Former mayoral aide Robert B. Robinson said yesterday he "pleaded and begged" with D.C. Mayor Marion Barry for more than nine months to settle the bill for Effi Barry's $4,500 fox coat, and that finally, in "desperation," he paid it with city funds to keep the furrier from complaining publicly about the delinquency.

Robinson said he had hoped to spare Barry "severe ridicule and embarrassment" over the past-due bill and that he used money from the city's ceremonial fund because it was an "off the books account" and he intended to repay the money.

It was the first time that Robinson, whom Barry blamed last year for lax accounting of official expenses, has given his version of the fur coat episode, and he provided new details of how he became enmeshed in Barry's personal affairs.

But Robinson, who made the comments during and after his sentencing for two misdemeanor theft charges in connection with two separate payments for the coat, refused to criticize Barry directly and said he accepted "sole responsibility for those acts."

He said only that he was placed in an untenable position, which made him uncomfortable, and that he had "confused" loyalty to the public he served with "loyalty to officeholders."

"I thought I could protect people from their own actions," Robinson said. " . . . I have learned a costly and a bitter lesson."

U.S. Magistrate Jean F. Dwyer placed Robinson on a year's probation and ordered him to perform 100 hours of community service. Dwyer, who received more than 30 letters in support of Robinson, said it was an "outpouring" unlike anything she ever seen before.

Assistant U.S. Attorney Daniel J. Bernstein, who had headed the federal investigation into allegedly improper uses of the mayor's office accounts, said in court that Robinson has been debriefed by FBI agents several times since he pleaded guilty last month.

He said Robinson's actions were "repugnant to social mores" and added, "Once again the people have been betrayed by one of their public servants." He said the fact that Robinson had not personally benefited from the use of the money had been "taken into account in the disposition of this case."

As the top administrative aide to Barry, Robinson said he took over the accounts in October 1984 and imposed the first fiscal controls after former deputy mayor Ivanhoe Donaldson and current mayoral aide Dwight S. Cropp had left Barry's immediate office. Robinson said their absence created a "vacuum" in leadership and that there was a "distinct mood of paranoia" among the office staff, which was also wracked by "internecine" squabbles.

He became involved in Barry's dispute with Chris Fotos of Le Parisien Furriers after a bill for the coat, purchased in November 1982, simply appeared on his desk, Robinson said. He took the bill to Barry's executive assistant, who told him that he had received it by mistake and to disregard it, Robinson said.

But several days later, Robinson said, he received a telephone call from Fotos, who had been referred to Robinson by Barry's executive assistant.

Robinson said he talked to Barry about the bill, and that at first the mayor thought he was intruding into his personal affairs. After repeated phone calls from Fotos, Robinson said he and the mayor met and it was decided that Robinson should go to Fotos' store and examine the coat, which by then had been returned by Effi Barry as defective.

The coat was repaired and, Robinson said, returned to Effi Barry. Fotos' calls then became more insistent, Robinson said, and contained "veiled threats" that Fotos would tell the news media about the delinquent account.

Robinson said he repeatedly talked to and wrote notes to Barry about the problems and on several occasions Barry said he had talked to Fotos. But, Robinson said, Barry hadn't.

Fearful that the "ideals and principles so important to me were being deteriorated and eroded" by Barry's inaction, Robinson said he paid Fotos $1,500 from the office accounts.

Robinson then reimbursed the accounts with his own money and Barry later repaid Robinson. Prosecutors have said they have no evidence the mayor knew of the illegal transactions.