Journal of the Chemical Society, Dalton Transactions p. 3805 - 3812 (1996)
Update date:2022-08-10
Topics:
Burrows, Andrew D.
Mingos, D. Michael P.
White, Andrew J. P.
Williams, David J.
The complex [Pt(cod)Cl2] (cod = cycloocta-1,5-diene, C8H12) reacted with 2 equivalents of PPh3 and an excess of 5-aminoorotic acid (5-amino-2,6-dioxo-1,2,3,6-tetrahydropyrimidine-4-carboxylic acid, H4L) in the presence of silver(I) oxide to give two isomers of [Pt(PPh3)2(H2L)] 1 and 2. Complexes 1 and 2 can be separated by fractional crystallisation but, in CDCl3 solution, each slowly converts into an equilibrium mixture of the two. Crystal structure determinations have shown that in both 1 and 2 the 5-aminoorotate ligand coordinates to the platinum atom as a dianion. In 1 this is achieved via deprotonation of the carboxylic acid and the loss of an amino NH2 proton, leading to a six-membered chelate ring, whereas in 2 it is by deprotonation of the carboxylic acid and loss of the amido proton, leading to a five-membered chelate ring. This difference in co-ordination mode leads to a difference in the orientation of the hydrogen-bond donors and acceptors remaining on the ligand which, in turn, leads to different supramolecular structures, dimers for 1 and tetramers for 2, with the latter structurally similar to guanine tetrads. These naturally occurring units are stabilised by alkali-metal ions, but reaction of 2 with a compound such as NaBF4 in a two-phase dichloromethane-water system led to [Pt2(PPh3)4(HL)][BF4] as the only platinum-containing product. A crystal structure determination showed that in this complex the ligand is trianionic, deprotonated at the carboxylic acid and both the amido and amino nitrogen atoms, co-ordinating to two platinum atoms via five- and six-membered chelate rings. When dppe [1,2-bis(diphenylphosphino)ethane] was used instead of PPh3 only one isomer of [M(dppe)(H2L)] (M = Pt 3 or Pd 4) was observed for both platinum and palladium, containing the five-membered chelate ring.
View Morewebsite:http://www.oceanchem-group.com
Contact:86-536-8596048
Address:9th floor,Building B future Plaza, No.88.Fenghuang Street,Weifang,Shandong,China
Chiral Quest (Suzhou) Company Ltd
website:http://www.chiralquest.com
Contact:+86-0512-62956066
Address:B1/9, 218 Xinghu Street, Suzhou Industrial Park
Shenzhen Hongyuan Import & Export Co., Ltd.
Contact:0755-26407171
Address:Shenzhen Hongyuan Chemical New Materials Technology Co., Ltd.
Nantong LiKai Chemical Co.,Ltd
Contact:+86-513-89068669
Address:Jincheng Science Park
Weihao Chemtech (ChangZhou) Co., Ltd.(expird)
Contact:051989185693
Address:NO 217 huangshan Rd ,Changzhou
Doi:10.1007/s11738-000-0085-3
(1957)Doi:10.1515/zpch-2014-0538
(2014)Doi:10.1063/1.448915
(1985)Doi:10.1039/c7cp07747e
(2018)Doi:10.1021/jacs.7b10433
(2018)Doi:10.1002/hlca.19840670620
(1984)
