Synthesis and spectroscopic studies of silver rhodium mono- and poly- nuclear complexes with multidentate phosphines (Ph 2P) 2CHR (R = H, Me, PPh 2)

Abstract

Trinuclear [{(Ph 2P) 3CH}Ag 3(O 2CR′) 3], dinuclear [{(Ph 2P) 2CHR}Ag 2(O 2CR′) 2], [{(Ph 2P) 2CHR} 2Ag 2](BF 4) 2 and (Rh 2(Cl)(CO) 2{(Ph 2P) 2CHMe} 2][RhCl 2(CO) 2], and mononuclear (Rh{(Ph 2P) 2CHR} 2](BF 4), (Rh{(Ph 2P) 2CHR} 2HCl](BF 4),d [Rh{(Ph 2P) 2CHR} 2Cl(HgCl)](BF 4) and (Rh{(Ph 2P) 2CHR} 2O 2](BF 4) (R = H,Me) were synthesized from the phosphines tris(diphenylphosphino)methane ((Ph 2P) 3CH), bis(diphenylphosphino)methane ((Ph 2P) 2CH 2) and 1,1-bis(diphenylphosphino)ethane ((Ph 2P) 2CHMe). The 1H, 13C and 31P NMR spectra were investigated and for the mononuclear rhodium compounds compared with their 1,2-bis(diphenylphosphino)ethane and 1,3-bis(diphenylphosphino)propane analogues. The 31P NMR spectra of the silver complexes revealed besides normal values for J( 107Ag− 31P) (640 and 500 Hz for the gAgP and AgP 2 systems, respectively) a small 3J( 107Ag− 31P) of about −4 Hz and an exceptionally large 2J( 31P− 31P) of 170 Hz. A large positive charge on the P-atoms in [{(Ph 2P) 2CH 2}Ag 2(O 2CR) 2] and [{(Ph 2P) 2CH 2}Ag 2](BF 4) 2 was calculated from the chemical shifts of the methylene protons. On the basis of 31P NMR data methyl substitution in (Ph 2P) 2CHR resulted in formation of only one of the possible isomers for [{(Ph 2P) 2CHMe} 2Ag 2](BF 4) 2, [Rh 2(CO) 2(Cl){(Ph 2P) 2CHMe} 2][RhCl 2(CO) 2] and [Rh{(Ph 2P) 2CHMe} 2O 2](BF 4), but two isomers for [Rh{(Ph 2P) 2CHMe} 2](BF 4) and [Rh{(Ph 2P) 2CHMe}HCl](BF 4). These results are interpreted in terms of metalchelate ring puckering.