Coordination of a Di-tert-butylphosphidoboratabenzene Ligand to Electronically Unsaturated Group 10 Transition Metals

A new boratabenzene-phosphine ligand, di-tert-butylphosphidoboratabenzene, [DTBB]−, has successfully been synthesized by reduction of the corresponding di-tert-butylchlorophosphidoborabenzene compound (2). The species was structurally characterized with both K+ (3) and 18-crown-6·K+ (4) as counterions. Reactions of two equivalents of di-tert-butylphosphidoboratabenzene with NiBr2(PPh3)2, PtCl2, and PtCl2(COD) were undertaken and were successful in yielding three new organometallic boratabenzene species, (μ-κ-η6-C5H5BP(tBu)2)2Ni2 (5), (η3-(C,B,P)-C5H5BP(tBu)2)2Pt (6), and (η3-(C,B,P)-C5H5BP(tBu)2)(κ-C8H12(P(tBu)2BC5H5)Pt (7), respectively. The di-tert-butylphosphidoboratabenzene species displays a remarkable tendency to coordinate to transition metal species in two distinct modes closely associated with other reported boratabenzene and allyl-like interactions. Also of interest is the ability for di-tert-butylphosphidoboratabenzene to be able to coordinate within monomeric as well as dimeric transition metal compounds. The synthesis and characterization will be discussed in detail along with DFT calculations in order to validate these research findings.