9,9-Dimethyl-4,5-bis(diisopropylphosphino)-xanthene (xant((PPr2)-Pr-i)(2)) derivatives RhCl{xant((PPr2)-Pr-i)(2)} (1) and IrHCl{xant((PPr2)-Pr-i)[(PrPCH)-Pr-i(Me)CH2]} (2) react with diphenylsilane and triethylsilane to give the saturated d(6)-compounds RhHCl(SiR3){xant((PPr2)-Pr-i)(2)} (SiR3 = SiHPh2 (3), SiEt3 (4)) and IrHCl(SiR3){xant((PPr2)-Pr-i)(2)} (SiR3 = SiHPh2 (5), SiEt3 (6)). Complexes 3 and 5 undergo a Cl/H position exchange process via the MH{xant((PPr2)-Pr-i)(2)} (M = Rh (8), Ir (E)) intermediates. The rhodium complex 3 affords the square planar d(8)-silyl derivative Rh(SiClPh2){xant((PPr2)-Pr-i)(2)} (7), whereas the iridium derivative 5 gives IrH2(SiClPh2){xant((PPr2)-Pr-i)(2)} (9), which is stable. In agreement with the formation of 7, the reactions of 8 with silanes are a general method to prepare square planar d(8)-rhodium-silyl derivatives. Thus, the addition of triethylsilane and triphenylsilane to 8 initially leads to the dihydrides RhH2(SiR3){xant((PPr2)-Pr-i)(2)} (SiR3 = SiEt3 (10), siPh(3) (11)), which lose molecular hydrogen to afford Rh(SiR3){xant((PPr2)-Pr-i)(2)} (SiR3 = SiEt3 (12), SiPh3 (13)). Treatment of 7 with NaBA(4)(F)center dot 2H(2)O leads to the cationic five-coordinate d(6)-species [RhH{Si(OH)Ph-2}{xant((PPr2)-Pr-i)(2)}]BAr4F (14) through a silylene intermediate. According to the participation of the latter in the formation of 14, this cation is an efficient catalyst precursor for the monoalcoholysis of diphenylsilane with a wide range of alcohols, reaching turnover frequencies at 50% of conversion between 4000 and 76 500 h(-1). The X-ray structures of 3, 6, 7, 9, 12, and 14 are also reported.