield LB ·BH 2 PH 2 GaH 3 ( LB = IDipp ( 7a ), Me 3 N ( 7b )), the first examples of a {GaH 3 } unit bound to a primary phosphine. The products can be characterized by multinuclear NMR spectroscopy and single‐crystal X‐ray structure determination.